uhoh7 Posted June 2, 2015 Share #61 Posted June 2, 2015 Advertisement (gone after registration) Always glad to learn new things thank you. Do you perceive that drop in practice really? Oh yes in infinity landscapes it's quite obvious, the CV skopar has a huge mid-zone dip, as do many of the 35s, as Edwards notes. Funny I don't notice it the 28 cron, but it may be there. Here is my ZM 35/2 in a shot where you can really see it's performance in this regard: fantastic mid zone, but extreme corners soften: L1020950 by unoh7, on Flickr I think the ZM 35/2 may really be the best landscape 35 in M, even today. Link to post Share on other sites More sharing options...
Advertisement Posted June 2, 2015 Posted June 2, 2015 Hi uhoh7, Take a look here Leica / Zeiss: Who is better?. I'm sure you'll find what you were looking for!
lct Posted June 2, 2015 Share #62 Posted June 2, 2015 Well i'm lucky enough to own several Leica, Zeiss, CV, Nikon and other lenses that i've been using for 30+ years and i can confirm than i've never seen the issue you're referring to out of my 50/1.4 asph so far. Same for the so-called focus shift of the 35/2 asph. That is why i would like to see pics showing such defects, if any. Link to post Share on other sites More sharing options...
Mornnb Posted June 2, 2015 Share #63 Posted June 2, 2015 What I have seen is that most tend to believe that the 50 APO is not much sharper than the Lux 50, especially stopping down when everything becomes a wash. I do beg to differ. Even on an optical bench that spits out these MTF charts, the APO shows much flatter curves compared to the Lux 50. It's there if you look for it. As I focus mainly on landscape and I want to keep my kit at the minimum (i.e. one lens for one focal), the APO is clearly superior than the Lux 50 ASPH as an all around lens. Technically, it's definitely better than the Lux, even if it doesn't have that f/1.4. The Lens Rental optical bench tests compared the APO and the Lux, as well as with Zeiss and Sigma lenses. (who make the best 50's for DSLRs) http://www.lensrentals.com/blog/2014/06/comparing-rangefinder-and-slr-50mm-lenses-version-0-7 The result at F/2. Note that the Lux is close to the APO but the APO is still clearly in lead. And the dip mid-frame due to field curvature is quite visible in these numbers, which the APO does not have. Note that even the lowest point in field for the Lux, still has more resolution than the peak sharpness of the Zeiss Planar and is close to the resolution of the Mandler Summicron mid-frame. Also note that the Sigma out performs the Lux and gets very close to the APO, you have to congratulate Sigma for being able to pull of this level of performance in a low cost environment. They beat Zeiss and get close to the APO. Sigma is the poor underdog here and they nearly came first. Link to post Share on other sites More sharing options...
uhoh7 Posted June 3, 2015 Share #64 Posted June 3, 2015 Roger's tests are very preliminary, but they look pretty good. However the mid-zone issue becomes a real concern for landscape if it's still around at F/8, which it is on some lenses. What that test tells me: the v4 50 Cron was a heck of a good design. Link to post Share on other sites More sharing options...
cpclee Posted June 3, 2015 Share #65 Posted June 3, 2015 I'd like to think Zeiss and Leica are quite equal in terms of their optical design expertise. But they design to a different "house look" in general, and in the 35mm category, Zeiss designs to a lower price point due to whatever market conditions they perceive. Having said that, I have no interest in the big ZM lenses that they are putting out even if they optically match or surpass the more compact Leica offerings. They are incredible but I'm personally not interested. Link to post Share on other sites More sharing options...
hiepphotog Posted June 3, 2015 Share #66 Posted June 3, 2015 The Lens Rental optical bench tests compared the APO and the Lux, as well as with Zeiss and Sigma lenses. (who make the best 50's for DSLRs) http://www.lensrentals.com/blog/2014/06/comparing-rangefinder-and-slr-50mm-lenses-version-0-7 The result at F/2. Note that the Lux is close to the APO but the APO is still clearly in lead. And the dip mid-frame due to field curvature is quite visible in these numbers, which the APO does not have. Note that even the lowest point in field for the Lux, still has more resolution than the peak sharpness of the Zeiss Planar and is close to the resolution of the Mandler Summicron mid-frame. Also note that the Sigma out performs the Lux and gets very close to the APO, you have to congratulate Sigma for being able to pull of this level of performance in a low cost environment. They beat Zeiss and get close to the APO. Sigma is the poor underdog here and they nearly came first. Thank you, this nicely supported what I presented in the previous page. I did compare my result with Roger's optical bench result and Leica's published MTF charts. What I found at f/1.4, f/2.8 and f/5.6 are consistent with the literature. So I have no doubt that my copy would be at all faulty. In the end, would it affect one's vision? It depends entirely on one's reference. But it is certainly there. Link to post Share on other sites More sharing options...
pgk Posted June 3, 2015 Share #67 Posted June 3, 2015 Advertisement (gone after registration) Note that the Lux is close to the APO but the APO is still clearly in lead. And at the first furlong ...... Link to post Share on other sites More sharing options...
edwardkaraa Posted June 3, 2015 Share #68 Posted June 3, 2015 The Lens Rental optical bench tests compared the APO and the Lux, as well as with Zeiss and Sigma lenses. (who make the best 50's for DSLRs) http://www.lensrentals.com/blog/2014/06/comparing-rangefinder-and-slr-50mm-lenses-version-0-7 The result at F/2. Note that the Lux is close to the APO but the APO is still clearly in lead. And the dip mid-frame due to field curvature is quite visible in these numbers, which the APO does not have. Note that even the lowest point in field for the Lux, still has more resolution than the peak sharpness of the Zeiss Planar and is close to the resolution of the Mandler Summicron mid-frame. Also note that the Sigma out performs the Lux and gets very close to the APO, you have to congratulate Sigma for being able to pull of this level of performance in a low cost environment. They beat Zeiss and get close to the APO. Sigma is the poor underdog here and they nearly came first. I have many doubts about lensrentals' test and its accuracy. Many of the numbers don't make any sense imho, especially when compared to official MTF figures and practical experiences with the lenses. For instance the 50 cron having the same super high resolution in the center, mid-frame and corners is just ridiculous and does not correspond to any photos I have seen from this lens including paid reviews. The Sigma results are also very suspicious as nowhere I have seen such performance. The Lux outperforming the Otus doesn't make any sense either. Ultimately you can believe what you want, but I personally look at 2 things: official MTF (measured not theoretical) and real photos. Link to post Share on other sites More sharing options...
biglou Posted June 3, 2015 Share #69 Posted June 3, 2015 The Otus is a very wonderful lens i own and i get easy and repeatable good results on an A7r. Apo-summicron also but its too short throw does not allow for easy and very accurate focusing, this in my opinion spoils part of the qualities of the lens. Link to post Share on other sites More sharing options...
jaapv Posted June 3, 2015 Share #70 Posted June 3, 2015 I have many doubts about lensrentals' test and its accuracy. Many of the numbers don't make any sense imho, especially when compared to official MTF figures and practical experiences with the lenses. For instance the 50 cron having the same super high resolution in the center, mid-frame and corners is just ridiculous and does not correspond to any photos I have seen from this lens including paid reviews. The Sigma results are also very suspicious as nowhere I have seen such performance. The Lux outperforming the Otus doesn't make any sense either. Ultimately you can believe what you want, but I personally look at 2 things: official MTF (measured not theoretical) and real photos. The official MTF figures by Leica are calculated, not measured. I think Zeiss publishes actual measured values, making the two impossible to compare. Link to post Share on other sites More sharing options...
Mornnb Posted June 3, 2015 Share #71 Posted June 3, 2015 The official MTF figures by Leica are calculated, not measured. I think Zeiss publishes actual measured values, making the two impoassible to compare. The only reason calculated MTF would not be the same as measured, is if the factory is unable to manufacture the lens to the precision assumed by the lens designers. Link to post Share on other sites More sharing options...
jaapv Posted June 3, 2015 Share #72 Posted June 3, 2015 No, that is not correct. MTF figures are not as objective and precise as they may appear. Nor do they describe more than a part of the performance of a lens. A much more precise and meaningful value is the OTF (Optical Transmission Function) but it is a bit complicated to be used in popular comparisons. Link to post Share on other sites More sharing options...
pgk Posted June 3, 2015 Share #73 Posted June 3, 2015 MTF figures are not as objective and precise as they may appear. I'd say that they are both objective and very precise but need to be interpreted for what they are - a snapshot of a specific part of the performance of a lens at specified settings. Nothing more. Few people will be able to translate this into actual image performance for a GP lens (as opposed to a copy lens say). And as someone who used to MTF test lenses, albeit a long time ago, let me assure you that a calculated MTF is not the same as measured MTF because of a thing called tolerance which optical engineers no doubt take into account but would have great difficulty in putting into a simple MTF chart. And individual samples of the same lens vary too. The bottom line should always be 'is the lens fit for purpose' as opposed to does it meet absolute design criteria. FWIW I would guess that the Summicron APO is built to a higher tolerance than many other lenses and can no doubt be adjusted should it require this after time. The same may or may not be true of other designs which may well perform well but which may have vastly different mechanics to make them cheaper to manufacture. A lens designer friend told me years ago that tightening tolerance in lenses was a good way of very quickly increasing manufacturing costs because it requires extensive testing by skilled people during manufacture of components and assembly.. Link to post Share on other sites More sharing options...
jaapv Posted June 3, 2015 Share #74 Posted June 3, 2015 And MTF figures are two-dimensional, whereas our subject matter is three-dimensional. Link to post Share on other sites More sharing options...
pgk Posted June 3, 2015 Share #75 Posted June 3, 2015 And MTF figures are two-dimensional, whereas our subject matter is three-dimensional. Absolutely, and nobody has come up with any realistic way of summarising the 'performance' of a camera lens simply - hence the continual arguments and discussions. Link to post Share on other sites More sharing options...
Cuthbert Posted June 3, 2015 Share #76 Posted June 3, 2015 In order to fire employees , the Carl Zeiss company gives him the task to improve the Summilux-M 1:1.4/50 ASPH If the victim fails within 2 weeks, he is fired because of lack of qualification. Is it possible to improve Summilux (within 2 weeks)? What Zeiss lens could compare with Summilux? What is the opinion in the forum? What is the experience with the design department of Carl Zeiss? Funny question: Zeiss and Leitz have been enemies for almost a century, both companies have a great History and emblematic design, and their customers don't want a Leica lens made by Zeiss and viceversa, they want their products to remain separate so if they buy both they can appreciate the difference between the Z design and the L design. Then they boast their glass on internet! Link to post Share on other sites More sharing options...
jdlaing Posted June 3, 2015 Share #77 Posted June 3, 2015 Enemies is too strong a word. Link to post Share on other sites More sharing options...
jaapv Posted June 3, 2015 Share #78 Posted June 3, 2015 There are quite a few mixed marriages between Leica and Zeiss employees in the area and the staff go to the same Biergarten. Rivalry in business is one thing, enmity on a personal level, or even between companies, is another. Link to post Share on other sites More sharing options...
hiepphotog Posted June 3, 2015 Share #79 Posted June 3, 2015 Absolutely, and nobody has come up with any realistic way of summarising the 'performance' of a camera lens simply - hence the continual arguments and discussions. A complete picture (no pun intended) of a lens performance can't be captured entirely by MTF charts. However, it still remains that certain characteristics of the optical performance can be evaluated, such as astigmatism and LCA, field curvature, contrast rise and drop (i.e. perceived sharpness) in certain part of the picture on the same focus plane. Even though real life scene is three dimensional and MTF chart is of a 2D target, a lens can only produce a thin plane of in focus, and the rest is just circle of confusion encompassing progressively more out of focus planes both in front and behind such. As such, I think we would agree that if the MTF chart of the "infinity" performance showing a drop in contrast at certain part of the test chart, we would expect to see the same thing on an infinity shot in real life. Performance at different distances will certainly be different. Now the question is how close the general rise and drop in contrast behavior at different distances would be compared to the infinity performance. I think the severity would change, but I doubt that there will be a distance where it would go from a noticeable field curvature at infinity to a complete (or close to that) flat field curvature. Paul, since you had experience in MTF measurement, what had you seen? Link to post Share on other sites More sharing options...
BerndReini Posted June 3, 2015 Share #80 Posted June 3, 2015 I honestly cannot find the focusing problems you mention in Google, except LaVida. What search words did you use? Sorry Jaap, I had lost track of this thread for a few days. If you google "Zeiss wobble" you will find reference to the problem. I'm glad you don't have any problems with your ZM lenses, and I would hope it doesn't affect every single lens, but it was really bad on my 21mm Biogon. I hadn't used it in six months and when I used it it sounded like a creaking door nail. My friend had the same problem with his ZM lens, another friend loves his 25mm. I have definitely found more references to these quality control issues, and purely subjectively when you own ten Leica lenses and one Zeiss lens, and the Zeiss one gives you issues despite being one of the newest, it just leaves a bad impression. Link to post Share on other sites More sharing options...
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