agencal Posted January 4, 2016 Share #1 Posted January 4, 2016 Advertisement (gone after registration) Hi Last week i have bought SL with the zoom lens.I realized that it has some focus shift but than i tought how can be focus shit on contrast detect af which focuses on the aperture you shoot.But Diglloyd also found that problem. So what will i do ? 1.Shoot every thing at f8 and f11 2.Call Leica to take it back? 3.Firmware update will fix it some day 4.Sell SL and go back to M Please help Link to post Share on other sites More sharing options...
Advertisement Posted January 4, 2016 Posted January 4, 2016 Hi agencal, Take a look here 24-90mm Focus Shift (Diglloyd). I'm sure you'll find what you were looking for!
Steve Ash Posted January 4, 2016 Share #2 Posted January 4, 2016 sounds odd to me. maybe you have difficulties to set the focus point correctly? Link to post Share on other sites More sharing options...
agencal Posted January 4, 2016 Author Share #3 Posted January 4, 2016 I am sure about the focus point. By the way,Ming Thein also found the same problem Link to post Share on other sites More sharing options...
profus Posted January 4, 2016 Share #4 Posted January 4, 2016 Could you explain a bit more about it? What do you exactly experience? I played with the zoom for 4 whole days and always shot itwide open ( f2.8 - f4 ) all the time - all images I took were perfectly focused...I was actually impressed how well, fast and accurate focus was... Link to post Share on other sites More sharing options...
LocalHero1953 Posted January 4, 2016 Share #5 Posted January 4, 2016 I'm puzzled by your description. Assuming auto focussing is actually happening wide open, then shooting at f8-f11 would create problems with focus shift. Surely your solution (as a "fix", not a permanent answer) would be to shoot wide open? Ming Thein and (I assume, because I'm not a subscriber) Lloyd imply the same. Also, I don't see what contrast detect has to do with it: again, I am assuming again that focussing is occurring accurately wide open, and the shift occurs after AF is complete, and the lens has stopped down. Apologies if I have misunderstood your experience. Edit: Ming Thein and Lloyd were using, I believe, pre-production versions of the lens, and were looking at the 90mm end. Has anyone seen any tests or reports that look at whether there has been any change in production lenses? And is there anyone with better technical knowledge than me who can say if this is something that could be corrected in firmware? (i.e. tell the lens to adjust the AF for smaller apertures - this seems unlikely, even as I write it). Link to post Share on other sites More sharing options...
jaapv Posted January 4, 2016 Share #6 Posted January 4, 2016 If focus shift is visible @ f 11 it must be massive not to disappear in DOF. On such a lens? And without exciting comment from the users on this forum, who can be a pretty critical bunch? Digiloyd is not too reliable, but Ming Thein must be taken seriously. Link to post Share on other sites More sharing options...
wlaidlaw Posted January 4, 2016 Share #7 Posted January 4, 2016 Advertisement (gone after registration) Leica may not have made aperture shift a priority on this lens, given that it was auto-focus. Similarly with it being parafocal, although it actually seems pretty good on this aspect, if you set it to manual focus and zoom, the focus does not change significantly. All lenses are a compromise between various things and if say you can improve the resolution of the lens or say the focus speed at the cost of some aperture shift, that might be a compromise worth making on an auto focus lens. Wilson PS I am far from convinced the lens is focusing wide open and then stopping down. You can hear the IS motor running but you don't hear the aperture motor fire up when you take a shot, if you hold your ear against the lens. W. Link to post Share on other sites More sharing options...
agencal Posted January 4, 2016 Author Share #8 Posted January 4, 2016 I'm puzzled by your description. Assuming auto focussing is actually happening wide open, then shooting at f8-f11 would create problems with focus shift. Surely your solution (as a "fix", not a permanent answer) would be to shoot wide open? Ming Thein and (I assume, because I'm not a subscriber) Lloyd imply the same. Also, I don't see what contrast detect has to do with it: again, I am assuming again that focussing is occurring accurately wide open, and the shift occurs after AF is complete, and the lens has stopped down. Apologies if I have misunderstood your experience. Edit: Ming Thein and Lloyd were using, I believe, pre-production versions of the lens, and were looking at the 90mm end. Has anyone seen any tests or reports that look at whether there has been any change in production lenses? And is there anyone with better technical knowledge than me who can say if this is something that could be corrected in firmware? (i.e. tell the lens to adjust the AF for smaller apertures - this seems unlikely, even as I write it). I am not sure if the focussing is actually happening wide open as DSLRs.The contrast detect AF works with the aperture you are currently using.I mean if you dial f8 the lens stop down the aperture and auto focus happens at that aperture.So how can a focus shift happen? But if you are right about focussing wide open and then stop down and shoot than focus shift can happen. Are you sure about process that SL uses? If yours is right than i need to shoot wide open in order to have exact focus.But what about landscapes or close focus stuations? Link to post Share on other sites More sharing options...
LocalHero1953 Posted January 4, 2016 Share #9 Posted January 4, 2016 OK - I don't have the lens (just the body), so assumed it focused wide open, but I'm interested in any answers you get - I'm wondering if I should give in and get it. Link to post Share on other sites More sharing options...
jaapv Posted January 4, 2016 Share #10 Posted January 4, 2016 Leica may not have made aperture shift a priority on this lens, given that it was auto-focus. Similarly with it being parafocal, although it actually seems pretty good on this aspect, if you set it to manual focus and zoom, the focus does not change significantly. All lenses are a compromise between various things and if say you can improve the resolution of the lens or say the focus speed at the cost of some aperture shift, that might be a compromise worth making on an auto focus lens. Wilson PS I am far from convinced the lens is focusing wide open and then stopping down. You can hear the IS motor running but you don't hear the aperture motor fire up when you take a shot, if you hold your ear against the lens. W. Maybe if you lock focus and then stop down. Link to post Share on other sites More sharing options...
agencal Posted January 4, 2016 Author Share #11 Posted January 4, 2016 Could you explain a bit more about it? What do you exactly experience? I played with the zoom for 4 whole days and always shot it wide open ( f2.8 - f4 ) all the time - all images I took were perfectly focused...I was actually impressed how well, fast and accurate focus was... When i focus to a near subject (lets say 3 meters) at f5.6 or f8 mostly at 75mm and 90mm most of the time focus point is now what i choose but a closer point to me is in focus.So i thing it is making front focusing. Link to post Share on other sites More sharing options...
agencal Posted January 4, 2016 Author Share #12 Posted January 4, 2016 Leica may not have made aperture shift a priority on this lens, given that it was auto-focus. Similarly with it being parafocal, although it actually seems pretty good on this aspect, if you set it to manual focus and zoom, the focus does not change significantly. All lenses are a compromise between various things and if say you can improve the resolution of the lens or say the focus speed at the cost of some aperture shift, that might be a compromise worth making on an auto focus lens. Wilson PS I am far from convinced the lens is focusing wide open and then stopping down. You can hear the IS motor running but you don't hear the aperture motor fire up when you take a shot, if you hold your ear against the lens. W. When you shoot with an AF lens what can be mere priority than accurate focus.If the subject i try to shoot is not perfectly focused what can i do with it's parafocalness? Link to post Share on other sites More sharing options...
jaapv Posted January 4, 2016 Share #13 Posted January 4, 2016 When i focus to a near subject (lets say 3 meters) at f5.6 or f8 mostly at 75mm and 90mm most of the time focus point is now what i choose but a closer point to me is in focus.So i thing it is making front focusing. That is not focus shift, that is front focusing which it should not do at all. Camera fault or (possibly but not likely) user error. I would consult Leica, or at least your dealer if I were you. Link to post Share on other sites More sharing options...
LocalHero1953 Posted January 4, 2016 Share #14 Posted January 4, 2016 I agree. If it is actually focusing at the taking aperture, then focus shift doesn't come into play at all - just focus error/fault. But Ming Thein certainly did report "focus shift", without discussing whether AF occurred wide open or stopped down. Link to post Share on other sites More sharing options...
thighslapper Posted January 4, 2016 Share #15 Posted January 4, 2016 What method of focussing are you using ? Point, field or zone ? Only point focussing will give you 100% accurate results that you can assess for what you claim is happening. Using the other methods the camera will tend to choose THE CLOSEST SUBJECT to the camera in the focussing field as the focus point. I have used point focussing from day one for that specific reason ..... and over thousands of exposures in varied circumstances I have never found ANY evidence of focus shift .... certainly nothing that is sufficient to impact on the final image. OK, so you get significant focus shift commonly in very fast lenses like to 50/0.95 and f2 and below ....but that tends to be rare above f2.8 in modern lenses ..... but f2.8-4 .... and with a complex lens with multiple elements and moving groups ??? .... I doubt Leica will have left anything of significance in their design ..... and certainly you are the first to complain of such problems .... Check your menu settings ! Link to post Share on other sites More sharing options...
Jared Posted January 4, 2016 Share #16 Posted January 4, 2016 I haven't noticed any focus shift with my lens, but I haven't checked for it yet. I'll run a couple tests today or tomorrow. In the meanwhile, though, I did check to see whether the 24-90 and 18-56 focus wide open and then stops down, or focuses at the selected aperture. They both focus wide open, then stops down for the image. Just like a DSLR. That is what I would expect since focus can be determined more precisely with a narrow depth of field. This means that lens focus shift can potentially be an issue. Since it is a contrast detect system rather than a phase shift system, wide open focus should always be accurate (though there may be some uncertainty as to the exact point selected or a failure to achieve accurate focus). You shouldn't have to worry about a camera that consistently front or back focuses since the imaging sensor itself is used to determine correct focus. - Jared Link to post Share on other sites More sharing options...
Jeff S Posted January 4, 2016 Share #17 Posted January 4, 2016 That is not focus shift, that is front focusing which it should not do at all. Camera fault or (possibly but not likely) user error. I would consult Leica, or at least your dealer if I were you. Is there a FAQ on focus shift vs front/back focus? Sorry, I didn't check. If not, there should be.....confusion arises regularly, it seems. Jeff Link to post Share on other sites More sharing options...
jaapv Posted January 4, 2016 Share #18 Posted January 4, 2016 Feel free... Link to post Share on other sites More sharing options...
Jared Posted January 4, 2016 Share #19 Posted January 4, 2016 OK, I did a quick test at 90mm and don't see an issue with my lens. If there is any focus shift, it is extremely minor and is easily covered by the depth of field as you stop down. I'm attaching some JPG's for your reference... All images were shot with the SL mounted on a tripod. FL was set to 90mm. Subject distance was a little under 1m. Single focus point used. The point of focus was the numeral "7"--the numeral itself, not the line that marks 7 inches. The subject was a photo trimmer turned on its side and oriented at about 45 degrees to give a nice scale. First, the full image... - Jared 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/255186-24-90mm-focus-shift-diglloyd/?do=findComment&comment=2962069'>More sharing options...
Jared Posted January 4, 2016 Share #20 Posted January 4, 2016 And here are the 100% crops from the center of the field. I see diffraction rearing its ugly head by f/11 (perhaps even a bit at f/8), but little sign of focus shift. Perhaps a touch? Towards near focus? Again, easily covered by the depth of field at f/11, though. Certainly not enough to be a concern for me, at least. - Jared 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/255186-24-90mm-focus-shift-diglloyd/?do=findComment&comment=2962070'>More sharing options...
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