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300mm lens comparison (Leitz/Minolta/Pentax)
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PostPosted: Tue Feb 21, 2017 9:15 am    Post subject: 300mm lens comparison (Leitz/Minolta/Pentax) Reply with quote

Today I've checked the differences of my 300mm lenses (280mm for the Leitz Telyt) on my Ricoh GXR-M (APS-C).
I've chosen to compare them at F5.6 which is the smallest common aperture. If stopped down further the quality will further increase, especially concerning the CA's. Every picture is followed by an 100% crop for pixel peeping purposes.
As usual shot RAW and converted in LR6 with minor adjustments (same for every lens).
Unfortunately it was slightly misty outside, that's why the pictures are not comparable to the yesterday ones of the 200mm comparison.
Please note also that 300mm on APS-C equals 450mm FOV on FF (420mm for the Telyt).

Leitz Telyt 280mm/F4.8 (M39 Visoflex) at F5.6:





Minolta MD Tele Rokkor 300mm/F4.5 IF at F5.6:





Pentax Asahi Super-Takumar 300mm/F4 at F5.6:





Just for reference my best 300mm lens, the Minolta AF 300mm/F4 HS APO fully open at F4 (unable to use exactly F5.6 on my adapter):





As already seen in the 200mm comparison, again the Leitz lens is best in terms of CA's (particularly purple fringing) and (no wonder) the Minolta AF lens is best all together (even when used fully open on FF together with the 1.4X converter it's beating the other 300mm lenses on APS-C).


PostPosted: Tue Feb 21, 2017 2:43 pm    Post subject: Reply with quote

Thanks Thomas!


PostPosted: Wed Feb 22, 2017 1:47 pm    Post subject: Reply with quote

Thomas has a nice collection of 300mm telephoto lenses. All the lenses presented seem capable of excellent photographic performance but, of course, when you look at the results very closely, the differences appear.

Telephoto lenses suffer a lot from chromatic aberrations, and it's just the CA that catches the eye of most people. Nonetheless, image quality depends on the combination of the effect of the other aberrations, not just CA. In fact, it is always good to remember that there are two basic types of CAs: the longitudinal and the lateral CA. These two types of aberration are important, but it is the lateral CA that is more familiar to most photographers. Fortunately, the lateral CA can be removed by post-processing with some ease.

The following remarks are based on the analysis of an image region slightly off center. The crops where scaled to 200%, so as to make the imperfections of the images more visible.

Leitz Telyt 280mm F4,8 at F5,6:

To my eyes, the Leitz Telyt is the worst lens in terms of image quality, although I agree with Thomas that the lateral CA is small. Perhaps the lateral CA is being masked by the other more intense aberrations, the spherical aberration in particular. Anyway, there is significant longitudinal CA, which can be noted, for example, in the greenish tone of the tree branches in the background.





Minolta MD Tele Rokkor 300mm F4,5 IF at F5,6:

Here I had the impression that there is some loss of resolution due to camera shake.





Pentax Asahi Super-Takumar 300mm F4 at F5,6:

I also have a Super Takumar 300mm F4, and I can guarantee that the lateral CA is the weak point of this lens. However, CA does not prevent the lens from performing very well in terms of pure resolution. Note for example how the readability of the letters on the panel is much better than for the two previous lenses.





Minolta AF 300mm F4 HS APO fully open at F4:

No doubt, the best lens in terms of CA, but the resolution is not much better than the Super Takumar.


PostPosted: Wed Feb 22, 2017 2:56 pm    Post subject: Reply with quote

Gerald, thanks for your observations.

Well, on pixel peeping level the differences are obvious, particularly if blown up to 200%.

Please note that the Minolta AF lens was used fully open (F4) and the Takumar was stopped down to F5.6. I'm sure that the Minolta AF lens can do better if stopped down as well or the other way round, i.e. the Takumar would be slightly worse fully open.
Camera shake (as you mentioned for a possible reason for the Minolta MD lens) can be excluded as I always used 10sec self-timer on tripod and the camera is mirror-less.

We have also put into consideration that those lenses are from different decades and therefore at different "evolutionary" level.

However, for normal photography those differences barely matter, though the purple fringing of the Takumar may under certain conditions still be obvious and disturbing. That's the reason why I am considering purple fringing above a certain level as the most critical failure as it may even be visible (in white) after tweaking in LR. At least that's my experience.

BTW, the distance to the blue sign is almost 400 meters (according google maps) and it was unfortunately a little bit misty. So the conditions have been semi-optimal. Wink


PostPosted: Wed Feb 22, 2017 3:48 pm    Post subject: Reply with quote

Before you consider camera shake, I would ask how you calibrated all the lenses to the same level of focus plane going exactly through the sign.

Sorry to be a spoilsport but that seems to be a major issue from my inept attempts at focusing mirror.


PostPosted: Wed Feb 22, 2017 4:38 pm    Post subject: Reply with quote

buerokratiehasser wrote:
Before you consider camera shake, I would ask how you calibrated all the lenses to the same level of focus plane going exactly through the sign.

Sorry to be a spoilsport but that seems to be a major issue from my inept attempts at focusing mirror.


Focus was set manually exactly on the blue sign. The focus aid in the used camera is most probably the best in existence. Focus error therefore almost impossible.