Test Targets for Dialing in B&W Development

[Sam L]

I've been playing with 510 Pyro with x-ray film and I'm trying to dial in ISO in different types of light, dilutions and development time. I've been creating stacks of the same photo of a sculpture I own lighted such that it has bright and dark sides, bracketed -1/0/+1 and targeting ~7 min development time. I have gotten to a point where I'm getting a reasonable negative but I think my current approach is too ad-hoc and I need to do something more controlled for the test target.

What are some good ways to approach this?

What do folks use for a test target?

[Doremus Scudder]

I like real-life subjects with a full range of tones and clear areas I can read easily with the spotmeter and place where I want them. Examining shadow detail tells the story on E.I., and seeing if the highlights fall correctly indicates development-time tweaks. Using a real subject with real lighting and both light and dark tones automatically takes lens and in-camera flare (which is a significant factor!) into account. Using a grey card or the like doesn't. Your sculpture may be just fine.

Remember it's not rocket science; we only need to get exposure full enough for the shadows we want and development close enough so that our contrast controls in the darkroom are adequate to make a fine image.

Best,

Doremus

[ic-racer]

Meters are calibrated to give an exposure to the film so the darkest parts of an excellent print have a slope on the H&D curve of three-tenths the slope of the straight portion of the curve. A super easy way to approximate this is the ASA method, whereby you can expose a uniform target to Zone I. If the processed negative cuts 1/3 of a stop more than a blank frame when placed over your meter, the settings to make the exposure were OK.

[Sam L]

Doremus and ic-racer, thanks for the tips. I'll try both directions.

I think I need better control of the lighting. The tricky part is that the film responds differently to different light because it's not panchromatic. Mid day ISO will be different than early or late in the day or artificial light. I might go with the uniform target to test the different ISOs and the introduce a more realistic target to verify and fine tune.

Thanks to both of you for pointing out that the exposure is for the shadows / zone I. While I know that and practice it when shooting, I somehow lost sight of it for this test.

[ic-racer]

Placing a diffusion sheet on the inside of a window works. If you move in close to frame it make sure the lens stays on infinity.

[Sam L]

ic-racer,

For the ASA method, how does development time play in?

[ic-racer]

ic-racer,

For the ASA method, how does development time play in?

To be exact, ASA specified development to achieve a specific point on an H&D curve. But for first time testing, consider that development has minimal effect on Zone I.
So, set your exposure index first, with a Zone I shot, then work on development time. When you have your development time you can go back and re-check the Zone I and see if it got lighter or darker based on your development time.

To keep expand on this KISS method. You would expose a Zone VIII image at your EI determined above. Make a print of minimum exposure to produce maxiumum black on the film base. Place a coin on the paper and expose the Zone VIII frame with those same settings on the enlarger. If you just see an outline of the coin, negative development time to match that paper is good.

[ic-racer]

When I first did this in the 1970s, I went hog-wild with minimum exposure for maximum black and wound up with negatives developed to way too high gamma. In real life, you can probably go with the enlarger exposure of the film base that has just at touch of gray. Otherwise the method will lead you to too much development time, compromising the mid tones.