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The Ongoing Legacy of Photographic Film

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

Many photographic processes have been developed which do not usesilver at all.  In fact, we argue in the next section thatphotosensitivity 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 snapshots can't. 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 silvercrystals 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 silvermakes that soluble salt easy to obtain (it's not the case for gold, for example).

Theionizationenergy of silver is  7.5762 eV, which corresponds to a frequency of 1831.9 THz or a wavelengthof 163.65 nm.  UV light can ionize metallic silver (photoelectric effect)  but visible light cannot.

(2015-08-01)  
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 photographypioneers was to identify substances that would fade fast...

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

The real challenge was thus to find substances that could react at all to low-energyvisible 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 thedirect action of light. Fixing is the process of making the image permanent and ensuring that no part of itretains 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 shorterexposure times until a miracle happened:  The captured image was no longervisible at all (by that time in history trying  to view the effect of a previousexposure on panchromatic films was no longer practical anyway, because any additionallight would ruin it).

So was born the great mystery of photography, which nobody understood forseveral decades: When a picture is taken, a latent  image is formed which willremain invisible until revealed  by the chemical actionof a developer  (which the French appropriatelycall 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 moreof its silver ions to their metallic state (thus releasing neutral bromide into the solution).

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

(2015-07-07)  
From wet plates to gelatin film.  How silver captures light.

The light-sensitive components of modern photographic films are insoluble tiny crystalsof 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)  silveris 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 silvernitrate 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 silverand dislodged from the structure of the crystal. The modification so induced is called a latent image.

When the film is processed chemically, the developer willignore the crystals which contain fewer than 4 metallic silver atoms (because their overall chemical potential isn't sufficient to attractthe 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 silverand forms a visible dark grain. Like any chemical reaction, the action of the developer is progressiveand 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 processoccurs when the emulsion is exposed to light, because the effects caused by90% of the captured photons dissipate before they have the chance to contributeto the formation of the latent image. In 1999, it was shown that this dissipation could be successfullyinhibited.

That could potentially increase basic photographic sensitivity bya factor of ten or, equivalently, allow a comparable decrease inthe 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.  Nature402, pp. 865-867 (23 December 1999).  By  Jacqueline Belloni-Cofler,Mona Tréguer-Delapierre,Hynd Remita  and René de Keyzer.

(2015-06-23)  
Price comparisons (June 2015).

Below are quotes from severalmail-order houses for developing a single 120 rollof 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).

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 opticalenlargements of the negatives.  All the others seem to use a process based ondigital scanning  (whoseresolution 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  (indpi).

Richard Photo Lab  offers two premium scanning options,at $2.50 and $6.50 per roll, respectively.  You can also payextra ($2.00)  to scan with theirfashionableFrontier  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 Kodachromefilm 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 atno 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.

(2015-06-25)  
Some photofinishers require this step ahead of any other service.

Once your pictures are in digital form, you can have them turnthe data files you select, at the time of your choice, intothe 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)...

Although the "enhanced scans" from North Coast Photographic Services  (4824 by 3533)were praised byKen Rockwell in 2008),the downside of that process is that you get the same resolution fromsmall-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 filmin the digital era.  However, you can go beyond that artificial limitation byscanning film yourself, as explained next.

(2015-06-23)  
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 butdefeats 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.

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 inAdotech CMS II,released in July 2014). Yet, that's only half the resolutionclaimed by ADOX for their best film (800 l/mm = 20000 dpi)  which is roughly the diffraction limit of a perfect lens at  f/2.

/D where    is the wavelength of light  (555 nmfor themost 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 isequal 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):

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

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

(2015-07-04)  
The soul of photography.

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

Agfa  (Germany)  now uses the Rollei  name.

Discontinued black-and-white films:

• Agfa 25.
• Efke 25, 50, 100.
• 1933-1987:   Kodak 5060Panatomic-X ASA 32.
• ADOX CHS 25 (620 nm),
• ADOX CHS 50 (620 nm),
• ADOX CHS 100 (680 nm). Discontinued in 2012 because spectral sensitizer became unavailable.  Replaced in 2013 by CHS100 II.

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

Early photographic films were typically orthochromatic,  which isto 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 sensitivityin 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 abrown 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 aroundISO 4 (ISO 6 in the Summer, ISO 2 in the Winter)  and processed slightly more than the recommendeddeveloping 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 backto 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-SpeedInfrared 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 machinesusing 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 ordinaryclear 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 rollof film which is loaded and processed in the usual way  (possibly allowing a longerstay and vigorous agitation in the stop-bath, to prevent corruption of the fixer bythe 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.)

(2015-06-30)  
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 whichmust be processed with the standard treatment normally reservedfor color negatives  (C-41). One example is  Ilford'sXP2. (I find this evolution rather repugnant.)

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

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

For 35 mm film, don't bother opening the cartridge: Instead, pull a little bit of the film out of the cartridge and first cutit square between two perforations  (do this in broad daylight). In total darkness, you can pull out a few inches of film at a time anduse the weight of the cartridge to provide a gentle tug which makesfor trouble-free loading onto aPaterson spool. When you can no longer pull any film out, just cut it offand 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 recommendPaterson'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-useKimWipes (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 properISO)
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).

(2015-06-30)  
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 andthe newer "Super System 4" which I also use.

In the new design, the lightproofing funnel is fully contained within anouter 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 evenneed the lid if you are satisfied with the built-in agitator anddon't use reversal agitation during processing). All the surfaces are now readily accessible.

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 usetraditional stainless-steel spirals and tanks (including the top-rated Hewes brand).

Other vendors are now making Paterson-compatible components which are worthconsidering,  including self-winding reels with larger take-upguide 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 imperviousto photographic chemicals.  Different sizesare available, according to the maximum number of films you intendto process at once.  (#114 doesn't accommodate 120 film at all.)

Paterson  "Super System 4"  Developing Tanks

Ref.	Model	Axis / mm	35 mm	120 or 220	Price
114	35 mm	45?	1	0
115	Universal	85	2 0	0 1	$34.19 w/ 2 reels
116	Multi-reel 3	139	3 0	0 2	$38.95 without reels
117	Multi-reel 5	214	5 3 0	0 1 3	$41.90 without reels
118	Multi-reel 8	345 350?	8 5 0	0 2? 5	$55.95 without reels
119	Auto-load reel				$14.95  Reel only
120	Six-pack				$57.25  for 6 reels

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

Paterson reels  (there's only one model)  can be adjusted to one of threefilm widths.  To do so, rotate the two halves very firmly clockwise  until they disengage.  Then you adjust the widthto 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 thisoperation is easier to do.  That's good because disassembling the reel isthe 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  for127 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 alarge tank  (not including the  3.4 mm  flange at the bottom of the axis). This tells you,  before purchase,  if a given tank will beable 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 of120 or 220 film). That particular combination was also the reason why I stored myprocessing solutions in bottles of  600 mL for many years  (before I learned aboutconcertina bottles). It's also the reason why such bottles were in stock at my localphoto store  (yes, there was such a thing not too long ago).

The above nominal values for the recommended volume of processing fluidare 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 diameterof the reels is  93.6 mm). To obtain the effective cross-section of the tank, deduct from the surface area  of that circlethe 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) / 4  =   74.15 cm²

The volume occupied by a reel  (at any width setting)  isslightly more than  40 ml. The film you put on a reel  (either a35 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 entireprocessing 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 reelby 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)  
The developer turns a latent image into actual metallic silver  grains.

Most people use commercial developers:

• Agfa Rodinal = R09 One Shot = Adox Rodinal = Adonal (5ml/film)
      The oldest developer still in use (1891).  Shelf-life  > 40 years.
• Ilford:  Ilfosol 3, ID-11, Ilfotec Dd-x  or Microphen.
• Kodak:  HC110, D-76  or Xtol.
• Sprint.

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 fullor near "completion".  Instead, best performance is obtained by interruptingthe process with an acidic stop-bath (seenext) at the exact time recommended by the manufacturer for a given temperature.

The key to successful processing is a precise monitoring of the time spentin the developer bath, according tothe effective concentration  (which may dependon the total surface area of the film already processed in it). The pre-rinse  (if any)  and thestop-bathshould 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  becauseit'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 headachesif 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 availablefor 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 temperatureas the developer and agitated with the same care). Agitate continuously for the first minute of development andfive seconds every minute after that...

Once the developing time has elapsed, pour the developer quickly outof the tank and pour in thestop-bath immediately.

(2015-06-30)  
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 controlbut some people are content with plain water, which merely slows downthe 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 than15 seconds).  I recommend soaking the film in an acidic stop-bath between30 seconds and two minutes, but it's not critical. To properly re-use stop-bath, check its acidity eitherby smell or with a color indicator. The stop-bath concentrates sold byKodak or Ilford consist, respectively, of acetic acid or citric acidwith an indicator dye already mixed in  (they're both primarily intended for tray-processingof 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 theindicator becomes visibly dark undersafelightwhen the bath is exhausted.  To make your own aceticstop-bath, you may mix one partwhite vinegar (6%) with 2 to 5 parts water.

Citric Acid   (15 to 20 g/L,  usinghydrate 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 indicatorturns purple  (it's probablybromocresol purple).

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

Designer Stop-Bath :

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

(2015-06-30)  
In 1819, John Hersheldiscovered that hypo  dissolves silver bromide.

Commercial brands of fixers include Ilford, Kodak  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 toappear clear.  Thefixerdissolves 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 wasJohn 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 ammoniumthiosulfate  (NH₄)₂ 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 offixing  (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 amountof extra time. When that total time exceeds fifteen minutes or so, the solution is nearly saturatedwith silver and it's time to dispose of it (you may confirm that fact withEdwal hypo-check).

(2015-07-07)  
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 washquality 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 secondsfollowed by 1 or 2 minutes in their HypoClearing Agent (HCA).  After that, a final rinse of 5 minutes in running waterseems 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 ofethylenediaminetetraacetic 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.

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)  
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 secondsin 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 200, Ilfotol, Fuji Driwel, Forma Flo, Nacco,  etc.

Edwal LFN is so potent that the manufacturer recommends using only 2 drops for500 mL  of tap water  (1 drop is enough with distilled water).

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

(2015-07-04)  
From autochrome plates and Technicolor® to the first color films.

For motion pictures, the impression of color can be achieved by projecting successive frames inthe 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 hedied of a heart attack in 1903. The historical significance of Turner's work was mostly ignored until some of hisoriginal 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'sfirst 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 GeorgeAlbert Smith (1864-1959) from Brighton. Kinemacolor  had some commercial success between 1909 and 1918,under the leadership ofCharlesUrban (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 workbyMaxwell 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 FrenchmanLouis Dufay)  and the similarGerman Agfa-Farbenplatte  (Agfa color plate).

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

The Technicolor Motion PictureCorporation  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 wasa 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 reproducecolors additively  for their audiences. System 1  was first usedto shoot and print the film entitled The Gulf Between  (1917).

In 1922, the films shot by those same Technicolor cameras wererecombined into a single subtractive  laminated printcontaining the proper color pigments. Such prints could be projected by unskilled projectionists using whitelight. This was called System 2.

In 1928, System 3  was introduced, which didaway with the cemented laminates and producedsingle-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)  andOscar-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 lightand letting red and blue through). It exposed two strips of  B&W  film with their emulsionsides pressed against each other.  The front film, sensitiveonly to blue light, had an emulsion with a thin superficial orange-redcoat.  Thus, only red light reached the panchromatic film in the back.

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

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

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 colorfilm as we know it today:  a single celluloid film with three differentlycolor-sensitized emulsion layers.

On April 15, 1935,  Eastman-Kodak officially introducedthe 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) andLeopold Mannes(1899-1964)  whose early research had so impressedKodak'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, butthe chemists at Agfacame 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 onthe older Frenchautochrome 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 atUFAhad to yield to the demands of the infamous Minister of Propagandaof 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 testswith a few dismal failures  (yellow grass and such) but a near-perfect end result (1941).

(2015-07-14)  
Agfacolor, Kodacolor, Ektar, Fujicolor...

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

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

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

(2015-07-01)  
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 ofcurrent color negative  (CN)  film. Other manufacturers use different names for equivalent processeslike CN-16 (Fuji) or AP70 (Agfa) but everybody mentions Kodak's C-41 as themain 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 thesame lab using the same chemistry.

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

Nevertheless, the process can be performed at home with ordinary black-and-whiteequipment.  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 criticalstorage 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  Kit	Rolls /L	1 L	2 L	5 L
Rollei C-41 Color Kit	16	$44.99		$74.99
Tetenal Colortec C-41, liquid	12	$24.95		$76.99
Unicolor C-41, powder	8	$21.99	$33.99

(2015-07-04)  
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 positiveform, including color balance,  directly from the film (possibly with the help of a magnifier). Color prints of superior quality could be produced from positive filmas easily as they can be obtained from negatives, usingCibachrome/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 projectionin family circles or elsewhere. Slide projectors became very popular in education and conference circuits. For intensive use of some slides, the cardboard was discarded andthe film mounted in a plastic equivalent between two thin windows of glass. This helped minimize deformations of the celluloid under the intense heatfrom 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...

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 Kodachromeprocess introduced in 1935. The production of both Kodachrome films and Kodachrome chemistrywas discontinued by Kodak in 2009. The last lab to operate a Kodachrome line was Dwayne's Photo,  which stopped acceptingKodachrome film at YE 2010 and processed its last Kodachrome roll onJanuary 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).

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

E-6  Kit	Rolls /L	1 L	2 L	5 L
Tetenal Colortec E-6, liquid	12	$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 numberof films which have been processed or are being processed in them.

The range and precision of temperature measurements are compatiblewith medical thermometers but most of thosearen'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 photographerswith 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 processwith 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.

As of March 2012, Kodak discontinued the production of all formsof color-reversal film (CR). A few ektachrome rolls remained on sale because they were refrigeratedto prolong their useful life.  Then, in January 2017, Kodakannounced that it would resume production of Ektachrome film in the Fall of 2017. A full-scale re-launch is expected for 2018, in 35 mm and Super 8 formats.