TAKO. INTERNET SEIT 1996.
Olympus-OM

Re: [OM] Zuiko manual lens options for Sony A7

Subject: Re: [OM] Zuiko manual lens options for Sony A7
From: Moose <olymoose@xxxxxxxxx>
Date: Wed, 14 Aug 2019 11:30:48 -0700
On 8/14/2019 5:09 AM, Wayne Shumaker wrote:
I agree. My50 serial number is 2,822,xxx.

Not the latest version.

I finally get what you mean by thick sensor stack and likely explains the "glowish" 
effect caused from the light angle hitting the sensor bleeding into adjacent sensor cells. I was 
wondering also, with back side illuminated sensors, that the micro lenses could be further from the 
actual sensor cells? Is this what you mean by "Stack".

There's lots of material on the web, if you search for "sensor stack". This is a pretty good one. <https://petapixel.com/2014/06/10/sensor-stack-thickness-matter/>

With BSI sensors, you can't polish away the backside and make it too thin?

I don't even know what that means. For the purposes of this discussion, sensor stack thickness from front of stack to the actual sensor is all that matters.

With the adapter on the Zuiko 50 it is about the same length as the Zeiss 55.

They would be, of course. Both modified Double Gauss designs, so the node(s) will be about in the middle, and close to the same focal length.


At 8/14/2019 01:37 AM, Moose commented:

On 8/13/2019 5:48 PM, Wayne Shumaker wrote:
Perhaps an unfair test, but couldn't resist. OM 50/1.8 vs Zeiss 55/1.8 @ 1.8.
First test with late series OM 50/1.8 with Fotasy adapter on a7riii, shot wide 
open, compared to Sony Zeiss 55/1.8, also manually focused the same way. This 
was highly rated 50 on Gary Reese's testing. I have a second OM 50 and should 
check it as well.
Based only on this one test I have to say the Zeiss way out performs the OM 
50/1.8 in sharpness and contrast. The OM 50 has a soft look too it, almost a 
fuzzy glow. Here are two 100% crops. The OM subject was more centered, the 
Zeiss shot subject was off to the right. This is not a super controlled test, 
and perhaps higher F stop would help the OM. I really like the Zeiss 55. That 
and the Sony 90 macro is nice and handles well, easily switching from AF to MF 
by pushing the focus ring forward...
OM 50/1.8 100% cropped
https://www.dropbox.com/s/p690qd1gxba2f01/7R301920_crop2.jpg?dl=0
Zeiss 55/1.8 100% cropped
https://www.dropbox.com/s/0ehikvsgwmyppip/7R301924_crop2.jpg?dl=0
Thanks for testing and showing us the results.

My highest serial # 50/1.8,  5,814,xxx, was produced in Sept, 1985, according 
to the date code on it. Although a consumer grade lens, it stomps the 1960-ish 
design, premium Canon 58/1.2, from roughly 25 years earlier. The Zeiss here is about 
30 years newer than the Zuiko, a period of great advances in glass, glass shaping 
and computer aided design. It's also a premium lens, with one more element - and 
three of the elements have at least one aspheric surface.

So, I'm not surprised the new Zeiss outperformed the old Zuiko.

I can think of a couple of reasons why your results may not be entirely 
representative of the inherent optical designs. The Zuiko is at least 30 years 
old, and may not be in perfect shape.
The A7 series have a very thick sensor stack that does have an effect on lenses 
not designed for it. The Zeiss is, and the Zuiko isn't.

A Spheric Moose

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