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Filtering a zoom lens

Marcus Friedlander

Marcus Friedlander

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Hey everyone,

Quick question.

If you are shooting on a 28-80 zoom, and you throw on a screw on diffusion filter, will there be an appreciable difference between how the diffusion interacts with the image at 28mm vs 80mm?

The reason I'm asking is that I'm thinking of buying a Zeiss 28-80 and it would love to be able to throw on a filter to "break" the Zeiss look when I need to. However, I would rather not have to change out filter strengths depending on where I am in the zoom range. Ideally, the screw on diffusion would live on the lens forever for that show. Is this possible? Or will I need to get multiple strengths of the same diffusion?

Thanks in advanced for any help!
 
There have been plenty of movies in the past that were shot on zooms and used the same diffusion filter on everything, though it doesn't hurt to carry one grade lighter for times when the diffusion is looking too heavy due to some combination of elements like a hot sky in the shot on a long lens, etc.

Yes, the diffusion will look a bit different at each end of the zoom and it also depends on how tight or wide the shot is, how much haze is in the scene, etc. But most of the time, it works OK to keep to one diffusion filter but occasionally you may want to pull it or switch to something lighter.
 
Great! Thank you for the information and advice sir!
 
Test, test, test. It's easy to put a diffusion filter on and shoot a test at various focal lengths and focus distances, etc.

Most of Geoffrey Unsworth's movies of the 1970's were shot with a Fog #2 and he was fond of zooms ("Superman: The Movie", "Zardoz", "A Bridge Too Far", "Cabaret", "Murder on the Orient Express", "The Great Train Robbery").

The period section of "Titanic" (DP Russell Carpenter) was mostly shot with a ProMist #1/4. But I'm sure there were some big action shots where he had to switch to a #1/8 or use no filter at all.


But you just have to have a back-up plan when the filter you choose is doing something you don't like for that particular shot, whether it means pulling the filter or switching to something lighter, or something that flares less. Unsworth insisted on using the Fog #2 for almost everything he shot back then, but on "A Bridge Too Far", which was shot on anamorphic zooms with doublers on them, the second unit DP asked Unsworth if he could switch to a Fog #1 for some battle scenes when the amount of smoke from the explosions was already adding too much haze to the image, and Unsworth let him . Then later in the shoot, while filming the big parachute drop sequence, the weather got so foggy that Unsworth had all the camera crews pull the Fog filters, which was the first time the camera assistant could remember Unsworth shooting clean in a long time.
 
I will add one more thing -- some diffusion filters like nets and Classic Softs have fairly large patterns that can come into focus at wide angles with deeper stops -- it can happen even with the more subtle pattern of a mist filter but that is harder to see, when a mist filter surface comes into focus too much, it looks like dust on the image. In other words, you need ND filters outdoors because many diffusion filters don't work well at deep stops.
 
Very interesting! Thank you for the sharing your knowledge!

I have already planned the types of diffusions, the strengths and how I am going to test them! All I need is the lens... And the filters hahaha!

And jacob are you sure about that? I'm fairly certain it's 95mm front threaded.
 
David Mullen ASC said:
But you just have to have a back-up plan when the filter you choose is doing something you don't like for that particular shot, whether it means pulling the filter or switching to something lighter, or something that flares less.
Click to expand...

On that point, I was recently on a feature where we shot with a 1/8 Hollywood Black Magic for most of the film. We had one shot with very hot windows where the DP had to pull the filter for something lighter. Of course, we were not carrying anything lighter on the truck. So he had us make a custom filter by taking an optical flat and lightly pressing it against his skin. We referred to it as the 'belly fat filter.'
 
I'm shooting a feature at the moment on Zeiss 28-80mm and 70-200mm CZ.2 zooms. About half the film plays in flashback, and for those sequences I've had a 1/2 Black Promist in front of the lenses at all times. Haven't noticed any significant issues moving throughout the zoom range on the same filter, so I think you'll be fine.
 
Yeah positive about the threaded front. I thought the same thing, i have a 95mm filter and both the 28-80 and 70-200 and the shoe doesn't fit.
 
Damn that really sucks. Does anyone know why that is? It seems like threaded fronts would be consistent with the idea of a compact zoom. I.e. Threaded lens means no mattebox, so a more compact system overall.

But now that I think about it, I don't think any the Cp.2's have threaded fronts so maybe it's just not a part of the Zeiss philosophy.

Btw does anyone know if there is a safe way to add threads to the front of a lens like this?

Thanks for for all the replies!
 
You can get a clamp-on adaptor and use round filters, assuming there is enough of an edge on the front of the lens for a clamp-on ring, though a small clamp-on matte box with rectangular filters would be fine too for handheld work. If you are going to put a diffusion filter on the front of your zoom, you are going to want a sunshade of some sort anyway.
 
Yes I think you are right, by that point I might as well use a super light clip on mattebox. Thanks!
 
Satsuki Murashige said:
On that point, I was recently on a feature where we shot with a 1/8 Hollywood Black Magic for most of the film. We had one shot with very hot windows where the DP had to pull the filter for something lighter. Of course, we were not carrying anything lighter on the truck. So he had us make a custom filter by taking an optical flat and lightly pressing it against his skin. We referred to it as the 'belly fat filter.'
Click to expand...

first of we need to know who that dp was, the name of the show and the AC with the fat greasy belly :)

to answer the question, typically you would use a lighter diffusion the wider you go on the lens. a lot of people dont use any on wide and a medium to heavy grade on tights, specifically if its faces.
that being said, you can use the lightest in the set, in my case the 1/8 black magic, and ride it the whole time without a noticeable difference, and if you need heavier when you go to a tight of someones face, then switch.
 
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