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SMC Pentax 50/1.4 vs Topcor 58/1.8
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PostPosted: Fri Apr 06, 2018 10:21 am    Post subject: Reply with quote
caspert79 wrote:
Judging from your corner crops I’m quite convinced that there’s something wrong with my Topcor lens.


Not necessarily, but maybe. I see at least three possible factors that might explain your results:

1) The Pentax may have a better central resolution than the Topcor, resulting in better images on micro 4/3 sensors
2) Your Topcor lens may be slightly "fogged", thus resulting in lower contrast even stopped down (it puzzles me that your Topcor never gets really contrasty!)
3) Your Topcor 1.8/58mm may be from a earlier series than mine, having an inferior optical construction (there are different optical formulas of the Topcor RE 1.8/58mm, but i'm not an expert on that)

Maybe it's even a combination of these three things ??

Stephan


PostPosted: Fri Apr 06, 2018 5:37 pm    Post subject: Reply with quote
Shine a flashlight through the lens(but don't look directly at the light), and look at the elements, they will probably have dust specks on them, but otherwise they should look clean, anything on the surface of the elements will glow like crazy, compare with another lens that has good contrast.


PostPosted: Sat Apr 07, 2018 8:06 am    Post subject: Reply with quote
Here is the first part of my test.

Asahi S-M-C Takumar 50/1.4 vs Asahi Pentax M 50/1.4 vs Tokyo Kogaku RE. Topcor 58/1.8 on a full-frame

Corner:


Mid frame analysis and full-size shots will be added later.


PostPosted: Sat Apr 07, 2018 8:55 am    Post subject: Reply with quote
Lightshow wrote:
Shine a flashlight through the lens(but don't look directly at the light), and look at the elements, they will probably have dust specks on them, but otherwise they should look clean, anything on the surface of the elements will glow like crazy, compare with another lens that has good contrast.


Glass is clear. Coating very bad though, many tiny scratches.


PostPosted: Sat Apr 07, 2018 8:59 am    Post subject: Reply with quote
y wrote:
Here is the first part of my test.

Asahi S-M-C Takumar 50/1.4 vs Asahi Pentax M 50/1.4 vs Tokyo Kogaku RE. Topcor 58/1.8 on a full-frame

Corner:


Mid frame analysis and full-size shots will be added later.


Interesting. But also confusing. Pentax better here, while in another test the Topcor had better corner performance.


PostPosted: Sat Apr 07, 2018 6:52 pm    Post subject: Reply with quote
caspert79 wrote:
y wrote:
Here is the first part of my test.

Asahi S-M-C Takumar 50/1.4 vs Asahi Pentax M 50/1.4 vs Tokyo Kogaku RE. Topcor 58/1.8 on a full-frame
...


Interesting. But also confusing. Pentax better here, while in another test the Topcor had better corner performance.


Interesting in fact. The Takumars in the above test look similar as mine, but obviously my Topcor RE 1.8/58mm is way better!
I'll have to check the serials of my three samples, and their proformance.

Anybody out there who has more knowledge about the different flavors of the RE Auto Topcor 1.8/58mm? Obviously there are different computations, but that's all in know.

Thanks Wink

Stephan


PostPosted: Sat Apr 07, 2018 7:14 pm    Post subject: Reply with quote
Here is the rest of the test.

Mid-frame (Topcor has 58mm focal length so the perspective is different)


Difference in size of "the corner area" at f4.0 is huge: Topcor vs Takumar

All full res:
RE. Topcor 58/1.8, serial no. 990xxxxx
http://abload.de/gallery.php?key=swt6hXQY

SMC Pentax M 50/1.4
http://abload.de/gallery.php?key=sd10NCe7

S-M-C Takumar 50/1.4
http://abload.de/gallery.php?key=srht92k4


PostPosted: Sat Apr 07, 2018 7:50 pm    Post subject: Reply with quote
Indeed. Interesting! Apparently not all Topcor 58/1.8's are the same.


PostPosted: Sat Apr 07, 2018 8:14 pm    Post subject: Reply with quote
y wrote:
Here is the first part of my test.

Asahi S-M-C Takumar 50/1.4 vs Asahi Pentax M 50/1.4 vs Tokyo Kogaku RE. Topcor 58/1.8 on a full-frame

Corner:


Mid frame analysis and full-size shots will be added later.


Please don't tell me that you have focused to the car in the middle of the image ...?? That would, of course, explain the results ...


PostPosted: Sat Apr 07, 2018 8:18 pm    Post subject: Reply with quote
stevemark wrote:
Please don't tell me that you have focused to the car in the middle of the image ...?? That would, of course, explain the results ...
Nope. The test shots were focused on the red crane - top right corner. TBH it's tough to test different focal lengths and (probably) different field curvatures Smile


PostPosted: Sat Apr 07, 2018 8:23 pm    Post subject: Reply with quote
stevemark wrote:
y wrote:
Here is the first part of my test.

Asahi S-M-C Takumar 50/1.4 vs Asahi Pentax M 50/1.4 vs Tokyo Kogaku RE. Topcor 58/1.8 on a full-frame

Corner:


Mid frame analysis and full-size shots will be added later.


Please don't tell me that you have focused to the car in the middle of the image ...?? That would, of course, explain the results ...


...due to field curvature, correct?

Exactly where within DOF should sharpest focus be placed for testing? At least that placement should be consistent.


PostPosted: Sun Apr 08, 2018 9:05 am    Post subject: Reply with quote
y wrote:
stevemark wrote:
Please don't tell me that you have focused to the car in the middle of the image ...?? That would, of course, explain the results ...
Nope. The test shots were focused on the red crane - top right corner. TBH it's tough to test different focal lengths and (probably) different field curvatures Smile


Good to know Wink

I'll run my entire set of three 1.8/58mm Topcors and two 1.4/50mm Super Takumars today.
Hopefully this will clarify the issue ...

Stephan


PostPosted: Sun Apr 08, 2018 10:01 am    Post subject: Reply with quote
stevemark wrote:
y wrote:
stevemark wrote:
Please don't tell me that you have focused to the car in the middle of the image ...?? That would, of course, explain the results ...
Nope. The test shots were focused on the red crane - top right corner. TBH it's tough to test different focal lengths and (probably) different field curvatures Smile


Good to know Wink

I'll run my entire set of three 1.8/58mm Topcors and two 1.4/50mm Super Takumars today.
Hopefully this will clarify the issue ...

Stephan


Awesome!


PostPosted: Sun Apr 08, 2018 11:51 am    Post subject: Reply with quote
Out of curiosity I've now compared my Super Takumar 50mm/F1.4 with my RE.Auto Topcor 58mm/F1.8 lens. Additionally I took my Minolta MC 58mm/F1.2.

My conclusion is that indeed in pixel peeping mode the Takumar beats the Topcor at least until F4. Starting from F4 they are nearly indistinguishable (besides from the slightly longer focal length of the Topcor lens and the slightly warmer tint caused by the radioactive thorium element of the Takumar).

However, at same aperture; i.e. F2, F2.8 and F4 the Minolta is best, at least by a very little margin. Wink

I've compared them on my Ricoh GXR-M APS-C camera without AA-filter and at least on APS-C all of these old lenses deliver stunningly sharp pictures already as from F2.8 from edge to edge. IMHO more than good enough for landscape and architecture.

I was too lazy to make all the crops and show them here. If somebody is really interested I can provide the originals via google drive or so...


PostPosted: Sun Apr 08, 2018 7:49 pm    Post subject: Reply with quote
tb_a wrote:
Out of curiosity I've now compared my Super Takumar 50mm/F1.4 with my RE.Auto Topcor 58mm/F1.8 lens. Additionally I took my Minolta MC 58mm/F1.2.

My conclusion is that indeed in pixel peeping mode the Takumar beats the Topcor at least until F4.
...
I've compared them on my Ricoh GXR-M APS-C camera without AA-filter and at least on APS-C all of these old lenses deliver stunningly sharp pictures already as from F2.8 from edge to edge. IMHO more than good enough for landscape and architecture.


That's certainly true for the cropped sensor. On FF, things look different. I have re-done my original test, this time with three 1.4/50mm Takumars and three 1.8/58mm Topcors.
Two of the Takumars were early ones with a metal focusing grip and strong yellow color cast (thorium lenses), the third Takumar was a later M42 version with rubber focusing grip and less strong color cast, obviously a different optical design (mid 1970).

The results are consistent; all three Topcors perform equally well (indistinguishable on 24MP FF); the two early Takumars perform identically, and the third (later) Takumar is slightly worse than the earlier two.

I have added the 100% crops from these test, taken at f1.5, f2 and f4, respectively.

Stephan

PLEASE CLICK / DOWNLOAD TO SEE THE IMAGE BELOW IN FULL SIZE!!



PostPosted: Sun Apr 08, 2018 7:56 pm    Post subject: Reply with quote
Corners better with the Topcors here.


PostPosted: Sun Apr 08, 2018 8:12 pm    Post subject: Reply with quote
stevemark wrote:
That's certainly true for the cropped sensor. On FF, things look different. I have re-done my original test, this time with three 1.4/50mm Takumars and three 1.8/58mm Topcors.
Two of the Takumars were early ones with a metal focusing grip and strong yellow color cast (thorium lenses), the third Takumar was a later M42 version with rubber focusing grip and less strong color cast, obviously a different optical design (mid 1970).

The results are consistent; all three Topcors perform equally well (indistinguishable on 24MP FF); the two early Takumars perform identically, and the third (later) Takumar is slightly worse than the earlier two.

I have added the 100% crops from these test, taken at f1.5, f2 and f4, respectively.

I'm afraid you can't judge the Pentax's optical design by its color cast amount. The S-M-C (all metal knurled grip) Takumars, later SMC (rubber grip) Takumars and PK SMC Pentax (K line) share the optical design - except for minor progress in coating tech. The amount of color cast depends on usage pattern - it gets yellower when the lens is not used (no UV rays).

Unfortunately, all the Topcors of yours share the same optical design judging from their serials - 116xxxxx. That one should be the most advanced optical design employed for the 58/1.8.


PostPosted: Sun Apr 08, 2018 8:54 pm    Post subject: Reply with quote
stevemark wrote:
tb_a wrote:
Out of curiosity I've now compared my Super Takumar 50mm/F1.4 with my RE.Auto Topcor 58mm/F1.8 lens. Additionally I took my Minolta MC 58mm/F1.2.

My conclusion is that indeed in pixel peeping mode the Takumar beats the Topcor at least until F4.
...
I've compared them on my Ricoh GXR-M APS-C camera without AA-filter and at least on APS-C all of these old lenses deliver stunningly sharp pictures already as from F2.8 from edge to edge. IMHO more than good enough for landscape and architecture.


That's certainly true for the cropped sensor. On FF, things look different. I have re-done my original test, this time with three 1.4/50mm Takumars and three 1.8/58mm Topcors.


One more reason that I couldn't care less about test reports from a Sony A7. Wink

I had recently a similar discussion about another 50mm SLR lens pair comparison with totally different results from different cameras and I start to believe that the A7 is very specific and somehow unique in terms of adapted lens performance, particularly in the corners and not only with RF lenses. Not even my old Sony A850 which I use sometimes with old adapted M42 lenses is performing that strange although it's equipped with a similar FF sensor.

In other words: If I compare 2 different M42 lenses on both of my APS-C and FF cameras I never had contradictory results so far (Ricoh GXR-M vs. Sony A850) and this is actually the second case that the A7 delivers something different. Unfortunately I'm not able to test the Topcor on the A850. However, I will certainly recheck my Takumar in the corners on my FF camera again.

Stephan, thanks a lot for your presentation.


PostPosted: Mon Apr 09, 2018 8:28 am    Post subject: Reply with quote
tb_a wrote:

...
I had recently a similar discussion about another 50mm SLR lens pair comparison with totally different results from different cameras and I start to believe that the A7 is very specific and somehow unique in terms of adapted lens performance, particularly in the corners and not only with RF lenses.


Of course, the Sony E system has its problems caused by the Filter stack (2.5mm thick, nD 1.51, Abbé number 64.2). However, these problems are limited to wideangle rangefinder lenses. I have checked fast SLR lenses such as the Minolta MD 1.2/50mm, and fast SLR wideangles such as the MD 2/28mm on both the Leica M240 (0.9mm Filter stack) and the Sony A7RII (2.5mm filter stack). Lens performance was identical. And Tele lenses are even less critical.


tb_a wrote:

Not even my old Sony A850 which I use sometimes with old adapted M42 lenses is performing that strange although it's equipped with a similar FF sensor.

It is possible (and even probable) that the A850/A900 has a thinner filter stack than the A7/A9 system. Canon's early professional DSLRs used to have something like 1.5mm, and Nikons D100 was at only 0.75mm! And micro 4/3 is in the range of >4mm!!

tb_a wrote:

In other words: If I compare 2 different M42 lenses on both of my APS-C and FF cameras I never had contradictory results so far (Ricoh GXR-M vs. Sony A850)

That's possible, but that's certainly by chance. If you look at measured MTF curves eg from the Zeiss CY Distagon 4/18mm, its performance is quite even from the center to 15mm image height (APS-C corners), but drops drastically at 22mm image height (FF corners). This has nothing to do with the camera; it's an intrinsic property of the lens itself.


tb_a wrote:

I will certainly recheck my Takumar in the corners on my FF camera again.


Me too Wink ... and i predict that my 1.4/50mm Takumars will have the same corner resolution problems on the A900. And on film of course, but that's another story.

Stephan


PostPosted: Mon Apr 09, 2018 9:38 am    Post subject: Reply with quote
Thanks for your comments, Stephan.

I've skipped my plans to go for any A7 camera until further anyway. I've too many RF lenses in my collection already. I'll rather go for the Voigtlaender Hyper Wide Heliar 10mm/F5.6 for my Ricoh and a Minolta AF 400mm/F4.5 APO G HS for my A850 instead. IMHO in the long run the far better investments.


PostPosted: Fri Apr 13, 2018 9:05 pm    Post subject: Reply with quote
The Topcor lenses do have field curvature -- that's their design compromise.

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


PostPosted: Sat Apr 14, 2018 11:10 am    Post subject: Reply with quote
It seems I have a weak Topcor. sn 11660794. At least on the A7. My copy looks to have strong field curvature.


PostPosted: Sat Apr 14, 2018 3:16 pm    Post subject: Reply with quote
I take back my previous statement.

Topcor 1.8/58


#1



SMC Takumar 1.8/55


#2



topcor



takumar



PostPosted: Sat Apr 14, 2018 10:31 pm    Post subject: Reply with quote
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


PostPosted: Sat Apr 14, 2018 11:25 pm    Post subject: Reply with quote
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.
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