-ph- Posted June 17, 2012 Share #21  Posted June 17, 2012 Advertisement (gone after registration) I have not any experience with that lens, but I shot with a Voigtländer 21mm on my M9 some days ago and also had the impression that it underexposes - but as it was only a few pictures, I did not really look into possible causes and unfortunately I don't have it in reach any more.  Ignoring the white car which obviously has a big influence on metering, a couple of reasons come to my mind which could cause underexposure. You should be able to figure them out with just a few tests. Choose a test target reasonably uniform in brightness (e.g. a wall) and measure with your 21 and e.g. a 35 or 50 to see whether they indeed do measure differently, and if so, by how much. Digital sensors have different sensitivity to light rays depending on their angle of incidence, so older lenses, especially wide angles, might cause less exposure.  If the lenses measure similar under controlled conditions, then it was some difficulty of metering in the given scene. I find it pretty difficult to get precise exposure with the camera meter in random locations like this one, where you have a person in front of a white car. So I have turned to use incident light metering in these situations with excellent results. A grey card can be had for $10, it will not only give you a precise exposure but also a precise white balance. And if you want the luxury solution, get an incident light meter. I recently got myself a Gossen digipro F and am very happy with it, but any incident light meter ever made should give you very reliable results. In any case, you would need to calibrate the light meter vs. your camera sensitivity at least once - so to do that you should get a grey card anyway. (The camera sensor ISO values are not exactly specified and also it would calibrate away any effect of the lens-sensor interaction)  Peter Link to post Share on other sites More sharing options...
Advertisement Posted June 17, 2012 Posted June 17, 2012 Hi -ph-, Take a look here 21mm Skopar Bad on Digital. I'm sure you'll find what you were looking for!
farnz Posted June 17, 2012 Share #22  Posted June 17, 2012 I have not any experience with that lens, but I shot with a Voigtländer 21mm on my M9 some days ago ... Peter,  The 21 Color Skopar is the same 21 mm Voigtlander lens you've referred to.  Pete. Link to post Share on other sites More sharing options...
-ph- Posted June 17, 2012 Share #23  Posted June 17, 2012 Peter, The 21 Color Skopar is the same 21 mm Voigtlander lens you've referred to.  Pete.  Ah funny, didn't catch that, thanks. So in one sense it is good (confirms the observation) and bad (as it reduces the sample variety for comparison)  Peter Link to post Share on other sites More sharing options...
lct Posted June 17, 2012 Share #24 Â Posted June 17, 2012 John, the exif data of your second pic say "Max Aperture = f/1". Makes me think that your lens is not coded if you did not code it like a Noctilux . It may explain vignetting to some extent, even out of the corners. Specially true with the little Skopar 21/4 which vignettes a lot on another crop cam like the R-D1. The M8 does a superb job with this lens provided it is coded naturally. Otherwise, your exif data say also "Brightness: +50". You have clearly got an exposure problem there. I don't know where it came from but the white car syndrom springs to my mind as well. Link to post Share on other sites More sharing options...
johnloumiles Posted June 17, 2012 Author Share #25  Posted June 17, 2012 Dude, just learn how to meter light!  Thanks! I was wondering why every shot I've taken over the last 15 years has come out underexposed. I'm going to give up on this whole incident split metering thing on your advice.  JohnLou - what film and processing regime are you using with the M6? Color negs and a lab? Slides? B&W film and roll-your-own prints? I would note that I ran an "average" filter over the M8 metering area on one of your shots, and it did come out darker than expected - 69% gray rather than 50%. So not only is the big expanse of white car dropping the exposure (which should result in 50% gray, and thus an underexposure for all that white) but the camera meter itself is about 1/2 stop below that.  Thank you for taking the time to run that filter. Film : Straight c41 lab process, scan myself. I'm glad I have you to lend me some support, at least now I know i'm not taking crazy pills. To me the car is about a 3/4 stop under what it should be. I wish I had an M6 image to compare but that picture taking session was impromptu. I've enclosed some film scans below. No pushing or pulling has been done via scan or pp.  Hello, I would like to ask a couple of questions which are kind of basic and I hope they are received in the sincerely helpful way they are meant, but might help suss out some alternative answers than to afix all of the blame on the lens for the exposure issues. A) do you have other lenses that are shot both on your M6 and your M8? If so, does the meter behave identically between cameras? Have you checked to make sure you haven't forgotten to dial out an exposure compensation setting in one of the menus? C) did you shoot this white car in bright sunshine with M6 at the same time and if so how did it do exposure wise? D) how much experience do you have with 'simple' center weighted ttl metering systems? Being an M6 owner I suspect you do, but assumptions are the shortest route to mistakes being made in my experience, anyway. E) what kind of film are you shooting with the 21 Skopar in the M6 because if it's negative film then it is quite easy for even moderate exposure misses to be camoflauged by modern high tech emulsions (especially color neg) and then the great equalizer called the printing process can hide missed exposures, especially if you're not the one handling every step of the development and printing of the images.Sincerely Richard Ward  A) Nothing scientific but i remember shooting at the widest a 25mm Skopar on both with no issues. Every lens above that I've had no issues except the random missed exposure.  Yes. Straight across the board.  C)No. Shoot was impromptu but was the most recent use of the 21 on the M8.  D) 10 years in other systems, 2 with Leica M. I've spent entire days testing behavior of the Leica M meter. Sometimes have incident meter mounted on top to cross check. If i'm doing a photo shoot I spot meter as well.  E) Last role was Ektar 100. Maybe you have something there.  Thanks for your questions, I appreciate it!  Below are latest with M6 + 21mm 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/181920-21mm-skopar-bad-on-digital/?do=findComment&comment=2042094'>More sharing options...
johnloumiles Posted June 17, 2012 Author Share #26  Posted June 17, 2012 It's bad metering technique. A lens by itself doesn't cause under exposure. Not understanding the relationship between the subject and the camera's metering can.  And the first untouched image redone with some pp showing there is still a lot of detail to pull out. The deep shadows are tricky, but with a big file they shouldn't be a problem to sort out. Although the first image is much too dark a darker file out of the camera could be expected if you intentionally metered to keep as much detail in the white car as possible, and then you would pull the rest up in pp. But I think with the original exposure there is still a long way to go before you lost detail in the whites.  Well—getting TTL metering right with wide-angle lenses generally is more difficult than with standard or telephoto lenses. This is true, to varying degrees, with virtually any TTL-metering camera. I guess it has to do with the exit pupil being small and close to the metering cell. But then, why is the issue absent in your M6? No idea ... maybe it isn't really absent but just less obvious. Maybe tolerances of the camera's light meter calibration and the film's latitude are adding up in another way than in your M8. Anyway—the issue is not specific to the Voigtländer Skopar lens. With any other 21 mm lens of similar speed you're going to have the same problem. (Faster lenses seem to be more accurately metered, even when metering happens at working aperture; don't ask me why.) I don't see any issue in your pictures that couldn't get cured through a slightly more generous exposure. Simply add half an f-stop (in back-lit situations) or one full f-stop (in front-lit situations) to the metering when using the 21 mm on the M8 in high-contrast lighting conditions. You may want to try carrying an external hand-held light meter for a while, to see under which conditions exactly your cameras are metering reliably and when not.  I feel like I need to clarify myself so I don't come across as a mindless dolt, at least in this particular situation.I walk into too many light posts in real life as it is, I don't want to do it figuratively as well. First off I should have put a question mark after the title of the post because that was not supposed to be a statement but rather a "hey has anyone else experienced this issue". Also I want to thank you 250 for doing a little PP. I always knew there was detail to be had but I'd rather nail the exposure...mostly because I like smooth tones in the face and pulling tends to grit it up sometimes with the M8. I do not think the lens is defective or by itself responsible for under exposures. More I thought it was a combination of the lens, the camera and me. This last time I shot with the lens I saw it was under exposing from the start so I started bracketing all the shots. What I found and really the point I'm trying to get across is that it is very difficult to find the sweet spot with this lens under certain condition. This is obviously because it is such a wide lens but I am still curious about the disparity between film and digital. I will do a proper test tomorrow. Link to post Share on other sites More sharing options...
johnloumiles Posted June 17, 2012 Author Share #27 Â Posted June 17, 2012 Advertisement (gone after registration) John, the exif data of your second pic say "Max Aperture = f/1". Makes me think that your lens is not coded if you did not code it like a Noctilux . It may explain vignetting to some extent, even out of the corners. Specially true with the little Skopar 21/4 which vignettes a lot on another crop cam like the R-D1. The M8 does a superb job with this lens provided it is coded naturally. Otherwise, your exif data say also "Brightness: +50". You have clearly got an exposure problem there. I don't know where it came from but the white car syndrom springs to my mind as well. Â It was coded but it wears off regularly and I have to keep reapplying. The marks were visible yesterday but not very fresh. Obviously I need to fix that, thanks for bringing it to my attention. Link to post Share on other sites More sharing options...
lct Posted June 17, 2012 Share #28  Posted June 17, 2012 It was coded but it wears off regularly and I have to keep reapplying... Dirty DIY with a $50 dremel tool and a sharpie. Somewhat ugly but effective. 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/181920-21mm-skopar-bad-on-digital/?do=findComment&comment=2042213'>More sharing options...
lars_bergquist Posted June 17, 2012 Share #29 Â Posted June 17, 2012 A slightly overcast sky will also tend to play havoc with your superwide exposures. There are two remedies: Measure incident light, or check your histograms frequently. Â The old man from the Kodachrome Age Link to post Share on other sites More sharing options...
lct Posted June 17, 2012 Share #30 Â Posted June 17, 2012 21s have a 28 FoV on the M8. Never got exposure problems there. YMMV. Link to post Share on other sites More sharing options...
adan Posted June 17, 2012 Share #31 Â Posted June 17, 2012 Thank you for taking the time to run that filter. Film : Straight c41 lab process, scan myself. I'm glad I have you to lend me some support, at least now I know i'm not taking crazy pills. To me the car is about a 3/4 stop under what it should be. I wish I had an M6 image to compare but that picture taking session was impromptu. I've enclosed some film scans below. No pushing or pulling has been done via scan or pp. Â Hi and thanks. Â My point would be that the scanning process itself amounts to "post-processing". Scanner software does exposure correction on the fly to get a well-balanced tonal range from the film. Unless you've switched off the autoexposure feature, and have never touched any of the brightness or contrast or curve controls as you scan, you are getting an "adjusted" version of what your M6 meter produced, not a "pure, unprocessed" image exactly as the camera produced it. Â That's why I asked about film type. E6 slides from the M6 (as seen by the eye, before scanning) would be a better measure of what its meter does with this lens, unaided by any other processing. Â BTW - the cyan tint in the car fender lower left in that shot is due to the failed lens coding not correcting for the IR filter. Pretty standard for any lens wider than 50mm if a filter is used and the coding isn't there or isn't working. Link to post Share on other sites More sharing options...
jaques Posted June 18, 2012 Share #32  Posted June 18, 2012 i like this tiny lens a lot... warts and all: 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/181920-21mm-skopar-bad-on-digital/?do=findComment&comment=2042702'>More sharing options...
lct Posted June 18, 2012 Share #33 Â Posted June 18, 2012 Dirty DIY with a $50 dremel tool and a sharpie. Somewhat ugly but effective. For those interested, better put a drop of Tipp-Ex or other white correction fluid onto the screw head to cover dark parts around it. Superb little lens on my M8.2. Would deserve easily a red dot compared to the Super-Angulons M or R of same focal length. Link to post Share on other sites More sharing options...
rramesh Posted June 18, 2012 Share #34 Â Posted June 18, 2012 Wouldn't the 21 Skopar be best coded as a 21 2.8 as opposed to a 21 2.8 ASPH? Link to post Share on other sites More sharing options...
lct Posted June 18, 2012 Share #35 Â Posted June 18, 2012 I did not notice a difference. I chose the 21/2.8 asph coding in the first place because it was advised by Carsten Whimster then and there are only two notches to drill out for it. Now i prefer the 21/3.4 coding which gives me the feeling to get a bit less color shift in the corners from time to time. I would not swear that it's worth the extra DIY work though. Link to post Share on other sites More sharing options...
250swb Posted June 18, 2012 Share #36 Â Posted June 18, 2012 I have the LTM version of the CV 21mm, so coding an M adapter is easy. But I have tried all the codes with my M9 and can't see a difference other than it should be for 21mm lens of some sort. Â Steve Link to post Share on other sites More sharing options...
johnloumiles Posted June 18, 2012 Author Share #37  Posted June 18, 2012 Hi and thanks. My point would be that the scanning process itself amounts to "post-processing". Scanner software does exposure correction on the fly to get a well-balanced tonal range from the film. Unless you've switched off the autoexposure feature, and have never touched any of the brightness or contrast or curve controls as you scan, you are getting an "adjusted" version of what your M6 meter produced, not a "pure, unprocessed" image exactly as the camera produced it.  That's why I asked about film type. E6 slides from the M6 (as seen by the eye, before scanning) would be a better measure of what its meter does with this lens, unaided by any other processing.  BTW - the cyan tint in the car fender lower left in that shot is due to the failed lens coding not correcting for the IR filter. Pretty standard for any lens wider than 50mm if a filter is used and the coding isn't there or isn't working.  Yeah I know E6 would have been a better measure. I had the scanner was zeroed out so I'm confident other then the normal generosity film provides in latitude, that was the exposure. I've come to the conclusion that bright, hazy conditions/ white cars aren't the best but otherwise it's fine. Link to post Share on other sites More sharing options...
BJDrew Posted June 21, 2012 Share #38 Â Posted June 21, 2012 Good morning. Given the little Skopar is one of my favorite implements, I can somewhat sympathize. Two things trick the meter consistently for me 1) There is always more sky in the frame than I think 2) There is always more flare than I think (even a little encourages underexposure) Â When I am outdoors, I always take two 'palm of the hand' readings in shade and in open sun to keep me honest while shooting (a convenient +1 EV) note the settings and compensate when the meter tries to fool me. Â When metering, I always am sure to quickly point the camera at a few parts of the scene... particularly into an area of shadow or even towards the ground. It often shows 1 or 2 stops underexposure. At this point, with film, you can bump up a bit and let the highlights fall where they may. Link to post Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.