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URSA Pro B4 Mount Confusion


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#1 Macks Fiiod

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Posted 02 August 2017 - 10:28 PM

This is to any URSA Mini owners. The wording on the listing isn't super specific. Also the B&H rep I talked to said he never used it.

 

On this product: https://www.bhphotov...ini_pro_b4.html

 

Will the camera need to be set to some form of crop sensor mode to be able to use B4 lenses?

Also when it's set there, how usable is the image at that point?

 

Thanks to all Blackmagic faithful.


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#2 Phil Rhodes

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Posted 03 August 2017 - 05:12 AM

Will the camera need to be set to some form of crop sensor mode to be able to use B4 lenses?

 

I would assume so. This would probably (though I don't know) preclude 4K. That's how it works with the MTF adaptor.

 

Also when it's set there, how usable is the image at that point?

 

Depends how good the B4 lens is, and how wide open it is. It's not going to have the same sharpness as a movie prime, of course, but the compensations may make up for that.

 

Obviously, don't go out and buy some twenty-year-old standard def TV zoom and expect it to hold up to modern Canon EF glass.

 

P


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#3 Macks Fiiod

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Posted 03 August 2017 - 06:54 AM

Thanks for replying, Phil.

 

I'd be putting Zeiss DigiPrimes on it, which I assume are the best B4 has to offer?

 

I was more speaking to the digital noise in the image. I remember using the RED One MX in crop mode and the camera's grain gave the image a little too much character if you get what I mean.


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#4 Phil Rhodes

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Posted 03 August 2017 - 06:18 PM

Digiprimes should be as lovely as you can get.

 

Clearly, the noise performance will be less wonderful than shooting the full sensor and doing a (nice) downscale on it. If you halve the area you're shooting with, the noise increase will theoretically be 6dB or almost exactly a stop.

 

Or, if you like, it'll be about as noisy as shooting 4K on the full sized sensor. But then the noise looks smaller compared to the size of the image, so it's less objectionable. It... eh. Noise is complicated.


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