schneider 210 depht of field question

[jose angel]

Could someone explain to me why we can find diferent Depth-of-Field Tables (4x5, 5x7, 8x10) in the schneider' web page (www.schneideroptics.com) for a 210mm. lens ? I can't understand why the same focusing distance could give diferent dephts of field in the diferent formats of this tables. Ex.: 210mm. lens, f/4, we can rea d 128ft. to 447ft. in 4x5 and 94ft. to infinity in 8x10. Could it refers to a di ferent 210', (like an apo-symmar in 5x7 and a super-symmar in 8x10)? I'll be thankful for any help. Jose.

[James Chow]

The 8x10 DOF is probably computed with a different CoC as less enlargement is required for a given print size/viewing distance,so I'd guess maybe 0.2mm or 0.3mm. 4x5 DOF tables seem to be computed around 0.1 or 0.11mm (Schneider's website lists it). You really need to determine your own CoC size according to your results on film and how closely you expect to examine the enlargements, and compute your own DOF tables for your lenses.

[jose angel]

James, thank you for your dedication. Then, I understand that I can use either of this three DOF tables with anyone of the formats, depending of the desired results, isn't it? Another question: Could I see differences in sharpness between two 8x10 contact prints, one with a COC of 0.3mm. and another with a COC of 0.1mm. (or less)? (Examining the prints on the hands, without loupe) I'm thinking to homebuild a 8x10 P&S camera. Suggestions are welcomed...