A lot of vignetting on Angenieux 12-240mm

[Diego Collado]

Hello!

I've got an Angenieux 12-240mm Zoom lens, which was sold to me on eBay as a Super 16 zoom. I wasn't able to find a lot of information about it, but I took the risk because the video reel that the seller sent me looked good enough.

After receiving the lens, I can say that I wasn't terribly disappointed! The glass is nice, although it's a heavy and inconvenient lens in many ways (hard to get filters working, as the focus sticks out).

The main issue I'm getting is a lot more vignetting than expected. Later, researching, I found this video on Vimeo, shot with what I believe is the same lens:

In comparison, this is the vignetting I'm getting as some focal lengths and focus distances on my Angenieux:

What could be causing these issues? Is it just a bad one from Angenieux? (I've had mixed luck with them, the one I had on my old 16BL was a great lens). Does it require some sort of adjustment?

The camera is an Arriflex 16SR 1, converted to Super 16 PL from an Arri Bayonet mount last year.

Thank you very much for your help!

Some pictures of the lens:

Edited October 1 by Diego Collado
clarity

[Gregory Irwin]

3 things:

1. Would you take a picture of the rear element? Let’s see what that looks like. 
 

2. Does it vignette all the way through the zoom range or does it begin at a specific focal length?

3. How is the vignetting at wide open?

I'm guessing that it’s either the rear element that is the source of the vignette or there is a matte inside of the element that may be possible to remove.

G

Edited October 1 by Gregory Irwin

[M Joel W]

This isn't an S16 zoom, although it should cover S16 over most of its zoom range. I'm not sure how abnormal your results are but I believe it vignettes at some focal lengths even in the best case scenario. 

Edited October 1 by M Joel W

[Dom Jaeger]

Well the most obvious issue is that the vignette is off-centre, which means the camera mount has not been properly recentred for S16. Perhaps check with whoever did the conversion. On many Arriflexes you can rotate the PL mount between Super and Standard, so hopefully they just forgot to set it to Super.

Otherwise, that lens is definitely not a S16 zoom, none of that era of Angenieux zooms covers S16 if the wide end goes wider than 15mm. So whoever sold it to you was being misleading. I can’t remember exactly, but I think it vignettes almost up to around 50mm. 

[Diego Collado]

15 hours ago, Gregory Irwin said:

3 things:

1. Would you take a picture of the rear element? Let’s see what that looks like. 
 

2. Does it vignette all the way through the zoom range or does it begin at a specific focal length?

3. How is the vignetting at wide open?

I'm guessing that it’s either the rear element that is the source of the vignette or there is a matte inside of the element that may be possible to remove.

G

Hi Gregory,

Thank you for your reply.

1. I've attached a couple of pictures of the rear element to this post.

2. The vignette comes and goes mainly when it's wide, but it also appears and disappears depending on the focus. At 45-50mm or so it almost fully disappears.

3. Wide open, as said above, the vignetting changes with focus. I've got some pictures of how it looks almost wide open when it's focused at 4-5 meters and when it's at its minimum focus.

[Diego Collado]

11 hours ago, Dom Jaeger said:

Well the most obvious issue is that the vignette is off-centre, which means the camera mount has not been properly recentred for S16. Perhaps check with whoever did the conversion. On many Arriflexes you can rotate the PL mount between Super and Standard, so hopefully they just forgot to set it to Super.

Otherwise, that lens is definitely not a S16 zoom, none of that era of Angenieux zooms covers S16 if the wide end goes wider than 15mm. So whoever sold it to you was being misleading. I can’t remember exactly, but I think it vignettes almost up to around 50mm. 

Thank you for letting me know about that. I'll check with the engineer that converted the camera about this.

(edit: just confirmed that the mount is on the N16 position. I just assumed that's how it'd look after converting it to S16! Thanks for pointing this out once again)

I was also wondering what this bit in the middle of the lens is, between the 'Patented W...' bit and the iris ring:

I found a picture of what looks like the same lens (although this could also just be a different Angenieux lens). It doesn't seem to have that part:

Edited October 2 by Diego Collado

[Gregory Irwin]

14 hours ago, Dom Jaeger said:

Well the most obvious issue is that the vignette is off-centre, which means the camera mount has not been properly recentred for S16. Perhaps check with whoever did the conversion. On many Arriflexes you can rotate the PL mount between Super and Standard, so hopefully they just forgot to set it to Super.

Otherwise, that lens is definitely not a S16 zoom, none of that era of Angenieux zooms covers S16 if the wide end goes wider than 15mm. So whoever sold it to you was being misleading. I can’t remember exactly, but I think it vignettes almost up to around 50mm. 

Hi Dom!

it’s been a while! About this lens, the asymmetrical vignette is a definite sign of no S16. From my experience of rebuilding 35mm lenses to cover large format sensors, do you think that there is a matte behind the rear element or is it the rear element itself causing the vignette? Also, would there be an iris stop that could be removed to allow the iris to open further to prevent vignetting? Thanks!

G

[Dom Jaeger]

12 hours ago, Diego Collado said:

..just confirmed that the mount is on the N16 position. I just assumed that's how it'd look after converting it to S16! Thanks for pointing this out once again)

I was also wondering what this bit in the middle of the lens is, between the 'Patented W...' bit and the iris ring

Good to know it’s just the mount was set to N16.

The unit at the back is a Chrosziel drag module, they were sometimes fitted to Angenieux zooms to allow a slow, smooth zoom. Turning the knurled ring should adjust the friction for the zoom.

[Dom Jaeger]

9 hours ago, Gregory Irwin said:

Hi Dom!

it’s been a while! About this lens, the asymmetrical vignette is a definite sign of no S16. From my experience of rebuilding 35mm lenses to cover large format sensors, do you think that there is a matte behind the rear element or is it the rear element itself causing the vignette? Also, would there be an iris stop that could be removed to allow the iris to open further to prevent vignetting? Thanks!

G

Hi Greg,

I don’t think there’s a matte, it’s just the limit of the lens image circle. The only way to expand it would be to add a focal length extender to the rear, which would change the focal range. 

Different parts of a lens can be the limit of the image circle, sometimes it’s the iris, sometimes it’s the rear element or another optic. In a zoom it can change as you adjust focus distance or focal length. On some zooms there can be a rectangular front element matte that limits the image circle, but that’s not the case with this zoom.

[Simon Wyss]

14 hours ago, Gregory Irwin said:

would there be an iris stop that could be removed to allow the iris to open further to prevent vignetting?

An iris never vignettes. The diaphragm takes the place where its size changes the flux of light, the hole of the optics.

[Dom Jaeger]

52 minutes ago, Simon Wyss said:

An iris never vignettes. The diaphragm takes the place where its size changes the flux of light, the hole of the optics.

An iris never vignettes into the coverage the lens was designed for, but if you project a lens so that you can see the full image circle, stopping down the iris sometimes reduces the circle diameter. So in these cases the iris is creating the limit of the image circle. I’ve seen it many, many times. In my work we often deal with S35 lenses being used on full frame sensor cameras, and working out the useable coverage is a common task. Some lenses will cover a larger format if they are not stopped down past a certain stop.

[Diego Collado]

Thank you all for the help, this is such useful information. As someone who has just relatively recently gone into the world of 16mm (four years now, but that's nothing compared to the experienced folk in here), there is so much to learn about lenses, formats, and camera mechanics! Really appreciate that you share so much of it on these forum threads.

I'll keep experimenting with the lens to see what's the best way of operating it. It doesn't seem to be an ideal zoom lens for S16, but it's what I've got, so it'll have to do. Thanks again!