center filter with step-up ring?

[Andrea Gazzoni]

hello, maybe a silly question.. but I am using a Fujinon SW 90/8 on my 6x17 back and the corners are dark. Its filter thread is 67mm but my only center filter is 77mm. can I just put a step up ring in between and go on, or will it cause some problem? I understand I would always want to tocus before putting the filter on.
thank you

[Mark Woods]

The key question is will the added ring cause a vignette when the camera is focused at infinity. And, you should focus the camera with the filter on. BTW, have you been following the thread about posting a photo of yourself with your camera? There've been only a couple of women who have posted. We know some of you are out there who are shooting LF.

[Henry Ambrose]

You'll have to try it to see. There might be a mis-match between the center filter density and the fall off of the lens. The result of that will be a halo like effect.

[erie patsellis]

The key question is will the added ring cause a vignette when the camera is focused at infinity. And, you should focus the camera with the filter on. BTW, have you been following the thread about posting a photo of yourself with your camera? There've been only a couple of women who have posted. We know some of you are out there who are shooting LF.

Mark,
FWIW, only in Italian is the name Andrea masculine...

[Andrea Gazzoni]

yes and I have beard also :-) why should I focus with the filter on? Is this a general rule?

[Mark Woods]

Whoops! My first name is Francis and that's caused some interesting comments over the years. The reason to focus with the filter on, particularly if the filter is BTL (behind the lens) is it can slightly shift the focus on the image plane. It's an optical element and should be part of the equation in focusing. BTW, you can still post a photo of you and your camera. ;-)