"is there any (practical) way to build actual MTF's from hubsands ZF25 ? comparing those MTF's to the ones published by zeiss ... wouldn't that tell us for sure whether Mark got a dud ? but i don't know how you build actual MTF's."
Yes ... and No.
You can construct an MTF curve using Norman Koren's Imatest program. Its not easy - because the first thing you will learn is that quantitative lens testing really does require more accurate focussing than practical photography. You do learn something - I believe that I have a better instinct for the practical limitation of the lenses I have tested.
However, although you can compare one lens with another with a fair amount of time and trouble, you can only make relative measurements. With digital images the values you get are influenced by the your raw converter's processing so the absolute values are not comparable with measurements made using different bodies or raw converters never mind the much more sophisticated instruments which I imagine Zeiss to use.
Last week I shot an image for an interior design client with the ZF25 and presented them with an A3 print. They complained about the corners looking soft compared to the centre, so I reprinted the image with Zeiss' MTF data alongside it, so they could see that, regardless of the evidence of their own eyes, the corners were, in fact, perfect.
When they saw the data, they agreed that the corners must be sharp after all, and that their stupid eyes had fooled them, and we all laughed and everything was fine.*
* Any resemblance to actual events or characters depicted in this post is entirely coincidental.
hubsand wrote:
Last week I shot an image for an interior design client with the ZF25 and presented them with an A3 print. They complained about the corners looking soft compared to the centre, so I reprinted the image with Zeiss' MTF data alongside it, so they could see that, regardless of the evidence of their own eyes, the corners were, in fact, perfect.
When they saw the data, they agreed that the corners must be sharp after all, and that their stupid eyes had fooled them, and we all laughed and everything was fine.*
* Any resemblance to actual events or characters depicted in this post is entirely coincidental....Show more →
The most difficult part about this situation is objectivity. Most folks on this forum, including myself, have an automatic predisposition towards the Zeiss, and feel the Canon's are rubbish. Even when hubsand's tests demonstrate the opposite, we are trying all sorts of rationalizations to get the results back to where we think they should be. If I needed a 24mm lens today, I would be asking to buy hubsands Canon 24/1.4L.
hubsand wrote:
Last week I shot an image for an interior design client with the ZF25 and presented them with an A3 print. They complained about the corners looking soft compared to the centre, so I reprinted the image with Zeiss' MTF data alongside it, so they could see that, regardless of the evidence of their own eyes, the corners were, in fact, perfect.
When they saw the data, they agreed that the corners must be sharp after all, and that their stupid eyes had fooled them, and we all laughed and everything was fine.*
* Any resemblance to actual events or characters depicted in this post is entirely coincidental....Show more →
jjlphoto wrote:
The most difficult part about this situation is objectivity. Most folks on this forum, including myself, have an automatic predisposition towards the Zeiss, and feel the Canon's are rubbish. Even when hubsand's tests demonstrate the opposite, we are trying all sorts of rationalizations to get the results back to where we think they should be. If I needed a 24mm lens today, I would be asking to buy hubsands Canon 24/1.4L.
But why would he sell it when it is likely the best 24L ever made? From what I have seen and heard, the vast majority of them do not perform like his. If they did, they would enjoy a reputation much closer to that of the holy trinity.
I'd be looking for a Zuiko 24mm 2.8. It held up very nicely during hubsand's 24mm tests and it is easily the cheapest of the lot, not to mention the obvious size and weight advantages.
Forgive me for quoting you, hubsand, but I find statements like this very encouraging:
"The Olympus is astoundingly good at f5.6-8 at distance, and produced the highest resolution captures of anything shot thus far at 24mm."
"We should also mention that the stellar little Olympus 24mm thrashed every other lens it encountered in the group stages of the 24mm World Cup, can be bought used for less than a decent filter for the 24L, and fits in the palm of your hand with room to spare. It's a gem."
marcwilson wrote:
does the little olympus suffer from the same sample variation as the canon..and perhaps the zeiss zf!?
People here have stated that it does. My own experience with just two made many years apart and one being the newer mulit-coated and the other single coated showed that, at least with this tiny sample, they were very close in performance. Really remarkably so. The worst faults I could find with either one was some pretty bad vignetting, really until about F8 or so and more distorition than I like to see. Both of these are easily corrected in Photoshop of course. The much poo pooed(here at least by Hubsand, Bjorn Rorslett really likes this lens as do I http://www.naturfotograf.com/index2.html) Nikkor 24mm AI with floating elements is really not that bad a performer at F8 excepting for the very extreme corners. I have noticed recently that it seems classic Wide Angle Nikkors do really well but then drop dramatically in resolution just at the extreme corner. Almost as if they were designed to never be seen here(such as a mounted slide?). Almost every one I have tested or used thus far really excel in color/contrast, Lack of vignetting(both the 24+28) and really good, low distortion geometry. All things which at one time were not easily corrected by post processing. The Olympus does not perform well comparatively in these respects and might not have been such as good choice back in the film only days.
Edited by Tariq Gibran on Feb 08, 2007 at 12:18 PM GMT
Edited by Tariq Gibran on Feb 08, 2007 at 12:19 PM GMT
I would expect *some* sample variation (among the 24/2.8 Zuikos), but I would not expect it to be all over the map like the 24L seems to be. Can't comment on the Zeiss at this point.
For the price of them, you could buy 4 or 5 of them and choose the best one. Not so easy to do this with the Canon or the Zeiss.
Tariq mentions the Nikons and I have been pondering those as well, including some of the Nikon 20mm lenses. About the contrast on the Zuikos (I've noticed it with my 21/3.5 as well), all I can say is that adding contrast in post is easier than removing it. In other words, I am beginning to appreciate the finer gradations in mid-tones that these "lower contrast" lenses produce. I think there is something called "too contrasty" and I don't particularly like it.
Back on Page 8, on January 30, husband referred to his communication(s) with Zeiss. Husband, have you heard anything back yet? I had thought that at least some of the personnel at Zeiss gave rapid replies.
cogitech wrote:
...I am beginning to appreciate the finer gradations in mid-tones that these "lower contrast" lenses produce. I think there is something called "too contrasty" and I don't particularly like it.
Could somebody elaborate how a lens could lower the scene contrast other than inducing flare?
Alex wrote:
Could somebody elaborate how a lens could lower the scene contrast other than inducing flare?
Alex
These "lower contrast" lenses don't lower the scene contrast. Rather, they render them accurately, as opposed to *increasing* the scene contrast to an unnatural state that has less overall gradations (as some of the ultra-contrasty lenses do). I'd much rather start with an accurate or "complete" range with lots of mid-tone content and add contrast if necessary than start with something overly contrasty and then try to recover the mid-tones. There is also the obvious benefit of reducing the likelyhood of blown highlights and/or lost shadow detail, because the sensor has to deal with less overall dynamic range.
This is a recent personal observation and I certainly don't expect many of you to agree with it.
cogitech wrote:
These "lower contrast" lenses don't lower the scene contrast. Rather, they render them accurately, as opposed to *increasing* the scene contrast to an unnatural state that has less overall gradations (as some of the ultra-contrasty lenses do). I'd much rather start with an accurate or "complete" range with lots of mid-tone content and add contrast if necessary than start with something overly contrasty and then try to recover the mid-tones. There is also the obvious benefit of reducing the likelyhood of blown highlights and/or lost shadow detail, because the sensor has to deal with less overall dynamic range.
This is a recent personal observation and I certainly don't expect many of you to agree with it.
Duffy wrote:
Back on Page 8, on January 30, husband referred to his communication(s) with Zeiss. Husband, have you heard anything back yet? I had thought that at least some of the personnel at Zeiss gave rapid replies.
Thanks for your efforts.
Zeiss' PR department have been quite communicative, but I haven't heard back from them since they referred my questions to R&D more than a week ago. I've chased them up on it twice. A timely word from an official source would end much speculation.
cogitech wrote:
Tariq mentions the Nikons and I have been pondering those as well, including some of the Nikon 20mm lenses. About the contrast on the Zuikos (I've noticed it with my 21/3.5 as well), all I can say is that adding contrast in post is easier than removing it. In other words, I am beginning to appreciate the finer gradations in mid-tones that these "lower contrast" lenses produce. I think there is something called "too contrasty" and I don't particularly like it.
I hear you. And I blame Leica. The DMR has been the most explicit demonstration of Leica's imaging philosophy we've ever seen: they're controlling all that we see. They control the horizontal and the vertical. They can reduce the focus to a soft blur, or sharpen it to crystal clarity . . . I'm drifting . . . What I'm trying to say is that the DMR sensor and software is esoterically in tune with the Leica glass, and it's been an education to see the results people have been getting.
It's made me rethink my Canon post-production to achieve a more Leica-like look: I now don't like the high-contrast look that typifies out-of-the-box Canon cameras and many Canon lenses. Fortunately the 5D and 1Ds are such versatile devices that they can be fine tuned to achieve (what seems to me to be) more sophisticated images. But I'll be looking very hard at the R10 and 1Ds III this summer.
cogitech wrote:
These "lower contrast" lenses don't lower the scene contrast. Rather, they render them accurately, as opposed to *increasing* the scene contrast to an unnatural state that has less overall gradations (as some of the ultra-contrasty lenses do). I'd much rather start with an accurate or "complete" range with lots of mid-tone content and add contrast if necessary than start with something overly contrasty and then try to recover the mid-tones. There is also the obvious benefit of reducing the likelyhood of blown highlights and/or lost shadow detail, because the sensor has to deal with less overall dynamic range.
This is a recent personal observation and I certainly don't expect many of you to agree with it.
Very interesting observation. Does anyone happen to know how it is physically possible for a lens to increase contrast? I can easily imagine that this is possible at the sensor level, but I'm clueless about how a lens could do that. Any input is very much appreciated!
