Guest zoz Posted August 17, 2010 Share #41 Posted August 17, 2010 Advertisement (gone after registration) Focus shift is an issue on SLR-Lenses and has been found and discussed on several Lenses by SLR users in the past. I do not agree that SLRs (with or without AF) focus generally not as accurat as RF. Compensating focus shift on an AF-Camera would just be a look up table in the lens/camera. I can´t see that this would be a big deal, if it´s reproducible with all lenses and not changing from copy to copy. Link to post Share on other sites More sharing options...
Advertisement Posted August 17, 2010 Posted August 17, 2010 Hi Guest zoz, Take a look here focus shift on fast voigtländer lenses. I'm sure you'll find what you were looking for!
stunsworth Posted August 17, 2010 Share #42 Posted August 17, 2010 I can´t see that this would be a big deal, if it´s reproducible with all lenses and not changing from copy to copy. I would have thought sample variation would prevent a 'one size fits all' solution. I believe that with the S2 each lens has its own individual corrections stored within the lens electronics. Link to post Share on other sites More sharing options...
Guest zoz Posted August 17, 2010 Share #43 Posted August 17, 2010 I would have thought sample variation would prevent a 'one size fits all' solution. I believe that with the S2 each lens has its own individual corrections stored within the lens electronics. I do not think that the focus shift is mainly a problem of sample variation then on lens design. So a compensation even if not 100% accurate would help to reduce the effect. Of course individual corrections are a perfect solution... Link to post Share on other sites More sharing options...
01af Posted August 17, 2010 Share #44 Posted August 17, 2010 Correct me if I'm wrong—but as far as I know, even the Leica S2 doesn't perform any focus shift compensation by the AF system. Instead, it avoids focus shift altogether through an extraordinarily high level of spherical aberration correction—just like in the latest Leica M lenses. No spherical aberration, no focus shift. Link to post Share on other sites More sharing options...
stunsworth Posted August 17, 2010 Share #45 Posted August 17, 2010 Correct me if I'm wrong—but as far as I know, even the Leica S2 doesn't perform any focus shift compensation by the AF system. Instead, it avoids focus shift altogether through an extraordinarily high level of spherical aberration correction—just like in the latest Leica M lenses. No spherical aberration, no focus shift. Search for 'focus shift' in the following S2 article... David Farkas Photography Blog: Leica S2 Review: Test Shooting in Germany Link to post Share on other sites More sharing options...
christer Posted August 17, 2010 Share #46 Posted August 17, 2010 Focus shift is at larger distance growing (like dof). The problem is not changing there. Even at infinity the lenses are not sharp when stopped down a little bit and set to infinity. Why do You think this is no issue for analogue photography? The film emulsion is thicker than the surface that captures the light in a digital camera. Link to post Share on other sites More sharing options...
Guest zoz Posted August 17, 2010 Share #47 Posted August 17, 2010 Advertisement (gone after registration) The film emulsion is thicker than the surface that captures the light in a digital camera. I don´t think this is compete able in this manner... Following my results with the 1.1/50 Nokton the image plane is moving more than 100µm. This exceeds at least the emulsion thickness of most films. ( I remember something in the range from 5-8µm for B+W Films.) Link to post Share on other sites More sharing options...
Nikkor AIS Posted August 17, 2010 Share #48 Posted August 17, 2010 I use the Voigtlander 28 1.9 ASPH @ 1.9 all the time on the M7/MP and have never seen a trace of focus shift. Voigtlander 28 1.9 ASPH on Leica M7 on XP2 Gregory Link to post Share on other sites More sharing options...
Guest zoz Posted August 17, 2010 Share #49 Posted August 17, 2010 I use the Voigtlander 28 1.9 ASPH @ 1.9 all the time on the M7/MP and have never seen a trace of focus shift. You won´t see focus shift with no lens on any camera if You always shoot at maximum aperture! That´s the problem with it. All is fine wide open, and then I stop down and the subject in focus is not getting sharper (as I would expect stopping down) but softer, because focus is moving backwards. Link to post Share on other sites More sharing options...
01af Posted August 17, 2010 Share #50 Posted August 17, 2010 Search for 'focus shift' in the following S2 article ... David Farkas Photography Blog: Leica S2 Review: Test Shooting in Germany Oh great ... evidently I stand corrected. According to that article, the S2 indeed does perform some focus-shift compensation using the AF system. Now I'm wondering what will happen in manual-focus mode—will the AF kick in for focus-shift compensation here as well? Link to post Share on other sites More sharing options...
jaapv Posted August 17, 2010 Share #51 Posted August 17, 2010 The film emulsion is thicker than the surface that captures the light in a digital camera.Well yes, even 5 micron is more than infinitely small, and this certainly has DOF and resolution effects, but in this context I would be looking more to less-than-perfect flatness of the film. Link to post Share on other sites More sharing options...
Guest zoz Posted August 17, 2010 Share #52 Posted August 17, 2010 Well yes, even 5 micron is more than infinitely small, and this certainly has DOF and resolution effects, but in this context I would be looking more to less-than-perfect flatness of the film. A digital Sensor with micro lenses and/or aa filter is a 3D structure with a thickness of several microns... Link to post Share on other sites More sharing options...
atufte Posted December 13, 2010 Share #53 Posted December 13, 2010 Here's a quick test to prove that not all copy's of the Nokton 50mm f/1.1 do shift focus or at least nothing that matters (with my copy that is), this was taken on a sturdy tripod with the focus set to focus on the light bulb box, (and focus ring fasten with scotch tape) only thing changed is the aperture from f/1.1 all the way up to f/11, i also changed distance to see if this did any difference but since it did not i won't bother to post them here... * 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! Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/128603-focus-shift-on-fast-voigtl%C3%A4nder-lenses/?do=findComment&comment=1529860'>More sharing options...
Guest zoz Posted December 13, 2010 Share #54 Posted December 13, 2010 Here's a quick test to prove that not all copy's of the Nokton 50mm f/1.1 do shift focus or at least nothing that matters (with my copy that is), this was taken on a sturdy tripod with the focus set to focus on the light bulb box, (and focus ring fasten with scotch tape) only thing changed is the aperture from f/1.1 all the way up to f/11, i also changed distance to see if this did any difference but since it did not i won't bother to post them here... * Sorry, but I see clearly a focus shift in this images: At f/1.1 focus is on front edge of the light bulb box, at f/2.8 it is on the middle to the rear end of the box. focus shift is happening between 1.1 and 2.8 after this usually there is no further shift. Link to post Share on other sites More sharing options...
atufte Posted December 13, 2010 Share #55 Posted December 13, 2010 Sorry, but I see clearly a focus shift in this images: At f/1.1 focus is on front edge of the light bulb box, at f/2.8 it is on the middle to the rear end of the box. focus shift is happening between 1.1 and 2.8 after this usually there is no further shift. That is called "soft" @ f/1.1 not focus shift... Link to post Share on other sites More sharing options...
Guest zoz Posted December 13, 2010 Share #56 Posted December 13, 2010 The front edge of the box is clearly sharper in the 1.1 image than it is in the 2,8. The little edge of the hidden box is much sharper in the 1.1 image. The focus point of the 1.1 image is hidden behind the pots. Try to use an Target with a continous surface. Then You´ll see it. Link to post Share on other sites More sharing options...
jaapv Posted December 13, 2010 Share #57 Posted December 13, 2010 I don´t think this is compete able in this manner... Following my results with the 1.1/50 Nokton the image plane is moving more than 100µm. This exceeds at least the emulsion thickness of most films. ( I remember something in the range from 5-8µm for B+W Films.) You are forgetting - film flatness is not optimal,unlessyou have a vacuum filmpressure plate. And that is measured in tenths of mms rather than microns. Link to post Share on other sites More sharing options...
jaapv Posted December 13, 2010 Share #58 Posted December 13, 2010 The front edge of the box is clearly sharper in the 1.1 image than it is in the 2,8.The little edge of the hidden box is much sharper in the 1.1 image. The focus point of the 1.1 image is hidden behind the pots. Try to use an Target with a continous surface. Then You´ll see it. And why would you want to see it? Each and everyone of these shots is perfectly in focus for any reasonable print. Link to post Share on other sites More sharing options...
atufte Posted December 13, 2010 Share #59 Posted December 13, 2010 The front edge of the box is clearly sharper in the 1.1 image than it is in the 2,8.The little edge of the hidden box is much sharper in the 1.1 image. The focus point of the 1.1 image is hidden behind the pots. Try to use an Target with a continous surface. Then You´ll see it. But if this is what all the fuzz is about I can live with this so called "focus shift" to me it just looks soft wide open which is good for portraits which again suits me perfectly...I also read someone at this forum saying that this lens was not a good landscape lens...? To me this it's the strictly oposite, since it is 47mm so slightly wider than 50, it is pinsharp stopped down and have a mild contrast making it perfect for b&w...one of the best 50's out there for landscape and portraits, make this lens very versitaile to say at least... Link to post Share on other sites More sharing options...
jaapv Posted December 13, 2010 Share #60 Posted December 13, 2010 A digital Sensor with micro lenses and/or aa filter is a 3D structure with a thickness of several microns...Which array captures the light in one plane focussed by the micolenses. The AA filter, IR filter and micfrolenses are not light-capturing devices, thus their thickness is irrelevant in this context. The emulsion as a whole is a light-capturing device, so that thickness is relevant. Link to post Share on other sites More sharing options...
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