Ad
Ad
Ad
Pages: [1]   Bottom of Page
Print
Author Topic: Optical Glass on sensor, how much affect does it have?  (Read 3207 times)
SZRitter
Full Member
***
Offline Offline

Posts: 187


« on: June 10, 2014, 09:44:48 AM »
ReplyReply

So, I read this article (http://petapixel.com/2014/06/07/glass-path-using-adapters-may-hurt-image-quality/), and it makes me wonder a few things:

1. How correct is it? To me, it makes sense and I honestly could see how it would affect things.

2. How many third party companies (i.e. Sigma, Samyang, Voigtlander, etc) refactor their lenses for the different mounts/optical glass? I at one point was thinking of just buying a Samyang/Bower lens in F-mount and adapting it to M43 with a dumb adapter, but if their lenses are actually made different for each mount, it would make sense to buy it in the mount of the camera I actually have.

3. In the case of M43, does Olympus, Panasonic and Black Magic all use the same optical glass thickness? (i.e. is it part of the M43 spec?)
Logged
ErikKaffehr
Sr. Member
****
Online Online

Posts: 8018


WWW
« Reply #1 on: June 10, 2014, 09:50:50 AM »
ReplyReply

Hi,

I would presume it is mostly a problem with non retrofocus wide angles, but it is clearly a problem.

Best regards
Erik

So, I read this article (http://petapixel.com/2014/06/07/glass-path-using-adapters-may-hurt-image-quality/), and it makes me wonder a few things:

1. How correct is it? To me, it makes sense and I honestly could see how it would affect things.

2. How many third party companies (i.e. Sigma, Samyang, Voigtlander, etc) refactor their lenses for the different mounts/optical glass? I at one point was thinking of just buying a Samyang/Bower lens in F-mount and adapting it to M43 with a dumb adapter, but if their lenses are actually made different for each mount, it would make sense to buy it in the mount of the camera I actually have.

3. In the case of M43, does Olympus, Panasonic and Black Magic all use the same optical glass thickness? (i.e. is it part of the M43 spec?)
Logged

Jim Kasson
Sr. Member
****
Offline Offline

Posts: 1078



WWW
« Reply #2 on: June 10, 2014, 10:01:03 AM »
ReplyReply

I would presume it is mostly a problem with non retrofocus wide angles, but it is clearly a problem.

Not restricted to those lenses, Erik:

http://www.lensrentals.com/blog/2014/06/the-glass-in-the-path-sensor-stacks-and-adapted-lenses

We should start thinking about non-fixed lens cameras as having the front elements of their lenses interchangeable.

Jim
Logged

Manoli
Sr. Member
****
Offline Offline

Posts: 735


« Reply #3 on: June 10, 2014, 10:13:27 AM »
ReplyReply

A very good follow-up article by Roger Cicala here :
http://www.lensrentals.com/blog/2014/06/sensor-stack-thickness-when-does-it-matter

Logged
SZRitter
Full Member
***
Offline Offline

Posts: 187


« Reply #4 on: June 10, 2014, 11:11:21 AM »
ReplyReply


So, the interesting thing to note is the exit pupil. It seems, in regards to Nikkor glass, that it was all over the map for different focal lengths. This would also explain why my 55mm micro Nikkor renders so well on an E-M5, as looking at the lens, I am fairly certain it's exit pupil is pretty far up there.
Logged
ErikKaffehr
Sr. Member
****
Online Online

Posts: 8018


WWW
« Reply #5 on: June 10, 2014, 11:22:22 AM »
ReplyReply

Jim,

You are obviously right. I have actually read the Roger Ciala article, but jumped conclusions. I guess that the optical package in front of the sensor needs to be taken into account when dsigning lenses.

The Roger Ciala article is quite an interesting read, BTW.

Best regards
Erik


Not restricted to those lenses, Erik:

http://www.lensrentals.com/blog/2014/06/the-glass-in-the-path-sensor-stacks-and-adapted-lenses

We should start thinking about non-fixed lens cameras as having the front elements of their lenses interchangeable.

Jim
Logged

Jim Kasson
Sr. Member
****
Offline Offline

Posts: 1078



WWW
« Reply #6 on: June 10, 2014, 12:50:17 PM »
ReplyReply

You are obviously right. I have actually read the Roger Ciala article, but jumped conclusions.

You were right, too, Erik. It's worse at wide f/stops and exit pupils close the the focal plane. The surprise for me was the small, but significant degradation even with a retrofocus 55mm lens.

Jim
Logged

Telecaster
Sr. Member
****
Offline Offline

Posts: 936



« Reply #7 on: June 10, 2014, 02:46:11 PM »
ReplyReply


Hmmm, very interesting. This surely helps explain why most wider rangefinder lenses perform so poorly on non-RF bodies regardless of sensor size. I'd expected the performance of these lenses on m43 cameras to be better than on APS-C bodies but this has definitely not been the case.

-Dave-
Logged
Telecaster
Sr. Member
****
Offline Offline

Posts: 936



« Reply #8 on: June 13, 2014, 10:44:21 PM »
ReplyReply

Here's another curious thing I've seen with certain Leica RF lenses on an A7r vs. the same lenses on my film M6 and electronic M8.2s: focus shift differences. One of my favorite RF lenses is the Rigid version of the 50mm Summicron. On Leicas there's a plateau performance-wise in the f/4–5.6 range with this lens but it's not a big deal. On the A7r, though (using the latest Voigtländer adapter), the focus shift is blatant and noticeably degrades performance in the same f-stop range (unless I work around it by focusing at the taking aperture rather than with the lens wide open). I wonder if CFA/filter stack thickness differences might be playing a role in this? I should test for proper infinity focus with the adapter too...it seems fine but I've never systematically checked it.

-Dave-
Logged
Vladimirovich
Sr. Member
****
Offline Offline

Posts: 1320


« Reply #9 on: June 14, 2014, 08:02:59 AM »
ReplyReply

I wonder if CFA/filter stack thickness differences might be playing a role in this?
CFA are on sensor surface under a layer of microlenses (in most cameras we have microlenses)... filter stack does not touch microlenses and separated by some gap from them...
Logged
Pages: [1]   Top of Page
Print
Jump to:  

Ad
Ad
Ad