Ground glass questions

First post, so please be gentle!

I have a KW Patent Etui 9x12 and an unmarked 9x12 plate camera (in pretty poor state - I only got it as it came with two plate holders that fit the KW). The ground glass back on the KW is not original although it fits. It's wood, covered with leather. The "glass" itself is some sort of plastic which has gone a bit green/brown with age and it's pretty useless as a focussing aid. I've removed it (being bendy helped - the plastic, that is, not me). I'm planning to replace it with glass, using an old, exposed 9x12 plate cut to size and ground on one side as per instructions on here and other places.

But how do I fit the glass once I've made it?

There are no visible screws or other obvious means of opening the back to fit the glass.

On the other camera, which has a similar wooden back, the bottom slot of the frame that held the glass contains a thin bit of sprung steel (a bit like a plate holder). The two top corners of the glass were cut off and pushing the glass down onto the spring allowed the top edge to clear the top slot, so that the glass could be removed. (I removed it to clean it but also because it was the wrong way round - with the ground side outwards instead of in. It's also a bit smaller than the glass on the KW or I would just swap the backs.)

There's no spring, however, in the back that came with the KW.

So...I'm looking for any advice fellow members can give on how to get a new ground glass to fit in my old back without it falling out!

As an aside, looking around the internet, plate cameras with similar plastic ground glass seem to be fairly common. Is that right? While obviously old, mine looks very much like a replacement for the original glass - presumably because, like me, a previous owner couldn't figure out how to get a new glass ground glass in there!

I think if nothing but plastic fit in to the frame after bending the plastic and if you want glass to fit to the same place , may be it is hopeless.

I think your best bet is to cut smaller size glass and attach to the frame - where ever is possible -with nails to wood , nail heads keep the glass in place.

I've only seen one 9x12 camera back like you have described. It was designed only for a flexible focusing screen to be installed. I'd say in this case . . . go with a similar screen. You may have to make your own, but once replaced it should work like a champ. Keep your eye open for original camera backs (w/focusing screens) on ebay. I know that could be a long-shot, but you might get lucky in that regard.

Just a side note; when using my plate camera in the field (hand-held), I leave the focusing screen in the bag. I use a little hand-held rangefinder and then I dial the distance in with the bed and distance scale. So, if working similarly, you may find that the actual focusing screen won't be used as often as one might imagine.

Thanks for the replies so far.

If anyone out there has a KW Patent Etui with the original focussing back, what does it use for ground glass - plastic or glass? I ask since this camera appears to have been marketed as being very lightweight and portable. So I wonder if it came with a plastic ground glass as standard.

On my wooden focussing screen backs, I've now noticed that both the top and bottom sections of the frame that holds the glass appears to be a sandwich of two layers. The main body of the back (which also forms the sides of the frame and incorporates the side rails) is thinner at the top and bottom than at the sides. But the top and bottom of the frame are then built up to the same thickness as the sides by thinner pieces of wood that've been glued in place. So I reckon that the glass must have been fitted and then these thinner pieces of wood glued on to hold it in place. Which makes getting new glass in there difficult without prying off at least one piece of this thinner wood (at the very real risk of breaking it).

Ho hum.

check the bottom + sides of the wood, there may be a slot cut
to feed the screen into a groove inside the back's frame, or if the plexi is flexible
enough and the groove is in there, with no way to set it in, you might have to
bow it from the middle and pop it out ( or cut the back in half and pull it out
and glue it together when you are done ..., hopefully you can just pop it out
and do the same thing to get it in ...
think of it parking a small car in a parking space that's too small for the car to fit ...
i used an asymetrical sander to scuff up my plexi screen, it worked like a charm

if you can't remove the screen without damaging the back, maybe you can scuff up the ground
side with it IN THE BACK, it might take elfin fingers and a small sanding block but i am sure it can be done
or try putting waxed paper right on top of the bad ground glass you have might help as well ...

fun project !
good luck
john

The Patent Etui should have a glass screen, mine is in Turkey, if I'd spotted your post on Wednesday I was there with the camera and I would have photographed the back. It's a few years since I replace the screen in mine but I know it was very simple.

I've found a photo of the back unfortunately the bottom isn't that sharp.



I think the screen needs to be pushed into the bottom against a spring until it clears the top and can be pushed in flat, the spring then pushes it into the top under the metal edges. That's the original screen I replaced. You may need to make a simple spring, probably easier to take one from an old plate holder.

Where about are you ? Just in case I can help.

Ian

Cheers, Ian. It's very helpful to see the back on an original KW focussing screen and good to know it should be glass. I'd love one of these but the back on my Patent Etui is clearly from a different 9x12 camera. So it'll have to do for now.

I'm pretty sure you're right, though, about the spring. Having examined both of my wooden-framed backs again, the bottom slot is about 5mm deep (compared with the upper slot, about 2mm). So there's room for a small spring and to allow the glass to be pushed down onto to it enough so that the top edge clears the top slot - and the spring will then push the glass up and hold it in place.

I suspect that the way the frame is constructed, with the two-layered top and bottom, was to allow the spring to be put in rather than to allow the original glass to be fitted. So I just need a new glass and a spring and I can get my focussing screen back into a more user-friendly state.

I have some other questions about my Patent Etui but I'll save them for another thread!

Thanks everyone who's helped with this.

Just a side note; when using my plate camera in the field (hand-held), I leave the focusing screen in the bag. I use a little hand-held rangefinder and then I dial the distance in with the bed and distance scale. So, if working similarly, you may find that the actual focusing screen won't be used as often as one might imagine.

Click to expand...

Hi DannL. - I would do this but my camera is not focussing at infinity when opened out. I need to extend the bellows to where the focus guide/distance scale on the camera bed says 3m (about 1cm of extra bellows). So I can't yet rely on the distance scale as being accurate. I also plan to use the camera for close-up/macro work, so accurate focussing at close range is critical. Thanks for the advice, though.