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Final Answers
© 2000-2015   Gérard P. Michon, Ph.D.

Photographic  Films
Capturing Light with Silver

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Silver Chloride Photochemistry  by  Nurdrage.
Photo-chemistry:  Silver Printing on Cotton Paper.
How it's made:  Developing photographs from negatives  (industrially)
Film digitization   |   Cinema camera   |   IMAX projector   |   Celluloid film (1930)
How Kodak Film is Made (1958, Czech)   |   Ilford factory tour (2013-11-18)
Dip & dunk Refrema machine  by Tarik Laaziz (6:12)  showing nitrogen agitation.
10 best film cameras (5:41)   by Matt Granger.  From Brownie to Mamiya-7.
Photographic Processes Series  by George Eastman House (Rochester, NY) :   1. Before photography  |  2. Daguerreotype  |  3. Talbot processes  |  4. Cyanotype  |  5. Wet Collodion  |  6. Albumen print  |  7. Platinum print  |  8. Pigment processes  |  9. Woodburytype  |  10. Gelatin Silver  |  11. Color Photography  |  12. Digital Photography


The Ongoing Legacy of Photographic Film

To my friends:  My work is done.  Why wait?
Suicide note of  George Eastman  (1854-1932)

The diversity of commercially available  photographic films is decreasing,  because of the lesser demand which results from the overwhelming success of digital photography.  Irreplaceable casualties include Kodak's HIE infrared film (2007) and the epoch-making Kodachrome  (2009).  More recently, Kodak stopped producing high-speed black-and-white films and Fuji discontinued all but one of its  B&W  films.  On the bright side, Ilford and Agfa have kept their entire lineup intact  (albeit at a high price point in the case of the later)  and have announced they'll keep doing so.  The chemists at ADOX are coming up with new products and maintaining the diversity of their own lineup, no longer sold under the Efke label.
In the past two centuries, analog photography has brought forth great scientific, cultural and industrial achievements.  A major artform was born which is incompletely embodied by its digital counterpart.  Even putting artistic considerations aside, the resolution obtained from large analog negatives still  surpasses by far  that of our best digital sensors.  Our sharpest images are analog ones.  Long live film!

(2015-08-07)   Why Silver ?
A few properties make silver uniquely suited for photography.

Many photographic processes have been developed which do not use silver at all.  In fact, we argue in the next section that photosensitivity is a very common property of a substance;  almost an unavoidable one.  Yet silver reigns supreme at the heart of film photography.  Photographic images can be made without silver but snapshot cannot.  What makes silver so special?  Well, several properties of silver turned out to be critical:

  • Monovalence.
  • The existence of insoluble halide crystals  (e.g. silver bromide).

Also important is the existence of at least one soluble silver salt  (namely silver nitrate)  from which calibrated insoluble silver crystals can be precipitated.  Silver is not a very special metal in that respect, since all nitrates are soluble.  However,  the fact that nitric acid can oxidize silver makes that soluble salt easy to obtain  (it's not the case for gold, for example).

The ionization energy of silver is  7.5762 eV,  which corresponds to a frequency of 1831.9 IHz or a wavelength of 163.65 nm.  UV light can ionize metallic silver  (photoelectric effect)  but visible light cannot.

 Come back later, we're
 still working on this one...

(2015-08-01)   The Great Mystery of the Latent Image
The continuous road from slow to fast photo-chemistry.

Virtually any chemical compound can react to light.  Light sensitivity is the rule rather than the exception.  As a  photon of sufficient energy impacts an atom, it's able to overcome its binding energy and dislodge it from a molecule or from a crystal.

It's a common observation that most dyes will fade faster in direct sunlight than in the shade.  Almost by definition, fading is slow.  The first challenge of the photography pioneers was to identify substances that would fade fast...

Little did they know that the speed of fading is only a symptom of something entirely different, which we have already mentioned:  The fact that light only exists in discrete bundle of energy call photons  (Einstein discovered them by properly analyzing the  photo-electric effect  in 1905 and was awarded the Nobel prize for that, in 1921).  A red photon has less energy than than a blue photon and a blue photon has less energy than a UV photon.  Some dyes that would last forever when exposed to copious amount of red light would fade fairly quickly when exposed to UV.

The real challenge was thus to find substances that could react at all to low-energy visible photons,  although nobody phrased it in those terms at the time.  What everybody would eventually notice is that it was easier to manufacture  orthochromatic  stuff  (sensitive to any visible light except red)  than  panchromatic  stuff  (sensitive to red also).

The second challenge was to  fix  the image obtained by the direct action of light.  Fixing is the process of making the image permanent and ensuring that no part of it retains any sensitivity to light.

A third challenge was to enhance as much as possible the image formed by light.  That chemical enhancement would allow pictures to be taken with shorter and shorter exposure times until a miracle happened:  The captured image was no longer visible at all  (by that time in history  trying  to view the effect of a previous exposure on panchromatic films was no longer practical anyway, because any additional light would ruin it).

So was born the great mystery of photography, which nobody understood for several decades:  When a picture is taken, a  latent  image is formed which will remain invisible until  revealed  by the chemical action of a  developer  (which the French appropriately call  révélateur ).

Silver was the Magic Bullet :

Science has now explained what the  latent image  is and how it can be developed:  If a small crystal of  silver bromide  contains at least  four  metallic silver atoms  (dislodged by the action of photons)  it has enough chemical potential for the developer to reduce more of its silver ions to their metallic state  (thus releasing neutral bromide into the solution).

This goes on exponentially until the entire crystal has been reduced to a visible dark grain of metallic silver, containing billions of silver atoms.

(2015-07-07)   The Magic of Light-Sensitive Photographic Emulsions
From wet plates to gelatin film.  How silver captures light.

The light-sensitive components of modern photographic films are insoluble tiny crystals of  silver halide  (silver iodide, silver bromide, silver chloride and several types of silver fluoride).  Silver bromide is what's most commonly used nowadays.  With the possible exception of fluoride  (which can't be used in traditional photography because it's soluble in water)  silver is univalent in all those halides, which are given the generic chemical formula  AgX.

The  AgX  crystals are obtained by precipitation in a gelatinized solution of soluble silver nitrate by halides of  alkali metals,  like potassium bromide or sodium chloride.  The alkali nitrates byproducts are usually washed off.

Because the crystals are isolated from each other by gelatin, they behave as independent particles.  When a photon strikes a silver atom in an AgX crystal, it's reduced to metallic silver and dislodged from the structure of the crystal.  The modification so induced is called a  latent image.

When the film is processed chemically, the developer will ignore the crystals which contain fewer than 4 metallic silver atoms  (because their overall chemical potential isn't sufficient to attract the developer, so to speak).  The other crystals  (which were sufficiently exposed to light)  may react chemically with the developer.  When one of them does, it's  entirely  reduced to metallic silver and forms a visible dark  grain.  Like any chemical reaction, the action of the developer is progressive and its speed depends on temperature.  It's usually stopped  (by an acidic stop-bath)  well before all the exposed crystals have been  revealed.  The chemical process is completed by dissolving all remaining AgX crystals  (this is the role of the  fixer).

There's much more to chemical photography than the above outline.  It's a fascinating subject which continues to attract gifted researchers.

The major source of inefficiency in that basic photographic process occurs when the emulsion is exposed to light, because the effects caused by 90% of the captured photons dissipate before they have the chance to contribute to the formation of the latent image.  In 1999, it was shown that this dissipation could be successfully inhibited.

That could potentially increase basic photographic sensitivity by a factor of ten or, equivalently, allow a comparable decrease in the grain size of our best emulsions.  One of the workers involved  (de Keyzer)  is affiliated with  Agfa-Gevaert.  The patents filed by Agfa  (US5985536)  have yet to be applied commercially.

Enhanced yield of photoinduced electrons in doped silver halide crystals.   Nature 402, pp. 865-867 (23 December 1999).   By  Jacqueline Belloni-Cofler, Mona Tréguer-Delapierre, Hynd Remita  and  René de Keyzer.

Silver mining   |   Latent image   |   Photographic emulsion   |   Nuclear emulsion   |   Photographie argentique

 Ektar 100, pack of 5 rolls of 120 film (2015-06-23)   Film processing
Price comparisons (June 2015).

Below are quotes from several mail-order houses for developing a single 120 roll of color film with 16 good exposures on it  (645 format)  and printing 16 standard proofs.

Only for C-41 compatible films, including Ektar 100  (shown at right).

CompanyPer rollPer printSheetImageS&HTotal
Blue Moon
(optical prints)
$4.50$0.75 4" x 5" 3" x 4¼" $8.00$24.50
Fromex $6.49$0.89 4" x 5"borderless $6.00$26.73
Dwayne's $0.00$5.99/16
4" x 5"
5" x 7"
(2500 dpi?)
Photo Place $0.00$14.00/16
4" wide
5" wide
(2000 dpi)
Old School
Photo Lab
4" wide
5" wide
4" wide
5" wide
borders or
Pro Image, NYC
(double prints)
4" wide
5" wide
borders or
San Francisco
4" wide
56x42 mm
Photo Lab
$16.50$2.50/16 4.5" x 6"borderless
120 Processing
Photosmith imaging
$10.00$7.00/16 4" x 6"borders $0.00$17.00
The FindLab

The services offered may differ in ways which can't easily be reduced to the same denominator.  The above is just my own interpretation of different pricing structures.  They may be outdated by the time you read this.

Only  Blue Moon  advertises old-school analog proofs obtained as optical enlargements of the negatives.  All the others seem to use a process based on digital scanning  (whose resolution may or may not be specified).

Photoworks San Francisco  will print a contact sheet for $7.00.  They offer three qualities of digital scans  ($5, $7, $15).   +8.75% tax for CA residents.

The Darkroom  offers optional  enhanced  ($4/roll) or  super  scans ($9/roll)  but they don't state exactly what numerical resolution this entails  (in dpi).

Richard Photo Lab  offers two premium scanning options, at $2.50 and $6.50 per roll, respectively.  You can also pay extra  ($2.00)  to scan with their fashionable Frontier  machine, instead of the  Noritsu  (which has a faster turn-around and outclasses the  Frontier  for B&W).

Dwayne's  handles 120 roll-film for some retail chains like Walmart.  They offer scanning to a CD, at processing time, for an additional $2.99 per roll.  They get you a set of proofs for what others charge for bare film developing.  Historically,  Dwayne's was the last lab in the world to process Kodachrome film after it was discontinued by Kodak in 2009.  (They processed the very last roll on January 11, 2011.)

Pro Image Photo  offers your choice of a CD or a second set of prints at no extra charge  (the latter is a terrific deal).  You can also opt for larger prints at processing time  R6  (6" width)  or  R8  (8" width)  for $0.99 or $1.99 per print, respectively.  Because they void the S&H charge for orders above $20, you can get two sets of sixteen 6" by 8" for $22.79  ($21.80 for 15 images, $20.81 for 14 and, probably, $20 for 10-13).  One of the best deals around.

Camera Film Thriving over Digital?   |   Long Live Film   |   Richard Photo Lab  (2012).

(2015-06-25)   "Develop and Scan"  Services.
Some photofinishers require this step ahead of any other service.

Once your pictures are in digital form, you can have them turn the data files you select, at the time of your choice, into the pictures of the size and gloss you want, with or without borders.  You can also do your own editing, retouching and reframing at no extra cost, before spending money only on the final printings of your favorite shots.

That sounds great until you take a look at the fine details  (literally)...

Develop & Scan Services
CompanyPer rollPer scandpiQualityS&HTotal
North Coast
Photo Services
2048 x 1536
4824 x 3533
5035 x 3776
$42.9 ?

Although the "enhanced scans" from  North Coast Photographic Services  (4824 by 3533) were praised by Ken Rockwell in 2008), the downside of that process is that you get the same resolution from small-format and medium-format negatives  (you get slightly better resolution directly from a good small-format DSLR).

If that were the entire story, there would be little or no point shooting medium-format film in the digital era.  However, you can go beyond that artificial limitation by scanning film yourself, as explained next.

(2015-06-23)   Scanning 120-film yourself at 9600 dpi  (= dots per inch ).
Large ultrafine-grain film negatives outperform the best digital sensors.

Even when they offer enhanced scanning, photofinishers will typically adjust their resolution to the size of the negative, so that the longest side is no more than  5000 pixels or so.  This matches the resolution of a small-format digital cameras but defeats the purpose of using larger formats to capture finer details.  Ultimately, if you want medium-format negatives digitized to their full potential, you have to do it yourself.

For a street price of  $170,  the  CanoScan 9000 F Mark II   is able to scan 120 film at 9600  dpi, both horizontally and vertically.  CanoScan 9000 F Mark II  CanoScan 9000 F Mark II
Interpolated resolution is 19200 dpi
This flatbed scanner comes with a lightbox in the lid and two dedicated film-holders  (for 35 mm and 120 film).
Other negatives can also be scanned directly  (strip by strip if wider than  3¼'' ).
The  optical  resolution of  9600 dpi  for backlit film is equivalent to a square pixel of  2.65 microns...
 CanoScan 9000 F Mark II

Thus, the entire surface area of a 645 frame  (2352 mm2 )  can be equivalent to a  336 megapixel  sensor  when the above scanner is used with ultra-fine grain film  (e.g., Adox CMS II ISO 20, developed in Adotech CMS II, released in July 2014).  Yet, that's only half the resolution claimed by ADOX for their best film  (800 l/mm = 20000 dpi)  which is roughly the diffraction limit of a perfect lens at  f/2.

Only excellent optics can take advantage of such high resolutions.  Even a perfect lens won't achieve a better angular resolution than the "diffraction limit" of  1.220 l/D  where  l  is the wavelength of light  (555 nm for the most visible light)  and  D  is the diameter of the iris  (equal to  f/A,  the focal length divided by the aperture number).  At infinity focus, the angular resolution at the center of the frame is equal to the linear resolution divided by the focal length.  Thus, the linear resolution depends only on the aperture number, not the focal length.  Resolution is often quoted as the reciprocal of the linear resolution  (dots per inch instead of inches or lines per mm instead of mm):
Diffraction limit of the resolution of a lens at aperture  A   (for  555 nm  light)
unitA 1.422.845.6 811162232
dpi37523 / A 26533187621326693816633 46903317234516581173
l/mm1477 / A 1045739522369261 185131926546

Of course, top-resolution scanning is quite slow  (fast high-resolution drum scanners cost thousands of dollars)  and produces large datafiles.  Opaque documents up to 8.5" by 11.7" (297 mm)  can be scanned at  4800 dpi.

Film-capable flatbed scanners for home users :
/ mm
/ mm
CanoScan 9000 F Mark II$1709600 x 9600 dpi 82 mm216 x 297
Epson Perfection V600$209 6400 x 9600 dpi69 x 241216 x 297
Epson Perfection V550$170 6400 x 9600 dpi69 x 241216 x 297

To put it bluntly, scanning a 645 negative at 2000 dpi doesn't make it sharper than a good small-format DSLR.  At an optical resolution of  9600 dpi,  the superiority of medium format shines through in demanding images, like class photos or detailed landscapes  (use a tripod, sharp lens and fine film).

Video :  Flirting with Film #1:  Film and Negative Scanning (5:07)  by  Ed Verosky   (2013-11-29).
Scanning Film w/ Epson V600  by  Matt Day.

 Ilford PanF Plus 50 (2015-07-04)   Black-and-white film.
The soul of photography.

Ilford  (UK),  Ciba  (Switzerland)  and  Lumière  (France)  merged together before 1962.

Agfa  (Germany)  now uses the  Rollei  name.

Prices are for one 120-roll of film   (shown in italics if part of a multi-pack).
PriceBrandB&W FilmSpeedNotes
$4.85 KodakTri-X400
$4.85 KodakT-Max100
$4.50 KodakT-Max400Push to 1600
2012 KodakT-Max3200
$4.62 FujifilmNeopan Acros100
2013 FujifilmNeopan400Push to 1600
2010 FujifilmNeopan Super Presto1600 Push to 3200
$4.95 IlfordPan F50Best fine-grain film.
$4.39 IlfordFP4125
$4.09 IlfordHP5400Push to 1600
$4.50 IlfordDelta100
$4.95 IlfordDelta400
$5.90 IlfordDelta3200Push to 12500
$7.49 IlfordSFX200Semi-infrared
$13.99 AgfaRollei Ortho25380-610 nm
$9.80 AgfaRollei ATP 1.132370-820 nm
$8.40 AgfaCopex56Microfilm
$9.19 AgfaRollei RPX25Push to 50
$8.79 AgfaRollei RPX100
$9.34 AgfaRollei RPX400
$8.60 AgfaRollei Superpan200Semi-infrared
$9.00 AgfaRollei Retro80sSemi-infrared
$8.00 AgfaRollei Retro400sSemi-infrared
$11.49 AgfaRollei Infrared400Infra-red
$10.99 AgfaRollei Infrared400IR, Boxed
$8.49 AdoxCMS II20Orthopanchromatic
$5.52 LomographyEarl Grey100
$6.64 LomographyLady Grey200
$3.99 FomaHolga100
$4.29 FomaFomapan Classic100
$4.39 FomaFomapan Creative200
$4.39 FomaFomapan400
$3.50 UltrafineXtreme100
$3.50 UltrafineXtreme400
Highlighted in pink are b&w films with extended red spectral responses which could be explored in infrared.

Discontinued black-and-white films:

Analog photography   |   Switching from Kodak to Ilford  by  Matt Day  (2015-02-11)

(2015-07-05)   Infrared B&W Film Photography
The only true IR film still on the market is  Rollei Infrared 400.

Early photographic films were typically  orthochromatic,  which is to say that they had reduced sensitivity at the red end of the visible spectrum.  It takes some special chemistry to make a film sensitive to red  (a film equally sensitive to all parts of the visible spectrum is called  panchromatic).  It's even more challenging to make emulsions acquire at least some sensitivity in part of the  infrared  spectrum.

Ilford's SFX-200 has a peak sensitivity at the very beginning of the infrared range  (720 nm).  Likewise,  Agfa's  Retro  films extend only to  770 nm.  I think such films are best used with a brown longpass filter  (I use 680 nm).

Rollei Infrared  is the last infrared film on the market!  It's identical to the  Agfa Aviphot Pan 400s,  formerly used in aerial surveillance. This is a panchromatic film with an extended infrared response  (up to  820 nm).  With a proper  720 nm  IR filter,  it's best exposed around ISO 4  (ISO 6 in the Summer, ISO 2 in the Winter)  and processed slightly more than the recommended developing time... 

That Rollei IR film has exactly the same formulation as the discontinued  Efke IR820 Infrared  and the related  Efke IR820 Aura  which allowed legendary artistic effects because of its lack of an anti-halation layer.  Like all  Fotokemika  products, the Efke films were discontinued in the Summer of 2012.  Now that the manufacturing has moved out of Croatia, Efke technology is reverting back to its German origin, under the  ADOX trademark, but infrared films have been left out.

"Due to declining demand",  Kodak  stopped the manufacture of the famous  High-Speed Infrared Film (HIE)  in 2007.  HIE was sensitive up to  900 nm.

Processing Infra-Red Film :

Although the chemical process is the same, most labs won't accept infrared 120-films for processing.  There are two possible reasons for that.  One is essential in industrial handling,  the other is incidental in manual handling:

  • Quality control and mending are done inside industrial machines using infrared cameras and lighting which could ruin infrared-sensitive film.
  • IR emulsions are normally laid on a very flimsy archival polyester base  (incidentally engineered to have a life expectancy  (LE)  of 500 years or more).  Such films are not rigid enough to be loaded in the usual way onto  Paterson  reels, for artisanal processing.

I don't how anybody else deals with the latter issue but my own method is to use an ordinary clear roll of film  (bathed in a fixer without having ever been developed)  strictly for mechanical support:  I put the clear film on the back of the exposed IR film and treat that sandwich as a thick roll of film which is loaded and processed in the usual way  (possibly allowing a longer stay and vigorous agitation in the stop-bath, to prevent corruption of the fixer by the solution trapped between the two films).  I then wash the IR film by itself, unrolled in a bucket of water...  (The clear film is also washed, dried and stored in a safe place to be reused over and over again for the same purpose.)

Rolleifilm (USA)

(2015-06-30)   Developing Black & White Negatives at Home
B&W films are easy to process yourself  (arguably, easier than cooking).

Nowadays, most commercial labs concentrate on color processing.  For business reasons,  fake  B&W films are now sold which must be processed with the standard treatment normally reserved for color negatives  (C-41).  One example is  Ilford's XP2.  (I find this evolution rather repugnant.)

B&W  film processing is  extremely  easy to do as well or better than any professional lab ever will  (the same isn't true of color processing).

The only part of the process which must take place in complete darkness is the loading of the film onto the processing reels of a  developing tank.  I dislike  changing bags  and prefer the comfort of a pitch-dark closet, preferably at night.

To test your own "facility", make sure you can't detect any light with dark-accustomed eyes  (it takes a few minutes).  All the problems so revealed must be addressed ahead of time.  The worst culprit is usually the floor-clearance under the closet door, which can be blocked by jamming a towel into it.  Additional safety is obtained by working relatively quickly with your back to the door.

For 35 mm film, don't bother opening the cartridge:  Instead, pull a little bit of the film out of the cartridge and first cut it square between two perforations  (do this in broad daylight).  In total darkness, you can pull out a few inches of film at a time and use the weight of the cartridge to provide a gentle tug which makes for trouble-free loading onto a Paterson spool.  When you can no longer pull any film out, just cut it off and complete the loading of the loose tail  (put scissors in your pocket, ahead of time).

The  only  photo-dedicated equipment needed to process roll-film is:

  • Tank and reels  (I recommend Paterson's System 4, or compatible).
  • A changing bag  (unless a very dark closet can be used at night).
  • Scissors and/or can opener  (for 35 mm cartridges only, see above).
  • A stopwatch or a timer  (mostly to measure time in developer bath).
  • A thermometer  (proper developing time depends on temperature).
  • A graduated beaker and agitator, for mixing chemicals.
  • A funnel, for pouring the reusables back from the processing tank.
  • One concertina bottle  (to safely store developer, if not one-shot).
  • Two other storage bottles  (for stop-bath and fixer).
  • Force film washer  (especially useful for multi-reel tanks).
  • Film squeegee wiper  (use only on wet film; always pre-moisten it).
    Single-use KimWipes  (sprayed with diluted photo-flo)  are  safer.
  • Film-clip pairs for drying  (one hanger and one weight per pair).
    For 120 film get #3 nickel-plated Bulldog clips  (#2 is slightly too small)  for less than $1 a piece.

The chemicals needed are, in order of use:

  1. Water :  Optional pre-rinse  (same temperature as the developer).
    I recommend skipping that first step.  So does Ilford.
  2. Developer :  (adjust time and/or temperature to achieve proper ISO)
  3. Stop bath (30 s to 2 min).  Diluted acetic acid or citric acid.
  4. Fixer :  Mostly a sodium hyposulfite solution  ("hypo").
  5. Hypo-Eliminator :  In a pinch, use a  2%  solution of sodium sulfite.
  6. Running water :  From the faucet, through the  force film washer.
  7. Wetting agent (30 s or more):  For spot-free drying  (dil. 1+199).

Choosing a B&W Film Developer  by  Christian Bale.   |   Appreciating Rodinal  by  Ed Buffaloe
Video:   Developing  B&W  Film  by  Matt Day  (He recommends a pre-rinse.  I don't; neither does Ilford!)

(2015-06-30)   Paterson System 4   (or  Super System 4 )
The dominant system of developing tanks and self-loading reels.

In the past 45 years, I have only used  Paterson's  "System 4"  equipment, which is wonderfully convenient.  There are no practical differences between my vintage system and the newer "Super System 4" which I also use.

In the new design, the lightproofing funnel is fully contained within an outer enclosure consisting of only two parts:  A red-rimmed vessel and a large soft black lid, which is force-fitted onto the rim  (you don't even need the lid if you are satisfied with the built-in agitator and don't use reversal agitation during processing).  All the surfaces are now readily accessible.

The reels, the central cylinder and the agitator rod are identical in both systems,  which are equally lightproof.  The new parts are simpler but more bulky.  The old lightproofing funnel was built into a double-walled top part with a small grey lid.  This screwed on top of the main vessel, using a grey gasket which has no counterpart in the new design.  Also, in the old design, the funnel was attached to the rest of the upper part by three smallish plastic tabs which made the whole thing fragile  (I had to glue back those two pieces on my first tank).

I've never lost a 35 mm roll or ruined a single frame  (except to scratching by a bad squeegee).  I don't wish to acquire the skills needed to use traditional stainless-steel spirals and tanks  (including the top-rated Hewes brand).

Other vendors are now making Paterson-compatible components which are worth considering,  including self-winding reels with larger take-up guide flanges, which seem better suited to 120 roll-film:

  • Kaiser 4298 self-winding reel.
  • AP.
  • Jessops.

The centerpiece of Paterson's  (Super) System 4  is a light-proof tank made from high-quality shiny black plastic impervious to photographic chemicals.  Different sizes are available, according to the maximum number of films you intend to process at once.  (#114 doesn't accommodate 120 film at all.)

Paterson  "Super System 4"  Developing Tanks
/ mm
35 mm120
or 220
11435 mm45? 10
115Universal85 2
w/ 2 reels
116Multi-reel 3139 3
without reels
117Multi-reel 5214 5
without reels
118Multi-reel 8345
without reels
119Auto-load reel   $14.95  Reel only
120Six-pack $57.25  for 6 reels

The Paterson reels feature a clever ratchet system  (involving twin stainless-steel balls)  which doesn't require any skills:  Just engage the film and the reel will swallow it effortlessly as you rotate its two halves back and forth.

Paterson reels  (there's only one model)  can be adjusted to one of three film widths.  To do so, rotate the two halves very firmly  clockwise  until they disengage.  Then you adjust the width to the proper click stop and turn counterclockwise  (which will be much easier).  The first time you do this, you'll think you are going to break something; don't worry, you won't  (get help if you have troubles opening jars).  After they've been disassembled a few time, the reels become looser and this operation is easier to do.  That's good because disassembling the reel is the best way to remove a film from it after processing.  It's also a good practice to leave the reels disassembled to let them dry thoroughly  (loading film onto a wet reel is asking for trouble).  The  (measured)  outer widths of adjusted Paterson reels are precisely:

  • 42.3 mm  for 35 mm film.   (290 mL nominal)
  • 53.4 mm  for 127 film.        (370 mL nominal)
  • 69.0 mm  for 120 or 220.    (500 mL nominal)

This data can be useful to compute the height of a stack of reels in a large tank  (not including the  3.4 mm  flange at the bottom of the axis).  This tells you,  before purchase,  if a given tank will be able to process the batches of films you have in mind.  For example,  with their combined processing height of  84.6 mm,  two 35 mm films fit in a Universal tank  (85 mm axis).  Of course, that's what this tank was mostly designed for  (with the added bonus that you have plenty of room to process a single reel of 120 or 220 film).  That particular combination was also the reason why I stored my processing solutions in bottles of  600 mL  for many years  (before I learned about concertina bottles).  It's also the reason why such bottles were in stock at my local photo store  (yes, there was such a thing not too long ago).

The above nominal values for the recommended volume of processing fluid are embossed at the bottom of Paterson tanks.  To compute such volumes more precisely, the following data is needed:

The inner diameter of  Super System 4  Paterson tanks is  98 mm  (the outer diameter of the reels is  93.6 mm).  To obtain the effective cross-section of the tank, deduct from the  surface area  of that circle the ring occupied by the center column  (outer diameter  25.6 mm,  inner diameter  22.2 mm).  In  square centimeters,  this amounts to:

S   =   ( 9.802  -  2.562  +  2.222 p / 4   =   74.15 cm2

The volume occupied by a reel  (at any width setting)  is slightly more than  40 ml.  The film you put on a reel  (either a 35 mm roll or a 120 roll)  occupies a volume of about  6 mL  (assuming  0.14 mm  thickness).  All told, the volume of the fluid needed to immerse an entire processing reel is:

  • For 135,   4.23 (74.15) - 46   =   268 mL   (vs.  290 mL).
  • For 127,   5.34 (74.15) - 46   =   350 mL   (vs.  370 mL).
  • For 120,   6.90 (74.15) - 46   =   466 mL   (vs.  500 mL).

To the above per-reel quantities we should add the  30 mL  or so which are needed to immerse the flange at the bottom of the tank.  The manufacturer's simplified recommendations are sufficient to cover that, except in the case of a single 135 or 127 reel, where that would be a little bit too short  (by about  10 mL).  Don't be too stingy when you process a single reel!

If you must, you can load  two  120 rolls on a single reel by pushing the first one  gently  with a specially-cut piece of cardboard  (if you have to ask how this is done, you probably shouldn't do it).  This way, you can load up to six 120-films into a single "Multi-reel 7" Paterson tank, or 10 films with a "Multi-reel 8"  (345 mm axis,  424 mm total height.)

(2015-06-30)   Developer
The developer turns a  latent image  into actual metallic  silver  grains.

Most people use commercial developers:

The developer bath is, by far, the most critical part of film processing.  Unlike photographic prints, negative films are almost never allowed to develop to full or near "completion".  Instead, best performance is obtained by interrupting the process with an acidic stop-bath (see next)  at the exact time recommended by the manufacturer for a given temperature.

The key to successful processing is a precise monitoring of the time spent in the developer bath, according to the effective concentration  (which may depend on the total surface area of the film already processed in it).  The pre-rinse  (if any)  and the stop-bath should always be at roughly the same temperature as the developer.

The film nominal sensitivity is achieved only for the recommended time  (some photographers call that  box sensitivity  because it's always prominently printed on box packaging).  Routinely, most films can be developed this way, using  any  developer by following the standard instructions provided by the developer's manufacturer.

Within limits, a roll can be exposed differently if you expect to "pull" or "push" its development time.  This practice influences contrast and grain too.  For optimal results, consider matching the developer to your specific film  (something professional labs rarely do, if ever).

Increasing both the ISO and the developing time of a film is called "pushing".  The less-common opposite practice is called "pulling".  It's straightforward if you do it yourself, but it's a major source of headaches if you have to tell somebody else to do it for you.

Standard developing time are normally given for a temperature of  20°C/68°F.  Correction factors are available for temperatures between  18°C  and  22°C.  Most manufacturers do not recommend experimenting outside that range.

To assure a uniform finish, manufacturers don't advocate a pre-rinse  at all  (except, possibly, with de-gassed water at the same temperature as the developer and agitated with the same care).  Agitate continuously for the first minute of development and five seconds every minute after that...

Once the developing time has elapsed, pour the developer quickly out of the tank and pour in the stop-bath immediately.

(2015-06-30)   Stop-Bath
The proper way to end the action of the  developer  is a diluted acid.

An acidic stop-bath  (e.g,  1% to 2% acetic acid)  is best for precise control but some people are content with plain water, which merely slows down the developing greatly by diluting the developer.  A proper acidic stop-bath is recommended  (it's cheap)  because it renders the film light-insensitive immediately and spares the fixer.

A fresh acidic stop-bath does its job almost instantly  (less than 15 seconds).  I recommend soaking the film in an acidic stop-bath between 30 seconds and two minutes, but it's not critical.  To properly re-use stop-bath, check its acidity either by smell or with a  color indicator.  The stop-bath concentrates sold by Kodak or Ilford consist, respectively, of acetic acid or citric acid with an  indicator dye  already mixed in  (they're both primarily intended for tray-processing of photographic prints but they're also usable for film).

If you ever must substitute a clear-water rinse for a proper acidic stop-bath,  at least make sure to avoid temperature shocks.  The folkloric  "spoonful of vinegar"  in such a rinse is all but useless.  Be serious; you need a glassful!

Acetic Acid   (1% to 2%, by volume) :

Example:  Kodak indicator stop bath  (dil. 1+63)  is 85% to 90% acetic acid.
Kodak's solution is nice for prints, since the indicator becomes visibly dark under safelight when the bath is exhausted.  To make your own acetic stop-bath, you may mix one part white vinegar (6%) with 2 to 5 parts water.

Citric Acid   (15 to 20 g/L,  using hydrate crystals) :

Ilfostop  (dil. 1+19)  is based on  citric acid,  which gives it a low smell.  Ilford's stop-bath can be re-used many times, until the mixed-in yellow indicator turns purple  (it's probably bromocresol purple).

A citric stop-bath shouldn't be used in combination with a hardening fixer  (the alum in such a fixer might precipitate).

The citric acid sold as a powder in food stores may contain up to 2% of silicon dioxide  (a glorified name for sand)  as an anti-caking agent.  I measured 1% in Ball ®.  Cloudiness indicates the presence of that junk and the need for a good filtering before photographic use  (at least for negatives).  I recommend preparing a  (filtered)  storage solution of citric acid at  1.0 M  concentration  (nominally  210.139 g/L  or roughly 212 g/L to allow for the anti-caking waste).  To make  1 L  of working stop-bath solution, use  70 mL  to  100 mL  of that concentrate.  (Again, citric acid is incompatible with hardening fixers.)

Designer Stop-Bath :

Sprint Block  is a vanilla-scented buffered stop-bath  (dil. 1+9).

(2015-06-30)   Fixing  images by dissolving unused silver halide.
In 1819, John Hershel discovered that  hypo  dissolves silver bromide.

Commercial brands of fixers include  IlfordKodak  and  Kodafix (with hardener).  Don't use a citric stop-bath before a hardening fixer like Kodafix.

The fixing time should be at least twice the time it takes for the film to appear clear.  The fixer dissolves all the milky  silver bromide  left by the chemical developer on the underexposed parts of the negative.  Two ways:

AgBr  +  2 S2O32-   ®   [Ag (S2O3)2 ] 3 -  +  Br-
AgBr  +  3 S2O32-   ®   [Ag (S2O3)3 ] 5 -  +  Br-

It was John Hershel (1792-1871) who discovered, in 1819, that what he called "hyposulfite of soda" is a solvent of silver halides.  This is still known as "hypo" among photographers.  The learned name is  sodium thiosulfate.  This substance forms pentahydrated crystals  (Na2S2O3, 5H2O)  at  248.185 g/mol,  commonly sold as  "hypo penta"  or  prismatic rice.

When in doubt, leave your film in hypo for a few more minutes.  However, do not prolong this precaution needlessly, as this makes the film more difficult to wash.

Some modern fixers  (e.g.,  Ilford Rapid Fixer )  use  ammonium thiosulfate  (NH4)S2O3  which works about four times faster than  hypo  (1 or 2 min.).

To get the most from your fixer, check the film after two or three minutes of fixing  (film is no longer light-sensitive at this stage).  If there's still some white residue on it, keep fixing and check back later.  Once the film appears clear, put it back into the fixer again for an equal amount of extra time.  When that total time exceeds fifteen minutes or so, the solution is nearly saturated with silver and it's time to dispose of it  (you may confirm that fact with Edwal hypo-check).

Professionals never dump spent fixer down the drain.  Although silver isn't nearly as toxic as some other heavy metals, it's not too good for the environment.  The most mindful method is to retrieve metallic silver by electrolysis before dumping the rest of the solution  (amateurs are under no legal obligation to do so).
The silver content of  B&W  emulsions is typically  4  grams  per square meter.  That's roughly  1 g  (currently worth about $0.50)  in 4 rolls of 120 film,  or  5 rolls of 35 mm  (36 exp.).  In properly exposed film, less than half of that silver stays on the film in metallic form.  The rest gets dissolved in the fixer.

(2015-07-07)   Washing processed film.
Salty water makes the final fresh-water rinse more efficient

A salty pre-wash  (mostly sodium sulfite, usually)  is particularly useful for removing the residues of a hardening fixer,  by  ion exchange.

It's not needed after an ammonium-based  rapid fixer.

A dubious legend has it that early Navy photographers had noticed that they obtained a better wash quality by using seawater before a shorter fresh-water rinse  (a precious commodity at Sea).

To mimic this, Kodak recommends a preliminary water rinse of 30 seconds followed by 1 or 2 minutes in their  Hypo Clearing Agent (HCA).  After that, a final rinse of 5 minutes in running water seems sufficient  (otherwise, 20 to 30 minutes would be prudent).  Their HCA packages list  4  components:

  1. Sodium sulfite   Na2SO3   (CAS 7757-83-7).
  2. Sodium metabisulfite   Na2S2O5   (CAS 7681-57-4).
  3. Trisodium citrate   Na3C6H5O7   (CAS 68-04-2).
  4. Tetrasodium salt of ethylenediaminetetraacetic acid  (tetrasodium EDTA)   Na4C10H12N2O8   (CAS 64-02-8).

The respective quantities  (not given by Kodak)  per liter of stock solution  (to be diluted 1+4 to make a working solution)  seem to be  100 g,  25 g,  2 g,  and  5 g.  The first component is essential, the second is for pH optimization, the third is a preservative.  The last component  (EDTA salt)  is a  sequestering agent,  similar to  Calgon®,  to accommodate  hard water.

Kodak no longer sells their dry mixture in small packets to make one liter of HCA stock solution.  You can only buy the "professional" size of  500 g  (to make one gallon of stock, or 5 gallons of working solution).  Once mixed, the stock solution is good for only three months in a stopped bottle  (the working solution lasts a week in a bottle but only 24 hours in a tray).  Most amateurs won't be able to use the whole thing in 3 months and must therefore fraction the powder.  This procedure isn't recommended in critical cases  (e.g., developer)  but it's perfecly acceptable for HCA.  Mix the powder thoroughly by  tumbling  it in a dry bottle  (the larger the better).  Shaking is not a good way to mix a powder, because of the Brazilian nut effect.  Then, weigh the proper quantity for the volume of stock solution you intend to make  (500 g per gallon, 125 g per quart, 132 g per liter).

Ilford Washaid  is sold as a liquid concentrate  (dil. 1+4)  with an unspecified shelf-life.  It seems to have a composition similar to HCA.

(2015-07-07)   Drying.
A wetting additive in the last rinse conditions rhe film for spotless drying.

The usual recommendation is to soak the washed film for at least 30 seconds in a conditioning bath of diluted wetting agent  (most commonly 1+199).

Several brands of equivalent wetting agents are marketed for photographic use:  Kodak Photo-Flo 200IlfotolFuji DriwelForma FloNacco,  etc.

Edwal LFN  is so potent that the manufacturer recommends using only 2 drops for 500 mL  of tap water  (1 drop is enough with distilled water).

Sprint's End Run  promises to leave an anti-static coating on the film after drying, if specific instructions are followed  (i.e.,  wipe film with a sponge instead of a rubber squeegee).

(2015-07-04)   History of natural-color reproduction:
From autochrome plates and Technicolor® to the first color films.

For motion pictures, the impression of color can be achieved by projecting successive frames in the three additive primary colors  (a black and white film was projected through a synchronized wheel of filters.) A British patent for this technology was issued to  Edward Raymond Turner (1873-1903) from London,  who produced the first natural-color motion picture in 1902.  Turner managed to  take  color footage this way  (the earliest known footage shows his children in the Summer of 1902).  However, he wasn't able to construct a satisfactory projector before he died of a heart attack in 1903.  The historical significance of Turner's work was mostly ignored until some of his original footage was found in 2012,  in the archives of the  National Media Museum  in Bradford.  Capturing every frame, the  British Film Institute  (BFI)  could finally show humanity's first color motion picture  to an audience, any audience, for the very first time...

The same idea was the basis for the less ambitious two-color  Kinemacolor  system, invented in 1906 by  George Albert Smith (1864-1959) from Brighton.  Kinemacolor  had some commercial success between 1909 and 1918, under the leadership of Charles Urban (1867-1942).  The projectors showed successive frames alternately through red and green filters.  Blue tones were missing and color fringing was visible on moving subjects.

For still color photographs, the earliest successful system  (beyond experimental work by Maxwell and others)  was based on the  Autochrome Lumière  system, patented by the  Lumière brothers  in 1903 and first marketed in 1907.  This included the process born as  Dioptichrome  or  Dufaycolor  (invented in 1907 by the Frenchman Louis Dufay)  and the similar German  Agfa-Farbenplatte  (Agfa color plate).

Both of those begat film products primarily meant for the motion-picture industry, around 1932.  In particular, the Agfa film went under the name of  Agfacolor before it was phased out by the introduction of the first proper tripack Agfacolor film, in 1936.

Technicolor:  Two-color in 1916,  three-color in 1932.

The  Technicolor Motion Picture Corporation  was formed in 1915 by  Herbert Kalmus (1881-1963),  Daniel F. Comstock (1883-1970)  and  W. Burton Wescott (c.1884-1952).  Kalmus and Comstock were MIT graduates, Wescott was a mechanical genius who would only get a degree in 1916.

Originally, Technicolor System 1  was a two-color process improving upon  Kinemacolor.  The main innovation was to use a beam-splitter to obtain  simultaneously  two shots of every frame with different color filters.  Skilled projectionists superposed the images from separate prints to reproduce colors  additively  for their audiences.  System 1  was first used to shoot and print the film entitled  The Gulf Between  (1917).

The Technicolor name would be retained to denote all subsequent evolutions based on beam-splitter cameras, which dominated Hollywood's color motion pictures for 30 years, between 1922 and 1952.  Ultimately, 3-color Technicolor  (System 4)  would receive high marks for its ability to achieve high levels of color saturation.

In 1922, the films shot by those same Technicolor cameras were recombined into a single  subtractive  laminated print containing the proper color pigments.  Such prints could be projected by unskilled projectionists using white light.  This was called  System 2.

In 1928,  System 3  was introduced, which did away with the cemented laminates and produced single-layer prints by transferring colored dyes directly on the substrate.  This was significantly improved in 1931, with better image quality and more vivid colors at a lesser cost.

Finally, in 1932, a full-color Technicolor camera was designed by  Technicolor founder  W. Burton Wescott  (who had apparently left the Technicolor corporation in 1921)  and Oscar-winner  Joseph A. Ball (1894-1951).  The new Technicolor camera exposed simultaneously  three  strips of  B&W  film.  The first beam from the beam-splitter went through a green filter  (blocking red and blue)  to expose one strip very sharply.  The second beam went through a magenta filter  (blocking green light and letting red and blue through).  It exposed two strips of  B&W  film with their emulsion sides pressed against each other.  The front film, sensitive only to blue light, had an emulsion with a thin superficial orange-red coat.  Thus, only red light reached the panchromatic film in the back.

All  three-strip Technicolor cameras  had expansive movements supplied by  Mitchell  and were owned and leased by the Technicolor corporation.

The three Technicolor negatives were used to produce the color matrices in the new  System 4  providing unsurpassed prints for distribution.  Yet, almost from the start, this system would be subjected to tough competition brought forth by the desire for camera simplicity and the need for a color negative that would rival the convenience of black-and-white.

Technicolor for Industrial Films (1949)   |   The Dye Transfer Printing Process - Technicolor 100 (1949)

The First Modern Color Films  (1935-1936) :

The revolutionary war of color films was fought in the mid 1930's between  America (Kodak)  and  Germany (Agfa).  The technological Holy Grail of that period,  for natural color reproduction,  went by the name of  integral tripack,  which described modern color film as we know it today:  a single celluloid film with three differently color-sensitized emulsion layers.

On April 15, 1935,  Eastman-Kodak officially introduced the first such  integral tripack  under the name of  Kodachrome.  (That name had previously been describing the two-color process due to  John G. Capstaff (1879-1960) which Kodak had released in 1915.)

This was the end result of years of efforts by  Leopold Godowsky (1900-1983)  and Leopold Mannes (1899-1964)  whose early research had so impressed Kodak's chief scientist  (C.K. Mees, 1882-1960)  that the two men were granted financial and technical support by Kodak to finish the job.

At the time, the Germans were more than one year behind in the race, but the chemists at Agfa came up with their own experimental version of an  integral tripack  color film just in time for the Summer Olympics of Berlin  (1936).  This new Agfacolor film was first tested in the swimming competitions  (a non-tripack older Agfacolor film had been introduced in 1932 which was based on the older French autochrome process).

It would take three years for that German technology to mature.  The turning point was the filming of the musical  Frauen sind doch bessere Diplomaten  (Women make better diplomats).  The producers at UFA had to yield to the demands of the infamous Minister of Propaganda of the Third Reich, Joseph Goebbels (1897-1945)  who wanted that film shot on new Agfacolor...  That transformed the shooting into a series of trial-and-error tests with a few dismal failures  (yellow grass and such)  but a near-perfect end result (1941).

Autochrome Lumière (1903)   |   List of color systems

(2015-07-14)   Color negative (CN) films.  Color prints.
Agfacolor, Kodacolor, Ektar, Fujicolor...

Here is a list of some currently available color negative films, or recently discontinued ones:

Prices are for one 120-roll of film   (shown in italics if part of a multi-pack).
PriceBrandColor Negative  (CN)SpeedNotes
$4.95 KodakEktar100
$5.50 KodakPortra160
$5.99 KodakPortra400
$10.79 KodakPortra800
$7.10 FujiFujicolor PRO NS160
$7.55 FujiFujicolor PRO H400
2013 FujiSuperia X-TRA400Fourth color layer
$4.17 Lomography683 Color Negative100
$4.84 Lomography682 Color Negative400
$5.84 Lomography684 Color Negative800
$4.84 LomographyRedscale XR100Blue at 50,  red at 200.
$3.87 LomographyRedscale100Reverse-rolled.
$11.90 LomographyLomochrome Purple400100-400 "creative"
$9.40 AgfaRollei Digibase CN200
Highlighted in yellow are nonstandard novelty films suitable for special effecrs but not natural-color reproduction.
 Fujifilm Superia X-TRA 400  

As the rendition of greens and violets may be wanting in some fast color films, Fuji added a fourth color layer to their  Superia X-TRA 400  to address that specific issue.  Unfortunately, the production of that innovative film has now been discontinued, at least in the 120 format.

Fujifilm stopped producing films for the motion-picture industry in  March 2013.

Kodacolor VR 100, VR 200, VR 400 and VR 1000.

 Come back later, we're
 still working on this one...

Down the Road :   Shooting Fujifilm Superia X-tra 400   by  Jim Grey   (2015-04-06).

(2015-07-01)   C-41 Processing at Home
The standard way to process color negatives.

The original Kodacolor film (1942) used  C-22  processing.  So did its Kodacolor-X successor (1963).  Eastman-Kodak introduced the C-41 process in 1972, as they switched  (over a period of a few months)  from Kodacolor-X film to Kodacolor II, the first C-41 film.

C-41 is now the  only  process used for all brands of current  color negative  (CN)  film.  Other manufacturers use different names for equivalent processes like CN-16 (Fuji) or AP70 (Agfa) but everybody mentions Kodak's C-41 as the main marketing and technical reference.  Differences between chemistry suppliers are insignificant  (5% contrast, at most).  You could have more variations from one day to the next in the same lab using the same chemistry.

Personally, I'm quite happy to leave C-41 processing to professional labs.

Nevertheless, the process can be performed at home with ordinary black-and-white equipment.  However, temperature tolerances are much tighter for color than for  B&W  and you can't simply adjust developing time to a casually-measured temperature.  With color films, such adjustments could adversely influence color-balance...

The developing temperature  must  be just whatever the manufacturer specifies, as precisely as possible.  The use of a controlled water-bath for the developing tank and critical storage containers is almost mandatory.  Some of the chemicals involved are nasty.  Glove protection is a must.

Unlike  B&W,  there's no room for creativity in C-41 processing.  Just follow carefully the instructions that come with any C-41 chemistry kit :

C-41  KitRolls / L1 L2 L5 L
Rollei C-41 Color Kit16 $44.99 $74.99
Tetenal Colortec C-41, liquid12 $24.95 $76.99
Unicolor C-41, powder8 $21.99 $33.99

C41 processing at home  (Google search).

(2015-07-04)   Positive color films.  Color slides.
Kodachrome and  K-14.  Ektachrome, Fujichrome and the  E-6 process.

The advantage of reversal color-film is to bypass the need for proof prints.  A professional photographer can examine all aspects of the picture in positive form, including color balance,  directly from the film  (possibly with the help of a magnifier).  Color prints of superior quality could be produced from positive film as easily as they can be obtained from negatives, using Cibachrome/Ilfochrome Classic  (which was discontinued in 2012).

For consumers, processing labs typically produced  slides  by mounting each frame of a positive film in a square of cardboard suitable for projection in family circles or elsewhere.  Slide projectors became very popular in education and conference circuits.  For intensive use of some slides, the cardboard was discarded and the film mounted in a plastic equivalent between two thin windows of glass.  This helped minimize deformations of the celluloid under the intense heat from the projector...

In the early days of color slides, the price of reversal film included processing  (a mailer was included in the box to send in your exposed film).  Such process-paid sales were ruled to be illegal in the United States in 1954, but the practice was not discontinued in the rest of the world...

Back in France, I was mailing my beloved  Kodachrome  rolls  (ASA-64 and 25 sensitivities only)  to  Kodak-Pathé, avenue Victor Hugo, 93-Sevran,  where up to 2100 people  (75% of them women)  were working day and night to process the pictorial memories of an entire nation.  With the advent of digital photography, that legendary site would just become an infamous wasteland  (la friche Kodak).

Kodachrome films  (Kodachrome 25  and  Kodachrome 64)  were processed in a specific way  (K-14)  which was only meant to be carried out by a few specialized professional labs, with chemistry supplied by Kodak.  K-14  (lastly K-14M)  evolved from the Kodachrome process introduced in 1935.  The production of both Kodachrome films and Kodachrome chemistry was discontinued by Kodak in 2009.  The last lab to operate a Kodachrome line was  Dwayne's Photo,  which stopped accepting Kodachrome film at YE 2010 and processed its last Kodachrome roll on January 18, 2011.

Since the demise of Kodachrome,  the only surviving process for color slides is the simpler  E-6 process  which evolved from the original process  (E-1)  introduced for Kodak's Ektachrome in 1946.  E-6  has also been widely used to process Fujichrome  (Velvia-50, Velvia-100, Provia-100, Provia-400X).

Agfa's equivalent,  dubbed  Process 44,  is intended for their own lineup of reversal films:  Agfachrome 64S, 100 or 200.

Professional labs use a six-bath version of the E-6 process.  By combining the reversal bath with the color developer and the bleach with the fixer,  a compatible "three-bath" version  (plus stabilizing bath)  has been devised as chemistry kits for individuals who use traditional  [Paterson]  black-and-white equipment  (albeit in a water-bath with stricter temperature controls than for  C-41).  That process was once also known as  E-7  but this has been abandoned for marketing reasons  (calling is "three-bath E-6", or simply E-6, better reflects the key selling point that the process works with all films labeled E-6).

E-6  KitRolls / L1 L2 L5 L
Tetenal Colortec E-6, liquid12 $68.49 $99.99

The four baths in the  three-bath E-6 kit  [sic] are  (assuming 500 mL tank).

  1. First (B&W) Developer  (FD).  37.5°C - 38.0°C.
    100 mL  of FD concentrate and  400 mL  of water.
  2. Reversal & Color Developer  (CD).  37.2°C - 38.3°C.
    100 mL  of CD-1,  60 mL  of CD-2,  340 mL  of water.
  3. Bleach & Fixer  (Blix, BX).  33.3°C - 38.9°C.
    100 mL  of BX-1,  100 mL  of BX-2,  300 mL  of water.
  4. Stabilizer & wetting agent  (STAB).  20°C - 25°C.   One minute.
    50 mL  of STAB concentrate and  450 mL  of water.

The timing of the first three baths depends critically on the number of films which have been processed or are being processed in them.

The range and precision of temperature measurements are compatible with medical thermometers but most of those aren't well suited to photographic purposes for two reasons:

  • They usually take too much time to reach equilibrium.
  • They record only the top temperature reached between resets.

Some equipment is available for individual professional photographers with serious processing needs, mostly in the field of large-format photography.  In a  video tutorial  Tony Santo  explains how to reliably execute the full six-bath E-6 process with the help of mechanized Jobo gear  (Jobo drums are not compatible with Paterson tanks).  This isn't for everyone.

Below is a list of some currently available color reversal films, or recently discontinued ones.  With the notable exception of discontinued  Kodachrome,  all of them are compatible with  E-6  processing.

Prices are for one 120-roll of film   (shown in italics if part of a multi-pack).
PriceBrandColor Reversal  (CR)SpeedNotes
$8.55 FujifilmFujichrome Velvia50
$7.69 FujifilmFujichrome Velvia100
$7.19 FujifilmFujichrome Provia100F
2009 KodakKodachrome25K-14 processing
2009 KodakKodachrome64K-14 processing
2013 KodakEktachrome E-6 processing
$7.50 LomographySlide X-Pro200
$8.99 AgfaRollei Digibase CR200
$7.99 AgfaRollei Crossbird200"Creative edition"
Highlighted in yellow are nonstandard novelty films suitable for special effecrs but not natural-color reproduction.

As of March 2012, Kodak discontinued the production of all forms of color-reversal film (CR).  A few ektachrome rolls are still on sale because they were refrigerated to prolong their useful life.

National Geographic:  The Last Roll of Kodachrome  (2009)   Steve McCurry.

visits since July 6, 2015
 (c) Copyright 2000-2015, Gerard P. Michon, Ph.D.