Blackmagic Mounts questions

The place for questions about shooting with Blackmagic Cameras.
  • Author
  • Message


  • Posts: 1
  • Joined: Tue Feb 13, 2018 5:12 pm
  • Real Name: Bill Ampatzoglou

Blackmagic Mounts questions

PostTue Feb 13, 2018 5:26 pm

Hello forum,

I am really new to blackmagic so I apologise if my question sounds stupid. Also I apologize for my English. I am not a native speaker.

I've been shooting events for 6 years and weddings for 2 years. I love photography but there is nothing like video and cinema. I was thinking on investing on a blackmagic camera. But there is a small problem. I have no idea about mounts. I know how to shoot, not the technical. Could you please help me with some info?

1. I just love the Blackmagic URSA Mini Pro. Love the specs and the way the camera looks. I saw that there is an F mount available (I'm a Nikon guy). My question is; Do I buy the camera with any mount (PL for example so I can be future-proof) plus the F mount and switch them? I mean; do the mounts get removed from the body so I can attach another or do I attach the secondary mount ON the primary?

2. Will FX lenses from Nikon be the same mm as is for Nikon FX bodies? So the 50mm prime will show me on the URSA the same image as in Nikon or is there a crop factor?

Thank you!

Denny Smith

  • Posts: 9899
  • Joined: Thu Aug 01, 2013 4:19 pm
  • Location: USA, Northern Calif.

Re: Blackmagic Mounts questions

PostTue Feb 13, 2018 6:40 pm

Bill welcome to the BM Forum, and your Englishmis better than my Spanish or German, no need to apologize mate.

1. The UM Pro comes with a EF Mount (no other option currently available). However, you can buy a PL or Nikon Mount and exchange the EF Mount for either one. You can also get some additional shim kits to correct any monitor FFD issue with a zoom, for example. The EF Mount is removed from the body, and the new mount PL or Nik replaces the EF Mount. You will need a special micro torque driver and the correct screw tip (I believe it is a small Torex bit) to remove and redo,ace the screws with equal tension on each, which will be indicated on the torque driver scale. These are not adapters, but actual mounts bolted to the camera body.

2. When shooting 4K, the FOV of your FX Camera will be a larger FOV look, so a 50mm on the UM Pro will be closer to a 35mm (full gate 4.6) or 30mm when shooting a smaller 4K window, but the aspect ratio is also going to be different from a DSLR, which gives the resulting image on a 16:9 Camera a different wider look. For comparison the UM Pro is closer in size to a Nikon DX sensor. The DX 23.6x15.6 and the UM Pro is 25.34x14. Your FX is 36x24, but in a 16:9 aspect ratio it is cropping to 36x20.3. Resulting is a FOV crop factor of about 1.44 based on the horizontal aspect.
Hope this helps.
Last edited by Denny Smith on Thu Feb 15, 2018 6:25 am, edited 2 times in total.
Denny Smith
SHA Productions


  • Posts: 48
  • Joined: Thu Aug 10, 2017 12:58 am

Re: Blackmagic Mounts questions

PostWed Feb 14, 2018 7:50 pm

Regarding Question 2, here is an update of a calculation I posted a while back. Here I attempt to calculate the image circle of the UMP at various windowed sensor resolutions. That is the table on the right. On the left is a table of how various lens focal lengths on the various windowed sensor resolutions normalize to Full Frame 35 focal lengths.

(This table does not apply to mounts that incorporate optics, such as the UMP’s B4 mount.)
UMP image circles.png
UMP image circles.png (654.58 KiB) Viewed 222 times

Return to Cinematography

Who is online

Users browsing this forum: Hjalmar Molin, Joshua_G, Rrrbbb and 22 guests