Zeiss Standard Speed MKII vignetting/portholing on s35 sensor?

[Justin Carlson]

Recently shot a project with a set of Standard Speeds on an ARRI Amira.

The focal length that gave me really bad vignetting was the 32mm. The 20mm, 28mm, and 40mm didn't give me any issues. The 32mm was originally a B mount that had a converter for PL mount. Its a temporary converter. My guess is that's the culprit.

Curious, has anyone here encountered this with that particular focal length? Or any issues using the original B mounts with converters?

I remember renting a set a few months back and seeing a few focal lengths show a slight sign of vignetting. But this 32mm was horrible.

https://www.dropbox.com/sh/hjvugrg4ge0ybvy/AAAppfrX76cbxqVoBcduxMoVa?dl=0

 

[William Long]

I would imagine it is the mount. Might be worth having a look if you haven't already seen this:

https://cvp.com/tools/cameralens

 

[Dan Kanes]

definitely not your PL to B mount adapter.

Was the portholing symmetrical ?

I can see that one side of the rear retainer ring on your rear element is flattened/shaved - ostensibly this could be so the retainer ring does not collide with a reflex mirror on a traditional film camera with a spinning mirror.

If that is occluding your ray bundle from the lens it would possibly vignette or darken.

If you have access to someone with a lens projector that would be a great way to investigate.

If the vignetting or porthole is not symmetrical - that is quite likely your culprit.

One thing to remember, is that these lenses were probably designed for a 4:3 aspect ratio delivery at a time before 1.85:1 "Super 35" formats existed - so roughly an 18mmx24mm imager area which is not necessarily large enough for our modern expectations.

It could be if its the retainer ring that a high quality and very experienced shop could retrofit the lens if its a retainer ring or other similar occlusion. Also if there was a hood added to the front of the lens, that's a very likely possible culprit as it may have been retrofitted without an examination into this particular parameter. Lots of variables.

A shop like P+S technik, Duclos Lenses, maybe even Denz in Munich could possibly help with. Maybe Alex at Zero-Optik too if those other shops aren't busy, although I'm quite certain Alex is very busy these days... Anyway - hope that helps.

 

[Chris Sharman]

Yep, this is down to the lens. I know these inside out and the 32mm is by far the worst focal length for portholing, though it's apparent on most of the wide-angles.

It's down to the design of these older lenses, they are not telecentric (this being less critical for film than digital sensors as I understand it). So the intensity fall-off is greater away from the centre of the sensor, where the light from the exit pupil is not striking the photo sites straight-on.

As I recall it does improve a bit as you stop down the lens. Don't let it put you off, real-world it's not too bad and they are lovely lenses! Just maybe not for that green screen/infinity cove shoot...

 

[Justin Carlson]

Thanks for the thoughts on this!

The portholing was favoring the bottom frame. When the lens is set in the camera, the flat end of the retainer is facing the right. I tried experimenting with the direction of how the lens would set in the mount and every other way would cause much worse vignetting.

Just shipped the lens to Duclos yesterday. Hoping it's something that they can fix.

 

[Justin Carlson]

Yep, this is down to the lens. I know these inside out and the 32mm is by far the worst focal length for portholing, though it's apparent on most of the wide-angles.

It's down to the design of these older lenses, they are not telecentric (this being less critical for film than digital sensors as I understand it). So the intensity fall-off is greater away from the centre of the sensor, where the light from the exit pupil is not striking the photo sites straight-on.

As I recall it does improve a bit as you stop down the lens. Don't let it put you off, real-world it's not too bad and they are lovely lenses! Just maybe not for that green screen/infinity cove shoot...

Found this lens test and it made me question why my 32mm was giving me such bad vignetting. https://vimeo.com/275500463

 

[Chris Sharman]

It's not a brilliant lens test for showing this but it is apparent. If you look at the T2.1 frame, the tree out of the window is much brighter next to his head than towards the corner of frame.

This is much reduced in the T4 frame, in fact the whole background appears brighter even though the level of his skin tone is more or less similar between the two frames.

This is what I'd expect to see from this lens. If you're getting worse than this or hard vignetting on a S35 sensor, maybe your lens has a different problem.