Vignette on B4 mount for URSA mini 4.6k?

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Wilson Luniz

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Vignette on B4 mount for URSA mini 4.6k?

PostSun Mar 11, 2018 11:40 am

Will I get vignette while:
- installing a 2/3” lens with 2x extender
- via Blackmagic B4 adapter for Ursa Mini 4.6k
- UM4.6k is in UHD windowed sensor mode
?
I know the answer for URSA mini Pro is no(no vignette). The optical lens for these two adapter(UM and UMP) are supposed to exact same. I’m just to confirm again.
Thank you!
Wilson Luniz
Generator Stage Production, Macau
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Denny Smith

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Re: Vignette on B4 mount for URSA mini 4.6k?

PostSun Mar 11, 2018 7:03 pm

The B4 Lens Mount for the Ursa Mini (it is not an adapter, but replaces the PL mount) optically is the same correction as the Ursa Mini Pro B4 Mount. The UM4.6 B4 Mount (as does the Pro) optically corrects the lens to work in a single sensor camera, eliminating the CA on most lenses. Also, the image is expanded about 1.3X to insure coverage on the HD window mode. Some better B4 lenses, like the newer Fujinon zooms or the cine zoom will even cover the 2K window mode.

So you will not get any vignetting with a good 2/3rds B4 lens in HD window, wither the ENG zooms or,the 2/3rds Cine lenses that pop up every now and then on the used market.
Cheers
Last edited by Denny Smith on Sun Mar 11, 2018 9:59 pm, edited 1 time in total.
Denny Smith
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Xtreemtec

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Re: Vignette on B4 mount for URSA mini 4.6k?

PostSun Mar 11, 2018 7:21 pm

So only in Windowed HD mode!! In UHD you will get vignette.. This is solved in the Ursa Broadcast which does 4K with a B4 lens. ;)
Daniel Wittenaar .:: Xtreemtec Media Productions ::. -= www.xtreemtec.nl =-
4K OBV, ATEM TVS HD, 1M/E 4K, 2M/E Broadcast Studio 4K, Hyperdeck Studio Mini, SONY FS7 4K, Ursa Broadcast 4K
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Wilson Luniz

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Re: Vignette on B4 mount for URSA mini 4.6k?

PostSun Mar 11, 2018 11:35 pm

Xtreemtec wrote:So only in Windowed HD mode!! In UHD you will get vignette.. This is solved in the Ursa Broadcast which does 4K with a B4 lens. ;)

Oh really? But I tested a b4 lens with built-in extender(enabled) works in UHD windowed sensor mode in URSA mini pro. Am I not mistaken?
Wilson Luniz
Generator Stage Production, Macau
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Denny Smith

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Re: Vignette on B4 mount for URSA mini 4.6k?

PostMon Mar 12, 2018 5:13 am

Yes Wilson, the built in tele-extender will increase the projected image circle, covering the area about the size of a MFT sensor or the UM in UHD crop. Daniel was referring to the normal, projected image circle of a B4 Zoom, without the tele-extender.
Cheers
Last edited by Denny Smith on Sun Mar 18, 2018 6:51 pm, edited 2 times in total.
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Xtreemtec

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Re: Vignette on B4 mount for URSA mini 4.6k?

PostMon Mar 12, 2018 9:18 pm

That is correct. But in the real world you dont want to use the 2x extender all the time ;) Light loss and 2x zoomed image is not preffered for a lot of shoots.. ;)
So i'm still thankfull for the new Ursa Broadcast that fixed this issue.. Mine is coming next week. 8-)
Daniel Wittenaar .:: Xtreemtec Media Productions ::. -= www.xtreemtec.nl =-
4K OBV, ATEM TVS HD, 1M/E 4K, 2M/E Broadcast Studio 4K, Hyperdeck Studio Mini, SONY FS7 4K, Ursa Broadcast 4K
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Denny Smith

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Re: Vignette on B4 mount for URSA mini 4.6k?

PostMon Mar 12, 2018 10:31 pm

Great, I have been look8ng st this camera also, it will be interesting to hear and see your results and take on the camera and it’s IQ.
Cheers
Last edited by Denny Smith on Sun Mar 18, 2018 6:51 pm, edited 1 time in total.
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Thomas Levitt

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Re: Vignette on B4 mount for URSA mini 4.6k?

PostSun Mar 18, 2018 1:06 pm

Xtreemtec wrote:That is correct. But in the real world you dont want to use the 2x extender all the time ;) Light loss and 2x zoomed image is not preffered for a lot of shoots.. ;)
So i'm still thankfull for the new Ursa Broadcast that fixed this issue.. Mine is coming next week. 8-)


In the real world you not want to use the extender unless absolutely necessary to achieve certain shots in certain situations.

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