Filters on Fujinon 90mm

[Sigurd Wik]

Hi,

I am looking into buying a lens/filter combo, wanted to hear if anyone would weigh in one useability.

Want to buy a Fujinon SW 90 mm f8, and new set of ND and color filters. AFAIK, lens has 67mm filter thread, and I want to get 67mm screw on glass filters from B+W. Question is if I would run into vignetting problems with one 67mm screw on color filter in addition to one 67mm screw on ND filter with a wide lens and this one in particular.

I haven't got the lens to test this myself, and can't seem to find info on it, so appreciate any info.

Thanks,
Sigurd

[Mark J]

I haven't got a lot of specific experience on this lens, but with Super-Angulon types like this, you will be vignetting the full coverage if you put two filters on there. Maybe you will be, even with one filter with a deep rim.
However it all comes down to the format you're using, and how much shift you expect to use. You will be well short of using the full coverage if you are working with 4x5" and moderate movements, so it may be fine in this case. If you are shooting 5x7", on the other hand, you will probably run into problems with two filters. I'm sure someone will be able to add to this

[Doremus Scudder]

Yep, Mark is right. Two 67mm filters stacked on that 90mm will vignette the image circle. If you need to use two filters, there are solutions. You can get a 67mm to whatever larger size step-up ring and use larger filters (e.g., 77mm or 105mm), but that gets expensive. Related to this is getting a center filter (expensive). These usually step up to a larger size like 105mm, but then you'd need the center filter and two 105mm filters...

You could also get gels or acrylic filters and a dedicated holder, larger than your lens, and use one screw-in filter and another, external square filter. Or, you can mount one filter behind the lens and one in front. Be sure to focus with the filter in place behind the lens if you use glass filter this way, since the behind-the-lens filter shifts focus. Mounting gel filters behind the lens is the best option if you use behind-the-lens filters. There are holders you can get/rig up, some as simple as magnets with a frame. Gels behind the lens don't introduce enough focus shift to warrant having to focus with the filter mounted.

Of course, you can get by with stacking filters if you aren't using all of the image circle, i.e., if the vignetted part of the image circle doesn't end up on the film. But, if you want to use movements, you should be careful. Note that you can use back tilts and swings with only the center of the image circle, but front movements displace the image circle so you are using the edges.

Learn how to check if you're vignetting or not. Check by looking back through the lens stopped down to taking aperture before inserting a film holder. You should be able to see all four corners of the ground glass. Alternatively, if you have clipped corners on your ground glass, stop down the lens to taking aperture and look from the corner to the aperture. You should be able to see all of it. If it is oval-shaped, you will have fall-off; if you can't see it, you're vignetted.

Best,

Doremus

[Mick Fagan]

An interesting question, I have that exact lens and I use 67mm glass screw on filters, but never two at a time. I don't have B&W filters, I have a generic glass filter set which, as far as I know, originates from China.

Regardless, I put one filter on, checked the corners, clear.

Put another one on for two filters, checked the corners, clear.

Put another one on for three filters, checked the corners, I could just see a slight amount of filter body in all corners.

Everything was centred and zeroed.

I have taken some phone pictures, but my email service is down at the moment. Once that issue is resolved I'll put up some pictures.

Pictures added.

[Sigurd Wik]

Thanks a lot, all of you. Very useful.

Mark, good point. Sorry didn't mention format, doing 4x5.

Doremus, thanks for sound advice. The idea of one screw on filter and one square is nice and would work for me, as I have an older Lee 100 square holder with wide angle adapter. Looks like the edges on that one builds up a bit less than some of the shallower screw on filters, so looks like that could work and still have some movements.

Very interesting test, Mick. Thanks for that, it is reassuring that two filters are ok with no movements on front standard. Did you do the test with lens wide open, or stopped down?

[Rick A]

I always use a step up ring and oversize filters on wide angles to avoid any chance of vignetting.

[Mick Fagan]

Sigurd,

I first did it wide open with two filters, which allowed me to see everything very clearly. Nothing to be seen.

Then I did it stopped down to f/22 with two filters. Nothing to be seen.

Then I did it wide open with three filters, big piece of curved filter ring visible.

Then I did it stopped down, but with three filters it was very clear that one could see the curved metal ring of the filter wide open or stopped down to f/22.

By slowly moving the aperture knob from wide open, I deduced that the curved metal ring of the filter was excluded at approximately f/32½ or roughly halfway between f/32 and f/45. I ran the aperture knob back and forward quite a few times before I was completely satisfied at where the filter ring disappeared.

Trust me when I say it is very dark stopped down that much, and with three filters on!!!!

Two filters should be alright.

[Doremus Scudder]

... Two filters should be alright.

Only if you don't use any movements. With rise/fall, shift and front tilts/swings, you are no longer using just the center of the image circle. Two filters will vignette the outside corner(s).

Doremus

[Eric Woodbury]

I would check it. At f/22, it may be okay. If not, call it a 95mm lens and crop the corners. It's fuzzy out there anyway.

Or, there are thin filters available. And "gels". Tape an ND gel inside behind the lens. I buy lighting gels and cut them up. Far cheaper.

[Paul Ron]

get a 67mm to 70mm ring adapter and 70 mm filters so your filters will be oversized and out of your viewing angle.

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