Ursa Mini Pro PL question

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Aaron Green

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Ursa Mini Pro PL question

PostTue Mar 06, 2018 3:29 pm

I'm going to be using Cooke i Anamorphics which I know work w/ the standard PL adapter for the UMP. What exactly is the shim set for? Which PL lenses would I need to add the shims, and why? Thanks.
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Denny Smith

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Re: Ursa Mini Pro PL question

PostTue Mar 06, 2018 5:17 pm

You only need the shims to set the back focus on a PL zoom, if it is not staying in focus during the zoom.
If your lenses are properly collimated and set for the correct FFD, you should not need the shim kit, unless you need to adjust the FFD to get the witness marks correct.

Given you sre using Cooke lenses, they should work fine without adding shims. That said, one if the advantages of thenPL Mount, is you can change the FFD with shims if necessary.
Cheers
Denny Smith
SHA Productions
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Aaron Green

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Re: Ursa Mini Pro PL question

PostTue Mar 06, 2018 5:40 pm

Thanks for the info.
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Anatoly Mashanov

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Re: Ursa Mini Pro PL question

PostWed Mar 07, 2018 4:56 pm

I am a physicist with home repair hobby (lens repair included), not a cinematographer, so my opinion is null and void. Nevertheless:

The shims are to tune the FFD of the camera ONLY. Then, you use a separate set of shims and/or screws depending of your specific lens to fine tune your zooms to be parfocal. And at last you focus the lenses to infinity or slightly past it.

If you use mount shims to tune one of your zooms to be parfocal you most possible spoil the tuning of all other zooms.
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Denny Smith

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Re: Ursa Mini Pro PL question

PostWed Mar 07, 2018 7:16 pm

Anatoly, you are correct. You want the camera mount set to the proper FFD (52mm for PL) and then have the lens collimated and on Zooms back focus set to get it parfocal.

I was assuming the lens was correctly collimated and back focus set, then using shims on the ca era to get the PL mount set to allow proper use of the lens.
Thanks for jumping in here.
Cheers
Denny Smith
SHA Productions

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