charles_osborne

I realize that your question is really asking for recommendations of a model, but I still think that other factors will continue to enter in. Moonrise was shot with a convertible but it was cropped in enlargement, as Adams normally did--so edge sharpness is less an issue. The same issue arises when you use 8x10 instead 5x7 or 4x5--on 8x10 you may be using the whole image circle and with movements the sharpest part may shift around in the image, perhaps into the dirt or the sky rather than where you prefer it.

 

Therefore the longest lens would be preferable because of the larger image circle. These lenses inherently have limited image circles for their length. I see from the published information that the new Schneider XXL large format Art lenses, which tout edge to edge definition, are apparently Dagor design, which means convertible--but I have not heard of anybody tryiung that. They are already rather slow in design, and also rather long for 8x10 in general landscape use.

 

Others have said f22 is sharper than f90, which is true and f22 is acceptable by general standards, but most of the reviews of actual tests that I have seen show peak resolution larger than that--f11 or f16, or even larger, though of course this throws the entire burden of depth of field onto the mercy of style and camera movements.

 

All in all, like the other guys, I am still a bit baffled in that paper (I am told) can only resolve 7 to 9 lines per mm, so that in contact printing the delicacy of any brand name lens (and some coke bottle bottoms) should be lost in the indelicacy of the process. I suspect that lenses with modest coverage (all convertibles and many primes as well), subjected to the demands of style and movements, are being pushed beyond the limits of design.

 

Also, nobody mentioned that long lenses (suitable for 8x10) are nowhere near as brilliant in resolution and contrast as the shorter ones, based on resolution testing. But for most people's money, they don't need to be (and the XXL's may truly be different).

May I respond even though a fair-sized book is already before us? First, all these considerations only confirm my love of 5x7--almost twice the neg of 4x5 (20 vs 35 sq inches), whilst having hardly more weight to carry than 4x5, using many of the same lenses, and having many of the 8x10 assets (big lenses, etc) and useable contact prints. Yet the 5x7 enlarger is practical and not much bigger than the 4x5--mine does both. So the 5x7 captures the best qualities of 4x5 and 8x10, case closed, I am vindicated in my long love of 5x7--which I am told is making a come-back in Europe and I see on ebay the prices are up.

Second, the 8x10 camera gives a CHOICE OF FORMATS in most cases, having changeable backs--not so with smaller cams.

Third, there is a law of format I learned I think from Christopher Perez (great site for lens tests: http://www.hevanet.com/cperez/testing.html )

which states that, due to limits of the human eye and of printing papers, an enlargement of good quality up to 3.5 times negative saize is not distinguishable to the eye from a contact print, but beyond 3.5x, it becomes increasingly noticeable. Thus a 35mm can be enlarged to 3.5x5, or a 4x5 enlarged to maybe 16x20 and look perfect. But the 8x10 made from 35mm--while excellent--will not look as good as a contact print, and a 3x4 foot print from 4x5 neg--while excellent--will not look as good as a contact print. Yet the 8x10 negative will. In fact the 8x10 negative can print a 5x6 foot mantel picture that is higher quality than an 8x10 from 35mm. So it is when we get to display sizes that the difference literally is visible to the eye. This confirms experience of course. The first time I saw a museum photo from large format (live, not in a book) I was dumbfounded (it was Adams' Moonrise).

One time I took the screw-in filter-type close-up lens from a set and put it in the shutter of my 13" Wollensak triple convertible (it fit!) and it was about as sharp as the Wollensak! The #3 is a 1/3-meter lens, or 330mm, the #2 is 1/2 meter or 500mm, and the 1 is a meter or 1000mm. The latter two should cover 11x14--but I think the diameter of the close-up lens may be a factor--mine was large, I think 62mm. The diameter may also influence exposure--the natural aperture being larger with a larger lens. The distance from film to lens is of course the focal length for infinity, closer for hyperfocal distance or for close ups. As with all lenses, the closer the focus the greater the coverage, but size of aperture does not increase coverage with all lenses--I think it would with a simple lens (miniscus).