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Archive 2014 · Where is Infinite Focus on Zeiss 25mm F/2 ZE (Canon)?

  
 
billsamuels
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p.1 #1 · p.1 #1 · Where is Infinite Focus on Zeiss 25mm F/2 ZE (Canon)?


I have a new Zeiss 25mm F/2 ZE (Canon mount) and today was the first time I've actually had the opportunity to use it as a landscape lens. For years, I've been using Canon L lenses and just got used to AF which are pretty dead-on sharp, but I just can't figure out with this lens where the lens is sharpest when dealing with infinite. I've been using both the view finder and live view and if I stop at the point that the far-off trees appear to be very sharp, the pictures appear to be sharp. But that's still a bit off from being turned until the focus ring stops.

If I turn the focus until it stops, it still looks sharp. And I can't tell if it looks less sharp at this point, or more sharp. It looks a bit different, but I can't tell why?

For those that have experience using Zeiss wide-angle lenses, what has been your experience with this issue?

I'm attaching a couple of photos that I shot both at "just sharp" (first photo) and then when I turned the focus ring until it stopped.

Please tell me what you think.

Thanks!
Bill




focused to sharpness






Focus ring turned until it stopped




Dec 29, 2014 at 01:48 AM
philber
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p.1 #2 · p.1 #2 · Where is Infinite Focus on Zeiss 25mm F/2 ZE (Canon)?


Bill, I've used a number of Zeiss ZE lenses on my Canon cameras. You cannot use the hardstop as a guarantee that you have focused at infinity, though, in most cases, you have enough DOF that it won't matter. You can try finding out exactly where infinity is on your focus ring by shooting wide open, where DOF will be a lot less. Or, if you are using a 5DII or 5DIII, you can micro-adjust, which I highly recommend with all lenses.
In my case, most of my Zeiss lenses reached infinity just a hair before the hardstop, so, with a WA (Z 21, ZE 25), I would usually go to the hardstop, pull back a hair, and know that I had proper focus.



Dec 29, 2014 at 01:58 AM
billsamuels
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p.1 #3 · p.1 #3 · Where is Infinite Focus on Zeiss 25mm F/2 ZE (Canon)?


go to the hardstop, pull back a hair, and know that I had proper focus.

That sounds like a great idea actually. I think there's a little more play between what I find as sharp and hardstop (thanks for the term too), but I think if I take the average, I probably would end up with something inbetween, which for a Zeiss, has got to be pretty darn sharp! I'm able to use a small F-stop anyway with this lens, smaller than the canon lenses I have, but I think because the canon lenses I have are the cheaper L lenses and they are F/4+. Thanks.

P.S. Don't know how this works with the cameras you mentioned, but probably not much differrent; I have a Canon 6D.



Dec 29, 2014 at 02:21 AM
jhg photo
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p.1 #4 · p.1 #4 · Where is Infinite Focus on Zeiss 25mm F/2 ZE (Canon)?


Philber described it perfectly.
Just turn the focus ring back by 1 mm or so after reaching the infinity hard stop.
This "over-infinity" feature compensates for tiny manufacturing errors in both body and lens dimensions and also for thermal effects due to expansion.



Dec 29, 2014 at 03:17 AM
Scott Stoness
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p.1 #5 · p.1 #5 · Where is Infinite Focus on Zeiss 25mm F/2 ZE (Canon)?


On my 25/2 zeiss, it is sharpest at infinity at just a wee bit less than hard stop. So when I am shooting in the dark I just crank it to hard stop and then an ever so small turn back and I am there.


Jan 01, 2015 at 09:15 PM





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