I was considering buying a viewfinder mask/frame for a filmback I have that has (amongst others)a 6x9 mask. But am a bit confused about what lense this will work with, Properly. I have a 135mm and a 90mm

The subject of viewfinder masks for "Speed Graphic" cameras and their press stablemates is rather intricate, because you have to take into account both the film format and the lens focal length.

Graflex published a table showing the appropriate mask (they were identified by a number) for use with a particular range of focal lengths, for each popular format. You can find such a table on this site. The table was revised and updated over time. The differences among the revisions are sort of interesting, but in practice, all describe the same system.

The masks are around, though it can be tedious to find a particular one if it was uncommon in its day.

As you see, the system represents a broad-brush approach, but it worked well in practice. It does not take into account the differences in aspect ratio among the three film formats -- there should be masks for 2¼x3¼ with cutouts shaped differently from the apertures in the 4x5 masks, but there aren't!

I ended up making my own mask for my Quarter plate Speed Graphic with the Optar 135mm lens,using a 120 roll film back.

First I worked it out by placing a 'mask' on the ground glass screen to see what was appearing on the 120 back.

Then looking through the tubular viewfinder,lined the exact point I was getting,cut out a hole in a piece of thin card to the measurements,and slipped that into the viewfinder instead of the metal mask.

Works a treat,right down to the nearest mm.Why,because I found the masks not to be quite accurate for what I needed with a 135mm lens reflecting onto a 120 aperture.

<font size=-1>[ This Message was edited by: Graflex Sid on 2005-05-13 09:33 ]</font>

That would be the way to go, if you did not need to change masks often (and few people do).

You might consider cutting the frame out of a piece of colored acetate, which would allow you to see things outside the field of view that are about to enter it, the way you can with the wire frame finder.

yep that makes sense, it was sort of what i was planning to do but at the moment I am trying to finalise a shipment or bits and peices from a store in the US and thought i'd treat myself to a mask or so in the process. Thin card or tinted acetate (i rather like that idea) sounds like a good way to save $20 per.
thanks
Perry

Sorry,I did leave out, to have the Graphic on a tripod while doing calculations,I presumed you worked that out,my mistake.

Making your own mask really does work,doesn't mean to say I haven't tried the metal frames I have...but trying to get a accurate framing to convert a 120 onto a Quarter Plate camera is no joke.Try it for other sizes you will be surprised at the results.
Look at your groundglass,then look through your tubular viewfinder.p.s. remember to change notches when doing close up,rather than infinity.That also applies to the open finder as well,very important.All adds for a better picture.