Metabones Speed Booster - Vignetting with Tele-Lenses

Started Jan 18, 2013 | Discussions thread
brian
Contributing MemberPosts: 975
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Re: Brian: 17mm TSE with SB and PF??
In reply to jpr2, Jan 27, 2013

jpr2 wrote:

brian wrote:

jpr2 wrote:

Serhan2 wrote:

Brian's test with Canon 17mm TS-E:

http://www.getdpi.com/forum/484484-post135.html

Brian is rather skimpy with details on that sample image and crops. I particular nothing is said whether it was tilted/shifted or not. However, knowing TSE17 as quite free from purple fringing, I find it a bit surprising to see the amounts of PF on these samples. Therefore some pretty extreme shift (tilting doesn't seem to be as prone to PF in my experience) needs to be assumed perhaps!!

Forgive me - I used to do alot of large format shooting with a view camera, so I tend to think in terms of "rise" and "fall" instead of "shift". So, the 12mm of rise that I indicated in my quick test shot is the same thing as 12mm of shift in the upward direction. This is the maximum amount of shift that the 17/4 TS-E is capable of.

thanks a lot for explanation, upon careful rereading it should be obvious... but I simply overlooked the "rise" and its possible meaning ,

PF is not huge there, but it is present, and it indicates quite well what one can expect from lenses less stellar than the TSE-17 when mounted through the EF to E-mount SB model - or... perhaps I'm wrong in this regard?

jpr2

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~

Actually the best objectives will tend to reveal any residual aberrations in the Speed Booster, especially when the image is magnified to pixel-peeing proportions.  Lenses that have significant aberrations, such as a 50mm f/1.2 used wide open, actually tend to give surprisingly good results.

Chromatic aberration in the deep violet proved to be very difficult to correct in the SB.  The reason for this is that we were very cramped for space between various lens obstructions on one side and camera obstructions on the other.  This forced us to use extremely high index glasses, which gave increased deep violet aberrations.  Ideally we would have had another 5mm or more space to work with between the attached lens and the sensor, which would have permitted a reduction in secondary chromatic aberrations.

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J. Brian Caldwell www.caldwellphotographic.com

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