B&W FILM PROCESSING 05

PART 5 OF 5

The Test Roll

Everything we have done up to now is to set the stage for the evaluation of the film, developer and time combination.

The first thing to do is go into the darkroom and make a test wedge of a part of the roll so that we can produce an accurate depiction of what’s happening on the film.

Test wedge

Take a short strip of the test roll approximately 5 to 6 frames and using grade 2 of your paper choice begin to make a stepped exposure wedge.

Firstly, stop down the lens on the enlarger so that you can end up with an exposure time of approximately 35 seconds. The steps in the wedge should be 5 seconds apart. That way we end up with a step wedge showing an exposure from 5 seconds to 35 seconds in 5 second steps. My reason for suggesting 35 seconds in total is because it gives you a sufficient amount of time for dodging and burning in the future.

How to evaluate the exposure wedge

The first thing you are looking for in the step is which step creates ‘maximum black with minimum exposure’. Redo this step until you have approximately a 35 second exposure for maximum black. This is done by stopping down the enlarging lens and or raising the enlarger head. Note that you should be looking at the rebate (sprocket hole area of the film NOT where the image is) and that you should be doing it in 5 second steps.

Its important to remember that when you have decided where that is and what the exposure is you should always repeat the exposure in 5 second bursts as photo paper has a reciprocity failure and 7x 5 second bursts is different to one 35 second exposure burst.

This is called ‘Minimum exposure for maximum black including film base plus fog’.

After doing the above the next step is to create a contact sheet of your test roll using this 7 x 5second bursts totaling 35 seconds. Mark the spot on the height of the enlarger and take notes of enlarger lens and f stop as you will use this from now on. This is done for consistency and repeatable contact sheets from now on.

Firstly, don’t worry if the images on the sheet look too light or conversely too dark as we need to know exactly what the film/development/time combination produces.

What we can learn from the contact sheet

  • Did the camera under/over expose?
  • Do we have a desired amount of shadow detail?
  • Are the highlights blocked up or conversely so underdeveloped that they just look grey?
  • Shortcomings in our processing technique.

Shortcomings in our processing technique

You can get a variety of the following; we all have from time to time. All of the following can be cured when we review and modify our film handling during processing.

  • Pump streaks; caused by excessive agitation which shoots the developer through the sprocket holes and creates areas of higher density
  • Bromide drag; this looks like mottled, dirty uneven highlights. Its caused by insufficient agitation. Sometimes associated with stand development and it is also more noticeable on sheet film development.
  • Air bells; these look like dark round spots. They are caused by not tapping the tank at the end of the agitation cycle on your bench. As I have previously said the tapping of the tank after agitation is to release the bubbles from the emulsion so that they rise to the top of the developer.
  • Crimping the film when loading it into the reel. This results in high-density areas.
  • The film sticks in small areas to itself during loading into a reel. This shows as areas of undeveloped film
  • Static marks; these look like star bursts on the film and usually happen during winter months when the air is too dry. This happens in camera and is associated with our handling of the film when it’s loaded into the camera.

So what does our contact sheet look like?

This evaluation step is critical and you should take notes of what you see.

  • If the images look too dark overall and remember you exposed the film at half the manufactures recommended ISO. You need to reduce the ISO and redo (shoot another roll of film and develop it). You have to do this until you get a contact sheet that looks good to you. It’s worth noting that any density below zone 5 (all the shadow density) is created by exposure and not so much influenced by development.
  • If the images have good shadow detail but the highlights are grey and muddy you will need to increase the development time. Then re-shoot a new test roll and review the results. If the development time starts to become excessive then you should change the developer dilution so instead of D-76 at 1:2 change it to 1:1.

Note: This is the most important!

You should only change one thing at a time and then re-shoot another test roll. So that you can either, rule out and continue the way you exposed/developed the first test roll and change another parameter to further refine your processing.

This will be the last posting of the development cycle. I will revisit the pages as this blog progresses and update with new information. The new information will be highlighted to make it easier to locate and read.

My next post will be about what I’m thinking about and listing upcoming book reviews from my own shelf. I will only review books I have purchased in the last 6 months and are on my shelf.

I would encourage anyone who has questions regarding the development of B&W films to leave comments and I’ll get back to you.

All future posts will be titled ‘Blah, Blah, Blah’.

Have a good one and see you soon.

Tom

Part 01

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