Shootist Posted January 4, 2010 Share #21 Posted January 4, 2010 Advertisement (gone after registration) Sorry, I meant to say that I was properly focused and did not change the focusing between shots. Just like with the other lenses. I focused once before the test shots and only changed the aperture. Well then you have a problem with the lens or the camera.. Link to post Share on other sites More sharing options...
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jaapv Posted January 4, 2010 Share #22 Posted January 4, 2010 I just did the math: At a 100% crop the COC is identical to the pixel pitch. At infinity ( I took 10.000 m) the front DOF is just 12 meters. That means your image is severely backfocussed. Link to post Share on other sites More sharing options...
DFV Posted January 4, 2010 Author Share #23 Posted January 4, 2010 I just did the math: At a 100% crop the COC is identical to the pixel pitch. At infinity ( I took 10.000 m) the front DOF is just 12 meters. That means your image is severely backfocussed. Uhhh... now in english please... How can I severely backfocus a subject that is 80 meters away with the two images in my finder coinciding perfectly well and the lens set only a small notch before being completely at infinity? Could the camera not be calibrated properly? As far as I am concerned anything beyond 60 meters on a 50mm lens is simply infinity or just negligible. Focusing a building 100 or 1,000 meters away is the same setting, or not? In any case I will wait until it stops raining and I will take time to do a REAL 100% controlled test including all f-stops with tripod and all... Will post much more extensive results asap. Link to post Share on other sites More sharing options...
el.nino Posted January 5, 2010 Share #24 Posted January 5, 2010 I am still thinking that everything is just fine with your examples. take into account that this is a 100%-view and we are looing at incredibly small details (ok not as small as leaves on a tree but still very small) and that nobody seriously uses f1.4 at these distances (especially on a digital-camera). Link to post Share on other sites More sharing options...
jaapv Posted January 5, 2010 Share #25 Posted January 5, 2010 It is quite simple. The lens is optimized at infinity at 1000x the focal length by Leica. The DOF is determined by the enlargement of the image. As soon as you go to a 100% crop you enlarge so much that the circle of confusion is the size of the pixel. That means your DOF shrinks to 12 meters in front of your infinity setting. An image at 80 meters will be out of focus. Your plan seems to me to be a good one. Use a brick wall at ten meters and focus bracket to eliminate focussing inaccuracies and CVA. The best comparison is a series of the same image in the centre and the corner. The reason to focus bracket is not only to compensate for focussing error but also judge curved field aberration, which can influence the result with the narrow DOF you have at 100% enlargement. You can repeat the test at an optimum aperture of 4.0 or 5.6. Beyond that image quality will start to deteriorate. Link to post Share on other sites More sharing options...
jaapv Posted January 5, 2010 Share #26 Posted January 5, 2010 I am still thinking that everything is just fine with your examples.take into account that this is a 100%-view and we are looing at incredibly small details (ok not as small as leaves on a tree but still very small) and that nobody seriously uses f1.4 at these distances (especially on a digital-camera). You are right there. In practice a high speed lens will be used at full aperture for one of two reasons, firstly to create a narrow DOF type of image, secondly in very low light. In both cases the corner performance is irrelevant. Link to post Share on other sites More sharing options...
thrice Posted January 5, 2010 Share #27 Posted January 5, 2010 Advertisement (gone after registration) Uhhh... now in english please... Perhaps you could do a little research of your own. http://www.lmgtfy.com/?q=circle+of+confusion http://www.lmgtfy.com/?q=depth+of+field+calculator The first link will give you some results explaining what circle of confusion is, the second link will get you some depth of field calculators where you can see that if you dial infinity into the lens at f/1.4 the depth of field of acceptable focus WON'T extend back to 80m, therefore your image is backfocused. I wonder how you get such brilliant and expensive tools in your hands without knowing the first thing about hyperfocus and depth of field. I'm 100% certain this is a case of a poor workman blaming his tools. EDIT: actually most online DOF calculators incorrectly will specify the CoC as the accepted film standard for 35mm, which if you're looking at 100% M9 crops is too large and needs to be set to the 5.6microns pixel pitch to get an accurate calculation. Link to post Share on other sites More sharing options...
el.nino Posted January 5, 2010 Share #28 Posted January 5, 2010 It is quite simple. The lens is optimized at infinity at 1000x the focal length by Leica. The DOF is determined by the enlargement of the image. As soon as you go to a 100% crop you enlarge so much that the circle of confusion is the size of the pixel. That means your DOF shrinks to 12 meters in front of your infinity setting. An image at 80 meters will be out of focus. but in his last post he says (actually he repeats) that the lens was not set AT infinity but "a notch before". and by the way: "1000 x the focal length" would be 50 meters with a 50mm-lens. Link to post Share on other sites More sharing options...
jaapv Posted January 5, 2010 Share #29 Posted January 5, 2010 but in his last post he says (actually he repeats) that the lens was not set AT infinity but "a notch before". and by the way: "1000 x the focal length" would be 50 meters with a 50mm-lens. You're right, I dropped a zero. And this is the first mention of a notch before... Link to post Share on other sites More sharing options...
el.nino Posted January 5, 2010 Share #30 Posted January 5, 2010 And this is the first mention of a notch before... With other words in post #6 Sorry, I meant to say that I was properly focused and did not change the focusing between shots. Just like with the other lenses. I focused once before the test shots and only changed the aperture. Link to post Share on other sites More sharing options...
ho_co Posted January 5, 2010 Share #31 Posted January 5, 2010 ... without knowing the first thing about hyperfocus and depth of field... FWIW, I believe the proper term in English is "hyperfocal distance," not "hyperfocus." Cf Hyperfocus - Wikipedia, the free encyclopedia. Link to post Share on other sites More sharing options...
carlmuck Posted January 5, 2010 Share #32 Posted January 5, 2010 I just did the math: At a 100% crop the COC is identical to the pixel pitch. At infinity ( I took 10.000 m) the front DOF is just 12 meters. That means your image is severely backfocussed.[\quote] leica's spec sheet contains a DOF table it shows the 'lux nearest focus when set to infinity at f/1.4 as 56m and change. I think his camera and lens are probably fine, as you first pointed out his technique may need some work. c. Link to post Share on other sites More sharing options...
DFV Posted January 5, 2010 Author Share #33 Posted January 5, 2010 I'm 100% certain this is a case of a poor workman blaming his tools. Interesting... so you assume that I am a "poor workman"? What makes you believe that I have no knowledge of HYPERFOCAL DISTANCE and depth of field? So just because English is not my native tongue and some "terms" and especial abbreviations are indeed foreign to me I simply am, according to you, not worthy of owning such brilliant tools? Well in your case my assumption regarding you is simple; I am sorry to say but you must be a very, very lonely person... As a final note to your stupid assumptions... I just came across this review THE LEICA 50 SUMMILUX ASPH REVIEW by Steve Huff that mentions something very similar to the problem I am having with my Summilux. I quote: Upon review of the images I was let down. I was feeling a bit uneasy as I just laid out some serious cash for this lens and it seemed to be soft, low contrast and produce odd colors. HOW COULD THIS BE?!?! I did some testing and it appeared it was front focusing. I was all set to send it back when I decided to take it out for a day and make sure it was not user error. I am only human after all. After a day of shooting and reviewing the shots it appeared it WAS NOT user error. This particular lens was defective and gave me very low contrast, blurred results and out of focus images when focusing at a distance. I shot with it for nearly two weeks thinking to myself, I KNOW THIS IS NOT RIGHT! I contacted my dealer and they swapped it out for me and I did get a new Summilux (this time in silver) and the replacement is astonishing. Just what I remembered it to be. Super sharp with creamy Bokeh, even at F1.4. If anyone out there has this lens and it is not PIN SHARP at 1.4 on an M8, it may need calibration or repair. But you know what? I am still going to make a full controlled test before making any gratuitous assumptions and going back to my dealer claiming there is something wrong with the lens... Link to post Share on other sites More sharing options...
thrice Posted January 5, 2010 Share #34 Posted January 5, 2010 So just because English is not my native tongue and some "terms" and especial abbreviations are indeed foreign to me I simply am, according to you, not worthy of owning such brilliant tools? Why ask for him to clarify in English then? You used a colloquial condescention, so I used one as well. I assumed you didn't know about hyperfocal distance or DOF because they are directly related to circle of confusion and the terminology he used. Perhaps if you had phrased your response properly I wouldn't have assumed thusly. Also, directly insulting me calling me a lonely man isn't very nice, but doesn't bother me. I'm perfectly happy with my family, girlfriend, and large circle of friends... So I don't need you, welcome to my ignore list. Link to post Share on other sites More sharing options...
telewatt Posted January 5, 2010 Share #35 Posted January 5, 2010 I think it is a focus problem at 1.4 ... the center should be a little sharper more like the f 16 shot... that the f16 shot is not so sharp is clear, the 1/40 sec. is to long AND the dropping of quality because of optical rules at that f stop... regards, Jan Link to post Share on other sites More sharing options...
MRJ Posted January 5, 2010 Share #36 Posted January 5, 2010 Rudeness is so tedious and self-indulgent; and “condescension” is not spelled with a “t”. Link to post Share on other sites More sharing options...
thrice Posted January 5, 2010 Share #37 Posted January 5, 2010 Rudeness is so tedious and self-indulgent; and “condescension” is not spelled with a “t”. Sorry, I wasn't aware the spelling police were out in force. DOF tables for lenses are useful but if one wants to test a lens, the subject should be precisely in the plane of best focus. Link to post Share on other sites More sharing options...
arthury Posted January 5, 2010 Share #38 Posted January 5, 2010 As I said, you don't avoid the focussing problem by taking just 80 meters as infinity... REF: Leica Camera AG - Photography - LEICA SUMMILUX-M 50 mm f/1.4 ASPH. Based on the Leica published DoF for this lens, it says if it is focused at infinity, the DoF is between [56.14 - infinity] meters. If it is, indeed, focused at infinity, wouldn't 80m be included in the DoF? Link to post Share on other sites More sharing options...
thrice Posted January 5, 2010 Share #39 Posted January 5, 2010 REF:Leica Camera AG - Photography - LEICA SUMMILUX-M 50 mm f/1.4 ASPH. Based on the Leica published DoF for this lens, it says if it is focused at infinity, the DoF is between [56.14 - infinity] meters. If it is, indeed, focused at infinity, wouldn't 80m be included in the DoF? arthury, indeed it would be contained within the depth of field for the standard convention used to calculate depth of field charts; that is, a 30micron CoC. With digital sensors, if the airy disks exceed the size of an individual pixel then the image will not appear to be per-pixel sharp. Therefore, precise sharpness will only extend as long as the airy disks are below 5.6microns on the M8 and M9. As this is the size of the pixels for a 100% zoom file viewed on-screen. If the OP (who's posts are now hidden from me) doesn't believe me, he needs to bicubic sharper resize his image to give an equivalent 30micron CoC. To do so, one must resize the image to 3.37megapixel. If the image still looks soft then perhaps he has a problem. To make things simpler just make the vertical resolution of the whole image 1500 and make sure constrain proportions is clicked. This will yeild a ~3.37Mpixel image. Link to post Share on other sites More sharing options...
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