URSA Broadcast EF Mount Crop Factor

I am looking to purchase the URSA Broadcast to use with B4 lens but also with EF lenses. I presume there will be a crop factor, and I guess this will be quite large. I have tried searching but can't seem to find much definitive info / test footage comparisons.

Although it works with 2/3 lenses, I understand that the sensor is nearer a Super 16 size so my hunch is that the crop factor is about 3x. Would this be close or could anyone please advise?

When you refer to the old still camera marketing term “crop factor” what are you referring to, the sensor size difference between a Broadcast camera sensor to what, a Full Frame Camera?

The Ursa Broadcast has a 1-inch sensor, 13x7.3mm. A full frame DSLR Camera in 16:9 uses about a 35.5x20mm area of its sensor, some crop down to APS/C about 24x14mm. So for a compariason between the Broadcast camera you need to be specific, compared to which camera. That said, the Broadcast camera with a EF mount will give you about a 2.78 difference compared to a 35.5x20mm FF Camera. Other words a 18mm lens is your “normal”, 50mm equivalents field of view lens.

When used with its native B4 mount, the optical block in the B4 lens mount, expands the lens image to cover the larger 1-inch sensor, works much like a tele-converter x1.5, which adds about a 1-stop light loss. Removing the B4 Mount and adding a PL mor EF mount gives you back then1-stop and turns the Broadcast camera into a S16 Cinema Camera (sensor is slightly larger than then S16/Micro Cinema Camera)

That said, forget the tern “crop factor” as this is mamstill Cameras term used to describe diffennt fields of view on cameras compaired to the old 36x24mm film size, and is not really of much nausea in Cinema Camera comparisons, where S35 24x14 is the reference standard.
Cheers

Thanks Denny.

When you refer to the old still camera marketing term “crop factor” what are you referring to, the sensor size difference between a Broadcast camera sensor to what, a Full Frame Camera?

I should have qualified my reference points. I am using the term "crop factor" to describe the stills EF lens I have in terms of a stills lens's field of view compared to a 35mm Full Frame. I must admit, I wasn't aware it was a marketing term and am more than happy not to use that term.

I am aware that when I mount these to my Canon 7D, there is the "crop factor" of 1.6. As I don't have a full frame camera, to a large extent, this is actually meaningless to me other than knowing that if I used the same lens on a 5D I would have a wider field of view.

So to answer your question, my actual point of reference is in fact the Canon 7D. The reason I ask is so I know what to expect in terms of achieving the same / similar, field of view when using my EF lenses on the URSA Broadcast.

I would rather use the term magnification, as I think that is more accurate (at least coming from using EF lenses on the Canon XLH1).

I am trying to gauge the equivalent field of view so I can visualise what to expect. If my understanding is correct, then following through this example:

Let's say I have a 16mm lens on my 7D right now. What I see is 1.6x larger than if the same lens was on a full frame camera (say a 5D). For the rest of this I am assuming this is a correct statement.

In order to get the same field of view on the 7D as I would if using the 16mm lens on a 5D (i.e. the same framing), I would have to use a 10mm lens on the 7D.

The URSA Broadcast is a magnification of 2.78 compare to a Full Frame sensor. So, 2.78 *10mm = 27.8mm

In other words, for me to visualise what my 16mm lens field of view would be on the URSA broadcast, I can put a 28mm lens on my 7D and see. If I apply a "magnification" factor of 1.7375 to the existing lenses I have, that will will tell me what to expect field of view wise when I put the lens on the URSA broadcast.

i.e. for equivalent Fields of View I am used to:

8mm ≍ 13.9mm (this is a fish eye lens)
11-16mm ≍ 19mm -28mm
30mm ≍ 52mm
50mm ≍ 86mm
85mm ≍ 174mm
100mm ≍ 173mm
400mm ≍ 695mm

I hope I have understood this correctly. Interesting to note the Cinema reference standard also, thank you.

Instead of magnification, I would use Field if View Equivalent, because that is what is actually happening, when a FF lens is used on a smaller sensor, the lens FOV is reduced. The focal length, however remains constant. The FOV difference factor you want from a APS/C sensor Canon camera like the 7D, to a EF mount on the Ursa Broadcast, the factor is 1.78, so your chart is close. You could also just use an application like pCAM, dial in the two cameras with a matching aspect ratio, and you will get the same info.

That said, it is quicker to learn the new format in terms to what filed of view you will get with a given lens.
On the Ursa Broadcast, the “normal” FOV (50mm FF equivalent) is 18mm, 9.5-16mm is a Wide Angle FOV, and going longer to 25mm and up is a tele FOV. For a portrait head and shoulder shot (a 60mm on the 7D) you would use a 30mm on the Ursa Boradcast, or a 20mm DigiPrime on the Broadcast 2/3rds Mount.

With a little practice this will become second nature. To get exact matches, you would need a zoom, as Primes are not available in odd focal lengths, like 29 or 33mm. I just go the the nearest focal length that gives me the AOV I want to shoot with. One of my favorite WA zooms is the Tokina Cine 11-16 PL mount (you can get it in a EF mount too), but mine is the excellent Duclos mod of the original Tokina 11-16.

Enjoy your new camera.