5/10/2026

Film Reciprocity Failure

This image is shot from the ground at the bottom of the spiral stairs in the Hatteras Lighthouse.

I had recently converted from 35mm to Hasselblad medium format, choosing the square format to make me rethink composition.

Shooting black and white film took me back 40 years to my first use of a camera (same 120 Kodak roll film). I had to learn what reciprocity failure was and how to calculate its effect on exposure time.

Reciprocity failure is an understanding that the longer the black and white film is exposed the less sensitive it becomes. The film is supplied with its reciprocity factor.

This exposure was for 30 minutes due to the low light, slow film and the reciprocity calculations.

11 Comments

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Courtney LangmoreMay 11, 2026

Going back to the same kind of film you started with 40 years ago is such a full circle moment. The Hatteras Lighthouse staircase sounds like it was worth every one of those 30 minutes.

Bill RichardsMay 11, 2026

Thirty minutes at the bottom of that lighthouse for a single frame. I can barely sit still for thirty minutes doing anything, let alone holding that kind of focus. And the fact that it brought you back to your first camera forty years ago makes it even better.

Bruce BurkeMay 11, 2026

Nice work. Oddly enough, I had just looked up the failure rate for TMax and it doesn't start until you pass 10 seconds, so you must have been shooting in candle light!

Chris BoeseHuman-Made ArtMay 11, 2026

Old film stuff, and 120! Do you remember Pan-X? So smooth. I even did a little 4x5 for a hot minute. Speed Grafix.

I shot 35mm and pushed Tri-X and T-Max it the other way, to golf ball grain, to 1600, shooting indoor basketball games without a flash. Sometimes I called it "Adventures of Supergrain!"

Martin BanksHuman-Made ArtMay 10, 2026

Did you use Ilford film? Does anyone else even make B&W film anymore?
Nice photo. The composition works, even though it's hard to see the full 1x1 in this forum.

Richard King PhotographyHuman-Made ArtMay 10, 2026

I used Kodak film. Mainly TMX 100.

Yes they still make B&W film. In fact it is having a revival.

Martin BanksHuman-Made ArtMay 10, 2026

I've been using Ilford in a Pentax medium format camera. I'll have to order some Kodak and give it a try. It looks nice.

Bruce BurkeMay 11, 2026

I've been shooting TMax 400 in 120. Seriously considering a roll of Tri-X, though - just to see. Film is doing well here in the Ft. Lauderdale area. The lab I use just moved to a better neighborhood.

Richard King PhotographyHuman-Made ArtMay 10, 2026

Not sure why you cannot see this as a bigger image. When I click on an image in a post I get a bigger version. For this it is about 5 x 5.

Martin BanksHuman-Made ArtMay 10, 2026

When I viewed the image in the original post, it was cut off at the top and/or bottom. In this thread, it appears correctly. Maybe some reformatting for the size of my laptop screen. Again, it's a lovely composition.