Filters on front and rear

[swmcl]

Hi,

I've got a 90mm 6.8 Grandagon and I have a 77mm filter suite. I am thinking of a centre filter. I believe the centre filter will screw on to the 67mm front and steps up to 86mm. I will then not be able to screw on any of my 77mm filters on the front because of this - let alone the issue of filter stacking.

Has anyone got experience with putting a screw-on filter at the rear as well as having the centre filter at the front? Can one use 2 step up rings at the rear say, a 58-67 and a 67-77 ... ??

Is the image significantly compromised by using filters at the rear?

Thanks in advance,

Steve

[camerasteve]

i can't see why quality should be any less with filters front and rear than 2 filters on the front. it should actually be better with regards to flare. a lot of short and long lenses for 35mm use filters on the rear.
you may need to check if the stepping rings will damage the bellows with tilts.

[Bruce Watson]

Is the image significantly compromised by using filters at the rear?

Using filters on the rear will shift your focus by 1/3 the thickness of the filter IIRC. So if you use filters on the rear element, you have to make sure you do a touch-up refocus after you install the filter.

Other than that, image quality should be fine. At least is was for me when I was doing the rear filter dance.

[walter23]

Just wondering why you want a center filter on the 90 f/6.8? Have you had a problem with falloff? In my experience with the same lens it seems I run out of image circle before I have much trouble with vignetting, but I might be willfully ignoring the signs on my slides

[swmcl]

Thanks guys,

Walter I have shot 6x17 on 90mm at f16 through 32. There is a fall off for certain. BUT! I also wonder whether having such a wide view contributes to it. The shots were taken with the sun and 90 degrees to the sun (all early morning dawn shooting)

I remember getting an almost black sky when I used a polariser in the north of Australia yet I didn't see it in the 35mm viewfinder! Some of these light fall off issues are a bit black magic for me as yet.

Hi Bruce, thanks for the insight. I plan on focussing with the filter in place.

Since I wrote the initial question I have found some prefer to use gelatin filters. I noticed this morning (in the freezing rain at dawn) that my 90mm may not actually have any thread on the camera side of the lens! This would necessitate a slip on arrangement of some sort. Life wasn't meant to be easy! (A quote from an Australian Prime Minister I believe ...)

Cheers guys.