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Zeiss Superspeeds


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#1 Zac Halberd

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Posted 09 June 2008 - 11:32 AM

Shooting some tests on the RED using superspeeds. Getting some soft shots, and am wondering if I need to back focus these lenses. I didn't know you had to back focus a prime lens. Sorry for the stupid question, but this is my first time using these lenses.

Thanks

Z
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#2 Max Jacoby

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Posted 09 June 2008 - 11:47 AM

You can't backfocus PL mount lenses. In all likelyhood the camera is not properly collimated. If after collimation the lenses still are soft, there might be something mechanically wrong with the lenses and you need to have them checked by a technician.
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#3 Mitch Gross

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Posted 09 June 2008 - 11:57 AM

You do backfocus PL mount lenses. It is called collimating and it is not something one does in the field. A large bench device called a collimator is used to measure the offset of the lens from a set standard in microns. Then the lens mount is removed and the depth set correctly by adding or removing thin metal shims.
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#4 Dan Goulder

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Posted 09 June 2008 - 11:30 PM

Are your soft shots occuring at infinity focus? If that's not the case, then the lenses may not be the problem.
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#5 Johnathan Holmes

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Posted 16 June 2008 - 02:44 AM

One thing I'm curious about, having used the Red only once and having two more jobs booked with it coming up... Is the mount on the body affected by temperature? I pulled for a feature that had a Sony EX1 mounted to a MovieTube with Superspeeds in February and during our exteriors (in -20 degree weather), the MovieTube shrunk just enough to put our shots out of focus. It was something we only noticed during playback much later on. To compensate, we had to adjust the focus on the EX1 to approximately 5' instead of Infinity. This was an extremely dramatic shift in back focus and troubled me constantly. I wonder if the Red could exhibit a similar problem, and if so, is this the cause of your shots being soft?

Curious to hear from anyone who has shot with the Red extensively in extreme cold or hot environments, and their results.
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