Question on projection vs enlargements

I'm just curious on a question about 35mm slides...and forgive my

ignorance, but, how is it that I can project 35mm slides on a 5ft or

larger screen, and have the image look clean and crisp without

excessive grain, but if you tried to enlarge that same slide in that

big of a size, it would probably be fuzzy, with excessive grain? Is

it that the photographic papers can't record the fine detail at that

large of a size from 35mm?

A critical look at a projected slide provides the answer. When projected, the sharpness you describe is an illusion, especially so when the image is viewed from a distance. On an up-close inspection, however, you will find that the lack of apparant grain is actually caused by lack of critical focus bewteen the slide and the screen.

 

Enlargements are made by focussing the film grain on the paper, using a high-power magnifyer, through an enlarger that is much like a projector. Photographic paper can resolve grain quite easily, and a sharp enlargement will reveal grain where a soft, projected image may not.

 

Additionally, our eyes get fooled when viewing a projected image on screen, partly because of the special reflective materials that the screen is made of, partly because of viewing distance, and partly because of the difference between viewing projected/reflected light, as opposed to reflected light off a enlargement.

 

The only way to determine if a slide can sustain a particular enlargement on print is to view the slide on a light table with a good quality loupe. If it's sharp in the loop, it will render a sharp print (up to a certain size). If it's soft in the loupe, you might be surprised to find that when projected onto a screen, it "appears" sharper than it really is.

 

Hope this helps!

Thanks! I see now why a lot of folks prefer to inspect their slides through a loupe, and not projection...although i do enjoy projecting my slides for others...i won't reveal the "secret" to them!