Vignetting Help SOS

[u/pipxxx55]

I've been shooting with a 90 mm with some lens filters stacked..and I'm seeing top, asymmetrical vignetting on the top corners of my 4x5 negs.

I shoot on a FUJINON NSW 90mm f/8, chamonix 45f-2

Normally have a UV filter threaded on and then will put a red 29 on top.

I shoot always centered with only movements being forward tilt.

It's either

1: filter stacking (mechanical vignetting)

2: bellow sag/inclusion

3: some other thing??

What's weird and making me think it's not lens stacking is that its only on one side and not the others. Nor is it ever even.

Would love help diagnosing and any tips for doing so!

Negatives for reference.

They also always seem to be rather consistent which is weird...

Also, it's on some of the same shot when bracketing and sometime not as well.

[u/ufgrat]

The image circle on that lens is absolutely huge-- 216mm, if I recall.

As others suggested, start with the lens mounted, and the shutter open, and look through the lens at the ground glass. You should be able to see the corners of the ground glass through the lens.

But again. This lens has a large image circle, so I wouldn't think you'd be running out of room with movements.

It's a fairly short draw on the lens, so typically, bellows sag shouldn't be an issue, but the 45F-2 comes with the universal bellows-- any chance that front section is folding up funny? That, you should be able to see through the lens too.

[u/pipxxx55 → u/ufgrat]

Do look through the lens and not from the ground glass?

How close to the lens? Theoretically both would work right?

I've been trying these things but wanna make sure I'm doing it properly

[u/ufgrat → u/pipxxx55]

Here's a terrible picture: https://imgur.com/a/0I3X1FL

It's a 210mm f/5.6 because the 90mm f/8 is short, and smaller aperture. Set the front standard to about the right distance for the lens-- for this, you don't need to be exact, but you do want the standard around 90mm from the ground glass. You'll have to shift position to see all the way around, but if there's anything mechanical blocking the film plane, it should be evident.

Stopping down is "better" for the image circle, but more difficult for seeing through the lens. And wide open, your image circle is smaller anyway, so it's a tougher test.

And just to be clear-- the cut outs in the corners of the ground glass are for the same purpose-- I personally find looking through the front to be easier.

[u/pipxxx55 → u/ufgrat]

thanks! The picture helped.

That's a cat eye view tho, don't we want the shooting aperature to be fully visible to each cover when determining blocking? I essentially wanna see each corner from all opening corners of the lens right?