Does exposing an individual B&W image (4x6)require more time than that same image on a contact sheet?

Answer 1

Theoretically, if your contact sheet is the same dimension as the print and you use the same lens aperture for both, the time should be the same. And this is true for small photo sizes. For larger print sizes, however there are two more things to consider - light scatter caused by the film and emulsion itself (base plus fog density - even the clear parts of the neg aren't really completely clear) and the distribution of light energy to the paper emulsion. Stay with me now, cause this is going to get harder to believe, but it's true. It is colder in the wintertime because the earth is farther from the sun, right? WRONG. The earth is actually closer to the sun in winter, at least in the northern hemisphere! In winter the earth tilts away from the sun so that the area of the earth bathed in direct overhead sunlight decreases. Sunlight is from more of an angle and shadows are long. Less direct overhead sun - the less energy there is to warm the earth.
Same holds true for making a large print from a negative. Light on the center axis of the lens / negative / condenser / light source is more intense than along the edges of the print. And when making a contact print, don't we usually make the exposure in the dead center of the light? that's why a contact print will take just a scosh less exposure than an enlargement.

Answer 2

If this is a question about using a darkroom enlarger and not a question about developing then yes, typically a contact sheet takes less time to expose as compared to the actual print. The reason for this is because typically with a contact sheet, you have the aperture for the enlarger open all the way letting in more light thus exposing the image faster. On the other hand, when you actually print the image you are most likely going to use a smaller aperture so as to increase the exposure time to light so as you may dodge and burn if necessary. Anyhow there are many ways to create a contact sheet and there are so many factors so check out the link below for more information. However, from my experience whether I am making contact sheets from 4x5 negs or 35mm negs, I have never had a final print take less time than a contact print, although beit I have really only been working in the darkroom for 10 years and I am still learning new techniques almost every time.

Answer 3

It depends on many factos actually, even the chemicals temp, is a factor, the light you use in the printer, if you use filters to correct stuff.

But I think that the contact sheet probably takes a bit more time than a single print.

It is because of the light quality when it hits the film and gets the paper to be exposed by the light coming through the film. When it is near the light source, it is stronger, than when it hits the contact press.

For more on this review the book The print by Ansel Adams