Hi!

I have question according the new 55/4. Are there any significant difference in sharpness between the center and edges wide open/stopped down. If there are a visable difference when do I see it(20x30 or lager?). I have the same questions for the 45/4.

Regards

Patrick

-- Patrick Bjorklund (patbj@itn.liu.se), September 24, 1999

Answers

I will answer the 45mm part of your question. This lens will be slightly soft at the edges when shot at f/4 but you will need to blow up larger than 16x20 inches to notice it. Stopped down to the middle apertures, this lens is very sharp both on axis and off. At f/22 it remains very sharp across the frame. SR

-- Steve Rasmussen (srasmuss@flash.net), September 24, 1999.

Leendert, how are you determining that the 75mm is slightly soft at the edges due to astigmatism and curvature of field? SR

-- Steve Rasmussen (srasmuss@flash.net), February 13, 2000.

Hi Patrick, I own the 55mm for about 3 years now. Like many others, I agree that this lens is very sharp. However I also have some reservations/remarks. First, F11 is definitely the best F-stop with best overall quality from center to corner, the edges being only very slightly softer then the center (as viewed with nose on paper of a 40X50cm enlargement).Actually, F8 has even higher resolving power with comparable macro/image contrast, but micro/detail contrast is lower, laying a light veil of softness over the sharpness, especially at the edges. Although center sharpness and contrast is good to ecxellent at F4 and F5.6, edge and corner sharpness is not good enough for high quality work(but who wants to do architecture at F5.6?). F16 is almost as good as F11, with almost uniform quality over the entire frame, very good image contrast and only very slightly less sharp, often preferrable to F11 for DOF. F22 is still good, some say very good, but in direct comparison with F16 one can see that the image is somewhat softer. All these observations apply to somewhat greater distances, say 2/3 metres to infinity. When you get closer, the image is less sharp, espescially at the edges, closing to F16 or F22 helps, but not entirely (no C.R.C. here!). Having no CRC probably causes the foreground-unsharpness to be not so very nice when focused on infinity (a bit like my old F3.5/28mm Nikon, as opposed to my current F2.8/28mm CRC MF Nikon). No complaints about the backgroud-unsharpness, however. As a general note, I have to say that the 55 has a very slight less overall image-contrast than the 45 (which I had on loan) and the 75 (which I owned). Center sharpness and-contrast of both 45 & 75mm is higher than that of the 55 and exceptionally good. However.., edge sharpness was better with the 55 than the 45 (softer edges, coma ?) and the 75 (seemed to have astigmatism and curvature of field). Distortion is very low with have astigmatism and curvature of field). Distortion is very low with the 55, it never bothered me, even with architecture and definitely lower than in the 45, which has a moustace-like distortion that could annoy the critical user (that you have find out yourself).I hope this helps, but I have to point out that my expectations/demands are probably not the same as yours, so it's the best that you try to make some testshots yourself, if that's possible. P.S., in the book " Photographing Plants & Gardens" by Clive Nicols (1994) you can find many pictures, with data, taken with the 55 and 135mm on Fuji Velvia. Greetings, Leendert.

-- Leendert van de Kippe (leenvdkippe@hetnet.nl), February 13, 2000.

Steve, I took pictures of objects in a grass field at f8 with the 75mm at a distance of aproximately 15 feet. In the grass the out of focus area did not seem to be starting as a strait line, the line bending slightly away from the camera at the far edge and corner. Also, in the out of focus area, there was at an equal distance from the camera, much more unsharpness in the corners. Lastly, I remember that, while focusing through the viewfinder, the same object focused in the middle produced an other distance setting than focused at the far edge and corner. I did not encounter this phenomena with the 55mm or 135mm. However, I must admit that I have only limited experience with the 75mm, since I traded it in for a 90mm (my favorite lens) after one month.. I also made some pictures atf11-16.These also were not so sharp at the edge and corner, but with hindsight, this could have been caused by shuttervibration. So, above observations seemed to point in the direction of curvature of field and astigmatism(the form of unsharpness), but a little doubt creeps in since there are so many enthousiastic user reports (including yours) in this and other forums about the 75mm. Leen

-- Leendert van de Klippe (leenvdklippe@hetnet.nl), February 15, 2000.