Archive 2008 · C/Y Zeiss 85/2.8 Sonnar Question

Mike Ganz
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p.1 #1 · p.1 #1 · C/Y Zeiss 85/2.8 Sonnar Question

I picked up a mint copy off ebay and was testing out on a 5D with a Cameraquest adapter. The infinity shots at 2.8 seemed to be just short of focus, so I added a single layer of scotch tape to the adapter at three points. According to the wife, the shots with the tape seemed to be more in focus. Adding a second layer of tape had a negative effect, so I backed down to the single layer. Below is a 100% crop of a picture of a neighbor's horse barn, taken at about a distance of 200 feet or so. I chose it for a test due to the seams and various angles. Shot in RAW, cropped and converted...no other PP or sharpening was applied. Hate to ask, but is this lens a keeper?

http://northlake.smugmug.com/photos/330192073_95FHT-XL.jpg

Edited on Jul 12, 2008 at 08:50 AM

Jul 12, 2008 at 08:45 AM

Jman13
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p.1 #2 · p.1 #2 · C/Y Zeiss 85/2.8 Sonnar Question

Just short of focus? Meaning you weren't quite at infinity, or you were PAST infinity? If you were past infinity, the tape will help, but not if you were short.

Anyway, looks sharp to me, for a 100% crop at that distance...that's pretty nice.

It's hard to say what my 85 Sonnar would do under the same conditions, I just know it's probably my favorite lens. It's just exceptional. I don't use it very often at infinity, though.

Edited on Jul 12, 2008 at 09:02 AM

Jul 12, 2008 at 09:01 AM

Mike Ganz
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p.1 #3 · p.1 #3 · C/Y Zeiss 85/2.8 Sonnar Question

Thanks Jordan. What I was trying to say is that it seemed short of focus at infinity, which is probably my twisted way of saying that it was focusing beyond the infinity mark. Thanks for the feedback (I was looking for some confirmation)...looks like I'll keep this one. Weird about all of these adapter variations...

I was hoping to do some test shots on the sunflowers around my pond, but with all the wind we're having today, the barn was the only object that was stationary.

Jul 12, 2008 at 09:15 AM

JimBuchanan
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p.1 #4 · p.1 #4 · C/Y Zeiss 85/2.8 Sonnar Question

At wide open, take a series of photos from the lens turned all the way to the infinity stop, and then back off (in near range direction) ever so slightly, for about 3-5 frames. load them into your viewer at 100% and compare. If your lens goes past infinity, one of the series will be in good focus. If you know how to remove the rubber focus grip and loosen the grub screws, you could then turn just the focus ring (while the actual lens assembly doesn't move) to its stop, then tighten the screws, and you have just calibrated infinity focus to that particular adapter. The weather vane would be a good target.

One of these days I plan on having a 85 Sonnar, too.

Jul 12, 2008 at 10:17 AM

Mike Ganz
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p.1 #5 · p.1 #5 · C/Y Zeiss 85/2.8 Sonnar Question

JimBuchanan wrote:
At wide open, take a series of photos from the lens turned all the way to the infinity stop, and then back off (in near range direction) ever so slightly, for about 3-5 frames. load them into your viewer at 100% and compare. If your lens goes past infinity, one of the series will be in good focus. If you know how to remove the rubber focus grip and loosen the grub screws, you could then turn just the focus ring (while the actual lens assembly doesn't move) to its stop, then tighten the screws, and you have just calibrated...Show more →

Maybe I'm using the wrong terminology? What I'm trying to say is that the lens was not achieving infinity focus before or at the infinity mark, which led me to believe that the lens would achieve infinity focus at some point past the infinity mark. Adding the tape to the adapter seems to have helped... On the other hand, I have an Oly 28/3.5 that achieves infinity focus just before the leading edge of the infinity symbol...in this case, loosening the grub screws and adjusting the barrel/focus ring would be the way to go?

Edited on Jul 12, 2008 at 11:20 AM

Jul 12, 2008 at 11:18 AM

JimBuchanan
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p.1 #6 · p.1 #6 · C/Y Zeiss 85/2.8 Sonnar Question

Mike Ganz wrote:
...On the other hand, I have an Oly 28/3.5 that achieves infinity focus just before the leading edge of the infinity symbol...in this case, loosening the grub screws and adjusting the barrel/focus ring would be the way to go?

Yes, that was what I was trying to describe.

In the case of the Sonnar, if you never get to infinity focus, and you want to adjust the lens grub screws, then you would loosen, turn the ring back a small amount, ans tighten to give more lens rotation. Then do the frame series again, to find the infinity position.

Edited on Jul 12, 2008 at 12:21 PM

Jul 12, 2008 at 12:16 PM

Mike Ganz
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p.1 #7 · p.1 #7 · C/Y Zeiss 85/2.8 Sonnar Question

Ahhh, got it. Thanks, Jim...this made everything much clearer.

Jul 12, 2008 at 12:52 PM

trumpet_guy
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p.1 #8 · p.1 #8 · C/Y Zeiss 85/2.8 Sonnar Question

If adding tape to the adapter makes an infinity image sharper, then
your lens was focusing past infinity. The lens elements move closer to
the sensor for far focus and farther away from the sensor to achieve close
focus. Thus, pushing the lens farther away by adding thickness (tape)
to the adapter acts to bring the focus closer.

Jul 12, 2008 at 11:29 PM


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