Lighting sources for film testing using a step tablet

odell1618photography · Feb 23, 2020

Is there a difference, especially determining personal EI, between contact printing the step tablet onto the film and loading the step tablet into a film holder and shooting a white target at Zone X ? This is assuming that the camera lens, shutter, etc are all up to spec.

Thanks in advance, Odell

Bill Burk · Feb 23, 2020

There is a difference, sunlight is what tests strive to simulate.

But you would likely make mistakes or have other inconsistencies that outweigh the advantage of using a real daylight source of light.

It's more practical to use incandescent light filtered with 80B or flash, in a contact printing arrangement.

Nodda Duma · Feb 23, 2020

Tungsten through an 80B produces a flat spectrum?

Bill Burk · Feb 23, 2020

I am oversimplifying a lot. There’s a specified Corning blue glass. But I think it’s pretty close to 80B.

Remember that’s the filter you use on daylight balanced color film when shooting under Tungsten. So if it will make color film look good, it must be pretty close to the difference between daylight and tungsten

Nodda Duma · Feb 24, 2020

Thanks... I shoot (have always shot) 99% outdoors so I’m not familiar at all with the needs of indoor photography. But now I learned something new.

Rudeofus · Feb 24, 2020

I have made the personal experience, that even good enlarger lenses produce quite a bit of flare, and that contact printing is the only way I was able to get reliable H&D curves. Even multi coated lenses have about 0.5% flare, and you can only imagine, what that does with a step wedge that goes all the way to D=3.0.

Rudeofus · Feb 24, 2020

PS: Here is an old posting comparing step exposure through lens with a contact print.

Lighting sources for film testing using a step tablet

odell1618photography

Bill Burk

Nodda Duma

Bill Burk

Nodda Duma

Rudeofus

Rudeofus

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