Tytan Posted March 22, 2015 Share #1 Posted March 22, 2015 Advertisement (gone after registration) I've noticed that my Summilux 50mm 1.4 ASPH lens might be having some back-focus issues. I'm using it with the Leica M-P 240 Here are 2 images. Shot at f2.0. 1st image. I focused on the circled area, and as you can see, the point of sharp focus is slightly behind. 2nd image. I focused on the same circled area first, and then i shifted my focusing frontward very slightly, but enough to see the focusing alighnment is slightly off in the viewfinder. And in this instance, the circled area (which was my original intended focus area) is sharp(er). Will you say my lens indeed does have a back focus problem? Or is this within tolerance ? Thank you. 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! Quote 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/242600-back-focus-issue-on-summilux-m-50mm-f14-asph/?do=findComment&comment=2784798'>More sharing options...
Advertisement Posted March 22, 2015 Posted March 22, 2015 Hi Tytan, Take a look here Back focus issue on Summilux-M 50mm f1.4 ASPH. I'm sure you'll find what you were looking for!
piblondin Posted March 22, 2015 Share #2 Posted March 22, 2015 It's hard to tell from your images. The circled areas look quite similar. Generally, you'll have more area in focus behind your focal point than in front of it, but it's of course up to you what you prefer. You may have very slight back focus, which could come from your lens or your camera body. Quote Link to post Share on other sites More sharing options...
FlashGordonPhotography Posted March 22, 2015 Share #3 Posted March 22, 2015 (edited) 1. you need to do this test wide open. That eliminates any potential focus shift (although it's not generally an issue on the lux) 2. It could be either the body or the lens. More likely it's the body. 3. Are you using a tripod. If you are then you can focus using the RF and then use the live view to confirm focus. 4. Your looks to only be out a tiny bit. Probably won 't be an issue in real life except wide open at minimum focus distance. 5. Do you get the same result when you focus in different directions? This would annoy me but I'm pretty anal about these things, even though I know it'll make little difference 99% of the time. Really you need another lens as sensitive to focus as the Summilux to see if it's the body or lens. Gordon Edited March 22, 2015 by FlashGordonPhotography Quote Link to post Share on other sites More sharing options...
Tytan Posted March 22, 2015 Author Share #4 Posted March 22, 2015 Thank you for your thoughts and insights. I do think it's only slightly back-focused. But I'm also rather anal about such things. So it's kinda annoying. And considering my body and lens are only about a month old, both bought new. I only have this lens to test the issue. I have no idea if it's the lens or the body. At f2, it's already showing me such results... i didn't think to test it wide open at 1.4. Am not using a tripod. When i use LiveView, the focus is pretty much spot on. Quote Link to post Share on other sites More sharing options...
Exodies Posted March 22, 2015 Share #5 Posted March 22, 2015 For these sorts of test you absolutely must use a tripod. Focus with the rangefinder then see what is in the focus peaking area on the lcd. If they are not the same part of the scene, send camera and lens in for recalibration. Quote Link to post Share on other sites More sharing options...
microview Posted March 23, 2015 Share #6 Posted March 23, 2015 For these sorts of test you absolutely must use a tripod. Focus with the rangefinder then see what is in the focus peaking area on the lcd. If they are not the same part of the scene, send camera and lens in for recalibration. But if you don't have a tripod you could place camera on level support (small table?) and set timer to 2s/12s. Quote Link to post Share on other sites More sharing options...
FlashGordonPhotography Posted March 23, 2015 Share #7 Posted March 23, 2015 Advertisement (gone after registration) If you only have the one lens then I suggest a trip to your local Leica dealer is in order. They'll have some lenses they'll be happy to try and sell you. Take your time and make sure you have a card in the camera. You want to be testing a 75mm 'lux or a 90 'cron, ideally. Also, try focusing from infinity position in a single movement and see what the results are. Focusing from infinity tends to make you focus slightly closer than focusing from close in. I get significantly more reliable results using this technique with my 50 'lux, which I know is spot on. If I focus from close in I miss about 30%. From infinity about 2%. The other thing is a mid distance test. Find an easy to focus object about 20 meters away. Small movements on the focus ring make a bigger difference the further you get. So if everything is good at 20m then it's most likely your technique that's the issue. If something is out it'll be really obvious at this distance. Test focus from both directions. Do all your tests wide open. I have purchased 4 Liecas in total. At some point all the bodies needed a small adjustment. But mine were all out by more than yours and were all reliably out at 20 meters. Calibrating an infinity position is easy, even on a type 240. Gordon Quote Link to post Share on other sites More sharing options...
Jean-Michel Posted March 24, 2015 Share #8 Posted March 24, 2015 Hi There are a under of good and precise way to check your focusing. Check this website: Squit Photo. Or check LensAlign. Even if you do not buy the LensAlign (which is really meant for adjusting the microfocus on dslr's) the information is really good and you can jury-rig a similar set-up. The squit target puts the ruler at a 45 degree angle which is ok but the LensAlign 20 degree angle is perhaps better. Using one of these is far better than focusing on some object and trying to remember where you exactly focused. Once you are fairly certain that your lens is focusing correctly you can just go about photographing -- not all your images will be tacksharp views at 100% on screen, so what! Enjoy the images anyway. Jean-Michel Quote Link to post Share on other sites More sharing options...
Lenshacker Posted March 24, 2015 Share #9 Posted March 24, 2015 For these sorts of test you absolutely must use a tripod. Focus with the rangefinder then see what is in the focus peaking area on the lcd. If they are not the same part of the scene, send camera and lens in for recalibration. Make sure that you measure the lens at the F-Stop you prefer to use before doing this test. Most fast lenses, even aspherical lenses, have some focus shift. The focus will shift towards infinity for lenses that are over-corrected for spherical aberration as you stop the lens down. Undercorrected lenses shift towards the camera as you stop down. "Bokeh Balls" give a good indication of whether the lens is over or under corrected. The RF cam does not compensate for focus shift, but the Liveview does. Redo the test at F1.4. Quote Link to post Share on other sites More sharing options...
jaapv Posted March 24, 2015 Share #10 Posted March 24, 2015 (edited) I must confess that I do not really see the benefit of all this testing; if I feel that a lens/camera is misbehaving I will run a few quick sanity-checks and if it appears to be out of adjustment I simply send it in, either to Leica or to Will van Manen (substitute your favourite repair person here). If there is nothing wrong it will be back within the week, if not, well, it would have had to be sent in anyway. Life is too short and better spent taking actual photographs... Edited March 24, 2015 by jaapv 1 Quote Link to post Share on other sites More sharing options...
lct Posted March 24, 2015 Share #11 Posted March 24, 2015 +1. Beware of rulers which can cause you paranoia and are useless to check focus accuracy at medium and long distance. I prefer real-life tests consisting of shooting 3-D objects at minimum, medium and long distance personally. Easy way to check if there is a focus problem somewhere before sending the lens in if need be. Quote Link to post Share on other sites More sharing options...
Jean-Michel Posted March 24, 2015 Share #12 Posted March 24, 2015 I must confess that I do not really see the benefit of all this testing; if I feel that a lens/camera is misbehaving I will run a few quick sanity-checks and if it appears to be out of adjustment I simply send it in, either to Leica or to Will van Manen (substitute your favourite repair person here). If there is nothing wrong it will be back within the week, if not, well, it would have had to be sent in anyway. Life is too short and better spent taking actual photographs... I agree with that wholeheartedly, however, if one wants to check by how much a lens back or front focuses then using a setup that is measurable makes sense. It makes sense to do that with equipment that has a microadjustment function for AF, such as my Canon 5D2 -- the system designed by Michael Tapes )LensAlign) does make sense and I know that it works well as I used that to adjust the microadjustment for all the lenses I use on my 5d2 and each one needed a different adjustment. There is no way to adjust a Leica body or lens that way, but a quick test on a lens will let you know if you should send it for adjusting. I just did that for my 35 Summicron (of 1962 vintage) that is back-focusing quite badly. I do agree that there is way, way too much angst over sharpness, lens comparisons, and so on these days. As you write, if in doubt, send the equipment for service, get it back, and just use it. Jean-Michel Quote Link to post Share on other sites More sharing options...
Tytan Posted April 1, 2015 Author Share #13 Posted April 1, 2015 Update. I was in Tokyo and dropped by Leica Customer Service at the Leica Ginza Store. Explained the situation, left my camera and lens with them. Went back to collect after 3-4 hours. They informed me that the camera body was fine. The lens was very slightly back focused and they calibrated it. Now it's all good. They told me that the back-focus issue with the lens was very slight and probably within tolerance of what was acceptable by Leica. I had my doubts on that though, and would be quite surprised if it were true, and definitely disappointed too. Guess i'll never know for sure. 1 Quote Link to post Share on other sites More sharing options...
Mornnb Posted April 1, 2015 Share #14 Posted April 1, 2015 Update. I was in Tokyo and dropped by Leica Customer Service at the Leica Ginza Store. Explained the situation, left my camera and lens with them. Went back to collect after 3-4 hours. They informed me that the camera body was fine. The lens was very slightly back focused and they calibrated it. Now it's all good. They told me that the back-focus issue with the lens was very slight and probably within tolerance of what was acceptable by Leica. It's somebodies job at the Leica factory to test the lens and calibrate, to paint pink dots in the lens to point out the optimal location of the helicoid. Somebody didn't do their job properly. Quote Link to post Share on other sites More sharing options...
jdlaing Posted April 1, 2015 Share #15 Posted April 1, 2015 It's somebodies job at the Leica factory to test the lens and calibrate, to paint pink dots in the lens to point out the optimal location of the helicoid. Somebody didn't do their job properly. It's also some courier services job to throw the box 25 feet across a parking lot into the truck. Quote Link to post Share on other sites More sharing options...
don daniel Posted April 1, 2015 Share #16 Posted April 1, 2015 With an M240 you don't even haven to press the shutter to test focus. Just compare what you have focussed on using the optical viewfinder with what you see when you turn on liveview and enlarge. Repeat several times. Your camera may not be moved during this process. Check at various distances always with aperture 1.4. I have worked with six rangefinder Leicas. Only one of them had a perfectly calibrated rangefinder. So it would be good to test with another lens too. But use either another Summilux 50 or a tele lens to notice the effect of a slightly misadjusted rangefinder. Probably you cannot see this with a shorter focal length lens. Quote Link to post Share on other sites More sharing options...
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