t024484 Posted November 12, 2007 Share #1 Posted November 12, 2007 Advertisement (gone after registration) Both pictures below were taken with my 28mm Cron, at f4 and 1/350 sec from a tripod, with the self release timer, and are 100% crops without any sharpening. Taken as DNG and then converted to JPEG with Lightroom. You see a forrest at 30 meter distance and a big tree in the foreground at 5 meter distance. Cron-1 was focussed on the forrest, 30 meter away. Cron-2 was focussed on the big tree 5 meter away. The strange thing is that the forrest is sharper when focussed nearby. No matter what diaphragm I used when focussed on the forrest, it did not get any sharper as the picture here. So to get the sharpest possible landshape picture, you should set your distance to 5 meter ? Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Cron-1 Cron-2 Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! Cron-1 Cron-2 ' data-webShareUrl='https://www.l-camera-forum.com/topic/37913-strange-effects-28mm-cron/?do=findComment&comment=400464'>More sharing options...
Advertisement Posted November 12, 2007 Posted November 12, 2007 Hi t024484, Take a look here Strange effects 28mm Cron. I'm sure you'll find what you were looking for!
jaapv Posted November 12, 2007 Share #2 Posted November 12, 2007 If truth be told, it looks more like motion blur to me. Gust of wind? If it were strong enough even 1/350th might blur slightly. I cannot imagine the focussing being so totally off..... Link to post Share on other sites More sharing options...
t024484 Posted November 12, 2007 Author Share #3 Posted November 12, 2007 If truth be told, it looks more like motion blur to me. Gust of wind? If it were strong enough even 1/350th might blur slightly. Not the slightest bit of wind. I have taken many pictures for reference, and the result is very consistent. Link to post Share on other sites More sharing options...
jaapv Posted November 12, 2007 Share #4 Posted November 12, 2007 I'm guessing here - are these the corner? Curvature of field might account for it, but I do not know whether this lens has any. Link to post Share on other sites More sharing options...
t024484 Posted November 12, 2007 Author Share #5 Posted November 12, 2007 I'm guessing here - are these the corner? Curvature of field might account for it, but I do not know whether this lens has any. This crop is exactly from the centre of the picture. Link to post Share on other sites More sharing options...
jaapv Posted November 12, 2007 Share #6 Posted November 12, 2007 In that case I'm as puzzled as you are Link to post Share on other sites More sharing options...
Shootist Posted November 12, 2007 Share #7 Posted November 12, 2007 Advertisement (gone after registration) You need to do some controlled test with static subjects at fixed distances. Looks like that lens may need some adjustment. Link to post Share on other sites More sharing options...
Daniel Ortego Posted November 12, 2007 Share #8 Posted November 12, 2007 Is this lens new from the box or perhaps second hand, whereby the handling is unknown? I’m curious since I just received a new 28-cron’ although I haven’t used it yet. Regards, Link to post Share on other sites More sharing options...
larry Posted November 12, 2007 Share #9 Posted November 12, 2007 I'd say the lens is focusing beyond what the rangefinder is indicating. The tree in the second shot looks a little soft. Larry Link to post Share on other sites More sharing options...
t024484 Posted November 12, 2007 Author Share #10 Posted November 12, 2007 Is this lens new from the box or perhaps second hand, whereby the handling is unknown? I’m curious since I just received a new 28-cron’ although I haven’t used it yet.Regards, Brand new, 6 bit coded, UV/IR filter on, Link to post Share on other sites More sharing options...
robsteve Posted November 12, 2007 Share #11 Posted November 12, 2007 Hans: It looks like your rangefinder is off. The best way to test the lens performance and eliminate any rangefinder problems influencing the test is to find a distant scene which you can shoot with the lens at the infinity stop. You can then look at different areas of the picture to see what is sharp. Link to post Share on other sites More sharing options...
t024484 Posted November 12, 2007 Author Share #12 Posted November 12, 2007 Hans: It looks like your rangefinder is off. The best way to test the lens performance and eliminate any rangefinder problems influencing the test is to find a distant scene which you can shoot with the lens at the infinity stop. You can then look at different areas of the picture to see what is sharp. My rangefinder works spot on with my 50mm Cron and my 75mm Cron, so this is probably not the cause. Given that when the 28mm Cron produces better sharpness at objects 30 meter away, set at 5 meter f4 than with the lens set at 30 meter, no matter what the diaphragm is, you can believe me that when the lens is set at infinity, the produced images are even worse at far distants. It seems like a lens problem to me , but I was anxious to hear wether I am the only one with this problem, or has it to do with the lens construction. One last thing to mention about the lens: A test picture under 45 degrees, 1 meter from the camera was spot on at f 2.8, a few cm of front focus at f 2 , and a few cm of back focus at f 4. This seems quite O.K. to me. Link to post Share on other sites More sharing options...
Ronazle Posted November 12, 2007 Share #13 Posted November 12, 2007 Hi, I just went out my front door with a tripod, M8, & 28mm cron. Mine acts as one would expect: best sharpness coincides with rangefinder indication. I was amazed at the F8 depth of field when focused on 5m. However, very time and and at each of several F stops (2.8 -11) the best focus of objects 10m - infinity was achieved by focusing dead on. Sounds like you have a lens problem. Link to post Share on other sites More sharing options...
Dantist Posted November 12, 2007 Share #14 Posted November 12, 2007 Hi Hans, I was just wondering if you have tried to see the DOF shown on the lens of the summicron 2/28. Your question seemed to me so obvious that I went straight to my own lens to check what's going on... On mine, if I make the infinity sign corresponding to f4 at right on the crown, it gives me on the other f4 mark at left a distance slightly over 3 meters... This means to me that if I put 30 (meters) on the focusing center point, I will have the shortest distance for DOF at a bit more than 5 meters. Excuse my french, but I hope I am understandable. If not, let me know, I shal try better words to tell you that upon now, everything seems reasonable and ok to me, about what you explained as a strange problem. Regards, Michel. Link to post Share on other sites More sharing options...
t024484 Posted November 12, 2007 Author Share #15 Posted November 12, 2007 Hi, I just went out my front door with a tripod, M8, & 28mm cron. Mine acts as one would expect: best sharpness coincides with rangefinder indication. I was amazed at the F8 depth of field when focused on 5m. However, very time and and at each of several F stops (2.8 -11) the best focus of objects 10m - infinity was achieved by focusing dead on. Sounds like you have a lens problem. Ron, Thanks for your feedback. It looks as if this is the second lens that I will have to send to Leica, the first was my 75mm Cron. I'm not happy to have quality problems with such extemely expensive lenses. My 75mm worked perfectly after repair, so let's hope for the best. Link to post Share on other sites More sharing options...
robsteve Posted November 12, 2007 Share #16 Posted November 12, 2007 Ron,Thanks for your feedback. It looks as if this is the second lens that I will have to send to Leica, the first was my 75mm Cron. I'm not happy to have quality problems with such extemely expensive lenses. My 75mm worked perfectly after repair, so let's hope for the best. If you just bought the lens, bring it back to the dealer and have them replace it. Link to post Share on other sites More sharing options...
jaapv Posted November 12, 2007 Share #17 Posted November 12, 2007 For testing infinity, always use an object many miles away, a star, the moon, etc.... Link to post Share on other sites More sharing options...
t024484 Posted November 12, 2007 Author Share #18 Posted November 12, 2007 For testing infinity, always use an object many miles away, a star, the moon, etc.... O.K. I will let you know. Link to post Share on other sites More sharing options...
Ronazle Posted November 13, 2007 Share #19 Posted November 13, 2007 Hans, You are quite welcome. Sorry that you have ANOTHER Leica lens problem. Hope it works out well. regards, rt Link to post Share on other sites More sharing options...
t024484 Posted November 13, 2007 Author Share #20 Posted November 13, 2007 For testing infinity, always use an object many miles away, a star, the moon, etc.... I used an object, 400 meters away, early in the morning. I took pictures at f 4, with lens distance setting resp. at 5 meter, 10 meter and infinity. 10 meters gave the sharpest image, 5 meter and infinity were comparable. Below I show 100% unprocessed crops of 10 meter and infinity settings. It seems quite obvious that my lens needs to be adjusted. Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! 10 meter f 4 Infinity f 4 Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! 10 meter f 4 Infinity f 4 ' data-webShareUrl='https://www.l-camera-forum.com/topic/37913-strange-effects-28mm-cron/?do=findComment&comment=401304'>More sharing options...
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