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Carl Zeiss Jena Prakticar 50mm f1.8 vs Pentacon Prakticar
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PostPosted: Sun Feb 12, 2023 11:35 pm    Post subject: Carl Zeiss Jena Prakticar 50mm f1.8 vs Pentacon Prakticar Reply with quote
A recent post from pandreas68 has prompted me to take out my copies of the 50mm f1.8 - Carl Zeiss Jena Prakticar, and Pentacon Prakticar.
Now I don't care about full frame corner sharpness, and I am more interested in the way the lenses exhibit sharpness at widest aperture, and their transition to out of focus and its rendering.
So for those who look for other things in lenses, this little test will not show much.
However here are a couple of simple comparisons shot at two different distances from the camera.
I have focused on the golden neck of the perfume bottle.
Sharpness is similar.
The out of focus rendering is different.

Carl Zeiss Jena Prakticar (Pancolar)
#1


Pentacon Prakticar (Oreston)
#2



Carl Zeiss Jena Prakticar (Pancolar)
#1


Pentacon Prakticar (Oreston)
#2


Here are the lenses with link shown:
https://zeissikonveb.de/start/objektive/normalobjektive/oreston.html



If anyone would like to contribute further to the comparisons, please do so
Tom


PostPosted: Mon Feb 13, 2023 3:19 am    Post subject: Re: Carl Zeiss Jena Prakticar 50mm f1.8 vs Pentacon Praktica Reply with quote
I have superimposed those two images in Photoshop. Their focusing point ist quite different. Look at the table: In one image the sharpest point is behind the base of the vase, in the other it is quite a bit in front of the vase (at least one inch / 3cm difference). I would expect that to have an influence on how blurred the background is.

Oldhand wrote:
A recent post from pandreas68 has prompted me to take out my copies of the 50mm f1.8 - Carl Zeiss Jena Prakticar, and Pentacon Prakticar.
...
The out of focus rendering is different.

Carl Zeiss Jena Prakticar (Pancolar)
#1


Pentacon Prakticar (Oreston)
#2


Here are the lenses with link shown:
https://zeissikonveb.de/start/objektive/normalobjektive/oreston.html



If anyone would like to contribute further to the comparisons, please do so
Tom


PostPosted: Mon Feb 13, 2023 4:00 am    Post subject: Re: Carl Zeiss Jena Prakticar 50mm f1.8 vs Pentacon Praktica Reply with quote
stevemark wrote:
I have superimposed those two images in Photoshop. Their focusing point ist quite different. Look at the table: In one image the sharpest point is behind the base of the vase, in the other it is quite a bit in front of the vase (at least one inch / 3cm difference). I would expect that to have an influence on how blurred the background is.



PMSL go back to squinting at the extreme corners. 3cm makes no difference at all in such a test as this, where the rendering of the oof portions of the image are of most interest - the oof portions are far enough out of focus that it doesn't matter.


PostPosted: Mon Feb 13, 2023 7:16 am    Post subject: Reply with quote
To be honest, I do not see a real difference in oof. Maybe that the oof lights have some sharper structures in the Pentacon as in the CZJ; so last remains of the typical Meyer bubbles found in many of their lens types:); but I need to zoom in to really notice this. Which other differences should I notice?

I practice the main difference of both lenses will be the perceived sharpness from center into the corners as a combination of actual sharpness and contrast at quite open aperture (1.8-2.8 ). Beyond 5.6 the differences may not be visible anymore.

Best regards,
Andreas


PostPosted: Mon Feb 13, 2023 12:56 pm    Post subject: Reply with quote
pandreas68 wrote:
To be honest, I do not see a real difference in oof. Maybe that the oof lights have some sharper structures in the Pentacon as in the CZJ; so last remains of the typical Meyer bubbles found in many of their lens types:); but I need to zoom in to really notice this. Which other differences should I notice?

I practice the main difference of both lenses will be the perceived sharpness from center into the corners as a combination of actual sharpness and contrast at quite open aperture (1.8-2.8 ). Beyond 5.6 the differences may not be visible anymore.

Best regards,
Andreas


If you superimpose the two images eg in photoshop, by clicking between one and the other image, you will see the (small) difference, which of course is irrelevant in practice.

The above (small) differences mentioned by Oldhand are a result of slight differences in focusing. I just have reproduced this effect by shooting two images - using only one lens, but with about 4 cm difference in focus.

Here are some 25% crops showing the effect:



By superimposing the two images A and B below, and clicking between A and B you will clearly see the effect:




Mystery solved Wink

S


PS both images were taken using the same Multi Coating Pentacon Auto 1.8/50


PostPosted: Mon Feb 13, 2023 7:23 pm    Post subject: Reply with quote
stevemark wrote:

PS both images were taken using the same Multi Coating Pentacon Auto 1.8/50


Thanks for showing the effect of different focus in background blurring. Yes, many bubbles with quite sharp edges, so I'd have guessed it beeing done with the Pentacon. Would be intesting for this very subject to see the comparision to the Pancolar...
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