Holy S---!! Pentax's medium format is only $9400!!!!
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From: David J. Littleboy on 12 Mar 2010 21:01 "Alfred Molon" <alfred_molon(a)yahoo.com> wrote: > In article <hnehls$rio$1(a)news.albasani.net>, stephe_k(a)yahoo.com says... > >> No problem? First test I pulled up show only REALLY good ones can pull >> those types of numbers at optimal settings. Most don't >> >> http://www.hevanet.com/cperez/MF_testing.html >> >> Stephanie > > What MTF do those lp numbers refer to in the test? That page is one of my favorites, and represents the results of a lot of hard, precise, carefully done work. It's incredibly useful for comparing MF film systems. (Bottom line: Mamiya 7 at f/11.) But it's not clear what his criterion for OK/NG is when stating lp/mm numbers. One could, however, argue that they are overly optimistic and correspond to a uselessly low MTF, since he's shooting a high contrast target and looking for a barely detectable response. (And the film used has an MTF50 at 100 lp/mm, so he really can see the numbers he reports for the Mamiya 7 lenses.) The bottom line, of course, is that the Mamiya 645 lenses I tested produce sharp images on the 5D2 in a very quick and dirty (handheld, f/8, ISO 800) test, so there really isn't a problem. FWIW, from looking at diffraction degradation as lenses are stopped down, I find that as long as your lens projects an image with an MTF of 50% at 2/3 or 3/4 of the Nyquist frequency, you'll be very happy with the images that pop up on your screen or appear in your prints. -- David J. Littleboy Tokyo, Japan
From: stephe_k on 12 Mar 2010 21:54 David J. Littleboy wrote: > "Alfred Molon" <alfred_molon(a)yahoo.com> wrote: >> In article <hnehls$rio$1(a)news.albasani.net>, stephe_k(a)yahoo.com says... >> >>> No problem? First test I pulled up show only REALLY good ones can pull >>> those types of numbers at optimal settings. Most don't >>> >>> http://www.hevanet.com/cperez/MF_testing.html >>> >>> Stephanie >> What MTF do those lp numbers refer to in the test? > > That page is one of my favorites, and represents the results of a lot of > hard, precise, carefully done work. It's incredibly useful for comparing MF > film systems. (Bottom line: Mamiya 7 at f/11.) > > But it's not clear what his criterion for OK/NG is when stating lp/mm > numbers. > > One could, however, argue that they are overly optimistic and correspond to > a uselessly low MTF, since he's shooting a high contrast target and looking > for a barely detectable response. (And the film used has an MTF50 at 100 > lp/mm, so he really can see the numbers he reports for the Mamiya 7 lenses.) So then look at the SLR 55mm lens numbers compared, ~1/2 this resolution. > > The bottom line, of course, is that the Mamiya 645 lenses I tested produce > sharp images on the 5D2 in a very quick and dirty (handheld, f/8, ISO 800) > test, so there really isn't a problem. > So shooting a hand held quick test of the very center of the lens on a different camera proves this Pentax can resolve enough for this pixel density to be useful beyond marketing numbers? OK, I'm sure you believe this :-) Stephanie
From: David J. Littleboy on 12 Mar 2010 23:10 <stephe_k(a)yahoo.com> wrote: > So shooting a hand held quick test of the very center of the lens on a > different camera proves this Pentax can resolve enough for this pixel > density to be useful beyond marketing numbers? OK, I'm sure you believe > this :-) It clearly shows that there's no problem producing sharp images with MF lenses at that pixel density, and that your claims of unsurmountable problems are silly, unfounded BS. And, yes, showing that resolution over the center 24x36mm of the frame for non-superwides is fully adequate proof: the 33x44 crop (from 46 x 56) is plenty to avoid any corners problems I've ever seen in any lens. -- David J. Littleboy Tokyo, Japan
From: Robert Spanjaard on 12 Mar 2010 23:29 On Sat, 13 Mar 2010 00:47:17 +0100, Alfred Molon wrote: > In article <e560e$4b9ab539$546accd9$13071(a)cache90.multikabel.net>, > spamtrap(a)arumes.com says... >> You don't even >> understand what the term "full frame CCD" refers to. > > Nope, you are not expressing yourself clearly. > > There are full frame transfer and interline transfer CCDs, but you are > talking about "full frame CCD", which is imprecise. > > With "full frame" cameras people usually refer to cameras with 24x36mm > sensors. See here > http://en.wikipedia.org/wiki/Full-frame_digital_SLR http://en.wikipedia.org/wiki/Charge-coupled_device#Architecture -- Regards, Robert http://www.arumes.com
From: Michael Benveniste on 12 Mar 2010 23:47
On Sat, 13 Mar 2010 10:56:27 +0900, David J. Littleboy wrote: > I don't think it was Oskar's fault. The "normal" lens is the widest lens > you can make easily with the Triotar, Tessar, and Planar sorts of > designs, and any longer lens would require a larger camera. The histories I've read stated that when Oskar was building the first fixed lens models, he chose 5cm because he felt that he couldn't get enough sharpness out of a shorter lens. But when it came time to sell interchangeable lens cameras, he stuck with 50mm as the "kit" lens even though that was no longer the case. If I remember correctly, the 50mm f/3.5 Elmar and the 35mm f/3.5 Elmar came in 1931 or 1932. Both are 4-element, 3-group designs. I know that Zeiss made a 40mm Tessar and a 45mm f/2 Planar, and Nikon's made a couple of 45mm Tessar-style lenses for 35mm as well. > Doesn't the AF system beep at you when you use MF lenses on the AF > versions of the Pentax 645? My 645n can beep, but I still find a prism viewfinder easier for manual focus. I'm convinced this is an area of photography where each person has to work out what's best for themselves. I do know that KatzEye has found a very nice niche business adding prism finders to various dSLR's. -- Mike Benveniste -- mhb(a)murkyether.com (Clarification Required) Amo conventum instituti. -- Artifex Hannibal |