Alan Marcus

You can check for light leak easily. Place a small keychain flashlight inside the camera. Sit in the darkroom with the camera on your lap. Waite for your eyes to dark adapt, about 15 to 20 minutes. Examine the camera from all angles. What leaks in also will leak out!

Manufactures of films, papers, and chemicals have had nearly 200 years to perfect their art and science. In this era of the digital image, don’t expect big strides in chemical photo techniques. That being said, the technique of chemical manipulation to alter results was routinely practiced. Mosly out of desperation due to exposure errors and darkroom misstates. Alteration of the dilution of the developer induces slight changes in contrast. A little more contrast can be had if Dektol is diluted 1:1 instead of the recommended 2:1. Developing in the stock solution straight, squeezes out a tiny bit more. The “normal” is 2:1 @ 68° 90 seconds. This delivers maximum dynamic range. This time / temperature recommendation is not engraved in stone. We needed to alter time in solution based on temperature and declining developer activity due to the number of prints that have been “souped”. A 2:1 Dektal affords time for the developer to percolate into the emulsion and do its thing. Too strong / too weak -- upsets the fresh developer in -- spent developer out cycle.

Color films are tweaked based on how the displayed image will be produced. Amateur films are made more contrasty because the camera is likely to be equipped with a substandard lens and because there will likely be a long delay between exposure and processing / printing. Professional films are fabricated with less contrast because this generates a longer tonal scale. Cine negative films are an intermediate step in the making of positive release prints for the theater. Movie projectors systems use high-quality lenses, and the image will be shown in a darkened room. Thus, the cine negative film has lowered contrast. If these films are to be used in a still camera developed and printed by printers with a diffused light source, exposure modification will make a better match film–to-final-output method.

The first Kodak product to bears the name Kodachrome was marketed in 1913, an invention by John Capstaff. Two separations black & white negatives made on g;ass glass plates. One exposed via a cyan filter, the other exposed. filtered red-orange. One glass plate was a panchromatic emulsion, the other insensitive to red light. They were both exposed in the camera as a sandwich, emulsion to emulsion with a red filter between them. This two-color process was marketed in 1915 as Kodachrome. It was later adopted as a method to make color motion pictures on 35mm film, mainly used in the making of cartoons. Originals at Library of Congress "Two-Color Kodachrome Method"

I use ordinary glass cleaner on my computer and TV screen, never had any issues. Works for me. I also use Windex on my eyeglasses and camera lenses, works for me. At the lens shop they use alcohol, vodka works (not kidding).

I have never seen this antistatic device. However, many such devices were available for darkroom use. Both black & white and color films naturally pick up an electric charge that attracts dust and lint. We used an antistatic device on each film just before we placed them in an enlarger. These devices quickly naturized the film's static electric charge. We followed up using a fine brush or blast of canned air. We did this because the enlarger naturally magnified any object that was on the film during the printing operation. If not removed, a white speck or outline of hair or the like is transferred to the print we are making. Dust removal was thus an important step in the dark room. Such antistatic devices are also sold on the internet to remove dust from CD's and DVD. These modern antistatic guns work on film. I would choose a modern one vs. the Durst model of years ago.

Member With the color head installed there are 2 configurations specified by Beseler condenser or diffusion. The optional 35mm mixing chambre allows shorter printing time when the enlarger is configured for color printing. This diffusion mixing chamber concentrates the light output over a 35mm film for faster printing. That might be useful in making large prints. The larger diffusion mixing chamber is for use with any sized negative (including 35mm) and is required for enlarging films bigger than 35mm.

Color photography is rooted in mixing varying proportions of the three light primary colors. We use red, green, and blue, the additive primaries. Such a system generates all of the spectrum colors, however spectrum colors are only approximated whereas most ordinary colors can be matched exactly. Now purple and magenta do not appear in the spectrum, however they too are produced approximately via this system. After the picture is taken, it must be somehow presented to our eyes. We us the additive system for TV and computer display but photo films and prints are best when a subtractive system is used. Both systems fracture the picture into super tiny elements. We are talking about pixels (picture elements) the smallest fraction of a picture that can convey intelligence. The additive system adjusts the proportions of red, green, and blue that reach our eye by controlling the relative intensities of red, green, and blue as displayed on a TV or computer screen. The subtractive system uses the complements (opposites) of red, green, and blue which are cyan, magenta, and yellow. The density of the cyan dye controls the amount of red light that reaches our eye. The magenta dye controls green and the yellow dye controls blue. These work together to control the amount of red, green and blue light that reaches the eye. Keep in mind that modern color films are complex. All are basically black & white film infused with colored dye. These films are silver-gelatin blends. Salts of silver react to light and when exposed become developable. The developer seeks out exposed silver salt crystals and reduces them to metallic silver and a soluble component. The metallic silver forms a black & white image of the vista. Cyan, magenta, and yellow dye are also included in this mix. The dyes used are incomplete. The three are missing a single needed ingredient which is in the developer. In other words, they are in a Leuco state (Latin for white or blank). The waters of the developer contain dissolved oxygen. As developing proceeds tiny tuffs of metallic silver, making up the image, form. The metallic silver is speedily attached by oxygen. This is the catalyst that causes the missing dye ingredients to unite with the Leuco dye. The dye blossoms forming the color image. They silver image conceals the color image. The silver will be afterwards removed. Finding cyan, magenta, and yellow dye that are Leuco and all missing the same ingredient is a challenge. The problem has never been satisfactorily solved. The yellow dye we use is OK, the magenta dye is fair, the cyan dye is poor. In the negative process, the poor cyan and magenta dye can be alleviated by giving them a warm tint that dissipates when they fully blossom. This forms the orange coloration you see in negative films. The two residual warm tints form two positive corrective images superimposed over the three negative images. Bottom line, to this date we have never been able to make a film or photo paper that yields a faithful image of a vista. The compromise is to make film and photo papers that deliver good facial tones. To this end, some color matching is forfeited.

By archival, the film image is suitable under archival storage conditions with a 100-year storage life. Modern color films are black & white films that additionally contain dyes that replace the black & white image with dye. Modern black & white films properly processed and properly stored can meet his definition. The dyes used in color films come from organic sources thus they are fugitive (they fade). As to color film being preserved on black & white film. I cannot confirm or deny. That being said, the original Technicolor process of 1928 used a camera that exposed three black & white rolls of film simultaneously. The image from the lens was directed through a prism and mirror system. One beam was filtered red, one green and one blue. These individually exposed black & white film (three separate rolls of film). These were the masters. Copies were made on three special rolls of black & white films chosen because they tolerated a developing process that caused the gelatin emulsion to bulge and deflate (ungulate) in proportion to density of the black & white silver image. In other words, a relief image somewhat like a rubber ink stamp. The red image film was soaked in cyan, the green image film in magenta, and the blue image film in yellow dye. These were pressed in register on a receiver roll of non-photographic film. Called an imbibition process, the result was a full color film suitable for projection. The three master films were the ones that needed to be archrival. The Technicolor method was very popular. It was replaced by color film called a try-pack. It has three emulsions coated on a single support. The dyes used are imbedded in the film during manufacture. Modern color film movies are made using a negative color film that is the master. Release prints are copies. made on copy film, they are positive image (transparency for projection).

The archrival properties of film is highly dependent on the adherence to the specifications of the developing process and on the storage conditions that the product undergoes. In the black & white process, the image is comprised of metallic silver imbedded in gelatin coated on an acetate base. The enemies are heat, humidity, moisture, and contamination. Moisture damages the gelation and promotes the growth of algae and mold. Contamination promotes chemical debasement of the silver image. Films made before the mid 20th century have a base made of cellulose acetate. This base deteriorates and becomes an explosive. Color film has the same enemies plus the dyes fade over time. Adherence to processing specification grants the best archrival results (100 years). Proper fixing and washing, is the key plus color film requires a proper stabilizer step. The stabilizer supplies a biocide and a gelatin preservative. Premature failures are likely due to improper fix, wash or stabilizer steps. Professional movie processors are less likely to make a mistake thus I think movie film has the edge when it comes to longevity.

@Ed_Ingold: The square root of 2 is 1.414 (1.4 will do nicely). To find the dynamic range we indeed divide the density range by 0.30. We do this because the time-honored unit of exposure is the f-stop. The increment of change of the f-stop is a doubling (2X increment). Density is measured using logarithmic notation base 10. The value (number) 2 converted to logarithmic notation base 10 is 10 elevated to 0.301 power. In other words, 1 f-stop exposure change yields a density change of 0.30 density units. However, this requires that the plot of film have a slope angle (gamma) of 1. Most films have a gamma of 0.8. This reduces the effect of one f-stop change to 0.30 X .8 = 0.24. Photo papers have a gamma of about 2. Thus 1 f-stop change yields 0.30 X 2 = 0.60. This gamma of 2 is due to the fact that we view prints by the light of a nearby source. This light plays of the paper traverses the image on the paper, hits the white undercoat and reflects back through the image to our eye. In other words, the viewing light makes two transits through the image to arrive at our eyes. The typical dynamic range of film is about 256 (about 8 f-stops). The dynamic range of chemical-based photo paper is about 32 (5 f-stops) for a glossy paper, less, maybe 4 f-stops for a matte paper.

For reversal films, the net density (density over base plus fog) is specified as 0.20. The formula is 8/Hm where Hm produces the stated density. From page 304 The Focal Encyclopedia of Photography.

Test it yourself easy to do this! Cut off a snippet of the film leader protruding (tongue) from a 35mm film cassette. In normal room light, swish this snippet in the working strength fixer solution. The film snippet enters the solution opaque gray. In just a few minutes, it begins to clear and turn transparent. Time this reaction. The correct fix time is twice the time it takes to become clear film. Work every time as this is a valid test procedure.

Photofinishing automated film processing machines require that the various solutions be replenished, a technique that keeps the solutions at working strength indefinitely. The film as it develops liberates bromine which is a restrainer. This restrainer is needed as it allows the developer to differentiate between exposed and unexposed silver salts. Thus, the developer replenisher formula is void of the needed bromine. We add starter (bromine) to the working tank when we initially mix a fresh tank. The bleach step follows the developer step. The developer solution is alkaline. Developer carryover is riding piggyback on the film. This carryover drives the bleach solution alkaline. The bleach replenisher is at the wrong pH for a working solution. In other words, carryover is required to set the pH in the working tank. The bleach stater is ammonia. This is a gas in a water solution. We add the blech starter when we make a new bleach tank from a blech replenisher formula. Ammonia effervescences out of solution. Thus, the bleach stater is a temporary pH adjuster. Carryover keeps the PH correct thereafter.

The 120 film paper backing has fathered edges that act as light traps. Likely no harm - no fowl.