BMPC 4K with Rokinon 10mm T3.1 Cine Lens

Hi everyone,

I just got my bmpc 4k last week and I have some questions for choices of ultra wide lens(not fish eye). But I run into a problem here because I was told that you will be seeing vignetting on the edges due to crop factor. Therefore , I want to see some sample of vignetting on Rokinon 10mm T3.1 Cine Lens. And I notice that whatever full frame lens I put on there will be a crop factor conversion going on, for example the BMPC 4K is crop factor is 1.7x, therefore, it will turn my 10mm into ~ 18mm which it means 18mm is widest you can go with this camera without having crazy distortions or using fish eye lens in theory. So, Im wondering how you guys deal with this problem when you like shooting for super wide angle shots " the money shot" without step back for few meter away since mostly of shot will be shoot in mountains, mostly are use for commercial display.

Thanks
Steven from Vancouver

Steven, you were misinformed. The image circle of that Rokinon 10mm rectilinear lens is 28.37mm. It's an APS-C design (crop 1.6x) that means the 10mm has a larger image circle than the BMPC4K camera. Remember the lens hood on that lens is built-in and not removable although there is a tutorial video on YouTube showing you how to saw it off! Enjoy!

The 10mm lens can even be used on the URSA Mini/Pro 4.6K cameras but not using the full sensor. All 4.6K windows would be usable though.

In case you are interested, Rokinon/Samyang's 16mm rectilinear lens is an excellent performer according to those who have used it including Vic Harris on this forum. It's image circle is 30mm and although that lens is also marketed as an APS-C lens, it is a very good choice for the BMPC4K and URSA Mini/Pro 4.6K cameras as well including full sensor. It's lens hood is removable and the lens has a 77mm filter thread.

Who knows, one day I may be able to use both those manual lenses on my old URSA Mini 4.6K PL camera if someone engineers an optional EF mount for my camera (rumoured to be a work in progress).

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Steven, you were misinformed. The image circle of that Rokinon 10mm rectilinear lens is 28.37mm. It's an APS-C design (crop 1.6x) that means the 10mm has a larger image circle than the BMPC4K camera. Remember the lens hood on that lens is built-in and not removable although there is a tutorial video on YouTube showing you how to saw it off! Enjoy!

The 10mm lens can even be used on the URSA Mini/Pro 4.6K cameras but not using the full sensor. All 4.6K windows would be usable though.

In case you are interested, Rokinon/Samyang's 16mm rectilinear lens is an excellent performer according to those who have used it including Vic Harris on this forum. It's image circle is 30mm and although that lens is also marketed as an APS-C lens, it is a very good choice for the BMPC4K and URSA Mini/Pro 4.6K cameras as well including full sensor. It's lens hood is removable and the lens has a 77mm filter thread.

Who knows, one day I may be able to use both those manual lenses on my old URSA Mini 4.6K PL camera if someone engineers an optional EF mount for my camera (rumoured to be a work in progress).

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Dear Ricky,

16mm in 35mm equivalency will be coming 25.6mm which is not wide at all. And can you tell what will be the best wide lens for BMPC 4K ? I want something less than 13mm in 35mm equivalency which I'm not sure if there are any things suitable.

You are out of luck here Steven. The widest Std 35mm Cine lenses made were 8.5 to 9mm (a 14-15mm 135 FOV equivalent). Most movies did not use lenses wider than 14mm, except for special effects in some scenes.
Trying to compare Cine lenses to still camera 135mm use is not a good way to select lenses, as still photograohers have different requirements, and the finished product is much different.

Wide angle lenses are normally used for an establishing shot, showing the whole scene or landscape area. Also the wider the lens at a given f or T stop, the bigger and heavier (and more expensive) the lens will be.
Special 5, 6 and 8mm lenses were custom made by Zeiss/Arri for specific movies, but they were all PL mount for the most part. A 14mm to 16mm on the BMPC would make a nice AOV for most wide shots, and landscape type shots. I used a 16 and 17mm on my AF100, and a 9.5 on my Pocket/Micro camera (S16 sensor) for my wide angle shots.

From an audience point of view, looking at a lot of Super wide shots can be disorienting, OK for short takes, but useually Super wides are not a Cinematography lens choice for general shooting.

That said, you can adapt and use lenses like the Rokinon 10mm, or get a Zeiss Standard Speed 10mm, which is the widest Cine 35mm lens in this set, which went from 10mm to 180mm. A 8mm EF mount lens is about as wide as you are going to find, and they are mostly "fisheye" type lenses, with lots of distortion, which would work for a special "in your face" effect.

Steven, if you want to stay with a rectilinear lens on the BMPC4K sensor with its 1.7x crop when shooting UHD 3840x2160, the 16mm lens gives the angle of view of a 27 mm lens on 135 film camera. The 10mm can be used and it gives the AOV of a 17mm lens on 135 film. I've seen video with the 10mm on a crop sensor and it's quite ideal when you're trying to do a first person perspective of someone under the influence or in a horror movie. It won't be disorienting to the viewer if the camera doesn't move, but when it does, if you don't want the lens to become the story, move very slowly.

I think the 10mm has its place but the 16mm (or perhaps a 14mm) are good wides for general purpose use. It is really up to you though as you know what you want to see with the camera.

I may not be giving the best advice for your purposes since I tend to be very conservative and seldom want the lens to be the story, therefore I use lenses that keep a respectful distance from the subject and be mindful of the viewer's vanishing point. But I agree there are many times you want to use the lens to help create the mood and be part of the story.

The other minor thing to keep in mind is that really wide lenses can have problems with infrared radiation if the IR Cut does its work using a glass coating. Any infrared radiation striking with an angle of view greater than 60 degrees may not behave properly. Using an iPhone app like Angle of View will show you how lenses will behave in terms of their applicable AOV on your sensor. Other apps like pCam are excellent tools for many purposes.

That can be a real concern when selecting lenses. For example my widest lens on the URSA Mini 4.6K PL camera is a 25mm and when shooting with the full sensor readout that has an AOV of 60 degrees. So for now I know I'm good, but I still want an 18mm lens when it's released and infrared pollution will be the first thing I test when I get it since it's AOV will be 78 degrees.

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Stephen, my mistake. The crop I gave you referred to the crop if you are shooting ProRes UHD 3840x2160. If you are shooting raw 4000x2160, the horizontal crop is 1.636x. So then the 16mm lens is like 26mm on 135 film and the 10mm is like 16mm on 135 film. I'll correct my post to refer to UHD.

To shoot with something like 13mm on 135 film, you need an 8mm lens. Refer to Denny's post. The Sigma 8-16mm APS-C Zoom might suit your needs perfectly:


http://www.bhphotovideo.com/c/product/689635-REG


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