eric@rtech.ARPA (Eric Lundblad) (02/20/85)
I have a question on view camera lens. I read somewhere that large format lenses are not as sharp as those for, say, 35mm cameras. Is this true? If so, is it a physics problem, or is just that more people buy 35mm cameras than view cameras? As long as I'm asking, does anyone know of a negative densitometer (for black and white) that doesn't cost an arm and a leg? Or perhaps where I could get a set of negatives of known densities? I'd like to be able to figure out the development times for various film, developer, and push/pull combinations. Thanks -- Eric Lundblad ------------------------------------------------------------------------------- For instance, try to draw a perfect circle; and since you can't draw a perfect circle, the involuntary flaw will reveal your personality. But if you want to reveal your personality by drawing an imperfect circle - your circle - you will bungle the whole thing. Picasso ------------------------------------------------------------------------------
hkr4627@acf4.UUCP (Hedley K. J. Rainnie) (02/24/85)
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Lens sharpness:
Perhaps it is the case that the sharpness of the lens never needs to exceed
the resolution of the film. I don't know much about view cameras, but I
believe that the best transparency film you can get in sheets is Ektachrome 64.
Placed against 35mm Kodachrome, the former is considerably grainier and
less sharp. Of course, enlargements to equal sized prints will show the
view camera to have far greater resolution. But take a square centimeter
from both originals, and the 35mm will have the higher resolution image.
Rei SHinozuka
ihnp4!cmcl2!hkr4627darrelj@sdcrdcf.UUCP (Darrel VanBuer) (02/25/85)
Angular resolution is proportional to the diameter of a lens. Since longer
lenses are farther from the film, you do generally get fewer lines/mm (this
is true for long 35 mm lenses too). In large format cameras, the loss in
resolution is more than made up for by the larger amount of film used by an
image. A good 35 mm normal lens give close to 100 lines/mm, an 8x10 lens
maybe 25 to 30 lines for an average lens, so you go from 2500 lines/picture
to 5000 lines/picture.
--
Darrel J. Van Buer, PhD
System Development Corp.
2500 Colorado Ave
Santa Monica, CA 90406
(213)820-4111 x5449
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VANBUER@USC-ECL.ARPAbriand@tekig1.UUCP (Brian Diehm) (02/27/85)
> > I read somewhere that large format lenses are not as sharp as those for, > say, 35mm cameras. Is this true? > As long as I'm asking, does anyone know of a negative densitometer (for > black and white) that doesn't cost an arm and a leg? This tends to be true because large format lenses have such a great field of coverage. Think of itZZ
briand@tekig1.UUCP (Brian Diehm) (02/28/85)
> I have a question on view camera lens. I read somewhere that > large format lenses are not as sharp as those for, say, 35mm cameras. Is > this true? If so, is it a physics problem, or is just that more people > buy 35mm cameras than view cameras? > > As long as I'm asking, does anyone know of a negative densitometer > (for black and white) that doesn't cost an arm and a leg? Or perhaps where > I could get a set of negatives of known densities? I'd like to be able to > figure out the development times for various film, developer, and push/pull > combinations. Well, yes, view camera lenses probably are less sharp than 35mm lenses, but it probably isn't anything to do with the market. The difference is the tremendous coverage that a view camera lens must have. Compare a "telephoto" 35mm lens of 210mm with a slightly long view camera 210mm. Both lenses produce the same size of image - something that is 3mm tall with one lens is 3mm tall with the other. But. The 35mm lens must cover an area 24x36mm, while the 210 must cover 4 x 5 inches. Not only that, but the 35mm lens is guaranteed to use the axis centered image area while the view lens may be used severely off axis. For this reason, my primary view lens (210mm Schneider Symmar S) will cover an 8 x 10 inch area clear out to the edges. This explains why a 210 lens is "telephoto" on a 35mm camera while being modest long on a view camera - the 35mm image is using only a "part" of the available image area, if you want to think of it that way. The implication that a 35mm image is inherently sharper than a view camera is wrong - the "enlarged" image area MORE than compensates for the coverage requirements of the lenses. Also, the grain reduction of large format comes into play. I personally have found that the grain factor outweighs ALL other sharpness factors. One of my view lenses is a 135 Zeiss Tessar, the original triplet design that led to all triplets being known as "Tessar type." This lens was out of production in the 1930s (if that late), and I'll put it up against any 135 on a 35mm, provided you make a large (8x10 or larger) print of the full image on the negative. The reason I think marketing doesn't have much to do with this area is that (this may come as a surprise to Pop Photo readers) large format is a HUGE market. Lens research continues, the Japanese have entered this area within the last five years in a BIG way, and a typical commercial lens alone will cost, and dearly. A 120mm Super Angulon (f8), about equivalent on a 4x5 to a 35mm on 35mm format, will cost you about $700-800 at discount. Typical top of the line Sinar view cameras will go to studios for $2000 to $3000. The neat thing is that you and I can get much less pretentious gear for pretty reasonable prices - the Calumet 540 is a real bargain at $250. However, you also need a lens :-) ! (My 210 Symmar is under $400 these days.) Last question - consider using one of the 1-degree spot meters as a densi- tometer. The secret is, each 1/3 f-stop deflection on the meter is equal to 0.1 transmission density. Read a light source without the negative, then read it with the negative - presto. Ansel Adams covers this in the second book of the New Basic Photo Series (1983?), but you have to look for it. Brian Diehm (who apologizes for the previous messed up posting)