Blackmagic Forum

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!

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

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.

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?

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

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.

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

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.

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

I just received my URSA Mini Pro camera with the B4 mount. I love the camera. My zoom lens is Canon YJ17x9.5B4. It's a CCD KRS SX12 17X. My problem is the image is severely vignetting. Like a port hole in the middle of the image. It does this at all image settings in the camera, from HD all the way up tp 4.6K. I must be doing something wrong. Are there different types of B4 lens that would yield different results?
Thanks

Yiu need to set the camera to the HD or 2K window mode. The B4 Mount only gives you enough of an image circle to cover the crop sensor mode, not the full sensor. The END 2/3rds lens you have, will probably only cover the HD window, but you could try the 2K window also and see.

Normal HD is just the 4K full sensor, downsampled to HD, so you are still using the full sensor, and getting the vignette port hole effect. The area inside of the print hole is what the lens will cover on the sensor.
Cheers

Bingo, problem solved. Thanks much!!