No this is not another thread to share wide open shots.
Since most of modern lens (not wide angle, say 135mm on 4X5) are plasmat design ( optimized at f22, normally focus at 5.6 shoot at smaller aperture). I was wondering if there are any older lens that are sharp wide open (or just one stop down).
Yes the Zeiss Jena Tessars are at one stop down really sharp!
Cheers Armin
Planar design lenses--notably the 135/3.5 Zeiss Planar, the 150/2.8 Schneider Xenotar, and the 135/3.5 Xenotar--do pretty well open wide, particularly in center. Still at f2.8 or 3.5 the depth of field is so narrow that sharpness really doesn't mean all that much. I have heard that the Zeiss Biogon was specifically designed for use at f4.5, but I can't say I have ever seen a sample to judge.
Rumor has it that the Kodak Ektar 203mm is sharpest wide open.
Wayne
Since the magnititude of some off-axis aberrations are affected by aperture, its hard to believe that any lens is best across the field covered wide open.
For numerical examples, look at Eric's calculated curves for many older designs, published at http://www.dioptrique.info/ .
That goes against all conventional wisdom, actual practice and also what Zeiss themselves have always said.Originally Posted by Armin Seeholzer
As someone who uses two Tessar LF lenses on a regular basis just the opposite is true. I tested a 1931 135mm f4.5 CZJ Tessar on a Crown Graphic extensively two years ago and sharpness only becomes a acceptable by modern standards by f16, any wider than that and edge and corner sharpness falls off rapidly as the lens is opened up.
Currently I'm using an early 1950's T-coated 150mm f4.5 CZJ Tessar, and also a late production (SN is 2001/2) 150mm f5.6 Xenar, while both these are excellent lenses again overall sharpness only really kicks in at f16 they are slightly better than the 135mm at f11 mainly because of their greater coverage. By f16 it's hard to see any difference in images shot with these Tessar designs or my Symmar's and Sironar's etc
That doesn't mean the lenses aren't usable at wider apertures, centre sharpness is OK wider open and that's fine for some photography but not my landscape work where I want overall critical sharpness. If pushed I can get away with using my Sironar at f11 but not a Tessar.
Ian
"Conventional wisdom" and "sharpness" are subjectiv sensations. And who is Zeiss? Carl Zeiss passed away years ago before the Tessar was invented. So let's talk about scientific measurements like resolution and contrast. And real people and their publications.
Reckmeyer, as I know a Zeiss staff member, coined the notion "critical f-stop", the f-stop a lens performes at it's optimum. The off-axis-abberations like spherical abberations are minimized and diffraction doesn't reduces the resolution in the center of the image circle. For a Tessar f/4.5 180mm he has measured the "critical f-stop" is f/12. In any case the resolution decreases in the center if a smaller f-stop is used but the resolution in the outer areas increases a little bit, the resolution in the whole image looks "smoother".
With shorter focal-lenghts like 135mm the "critical f-stop" decreases to bigger aperture sizes up to one stop down for small focal-lenghts used in MF- and 35mm-cameras. And special Tessars like the Luminar are nearly "diffraction limited"-lenses. So this lenses should be used wide open to get maximum resolution.
Peter
Thanks everyone for the input, In fact, I just need sharpness in the center. not necessary all the way to the corner, and also, I don't need any movement as long as it covers, it should be ok.
Zeiss, is of course the company Peter
Ian
Zeiss, is of course the company Peter
Ian
Hanging out in bad company, Ian? I always thought that you Brits said, "Zeiss are the company".
Charley
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