Medium Format Lens FOV With Ursa?

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

Thomas Koveleskie

  • Posts: 39
  • Joined: Sun Jun 25, 2017 9:07 pm

Medium Format Lens FOV With Ursa?

PostSun Jan 28, 2018 9:28 pm

I've done a lot of searching trying to come up with the correct real world answer for the Field of View on the Ursa 4K using a Medium Format lens. Am I correct in assuming that an 80mm prime MF lens over the Ursa super 35 sensor would actually have the FOV as wide as a 35mm SLR lens at 50mm or there about? Given the shot is being taken at the identical spot for comparative purposes.

I'm putting together a kit of pl mount vintage soviet primes for the 4K big Ursa for use with a 70's themed project. I need a 80 to 90mm lens. Someone has offered me a mint 80mm Medium Format lens, but on the Ursa won't the field of view actually be wider and closer to that of a 50mm DOF SLR lens?

I want an 80mm in the kit for closeups. Using a MF lens, wouldn't I need something like a 180mm to get the FOV on the Ursa to appear like 80mm on an SLR 35mm lens?

I'm trying to find a mint 35mm Jupiter 9 f2.8/85mm and the MF lens I was offered is a mint MC Volna 80mm medium format.

Any insights much appreciated.
Computer: AMD FX-8370 4.2 GHZ 8 core, 16GB RAM, GTX 780 TI, Win 10 X64, system drive OCZ 240GB SSD, storage HD's: 5 TB, 2 TB, 1 TB.
Offline
User avatar

rick.lang

  • Posts: 8021
  • Joined: Wed Aug 22, 2012 5:41 pm
  • Location: Victoria BC Canada

Re: Medium Format Lens FOV With Ursa?

PostSun Jan 28, 2018 10:18 pm

Thomas, read through this review and note the comments re light leak on the Volna 80mm medium format lens:

http://www.pentaconsix.com/StandardLenses.htm

As for the focal length, 80mm lenses provide the normal angle of view on a medium format camera with a large image circle, so you are correct the 80mm on a medium format camera would provide a similar field of view to a 50mm on a 135 film camera. But if you put that 80mm lens on a 135 film camera with a smaller sensor with no other optics, you will be cropping the image circle so that your angle of view is closer to a stills portrait lens.

If you put the 80mm lens on the URSA, it’s going to feel like a medium telephoto due to the greater crop of the image circle. Depending upon the perspective you actually prefer, that may seem fine to some or it may seem too flat for an intimate portrait.

As you know on a 135 film camera, a typical stills portrait lens is 85mm. If you like that ‘look’, then on the URSA you could use a 50mm lens designed for a 135mm camera or a 35mm lens designed for a medium format camera.

I don’t think you want the Volna 80mm for these two reasons.

Since I don’t use medium format lenses, I hope I haven’t got this wrong!


Sent from my iPhone using Tapatalk
Rick Lang
Offline

Denny Smith

  • Posts: 7935
  • Joined: Thu Aug 01, 2013 4:19 pm
  • Location: USA, Northern Calif.

Re: Medium Format Lens FOV With Ursa?

PostMon Jan 29, 2018 2:20 am

Well almost a Rick. A 80mm lens is a 80mm lens regardless of the projected image circle. On a 6x7 medium format camer, 80mm gives you a normal AOV, like a 50 on 135 and 35mm on a S35 Cine Camera.

On a Ursa, it is still going to be a 80mm, short telephone, with a AOV similar to a 105mm lens on a 135 DSLR. The main difference is the medium format lens will project a larger image checked than a 80mm 135 lens, ad will be larger and heavier in size, unless you get a slow f/3.5 Tessar design lens.

Also, the larger format lenses have less resolving power, and will be a little softer in look than a smaller format S35 or 123 mm lens will. This added softness is a feature some like, to take the digital edge off the 4K sensor cameras.
Cheers
Last edited by Denny Smith on Tue Jan 30, 2018 1:16 am, edited 1 time in total.
Denny Smith
SHA Productions
Online

Thomas Koveleskie

  • Posts: 39
  • Joined: Sun Jun 25, 2017 9:07 pm

Re: Medium Format Lens FOV With Ursa?

PostMon Jan 29, 2018 6:03 pm

Thank you Rick and Denny.

Denny you are saying that the fov of the 80mm MF will be the same as the 85mm 35 SLR lens? So I can assume that if I had the camera locked off in a certain spot and just changed the lenses from MF 80mm to SLR 85mm, I would see basically the same width picture, and the 80mm MF would not be wider than the SLR 85mm lens?

The extra softness of the MF lens compared to my other 35mm SLR lenses I'd be using may be a problem although. Thanks for pointing this out. Probably have to stay with the SLR lenses. I have a MIR-1B 37mm, Helios 44-2 58mm and a Jupiter 37A 135mm. I'm looking for something in the 80-90mm range that is/can be adapted for PL mount and at bought at a reasonable price.
Computer: AMD FX-8370 4.2 GHZ 8 core, 16GB RAM, GTX 780 TI, Win 10 X64, system drive OCZ 240GB SSD, storage HD's: 5 TB, 2 TB, 1 TB.
Offline
User avatar

rick.lang

  • Posts: 8021
  • Joined: Wed Aug 22, 2012 5:41 pm
  • Location: Victoria BC Canada

Medium Format Lens FOV With Ursa?

PostMon Jan 29, 2018 6:22 pm

The angle of view of the lens isn’t the question as that doesn’t change. But the angle of view you get on the camera depends on the size of the sensor area and the 80mm medium format image cicle is significantly cropped on the 135 film area and cropped further again on the 4.6K sensor so your field of view is reduced. That’s my thinking.

If you used a focal reducer that brought the image circle down to match the smaller sensor, then there is no crop and the 80mm would be okay as a portrait lens. However the OP doesn’t imply a focal reducer would be used.

Sent from my iPhone using Tapatalk
Rick Lang
Offline
User avatar

Mattias Kristiansson

  • Posts: 44
  • Joined: Mon Sep 26, 2016 6:15 pm

Re: Medium Format Lens FOV With Ursa?

PostMon Jan 29, 2018 11:27 pm

As previously stated, all 85 mm lenses will give the same angle of view on the big URSA, no matter if they are made for APS-C, FF, MF or even large format cameras. A lens made for larger format will just have a larger image circle, most of it being wasted since the big URSA has such a small sensor anyway. In fact, the extra image circle might even cause more scattered light inside the camera, lowering contrast. A lens made with smaller image circle can be more optimized for that, and thus be made sharper and faster.

That being said, you might like the bokeh, the flare or something else about the look of some MF or other lens, and if it's the look you're after, just go for it! I have some Hasselblad Zeiss lenses for 6x6 (the 110mm/f2 is nice), some Mamiya lenses for 6x4,5 and adapters to EF mount so I can put any of these on my URSA if I like to. As they are made för MF they have pretty long focal lengths though, so the angle of view gets very narrow.

Funny you should mention the Jupiter 9 85mm/f2, I have one of these. I also have the Helios 44 58mm/f2 and Mir 1V 37mm/f2.8 lenses, all in M42 mounts. These old soviet era lenses can be bought cheap on eBay and can be quite fun. I think the Mir 1V is the most useful of the bunch, at least for me since I usually like to have a reasonably wide field of view.
Offline

Denny Smith

  • Posts: 7935
  • Joined: Thu Aug 01, 2013 4:19 pm
  • Location: USA, Northern Calif.

Re: Medium Format Lens FOV With Ursa?

PostTue Jan 30, 2018 1:25 am

Thomas Koveleskie wrote:Thank you Rick and Denny.

Denny you are saying that the fov of the 80mm MF will be the same as the 85mm 35 SLR lens? So I can assume that if I had the camera locked off in a certain spot and just changed the lenses from MF 80mm to SLR 85mm, I would see basically the same width picture, and the 80mm MF would not be wider than the SLR 85mm lens?


No, that was a typo, sorry about that, it will be more like a 1or 120mm on a 135mm Camera.
That said, forget trying to compare the Ursa camera focal lengths to a 135mm still Camera, the aspect ratio and format are different. Instead, learn how a given focal length lense gives you the AOV you want.

Start with a 35mm lens which gives you a “normal” AOV. A 25mm a wide shot, and a 50mm your med close, shot. A 60mm/65mm is going to give you the sweet tight portrait shot perspective. Learn yiur Camera and the lens focal lengths you like to use. A short zoom like a 18-35 or 20-120mm is a good way to wrok out the focal lengths you like best for adding primes.
Cheers
Denny Smith
SHA Productions
Online

Thomas Koveleskie

  • Posts: 39
  • Joined: Sun Jun 25, 2017 9:07 pm

Re: Medium Format Lens FOV With Ursa?

PostTue Jan 30, 2018 5:07 pm

Thanks Denny, but I do understand very well focal lengths and what I want. I'm compiling a set of pl mount primes from wide 28mm up to 200m or so. I've used ENG cameras and zooms for decades. My only question was concerning 35mm lens vs MF lenses of same focal length. I had read where they would not give same AOV for same focal length i.e. 35 mm 80 vs MF 80mm. This was confusing to me as I am not a prime lens expert and wasn't going to purchase a lens without fully understanding the scenarios.
Computer: AMD FX-8370 4.2 GHZ 8 core, 16GB RAM, GTX 780 TI, Win 10 X64, system drive OCZ 240GB SSD, storage HD's: 5 TB, 2 TB, 1 TB.
Offline

Denny Smith

  • Posts: 7935
  • Joined: Thu Aug 01, 2013 4:19 pm
  • Location: USA, Northern Calif.

Re: Medium Format Lens FOV With Ursa?

PostTue Jan 30, 2018 6:57 pm

Good Thomas, was not sure of your previous experience, hence my standard “learn your Camera” response. I do not know what yiu read, but the only difference between MF and 135 format lenses are the projected image circle size, set to cover their respective film gates. Focal length, as previously explained, does not change so a MF 80mm is going to give the same AOV on your Ursa, as a 135mm 80mm or a S35 80mm lens.

Good luck with your quest. You might look at the SLR APO Primes, which are PL and EF, and have a excellent projected image circle that covers the newer larger Ursa Mini 4.6K sensor and EVA 5K sensor.
Cheers
Denny Smith
SHA Productions

Return to Cinematography

Who is online

Users browsing this forum: Thomas Koveleskie and 15 guests