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Mask for R Series Ground Glass

MILESF

Member
I have recently bought the A-S Rotaslide for my Factum and am trying to work out the best way to mask the 6x9 ground glass for an IQ260. The main aim is to use the ground glass for critical focussing.

Initially I put a piece of acetate with the mask cut out under the small 'bars' that hold the glass in place. Two problems: the acetate wouldn't lie flat and then it started snowing when I was in the field and the acetate went all sticky.

It's been suggested to me that I should either mark the boundary of the mask on the glass with a permanent Stabilo marker or cut the mask from a sheet of lighting gel and and fix it to the glass with an adhesive.

Neither feel quite right and I wonder what solution others may have found ?

The holder for the ground glass on the newer Rotaslides doesn't rotate. I can always take it out and turn it 90 degress but the ideal solution would have the mask in both landscape and portrait shapes i.e. a cross/"plus sign" shape.

Any ideas or better solutions would be much appreciated.
 

Chris Valites

New member
You could print it out and use the printout as a template on some thin cardboard/felt. Won't be as exact as the Arca Swiss mask but may work in the meantime...
 

gazwas

Active member
I printed the chip dimensions onto a sheet of acetate that you use on over head projectors and cut it to fit snugly to the size of the full 6x9 frame of my Arca. This way, unlike the masks that Arca produce, you don't loose the periphery framing. Not 100% accurate but worked perfectly for me.
 

MILESF

Member
I printed the chip dimensions onto a sheet of acetate that you use on over head projectors and cut it to fit snugly to the size of the full 6x9 frame of my Arca. This way, unlike the masks that Arca produce, you don't loose the periphery framing. Not 100% accurate but worked perfectly for me.
Thanks, that's logical and exactly what I did. That gave rise to the two problems that I mentioned. I couldn't get the OHP slide film to lie flat on the glass - that was maybe down to me but it bowed as I tightened the screws to hold it in place. But then it all went sticky when it started snowing. The same would happen in the rain.

I think the method is right but is there a better (printable) material than OHP film and is there a safe (ie non permanent) adhesive to use to attach it to the ground glass to create a solution which will work in bad Scottish winter weather ? And when the subject is a close-up on the ground so that some rain or snow on the mask is nigh on impossible to avoid (even with a dark cloth) ? Has anyone tried drawing the mask with a permanent Stabilo marker ?

I can try again but I was just wondering if someone had found a better solution.
 

jianghai

Member
Thanks, that's logical and exactly what I did. That gave rise to the two problems that I mentioned. I couldn't get the OHP slide film to lie flat on the glass - that was maybe down to me but it bowed as I tightened the screws to hold it in place. But then it all went sticky when it started snowing. The same would happen in the rain.

I think the method is right but is there a better (printable) material than OHP film and is there a safe (ie non permanent) adhesive to use to attach it to the ground glass to create a solution which will work in bad Scottish winter weather ? And when the subject is a close-up on the ground so that some rain or snow on the mask is nigh on impossible to avoid (even with a dark cloth) ? Has anyone tried drawing the mask with a permanent Stabilo marker ?

I can try again but I was just wondering if someone had found a better solution.
I think the GG material that faces the user is glass, so IMO the best solution is get a new sharpie and draw the shape yourself. If you ever want to get rid of it just wipe with isopropyl alcohol. I much prefer this to any adhesive as most (even the ones that promise not to) leave residues.

J
 

gazwas

Active member
Thanks, that's logical and exactly what I did. That gave rise to the two problems that I mentioned. I couldn't get the OHP slide film to lie flat on the glass - that was maybe down to me but it bowed as I tightened the screws to hold it in place. But then it all went sticky when it started snowing. The same would happen in the rain.
I don't have my Arca any more but from memory the etched rear glass and fresnel were two parts so could you sandwich the acetate between the two for better weather protection? I only used the crop mask for inital framing then removed it so never had issues of it getting wet
 

MILESF

Member
The ground glass is indeed two separate parts but A-S said not to separate them as the Fresnel can scratch of the silk screen marking on the inner side of the glass.

A-S do in fact have a metal mask for the IQ260 sensor size. They recommend holding it in place with Pritt Glue Dots (I think. Pritt for sure and Glue Dots look the closest to they described. They make one labelled as 'Repositionable' ).

So the IQ260 mask is in the post and I'll try that as a next step.

Thanks all for comments, suggestions and PM's.
 

gazwas

Active member
A-S do in fact have a metal mask for the IQ260 sensor size. They recommend holding it in place with Pritt Glue Dots (I think. Pritt for sure and Glue Dots look the closest to they described. They make one labelled as 'Repositionable' ).
I didn't like the metal mask as it made the GG all small and pokey, loosing all the periphery framing the 6x9 GG gave. I liked this especially when stitching to see the whole picture in one but I hope it works out great for you however.
 
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