Digital BW, The Print

And while we're on the subject of image receptor size
- don't forget that depth-of-field is inversely
related to actual aperture and NOT relative aperture
(f-number).  What this means, regardless of whether
the receptor is film or digital, is that larger
receptor cameras have lesser depth-of-field and
smaller ones have greater depth-of-field at a given
f-number. Tilts and swings on view cameras can only
compensate for a portion of this loss in some
situations.

So, for example, a 'normal' lens for an 8x10" camera
is about 300mm whereas for the 6x7cm about 100mm.(As
I'm sure you all know the focal length of a  "normal"
lens is roughly the diagonal (hypotenuse) of the
receptor size.)  So you lose roughly about 3 stops of
'speed' with the 8x10 for the same depth-of-field
relative to the 6x7cm and even more relative to
'normal' 50mm for a 35mm film or "full field" digital
camera.

Conversely smaller than "full field" digital receptors
have a grater depth-of-field at a given f-number.

I usually like sharpness  - but sometimes I just want
depth-of-field and grainlessness - sort of large
format pin-hole effect. Stopped down digital on less
than full-field receptor mimics this effect to some
degree. Pinhole's typically have f-numbers of about
300 and have near infinite depth-of-field but
diffusion unsharpness throughout.

For my 8x10 I have an APO lens that is sharp as a tack
and most often this was the lens I used - but i also
have an uncoated variable soft-focus turn-of-the
century Velostigmat that, even though it looks like it
has been used as a doorstop, took and takes very
pleasing portraits.  It's all in how you want the
image to look and the feeling you want to convey. It's
NOT just about mega-pixels, or grain, or in-plane
sharpness, or whatever.

Respectfully,
Michael Vendrell 


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