Lesson 14 The Underwater Photo Course
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Preparing the slides

Now that you have successfully exposed your slides, the next step is development.

Holiday vs. Home developing

Of course, it may not be that easy, and you may be in a remote location where slide developing is unknown or unreliable. In such cases, it is preferable to keep your film in its original canister, and in a cool and dry place, until you can take it home and have it developed there.

The value of having your films developed soon after shooting, especially on a longer expedition, is invaluable. It permits you to quickly spot any camera or lighting faults you have ("I'm sure the strobe fired every time"), and allows you to accurately assess your results and correct any problems you might have on the spot, before you shoot the next roll of film.

The downside is that poor processing will ruin whatever shots you have already taken, however good the results. I had four rolls of film developed early one holiday by the local lab, and was just not happy with the quality of the results, which left a slight haze in the emulsion. I was later to discover that this was due to an exhausted final fixing bath, that had left the emulsion still slightly light sensitive, and when I finally had the rolls re-fixed at my home lab, they were hopelessly overexposed and lacking in contrast and colour.

If you have any doubts about a lab, take a test film out with you, and submit that to them at the beginning of the vacation. If they ruin this, then you have not lost anything, but if they appear to develop it correctly, then you can approach them with your real shots with slightly more confidence.

With very few exceptions, most airport X-ray machines are quite safe for the ISO 50 to 200 film that we underwater photographers use, but if you want additional peace of mind, then go out and purchase one of those lead-foil bags designed for carrying film in airports. Always carry film, exposed or unexposed, in hand baggage, as X-ray units used for hold baggage may be considerably more powerful.

The development process

Most films that you use will require development in E6 chemistries, with the exception of Kodachrome emulsions which require K-14. The K-14 process for these films is complex and requires special equipment. Kodak and some other firms are equipped to process Kodachrome films, and you are best advised to use the agent in your country. In many places Kodachrome is only sold as a process-paid film, and it therefore does not make economic sense to process this in any other way than by sending to the lab in the provided envelope.

E6 chemistries are designed for high-speed machine processing at high temperatures. Process times are so short and solutions so warm that meticulous quality control is essential for good results. For this reason, home kits are available which are adaptations of the main processes, often with simpler chemistry, lower temperatures, and longer process times. Despite this, home chemistries require careful temperature regulation, usually at 100.4 degrees Fahrenheit, with little leeway for error.

Generally, at a processing cost of about UKP3.00-4.00 per roll for developing in a professional lab, there isn't a very strong argument for do-it-yourself processing of E6, unless you are particularly keen on doing it for the sake of it, don't have easy access to a lab, or shoot large quantities of film every year, meaning probably over 250 rolls.

Process paid films work out even cheaper, at between UKP2.00 and UKP2.50 per roll, which is much better value bearing in mind that the slides are also returned to you in plastic mounts, and are frequently numbered as well. However, not all films are available process paid, and those which aren't must be developed by a lab of some description, which will be happy to mount your sides, and even label them, for an additional fee.

Intended changes in effective film speed of Ektachrome films can be adjusted for by processing. Push processing increases the effective film speed by overdevelopment, and pull processing decreases the effective film speed by underdevelopment. Ektachrome can be pushed as much as three stops, and pulled by up to two stops, meaning that an ISO 100 speed film can be exposed at up to ISO 800 or down to ISO 25, and corrected for in development.

Naturally, this over/under development requires an extension or interruption to what is usually an automatic process, and labs will frequently have to do special processing runs just for your film which will attract a surcharge of probably 100% or more. Push/pull processing in underwater work generally means that you didn't select the right film in the first place, or ran out, and is best avoided. Films rated at ISO 100 usually give their best performance at this speed, and push/pull processing is bound to affect the final quality of the image.

Common processing faults

Even if you swear never to do your own E6 processing, you still need to be aware of the common processing faults, so that you can complain when you have to, and not put the results down to some fault of your own.

Most problems with E6 processing arise when one solution is contaminated with another, or less commonly, when solutions are exhausted. Symptoms may be

A green cast

Other colour cast

Dark transparencies and a blue cast

Dark transparencies without a blue cast

Light transparencies and a yellow cast

Light transparencies without a yellow cast

Areas of light density

There are a number of other possible problems, such as fogging due to light getting on the film either in the camera, or before or after exposure, and the milky results I mentioned earlier from an incorrect fixing bath. Remember that any processing fault will affect the film edges as well as the image itself, so a green cast that appears in the image, but not on the rest of the emulsion is more likely to be your fault than the developer's.


Usually it will be your choice as to how the film is returned to you. It may be returned in one long strip, cut up into strips of 4, 5 or 6, or placed into slide mounts for you. It is up to you to decide and specify the method that you find most convenient.

Slide mounts that are returned to you from the labs will usually be single-use plastic mounts sealed by special glues, or 'spot-welded' either thermally or ultrasonically. AGFA process-paid films are returned in special CS mounts to fit the CS slide storage and projection systems.

If you are mounting your own, then you have a choice of either the CS, or standard 2 piece with or without glass on each side. The use of glass helps hold slides in place, and prevents loss of focus due to 'popping' when used in projectors. Special glass, called 'Anti-Newton' prevents diffraction rings forming where the emulsion touches the surface of the glass.

Cutting and mounting your own slides is an easy, but time consuming process. I do all my own, as I use the CS system, and few labs stock these mounts. One word of warning - even with a newly returned 'dry' film strip, there is likely to be some degree of water still held in the emulsion which will dry out further over the course of a few days. During this time, the emulsion is still quite soft, and is very prone to scratches, so if you must mount during this time, be especially careful not to damage the film emulsion.

Viewing and editing

I personally don't mount any of my slides until I've been through this step. I see no point in mounting slides which I'm unhappy with, or know I'll never use. As rolls of developed film are returned to me, I cut them into strips and store them in A4 negative binders, throwing out strips that contain no exposed images. I find this a compact and efficient system of initial storage - the slides can easily be pulled out and mounted when I want, or have time, and will stay there happily until then.

Obviously, if your slides are returned in mounts, then you can immediately see them, the two obvious options being,

although there exist various pieces of equipment that fall somewhere between the two, but which I have yet to find a burning need for.

My primary editing equipment consist of an A4 lightbox, balanced to natural daylight, and a small cheap 8x magnification lupe. As all things, you generally get what you pay for, and lightboxes vary in price from the cost of a few rolls of film to over ten times that amount or more. Lupes come in a variety of shapes and sizes from a common-or-garden variety such as I use for under 10, to the Nikon 8x lupe at around 20, to the Nikon 4x lupe and similar models from other manufacturers for about 80. Of course, we mentioned earlier that the trusty 35mm Nikonos lens makes a very good lupe, when you can spare it from its paperweighting duties.

In the process of editing, you should be prepared to throw out (or choose not to mount) anything that you consider is not up to the standard you have set yourself. Of course there are exceptions, and generally I keep (or mount),

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This page was last updated on 11 August 1998
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