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Re Auto Topcor 58 f/1.4 vs 58 1.8 : How much better
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PostPosted: Sat Oct 24, 2020 8:42 am    Post subject: Reply with quote
I have yet to encounter lens where F1.4 version is "better" wide open then it's slower brother. You don't get faster lens for that purpose. But apertures equalized, usually faster wins. But no more round bokeh.


PostPosted: Sat Oct 24, 2020 3:01 pm    Post subject: Reply with quote
cbass wrote:
The lens is ridiculously sharp.
This is stopped down to f/4.
150% crop of the original image.
Shooting portraits you'll want to leave it open wider and miss focus slightly.


No pun intended - but nearly any vintage 1.4/50, 1.4/55 or 1.4/58 lens from the 1960-1980 time frame will have excellent center performance at f4.


cbass wrote:
This is a handheld night shot. Wide open. ISO 4000. On APS-C. Looks sharp corner to corner to my eyes. Perhaps this wouldn't be the case on full frame, but on the crop sensor it is.



Again, using an 1.4/58mm vintage lens on APS-C will "crop" the weak areas of the lens. Look at the MTF of the Zeiss CY 1.4/50mm, for instance: The red area is "used" by APS-C sensors, and the performance therein is well balanced and even at f1.4, and absolutely excellent at f5.6. Keep in mind that these are measured MTF, unlike the "calculated" MFT published by most manufacturers!



S


PostPosted: Sat Oct 24, 2020 4:31 pm    Post subject: Reply with quote
Pancolart wrote:
I have yet to encounter lens where F1.4 version is "better" wide open then it's slower brother. You don't get faster lens for that purpose. But apertures equalized, usually faster wins. But no more round bokeh.


I wasn't implying that. The 58mm f/1.8 indeed is better wide open than the F1.4. However, the F1.4 still does well.


PostPosted: Sat Oct 24, 2020 5:07 pm    Post subject: Reply with quote
stevemark wrote:

No pun intended - but nearly any vintage 1.4/50, 1.4/55 or 1.4/58 lens from the 1960-1980 time frame will have excellent center performance at f4.


That is true. To my eyes it seems that certain lenses are slightly crisper though. That may be preference. That may be slightly better focus. That might be bias on my part and not actually true.

However, if we are going to be honest. Then almost any quality fast 50ish mm lens stopped down to f/4 will have excellent center performance and often good corners. From an optical perspective it seems that modern lenses have mostly improved at corners at wider apertures and this is largely due to aspherical lens elements. Perhaps even due to more correcting elements made possible by computer calculations and simulations? (Meant to be a question as this is speculation). Stopped down it's difficult to see sharpness differences between old and new lenses.


PostPosted: Mon Nov 02, 2020 1:05 am    Post subject: Reply with quote
I found this comparison.

https://theothersideofbokeh.wordpress.com/2017/08/10/fifty-fifties-final-evaluation-of-sharpness-at-a-longer-distance/

The RE Auto Topcors manage to make it into the top 10. It looks like the 58mm f/1.4 is in the top 10 for center sharpness. The 58mm f/1.8 appears to have an advantage in the corners. In one test it's the 4th sharpest lens in the corner out of 50.


PostPosted: Mon Nov 02, 2020 6:00 am    Post subject: Reply with quote
Here is a more controlled test using a test chart with rankings.

https://theothersideofbokeh.wordpress.com/2018/01/06/50-fifties-measuring-sharpness-and-contrast/

What is interesting is he appears to have two Topcor 58mm f/1.4 lenses:

Topcon RE Auto-Topcor 1.4/58 (si)
Topcon RE Auto-Topcor 1.4/58 (bk)

I assume Si is Silver and bk is black. They seems to follow a different curve. The black is sharper wide open to about f/2 and the silver is sharper stopped down.


PostPosted: Mon Nov 23, 2020 12:30 am    Post subject: Reply with quote
One presumes that they tested the newest version of the 58/1.8. One would hope that both the 58/1.4 were the new version with serial number starting 112, but one might be the older 94.

The 58/1.4 MTF charts suggest that the 58/1.4 has a lot of field curvature, so the corners are weak until you stop down enough to overcome that. From reviews I've read, Topcon accepted field curvature to make other aspects of performance better. It's a trade-off.


PostPosted: Mon Nov 23, 2020 7:06 am    Post subject: Reply with quote
What do you know about the earlier 58mm f/1.4 with serial number 94? Do you know what optical changes they made when they went to 112?


PostPosted: Sat Jan 07, 2023 4:04 pm    Post subject: Reply with quote
I've recently tested a 58/1.8 1162x against an older 58/1.8 990x and a 58/1.4.



It might be attributed to sample variance, but the newer 58/1.8 1162x design seems to be the sharpest one at f/1.8.


PostPosted: Sat Jan 07, 2023 4:18 pm    Post subject: Reply with quote
y wrote:
I've recently tested a 58/1.8 1162x against an older 58/1.8 990x and a 58/1.4.



It might be attributed to sample variance, but the newer 58/1.8 1162x design seems to be the sharpest one at f/1.8.


Did you take multiple pictures per lens? The first one seems unusually unsharp, like there was some vibration or movement.


PostPosted: Sat Jan 07, 2023 7:08 pm    Post subject: Reply with quote
caspert79 wrote:
Did you take multiple pictures per lens? The first one seems unusually unsharp, like there was some vibration or movement.

Yes, it looks strange. A defective lens can't be ruled out. Here is the 58/1.8 sn. 990x at:

* f/1.8
* f/2.0
* f/2.8


PostPosted: Sat Jan 07, 2023 7:18 pm    Post subject: Reply with quote
One thing we can learn from the Topcor threads on this forum it is the high variability in optical performance amongst Topcor lenses, even within the same generation of lenses.


PostPosted: Mon Jan 09, 2023 4:07 am    Post subject: Reply with quote
John Shriver wrote:
One presumes that they tested the newest version of the 58/1.8. One would hope that both the 58/1.4 were the new version with serial number starting 112, but one might be the older 94.

The 58/1.4 MTF charts suggest that the 58/1.4 has a lot of field curvature, so the corners are weak until you stop down enough to overcome that. From reviews I've read, Topcon accepted field curvature to make other aspects of performance better. It's a trade-off.


Where is this MTF chart or better yet where are the MTF charts for the Topcors?


PostPosted: Mon Jan 09, 2023 5:48 am    Post subject: Reply with quote
On this page linked further up the thread. Looks interesting...

https://theothersideofbokeh.wordpress.com/2018/01/06/50-fifties-measuring-sharpness-and-contrast/
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