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Thread: How do MTFs of wide angle lenses compare?

  1. #1
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    How do MTFs of wide angle lenses compare?

    Bradley's post in the 205FCC thread is very informative,
    making me wonder how the MTFs of other wide angle lenses compare
    against the 40mm IF CFE.

    While I realize the best test is to use each lens under one's conditions,
    would anyone care to comment/explain the differences between:

    Apo-Sironar digital HR 35mm f/4

    Schneider Apo-Digitar 5.6/35

    Distagon T* 3.5/35 for Contax 645

    HC 3.5/35 for Hasselblad H

    Biogon T* 4.5/38 CF on SWC

    DistagonT*_4/40_ZH for SinarM

    Distagon T* 4/40 IF CFE

    Super Angulon 3.5/40 for Rollei Page 1 Page 2



    Schneider Apo-Digitar 5.6/24

    Apo-Sironar digital HR 28mm f/4.5

    HCD 4/28 for Hasselblad H

    Does anyone have a link for Mamiya's 28mm f/4.5 Sekor D Aspherical?

  2. #2
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    Re: How do MTFs of wide angle lenses compare?

    Hi, Billy,

    Um, wow! Did you see how much it took to compare just two lenses??

    Son may have enough real-world experience to be able to comment on many of these, but in terms of comparing MTF's it's a dicey proposition, unless done very carefully. Why?

    * MTF charts should tell you what focal distance (or equivalently scale) they're measured at (often infinity), but frequently don't.

    * Many manufacturers measure the theoretical maximum of the design (ie. via ray tracing simulation). If the tolerances specified by the design are too strict, limits in real-world manufacturing capabilities can cause poor performance in the manufactured lens--sometimes even poorer than if the lens had simply been designed for lower performance (often more practical to manufacture) in the first place.

    * Ideally they will also tell you about the light spectrum the lens was measured under--for example, by using monochromatic light, an MTF chart will appear better because there would be no chromatic aberration (which requires more than one frequency of light) to measure!!

    As you can see, there's a lot to watch out for.

    Still, are there any MTF's that can be safely compared?

    Zeiss has put themselves on the record for measuring the actual MTF of a real-world (prototype) lens. All Hasselblad lenses follow this standard, and the new H-series Fuji lens MTF's can be directly compared to V-series Zeiss MTF's. Also Rollei's Zeiss MTF's can be directly compared to Rollei's Schneider MTF's. And if you look you will see that the Hasselblad Zeiss MTF's and the Rollei Zeiss MTF's match perfectly, so all four lens types' MTF charts can be directly compared.

    I have not looked closely at Contax' MTF's but again, being Zeiss designs, I suspect comparisons between their MTF's and Hasselblad's and Rollei's will be valid.

    For all the other brands... it's really hard to say how valid MTF comparisons might be. Still, I know we all do it...

    But I can do a quick run-through of the 40/4 CFE IF vs. the HC 35/3.5 for you--I did look carefully at the HC lens series for my H2 before deciding to go with the V-series glass with an adapter. (Again, as with the 40/4 CFE IF vs. the 40/4 CFE FLE I wrote about in the 205FCC thread, none of this is a knock against HC glass, instead, personally, I found elements of the Zeiss offerings that worked better for me, so that is what I went with).

    Quick thoughts on the Fuji HC 35/3.5 vs Zeiss 40/4 CFE IF MTFs:

    * Both have excellent (~78%) center performance for high-frequency (detail) curve [tie]
    * Fuji holds, then falls as we move away from the center, while the Zeiss yields a straighter curve. IMO, straightness is a bigger contributer to perceived IQ than actual MTF score (within reason). [Zeiss]
    * Zeiss shows more astigmatism (difference between sagittal and tangential curves) [Fuji]
    * Fuji lenses are not optimized for infinity (they're designed for studio work). Because all Hasselblad MTF's are consistent, I believe these are measured at infinity. I do not know the distance the Zeiss is optimized for, but I assume it is infinity. From this, you may expect the Fuji to perform relatively better at studio working distances. [??? - too much speculation]
    * By 25mm, Fuji's high frequency performance has fallen to the low 20's, while Zeiss is between 40 and 60 at the same point. Expect significantly better (but somewhat astigmatic) edge performance from the Zeiss. [Zeiss]
    * Zeiss has ~60% more distortion than the Fuji. [Fuji]
    * These characterizations seem to hold through f/8 as well.

    What's missing from the MTF curves?
    In addition to the above mentioned comments (ie. how they perform closer than infinity, spectral light they were measured under, etc.), bokeh performance is also not reflected in an MTF.

    And finally, strictly speaking, any comparision comparing different focal lengths (and maximum apertures) has to be taken with a grain of salt.

    Anyway there's a start--I won't be able to do an analysis of all of the lenses you asked about, but I'm sure there are folks here who can chime in who are better qualified than I am anyway.

    And let me reinforce something you said to others who might be wading through this tome, don't let the charts or analysis tell you what works for you--you do want to try these lenses out, wherever possible--you just might like what you see, regardless of what the MTF curves say.

    Best regards,
    -Brad

    P.S. For those interested in this sort of thing, I have been thinking about publishing a "Battle of the 40's" article sometime soon, once my Hy6 arrives. I intend to put the Hasselblad Zeiss 40/4 CFE IF up against the Rolleiflex Schneider Super-Angulon 40/3.5 to compare both objective and subjective differences. (But after that, I plan to sell my CFE IF, along with the rest of my Hassy gear because I won't need two medium format systems, so I doubt I'll be able to do many more "Battle of's..." beyond that.)
    Last edited by BradleyGibson; 15th May 2008 at 22:01.

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    Re: How do MTFs of wide angle lenses compare?

    Thank you, Bradley.

    I guess I won't ask for a shootout between 47mm Digital, 50mm Super Angulon for Rollei, 50mm FE and 50mm FLE.

  4. #4
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    Re: How do MTFs of wide angle lenses compare?

    I guess you just did!!!



    Thierry

    Quote Originally Posted by BJNY View Post
    I guess I won't ask for a shootout between 47mm Digital, 50mm Super Angulon for Rollei, 50mm FE and 50mm FLE.

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    Re: How do MTFs of wide angle lenses compare?


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    Re: How do MTFs of wide angle lenses compare?

    OK I won't ask for a comparison either ;-) .... BUT since its all hypothetical you might as well add the 55mm PCS to that list of lenses.

    Of that whole list above the only ones I have experience with are the Rollei 50mm f/2.8 and the 55mm PCS. From my limited testing the 55mm is a better lens than the 50mm f/2.8 SA.

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