loquax ludens
Well-known
I've made myself a note to try this soon. I think that I could tell the difference between a 5x7 print from a 35mm negative and one made from a 6X4.5 neg. But that could just be my biases and pre-conceived notions fabricating a simulacrum of reality. I've never actually tried to do a comparison like that. Should be fun.
tlitody
Well-known
A reason why 35mm breaks down when compared to MF at same print size.
Lets take a 24x24mm crop from a 135 neg compared to a 56mm x 56mm neg and make a 12x12 inch print. We'll set enlarging lens aperture to F5.6.
That's a 12.7 times enlargement for the 135 neg and 5.44 times enlargement for the MF neg. We'll use a 50mm lens for the 135 enlargement and an 80mm lens for the MF neg.
Because an enlarger is a macro camera and we are getting real close up to the subject (the negative) we need a lot of lens extension. When you add that lens extension you alter the effective aperture. So much so that for the 135 neg the set aperture of 5.6 becomes an effective F65.5. At that aperture you get are going to get a lot of diffraction showing in the print.
With MF neg the lens extension makes the effective aperture F24 so you get a lot less diffraction in the print.
And if you use a 4x4inch crop from 4x5 neg with a 150mm lens for same 12x12 print which is 3 times enlargement, you get effective aperture of F11.2which is very close to the optimum of the lens.
So I think a big reason why larger format negs look smoother when printed(at same size) is due to less image breakdown caused by diffraction which is like saying because of less enlargement only taking the explanation a little further.
I may be wrong cos I'm no optics expert but I think it's right.
Lets take a 24x24mm crop from a 135 neg compared to a 56mm x 56mm neg and make a 12x12 inch print. We'll set enlarging lens aperture to F5.6.
That's a 12.7 times enlargement for the 135 neg and 5.44 times enlargement for the MF neg. We'll use a 50mm lens for the 135 enlargement and an 80mm lens for the MF neg.
Because an enlarger is a macro camera and we are getting real close up to the subject (the negative) we need a lot of lens extension. When you add that lens extension you alter the effective aperture. So much so that for the 135 neg the set aperture of 5.6 becomes an effective F65.5. At that aperture you get are going to get a lot of diffraction showing in the print.
With MF neg the lens extension makes the effective aperture F24 so you get a lot less diffraction in the print.
And if you use a 4x4inch crop from 4x5 neg with a 150mm lens for same 12x12 print which is 3 times enlargement, you get effective aperture of F11.2which is very close to the optimum of the lens.
So I think a big reason why larger format negs look smoother when printed(at same size) is due to less image breakdown caused by diffraction which is like saying because of less enlargement only taking the explanation a little further.
I may be wrong cos I'm no optics expert but I think it's right.