is it possible that some of these lenses are outresolving the sensors they are put infront of? some of the shots posted here and else where regarding MF glass on digital 35mm sensors seems to look like the glass might be out resolving the sensor.
mrkauffman wrote:
is it possible that some of these lenses are outresolving the sensors they are put infront of? some of the shots posted here and else where regarding MF glass on digital 35mm sensors seems to look like the glass might be out resolving the sensor.
mrkauffman wrote:
is it possible that some of these lenses are outresolving the sensors they are put infront of? some of the shots posted here and else where regarding MF glass on digital 35mm sensors seems to look like the glass might be out resolving the sensor.
What are the indicators of when a lens is 'outresolving' a sensor?
Jim Schemel wrote:
Maybe your copy was not sharp.But i do not think you can speak for them all.Maybe you mis - focused or something.All i know is that my copy is extremely sharp, and i have tried other glass such as Zeiss,Canon,Sigma etc.
-Jim
Jim, if you really dig for the few online reviews & threads, you'll find that the 45mm is pretty much universally panned. Yours must have been an exception.
No no. The 45mm is about as well regarded as the 35 and 55. All are very good, according to the copious owner reports I came across when researching this series.
The lens-sensor resolution question is a good one with no clear answer, so 'it depends'. Reading between the lines of Zeiss's papers, some top lenses *may* out-resolve modern sensors but are unlikely to do it at all apertures or in all parts of the frame. It's a moot point though because it is not a weakest link situation - total IQ is multiplicative - essentially a product of sensor and lens MTF.
Even a poor lens (one with MTF clearly less than the sensor) on say a 5DII or a Sony A900 will do as well as a great lens on say, a D700, due to the large MTF margin the high res sensor has over the low res sensor. Which is not to say that the best lenses will not deliver the best the high res sensor is capable of - they will. Having high res lenses is a great idea because you are ready to get the best from the next gen sensors.
Cableaddict wrote:
Jim, if you really dig for the few online reviews & threads, you'll find that the 45mm is pretty much universally panned. Yours must have been an exception.
My 45/2.8N was every bit as good as my 35/3.5N and 55/2.5N. I sold it because I didn't need that many similar focal lengths, not because of any issues with its performance. Prior to buying into the M645 lens leneup, none of my research indicated any particular problems with the 45mm.
i dont know of any definitive signs the glass is out resolving, i just remember seeing a small number of reviews or examples on the internet some time ago with zeiss lenses out resolving a sensor. ive seen it mentioned maybe 5 or 6 times in the past 3 years with examples posted. i dont know if the persons right but its just a look the picture has, im probably completely wrong but your eyes are a lot smarter than you think.
I'm not necessarily wondering how to determine whether or not the lens is capable of outresolving the sensor, but rather how does that affect IQ (positively/negatively/neutral) in the pic ??
Given that the output is multiplicative ... it would seem that you would want the best resolving glass no matter what the sensor (other preferences notwithstanding) ... unless there is some kind of 'side effect' like more propensity for aliasing, fringing, or ?? when the lens does in fact out resolve the sensor.
But then it would seem that virtually ALL lenses outresolved sensors just a few years back when single digit MP was the best there was. What issues were there then ??
RustyBug wrote:
I'm not necessarily wondering how to determine whether or not the lens is capable of outresolving the sensor, but rather how does that affect IQ (positively/negatively/neutral) in the pic ?
It depends on how you want to view the image. I figure that if the system resolution is within the COC for the DOF that you're trying to make sharp, then you're OK; otherwise, the resolution is affecting the sharpness you desire. Of course, this is the first time that I thought of it that way, so maybe it'll take more thought...
RustyBug wrote:
... it would seem that you would want the best resolving glass no matter what the sensor (other preferences notwithstanding) ...
Yes! I always want the best glass. Of course, that's not always the 'best resolving' glass. Sometimes the other preferences are more important than resolving power. Hence, the utility for 'soft' lenses and 'character', and things like tolerance to using it in an environment from which it might not return (a.k.a. 'expendability').
RustyBug wrote:
But then it would seem that virtually ALL lenses outresolved sensors just a few years back when single digit MP was the best there was. What issues were there then ??
Heck, no. There's many lenses that can't out-resolve a paper bag. Some of them cost a lot of money. Also, the current penchant for minutely examining 100%+ digital crops has nothing on high resolution film testing - except that now anybody can try to do it.
I understand that character can take preference to resolution, I guess I didn't make that quite clear enough ... and when I said virtually all lenses, I guess I had only the glass that we routinely discuss in the ALT threads in mind ... meaning any of the quality glass we aspire for would easily have been outresolving a 4MP-6MP camera.
Not meaning to take this into a lens discussion, but I still don't understand what effect using a lens with higher resolving capability than the sensor has ... other than a higher resolution image ??
Define "resolution", and then define "effect". Then I might be able to answer... :-)
Quick and easy: none. Resolution does not get higher, but the available contrast (without sharpening) at the maximum sensor-limited resolution gets higher. This is not "higher resolution", but in many cases it's actually interchangeable unless you print 1.5x1m posters at 300dpi each and every day.
Most major manufacturers afford to put properly calculated AA-filters in their cameras, only small-time players like Leica and the MF-crowd have to skimp on this (it would quite probably add 1000's of $ to the price on products with so small series production runs). This means that you run into a slope of diminishing returns with high-res lenses, but very few losses - as in every other field. There are a lot of lenses out there that outresolve a D700 by a very fair margin, and in some circumstances also quite a lot of lenses that outresolve the 21-24MP crowd. I know for a fact that some lenses I own outresolve a Canon 7D, and that means having like ~50MP in my D700 FX. I see no "effects" when using them on the D700 except that the pictures are quite sharp. :-)
On topic:
I'm pretty set on buying a 150F/2.8A come monday, I got a good quote for it. Does anyone have any Mam645->NikonF adapter experiences to share? I'm planning on using the 150"A" (and next month the 200APO) mainly on my Nikons, but maybe also with a modified adapter to facilitate use on the A850.
"Not meaning to take this into a lens discussion" - too late, and in any case it is a system resolution discussion.
"Resolution does not get higher" - I use the term 'resolution' only as a kind of shorthand because of the difficulties people (including myself) have with the MTF concept. Speaking in terms of MTF, the ability to separate very fine sinusoidal lines may be quite well approximated by the term 'resolution', with that proviso that contrast is the essential issue.
The best way to see the matter is that a high MP camera will (i) deliver substantially better results (lets call this IQ) than a low MP camera, ceteris paribus; (ii) high Mp cameras are much more tolerant of lesser performing lenses, (iii) high performance lenses add great value to IQ no matter what MP camera they are on, due to the IQ equation being a product, and (iv) high performing lenses combine with high MP cameras to deliver a 'double positive' effect re system IQ, no matter which element has more MTF.
So what this means is that each component (lens or sensor) contributes what it can to IQ and there is no 'holding back' the other element in regards to total IQ. Each time you upgrade either sensor or lens you get full value - nice. One reason this is hard to grasp is that it is counter-intuitive and runs against other elements in the image chain. For camera shake, lens defects, etc. once IQ is gone, it does not come back.
I see few photographers downsizing to 6MP DSLRs from say 12MP DSLRs...why would it be any different for 12MP and 24MP DSLRs?
The Nyquist Limit for 24MP is 84lpmm and for 12MP is 59lpmm - a difference of 42.4% more 'resolution'. Which is why the Nyquist Limit for the Canon 7D is about the same as a 24MP DSLR - it's a pixel size characteristic, but of course with fewer pixels.
For MTF-intensive applications, e.g. detailed landscapes intended for large prints, the message is clear - more pixels are better, again ceteris paribus, and the high MP cameras are just what the image doctor ordered.
Zeiss have this to say, with uncharacteristic certitude: "...combining any optical performance with a camera with a higher resolution limit and a low-pass filter designed to match improves the transfer function."
theSuede wrote:
Resolution does not get higher, but the available contrast (without sharpening) at the maximum sensor-limited resolution gets higher.
Now THAT, I can see showing up in the pics (although not necessarily a problem.)
On topic:
I'm pretty set on buying a 150F/2.8A come monday, I got a good quote for it.
This was my first M645, a definite keeper ... congrats.
philip_pj wrote:
"The Nyquist Limit for 24MP is 84lpmm and for 12MP is 59lpmm"
Does anyone have any mtf or lp/mm info on the M645 glass? Not that I need it, since the proof is in the pics, but it would be interesting to see how it matches up for some myth busting about using MF on DSLR.
"and a low-pass filter designed to match improves the transfer function."
Uh-oh ... a new wrinkle into the technical equation, so just how does the low-pass filter improve the transfer function?
I have to get back to correct some things I have got wrong, with respect to the Canon 7D. I did not realise this camera has 18MP, quite an achievement. Yes, as theSuede points out, a full frame equivalent would have around 47MP! And still most good lenses are better at their best apertures.
Kent, I have searched far and wide and no luck with M645 MTF or just about anything else technical on them! It amazes me there is so little apart from brochures on the technical side of our hobby, err, obsession.
Back on the lens res issue for a moment, a guy I greatly respect, Chris Perez, had this to say recently on Lenswork's blog:
"The Canon 7D (the highest pixel density sensor of current DLSRs) resolves 116 line pair per mm.
After putting old prime Nikon and Pentax manual focus, as well as current generation prime Sigma and Canon AF zoom and prime optics to the test, I found all of them out-resolved the sensor. From wide open (in the center of the field, at least).
Think about that for a moment, and then consider how freeing it might be to realize that, by and large, perhaps avoiding the deliberate lowest cost products, currently commercially available lenses are better than the sensor!
Said another way, it takes a really poor optic to under-perform a sensor."
Which is pretty much wat Zeiss say, not in so many words...Sorry for that add-on, last word on it - promise!
AAArgh...
He also had a 200F/2.8APO he wanted to move at 650$ - mint condition (almost), optically perfect. I think I manged to make him hold on to it for me for a few weeks. Weather today is pretty overcast, testshots from the 150 to follow later - gotta go back to work now.
There's a 200APO on ebay right now for 300GBP, but somebody already made the first bid. I see this lens doesn't have a tripod collar - wouldn't it be a bit risky to have this lens hang off the camera mount? I read on diglloyd's forum that he had an issue with a warped camera mount because of this (with some heavy 70-200/2.8 zoom I think), causing uneven image sharpness with every lens mounted on it.
Didn't see Philip's post until after I sent my last (frustrated) post, hadn't updated the window since yesterday.
Rusty:
The "transfer function" has to be seen as the sum of the system - and in this system the de-mosaicing software algorithms also has to be included (if you want a picture you can actually look at!). A properly balanced AA-filter improves reality-to-picture transfer fidelity as an AA-less starting point gives the de-mosaicing software no clue whatsoever in how to interpolate the missing colours in each pixel. This improves (synthetically - has no necessary coupling to reality whatsoever) pixel to pixel contrast at the cost of a very much lowered result certainty/fidelity. Some see this effect as "sharpness", I (and many others working with pictures professionally) see it as digital noise, dither and aliasing effects.
Seen as a whole the AA-filter makes the resulting picture more true to reality, even though it lessens the raw p-t-p contrast. In most cameras, this lowering of contrast is held at ~15-20%, not a noticeable amount in the scope of postprocessing. The D3x contrast loss is about 8-10%, which makes it a stunning resolution camera at low ISO's - but also a slightly less forgiving camera at higher ISO's, where the de-mosaic engine needs more "support" to make "intelligent guesses" and not just "guesses". Strong AA-filters improve high-ISO performance.
MF glass pros:
Less prone to decentering faults (larger glass diameters, same mounting tolerances)
Field is flatter (as it is meant to extend quite a bit further than a 135-circle optic)
More evenly shaped defocusing circles over the field (same reason as above)
In most cases same potential for resolution
Cons:
Weight, only full manual available (stop-down or go by feel, and MF of course). No real WA's.
*It started raining after work, no testpics today... :-/
-A friend of mine has the Sigma 150F/2.8 macro - which I know to be an excellent piece of glass. I'll try to snag it off him for the weekend to make some comparisons.
AhamB wrote:
There's a 200APO on ebay right now for 300GBP, but somebody already made the first bid. I see this lens doesn't have a tripod collar - wouldn't it be a bit risky to have this lens hang off the camera mount? I read on diglloyd's forum that he had an issue with a warped camera mount because of this (with some heavy 70-200/2.8 zoom I think), causing uneven image sharpness with every lens mounted on it.
The Mamiya A 200/2.8 APO is not especially heavy (at 1.1 kg). The 200 APO is not a serious challenge to a Canon body mount. OTOH, it might cause issues with an el cheapo adapter. It works fine with the Fotodiox Pro adapters that I use.
I normally carry a 70-200/2.8L IS for extended periods, using a Domke Gripper shoulder strap (the best!) attached to the body strap lugs - never a problem with the mount. I expect that might change if the front of the lens hit something immovable; otherwise, the body should be fine.
jcolwell wrote:
The Mamiya A 200/2.8 APO is not especially heavy (at 1.1 kg). The 200 APO is not a serious challenge to a Canon body mount. OTOH, it might cause issues with an el cheapo adapter. It works fine with the Fotodiox Pro adapters that I use.
The 120/4 is much lighter (0.7 Kg) but the fact that it gets so long is a major PITA AFAIAC even though the mount is fine. I even considered selling it but then I found one of my friends is an engineer which design things for a living. As he is also an amateur photographer he recently designed and made a gimbal type tripod head for his 100-400 IS (this was the first version). I thus asked him to make me a tripod collar for it. He said O.K. but he has not done it yet....
