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SMC Pentax 50/1.4 vs Topcor 58/1.8
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PostPosted: Sat Apr 14, 2018 11:38 pm    Post subject: Reply with quote
blotafton wrote:
Oldhand wrote:
Is there a problem with your lens mounts. Neither of those images looks right to me at any aperture.
I find it hard to believe that both of your lenses could be defective in some way
Tom


These are crops from the left side, with the center in focus. Taken with my Sony A7 so full frame. There is nothing obvious wrong with the lenses. I'm not sure what's up.

Yes a puzzle to me too
Tom


PostPosted: Sun Apr 15, 2018 3:06 pm    Post subject: Reply with quote
Off topic but.
My image posts with a Zuiko 55 1.2, Prakticar 50 1.4, Meyer 50 1.8 and Riconar 55 2.2 also got comments that they were defective.
It must be something else than the lenses.


PostPosted: Sun Apr 15, 2018 3:48 pm    Post subject: Reply with quote
A lens can perform differently on sensor size and different magnification. Sometime, the use of a proper hood and lighting conditions may have significant impact on the photo. The lens may look defective to one but not the others.


PostPosted: Sun Apr 15, 2018 6:18 pm    Post subject: Reply with quote
John Shriver wrote:

On the other hand, the Sony a7 cameras like lenses with field curvature. All their lenses have field curvature to match the sensor.


The lenses we're talking about look exactly the same on a Leica M9/M240 (extremely thin sensor glass) and the Sony A7 24MP series (2.5mm glass).

Stephan


PostPosted: Tue Apr 24, 2018 11:08 am    Post subject: Reply with quote
stevemark wrote:
John Shriver wrote:

On the other hand, the Sony a7 cameras like lenses with field curvature. All their lenses have field curvature to match the sensor.


The lenses we're talking about look exactly the same on a Leica M9/M240 (extremely thin sensor glass) and the Sony A7 24MP series (2.5mm glass).

Stephan


Because I've changed my mind I've acquired a A7R2 recently and out of curiosity I've redone the comparison on my new FF camera as these lenses are still lying around...

Interestingly I've got exactly the same result as from my Ricoh APS-C camera; i.e. up to F4 the Takumar is better in the corners at same apertures and as from F4 the lenses aren't distinguishable anymore.

However, I've used proper lens hoods on both lenses and shot at lowest ISO from a sturdy tripod at highest resolution uncompressed RAW. Maybe the much higher resolution of the A7R2 in combination with the lack of the low-pass filter is the decisive factor here.


PostPosted: Tue Apr 24, 2018 2:17 pm    Post subject: Reply with quote
@tb_a

Do you happen to have a Rikenon XR 50/2.0? I’m very curious how it performs on an A7II.
From tests with my E-pl5 it seems to be a strong performer. I’m curious about its corner performance.


PostPosted: Tue Apr 24, 2018 2:28 pm    Post subject: Reply with quote
caspert79 wrote:
@tb_a

Do you happen to have a Rikenon XR 50/2.0? I’m very curious how it performs on an A7II.
From tests with my E-pl5 it seems to be a strong performer. I’m curious about its corner performance.


Sorry, although I have rather many lenses, I don't have any Rikenon.


PostPosted: Wed Apr 25, 2018 8:53 am    Post subject: Reply with quote
calvin83 wrote:
A lens can perform differently on sensor size and different magnification. Sometime, the use of a proper hood and lighting conditions may have significant impact on the photo. The lens may look defective to one but not the others.


I am sure you are correct, I have a Sony NEX 5t & A6000. I have noticed that the NEX's 16 meg pics are more vibrant & have more contrast when compared to the A6000 24 meg when using the same lens? I have checked several times to make sure both cameras have the same settings?

Both are equally as sharp & the quality of the photo's are good, just the A6000 looks a little bit washed out prior to any adjustments in Lightroom. After processing both end up almost the same. I have tested this a few times, same lighting, same subject, same lens just swapped cameras. It is not a problem, just an observation.


PostPosted: Thu Apr 26, 2018 6:35 pm    Post subject: Reply with quote
tb_a wrote:

Because I've changed my mind I've acquired a A7R2 recently
...
Interestingly I've got exactly the same result as from my Ricoh APS-C camera; i.e. up to F4 the Takumar is better in the corners at same apertures and as from F4 the lenses aren't distinguishable anymore.
...
Maybe the much higher resolution of the A7R2 in combination with the lack of the low-pass filter is the decisive factor here.


I don't think there's such a difference between A7 and A7RII. The sensor pack of both cameras has the same thickness (2.5mm).
Since my three RE Topcors 1.8/58mm are indistinguishable from each other, and so are my two early 1.4/50mm Takumars, i suspect we have different designs - either yout Topcor or your Takumar probably has an earlier or updated computation. It was quite common in those days to improve performance of a certain lens without advertising it. We know for sure that Minolta did this with their 1.4/58mm lenses; Nikon had quite a few slightly different 1.4/50mm lenses, and there are different versions of the Topcor 1.8/55mm. I don't know about the Pentax, but i would assume they did the same.

Stephan


PostPosted: Thu Apr 26, 2018 11:47 pm    Post subject: Reply with quote
caspert79 wrote:
@tb_a

Do you happen to have a Rikenon XR 50/2.0? I’m very curious how it performs on an A7II.
From tests with my E-pl5 it seems to be a strong performer. I’m curious about its corner performance.


I have one. I could put it on my K-1

edit: Here http://forum.mflenses.com/viewtopic,p,1511161.html#1511161
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