6x12 mask compositional guide lines

[Leigh Perry]

I have recently upgraded from Ebony SW45 to 45SU. For 6x12 composition, I previously used a home-brewed clip-on mask. That solution is no good for the 45SU because it obscures the asymmetric tilt lines.

It looks like I need to mark some crop lines on the groundglass.

[1] How is this normally done? Using pencil on the ground side?

[2] Any tips for achieving accurate registration of the crop lines (apart from burning a lot of film)? To fit the 6x12 RFH, I need to remove the groundglass, so lining the two up to 'trace' the rectangular film opening onto the groundglass isn't a solution as far as I can see.

[3] Are there any other considerations? Longevity? Alternatives to pencil?

Thanks. (Apologies if this topic has been covered before. I couldn’t find it.)

[paul owen]

Hi Leigh. I use the SU with a similar sounding clip-on, homemade mask. I began to use it by composing the image on the screen for 6x12, removing it and applying any tilts,swings etc and then reapply to double check composition. Now I "remember" where the 6x12 format is (roughly) on the screen, apply any movements and then quickly slip on the mask to recheck composition - don't let the additional assymetric lines distract you! Good luck!

[Wisawa S.]

Why don't you just use a permanent marker write on the GG? That 's the way I used with my Arca-Swiss. Some alcohol can be used to erased this mark in case you don't need it.

[Jeffrey Scott]

Why not make the mask out of clear acetate with the guide marked in black, pretty simple it seems.

[Paul Schilliger]

Hi Leigh, I simply mark the corners of the frame with a thin permanent marker. I wouldn't do it on the matt side as it would be difficult to correct any mistake there. If you fail, just wipe it off with some spirit. It has to be redone once in a while after some years, really not a big deal. Good light!

[Leigh Perry]

Thanks all.

Paul (or anyone else), do you have any tips for achieving perfect registration? With the interchanging of groundglass and Graflok RFH, it's not so simple to get the lines in the right position...

[Paul Schilliger]

Leigh, my GG had always 6x7 and 6x9 marks and it was easy to make the 6x12 extensions from there. But otherwise, you could cut a piece of board or thick paper the size of the GG and cut a centered window the size of the image in it, position the result over the GG and mark the outline, wait a few seconds to let it dry before you move the patron. If you miss it, simply wipe it with soft paper and spirit and do it again. Use a good quality very thin black marker. Good luck!

[Ralph Barker]

To get reasonably precise registration, Leigh, I think you'll need to set up a target with annotated grid markings, and take a photograph with the RFH. Then, process the film without disturbing either the camera or the target. Compare the processed negative to the image on the GG, and mark the GG accordingly.