Color Print Film for Photomicrography

Text and photography copyright Thomas Webster 2003. All rights reserved.

 
 
 
 
 
 
 

One of the sheer joys, to me, of owning a microscope is that I am capable of sharing what I see with others through the use of photomicrography. It is quite satisfying to acquire personal knowledge of a subject or organism but it is much more satisfying when that knowledge can be shared. I dabbled in sketching my observations for a few years and came to the conclusion that I needed to find a different avenue of recording my observations. When Paramecium takes on the appearance of an amoeba, well then, the accuracy of my drawings may be called in to question! Needless to say I needed another way to record my observations.

I have had a lifelong love affair with photography, so it was only natural that I turned to using the camera to record my observations. Mind you, I am not a scientist attempting to record scientifically accurate images. I am just an ordinary guy wanting to share what I see with my friends and colleagues. At first I made my images with color transparency films. This was OK for a while but started to get expensive. Transparencies would have color casts and I would have to add color correction filters to the light path to eliminate the color casts in the transparencies. Basically, a roll of film would be shot, processed, inspected, and reshot if necessary. My rejection pile of transparencies rapidly exceeded my "keepers" pile. Because of the necessity of reshoots, this was getting expensive! The cost of the color transparency film plus the cost of processing was adding up. Sure, I bought my film in "bricks" so that I would have consistent color reproduction for a while but transparency film is very touchy when it comes to exposures and this made for the need to bracket my exposures. Improperly exposed transparencies outnumbered properly exposed transparencies 3:1. I needed a better film for my needs.

A few years ago I tried some color negative print film. I reasoned that it was much easier to hand around 4" x 6" color prints for people to view than it was to drag out a slide projector and screen for a slide show or to force people to view 35mm transparencies on a light table with a focusing loupe. Frankly, I was unimpressed with the results. Machine-made color prints still had color casts to them depending on the care in color correcting the prints exercised by the person operating the printing machine. I was also disappointed as to how little contrast and color saturation the machine-made prints recorded. I could have hand-printed photographic enlargements made but this ran into quite an expenditure, too. I shelved this idea and continued to photograph my subjects using color transparency film.

I turned my thinking around when the digital revolution hit. I purchased a dedicated film scanner for my professional photography and decided to go back and scan some of my older color negative photomicrographs. After a little experimentation I found I was able to make scans of the negatives that competed fairly well with the scans of my transparencies. Scanning the negatives and manipulating the images in Adobe Photoshop® allowed a great deal of leeway in removing color casts as well as creative cropping and selective sharpening of an image. With the advent of photo-quality inkjet printers I could make relatively cost effective prints of my negatives to share with my friends and colleagues. I decided to take another look at using color negative films for photomicrography.

 

Today I use color negative print films almost exclusively for photomicrography. I have found several advantages in doing so. First, color negative emulsions have come a long way in terms of color saturation, contrast, and sharpness. Older color negative emulsions had coarse grain compared to color transparency films. Today's color negative films are approaching as fine emulsion grains as color transparency films. The ability of today's color negative films to capture fine image details has been improved by an order of magnitude as compared to color negative films of just a few years ago. Color saturation and contrast have been greatly improved, too. Today's color negative films have greatly extended exposure ranges as compared to color transparency films.

A second advantage to using color negative film is that the exposure latitude of print film is greater than the exposure latitude of color transparency films, especially when image tones approach the lighter end of the exposure scale. As little as 1/2 of an f. stop in exposure error can spell the difference in having details in lighter image tones or losing those details when using color transparency films. Color transparency films generally have an exposure range of approximately 5 f. stops from pure black to pure white in a transparency. Color negative films expand that range to approximately 7 1/2 f. stops. This is an advantage in recording those lighter image tones. Whereas with color transparency films if you overexpose the light tones any image detail is lost in those tones, if you overexpose color negative films, the details are still recorded on the film and the details can be retrieved with a little extra work with the scanning software.

Color transparency films must be exposed carefully to retain details in the highlight areas of the images. Because the exposure latitude of color transparency films is so limited, details in darker image tones can be rapidly lost, too. However, with color negative print films having an extra 1 1/2 f. stops to 2 f. stops extra latitude, more highlight and more shadow details may be captured in the image than can be captured using color transparency films. This becomes especially important when scanning the images with a desktop film or flatbed scanner. Desktop scanners have limited dynamic ranges (the ability to record slight differences in tones in highlights and shadows of an image) and the best images to scan are those that contain maximum details in both the highlight and shadow areas of the image. My film of choice for photographing crystals through my microscope is Kodak Gold 100 color negative print film. This emulsion is almost too saturated for general photomicrography but is just what is needed for recording the colors of crossed-polarized crystals. In fact, the color saturation of this emulsion is greater than my scanners ability to record the colors produced by the negatives!

 

The expense of making photomicrographs on film cannot be ignored, either. A 36 exposure roll of Fujichrome Velvia 35mm color transparency film costs about $4.50 US per roll under the best of circumstances. Processing the color transparency film will cost, on average, $5.00 US per roll. Some labs charge more, some labs charge a little less. Cost per image then becomes about 27¢ US per image if there are no reject images due to exposure errors. If you keep one image for every three images you make in a bracket of exposures, then the cost per image rises to .79¢ US per image. Color print film, on the other hand, may be purchased for considerably less. I purchase 24 exposure rolls of 35mm Fujicolor Super HQ color film for $4.99 US for 4 rolls in a pack of film. This works out to $1.25 US per 24 exposure roll of film. Processing only for a 24 exposure roll of color negative print film will cost, on average, $2.50 US per 24 exposure roll. If all of the images are "keepers" then the average cost of an image on color negative print film is approximately 16¢ US per image. I average about 18 keepers per each 24 exposure roll of print film. My final image cost works out to about 21¢ US per image. This is nearly 1/4th the cost of using color transparency films! This allows me to make 4 times the number of images on my limited film budget.

I can hear some of you already thinking that the costs I have presented do not include the costs of making prints from the color negatives. That may be true but keep in mind that my "final" purpose is a digital image, not a physical print. Whether I make my images on color negative films or color transparency films, scanning these images to make digital image files requires the same amount of time and effort. It becomes a "wash" as far as scanning expenses go. If I want a physical print of either an image from a color print negative or from a color transparency image I would use the same output devices for either type of film.

 

Speaking of output, I sometimes print the scans of my color negatives on a photo-quality inkjet printer. Passing around small 4" x 7" or 5" x 7" prints is still an easier way to view my images than setting up a slide projector and screen and is much better than having a bunch of people crowding around a computer monitor. Today's inkjet printers are truly amazing and the output rivals photographic prints in many ways. Having a "digital darkroom" allows for ultimate control over all aspects of the image's appearance. I have printed my favorite images as 11" x 14" prints and hung them on my walls. Visitors to our house cannot distinguish these prints from my many other photographic images spread throughout our home.

If I need a transparency made from a scan of a color negative I use one of the many "digital darkrooms" advertised on the Internet. If I need slides simply for projecting on a screen I have slides made at Color Services in Santa Barbara, CA, USA. I send them the image files and they send me excellent, 4k 35mm slides for $8.00 US per slide. If I need reproduction grade transparencies I use a local professional photo laboratory that outputs image files with a Kodak LVT film recorder, the best in the business! Of course, these come at a much higher cost!

Recently, Fuji has introduced the Fuji Aladdin ADPC IV Digital Photo Center in many department stores and drugstores. The Fuji Aladdin Digital Photo Center allows photographers to input images off of Cd's or digital camera memory cards and make prints of their images as either wallet-sized, 4" x 6" or 6" x 8" sized prints. Rather than printing a large group of 4" x 6" prints on my inkjet printer to hand around to my friends I will save the image files to a CD-R disk and print them out on the Aladdin Digital Photo Center printer. Prints are made on specially coated Fuji papers and are nearly indistinguishable from regular photographic prints. The quality is very high and the cost is extremely reasonable. Our local Walgreens Drugstore charges a mere 29¢ US for a 4" x 6" print!

My favorite color negative films are Fujicolor Super HQ ISO 100 and Kodak Royal Gold ISO 100. For general photomicrography I will use the Fujicolor film. The images of the copepod nauplius and Paramecium accompanying this article were made on Fujicolor color negative film. The images of magnesium sulfate crystals were made on Kodak Gold 100 color negative film. The Kodak Royal Gold is a fine emulsion for very saturated subjects but is a little too "brutal".

I rarely expose these films at the rated ISO settings. Camera meters don't seem to analyze a scene lighted by backlighting, even though the subject is transparent, as they would a scene lighted by reflected light. I have found that most cameras have a tendency to overexpose these films when used for photomicrography. When using the microscope's tungsten Kohler illumination system I rate both of these films at EI 200 or EI 300. With both films I have to adjust the color temperature of the light with an 80B filter to yield daylight temperature lighting. The 80B filter also makes a fine filter for visual observation. When I use a modified electronic flash as the light source, I dispense with the 80B filter (the electronic flash is already daylight temperature) and rate both films at EI 300.

 
 
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