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lense contrast variations


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#1 Martin Amezaga

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Posted 23 November 2007 - 11:12 PM

Hi, I wonder if anyone out there could help me with this. I´m shooting a short film whith a Carl Zeiss 10-100 Zoom and whith a Carl Zeiss 1.3 prime set. I´ll only have acces to the prime lenses for half of the shooting time. (2 days)

So here are the questions:

-What kind of contrast/color/sharpness variation shoul I espect to have when I join the zoom and prime material?

-Is this variation significant?

-Should I work all the way through with the zoom lense to avoid it?

-Is there a significant variation when shifting focal lengths whith the zoom lense?

-What kind of image qulity alterations should I espect when using an 85B filter? (besides the color temperature compensation).

Hope anyone could help me with this, thanks before hand anyways.
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#2 David Mullen ASC

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Posted 24 November 2007 - 12:35 AM

They match OK, contrast-wise, the primes just a little snappier -- the only thing is that the zoom will flare more when pointed into bright windows, etc. because it has so many more elements in it. So in that situation, the zoom will look lower in contrast.

If you're talking about the older T/3.1 10-100, rather than the T/2 version, I'd say that the T/3.1 needs to be stopped down to at least T/4 or more to be sharp. Of course, the T/2 should probably be stopped down to T/2.8 for the same reason.

I haven't looked at these clips, but maybe there is something interesting here for you:
http://arri16s.com/FilmClips1.htm
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#3 Chris Keth

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Posted 24 November 2007 - 01:16 AM

They match OK, contrast-wise, the primes just a little snappier -- the only thing is that the zoom will flare more when pointed into bright windows, etc. because it has so many more elements in it. So in that situation, the zoom will look lower in contrast.

If you're talking about the older T/3.1 10-100, rather than the T/2 version, I'd say that the T/3.1 needs to be stopped down to at least T/4 or more to be sharp. Of course, the T/2 should probably be stopped down to T/2.8 for the same reason.

I haven't looked at these clips, but maybe there is something interesting here for you:
http://arri16s.com/FilmClips1.htm


I shot with that exact same stuff a lot in school and David is spot on. Adjusted properly, that zoom is a very nice sharp lens that is just a tiny bit different than those primes. It's only noticeable projected so if you're going to video, you're golden.

Should you find that the zoom is a bit suspect (as sometimes my school's stuff was) and have no other choice, you could shoot the primes with a very light diffusion and shoot the zoom bare. I found that it will help hide the sharpness differences in a very subtle way.

Another thing to check is which series of superspeeds you have. Some of them (MKII?) have triangular irises that would have a bit of a different look than the zoom in the out of focus areas. I find the triangular bokeh a bit harsh-looking but others like them.
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#4 Martin Amezaga

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Posted 25 November 2007 - 10:39 PM

Like always, Thanks a lot!
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