What is this filter holder/clamp/adapter called?

[gibbo]

So I'm shooting a short film on Zeiss super speed S16 mark 1 and 2 lenses using my black magic pocket cinema camera NEXT WEEK (eek!) and I would like to use my "photography filters": A 77mm vari ND fader and a 77mm circular polarizing filter.

The lenses have standard 80mm fronts on them, no threads and I was told a cokin p series clamp on adapter (or cokin style) would work, apparently there's a photography one that comes in 80mm and still allows the filter to rotate, so not a square filter one like standard cinema ones.

I've searched but can't find anything about it... does anyone have any idea about it or any other ways/ideas to use 77mm round photography filters on lenses with an 80mm flat/threadless front cine lens? Thanks!

 

[Will Vincent]

What you're thinking of is called a step-down ring. But those are intended to screw on...

Problem is, 80mm is not a very standard size, and you probably don't want a smaller filter on your lens than what the lens is intended for as it may obstruct part of the image and cause vignetting.

Of course, a potential bigger issue is most S16 lenses don't have a large enough image circle to cover the sensor of your Black Magic pocket... have you done any tests with these lenses?

You'd be better off using a matte box and 4x4 or 4x5.65 filters than a screw-on variable nd with these lenses.. it's kind of what they're designed for.

 

[Gonzo_Entertainment]

^ This.

The lens has no filter rings because it's a cine lens and they expect you'll be using a matte box and square filters.

 

[gibbo]

Thanks for the replies guys.

What you're thinking of is called a step-down ring. But those are intended to screw on...

I own many step-up rings and initially thought of a step-down ring but the lenses don't have filter threads so I asked a rental house if they had anything and he suggested a cokin p series "slide on and screw/clamp in" type one that will still allow photography filters to work (was quite vague though).

Problem is, 80mm is not a very standard size, and you probably don't want a smaller filter on your lens than what the lens is intended for as it may obstruct part of the image and cause vignetting.

Hmm yeah good point. I hadn't thought of that. I just assumed they would be fine because 77mm is relatively large.

I unscrewed the fronts and the other little ring bit as seen in the pictures below, the inside thread looks to be 65/66mm, no idea if they are the correct thread spacing though.

Of course, a potential bigger issue is most S16 lenses don't have a large enough image circle to cover the sensor of your Black Magic pocket... have you done any tests with these lenses?

I did a quick test with the 16mm lens, and it did not vignette at all thankfully. Battery ran out before I got to test the others though. I will have access to set of Leica R's I can use if something happens and the Zeiss don't work. Infinity focus seemed fine, using the fotodiox MFT - PL adapter:

You'd be better off using a matte box and 4x4 or 4x5.65 filters than a screw-on variable nd with these lenses.. it's kind of what they're designed for.

Can you give some more detail about how the screw on variable ND would work in that situation? Thanks.

This is an option but I didn't want to have a big rig, wanted to be low key as possible. Also, I have no idea what square filters they own as they were borrowed out and the employees weren't 100% sure. She did say they have an ND set, but no idea about a polarizer.

Regarding polarizers, it would have to be a linear one if using a matte box wouldn't it?

They did just get a new matte box that holds 4x5.65 filters though.

^ This.

The lens has no filter rings because it's a cine lens and they expect you'll be using a matte box and square filters.

I'm sure I've seen videos online of people using the pocket with s16 lenses with photgraphy filters. I might be mistaken though

 

[jax_rox]

Go to a rental house, rent out a clamp on matte box and the appropriate square filters. I'm not sure why you would put a $6,000 lens on your camera, and then want to put a <$200 piece of glass in front of it.

Of course, a potential bigger issue is most S16 lenses don't have a large enough image circle to cover the sensor of your Black Magic pocket... have you done any tests with these lenses?

Most S16 glass should cover the Pocket fine. The Cinema Cam they won't, and standard 16 lenses will likely vignette, but glass made for S16 coverage should all be fine.

Can you give some more detail about how the screw on variable ND would work in that situation?

. It wouldn't. He said than (as in: a rather than b), not then

Regarding polarizers, it would have to be a linear one if using a matte box wouldn't it?

Nope. You can get circ polarizers that sit in the donut, or that sit inside a square filter tray with rotators at either side. You can also get a matte box with a spinning filter tray.

I'm sure I've seen videos online of people using the pocket with s16 lenses with photgraphy filters. I might be mistaken though

Specifically with Super Speeds? There are older/different lenses that would have screw threads on them that you might be able to use photographic lens type filters on, but not on Super Speeds.

 

[Will Vincent]

Go to a rental house, rent out a clamp on matte box and the appropriate square filters. I'm not sure why you would put a $6,000 lens on your camera, and then want to put a <$200 piece of glass in front of it.

Exactly this!