DIY ground glass tip - useful for confirming focus

Deckard

Deckard

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Ben
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Thought I'd share this little tip with some fellow filmies.

I've recently bought a Lubitel 2 and a FED4 rangefinder. The Lubitel's lens required disassembly to clean some internal fungus and hence needed recalibration, and I wanted to check the calibration of the FED's rangefinder too.

I'm not going to witter on about how to do it for each camera, but you need a sheet of ground glass placed at the film plane to confirm focus at the lengths you've chosen.

Now most of us don't have sheets of ground glass knocking around, but I found a tip on the net [apologies, can't remember the original link now to credit] which suggested using a CD case. It suggested finely sanding one side [I used wire wool actually] to create an opaque finish. You can then score the plastic and snap off the excess [don't forget to wash all the dust off]. This can then be held at the film plane, rough side towards the lens and examined with a loupe/magnifier to confirm focus.

A cheap and simple tip which helped get my Lubitel sorted and confirmed that my FED was in order.
 
Deckard said:
Thought I'd share this little tip with some fellow filmies.

I've recently bought a Lubitel 2 and a FED4 rangefinder. The Lubitel's lens required disassembly to clean some internal fungus and hence needed recalibration, and I wanted to check the calibration of the FED's rangefinder too.

I'm not going to witter on about how to do it for each camera, but you need a sheet of ground glass placed at the film plane to confirm focus at the lengths you've chosen.

Now most of us don't have sheets of ground glass knocking around, but I found a tip on the net [apologies, can't remember the original link now to credit] which suggested using a CD case. It suggested finely sanding one side [I used wire wool actually] to create an opaque finish. You can then score the plastic and snap off the excess [don't forget to wash all the dust off]. This can then be held at the film plane, rough side towards the lens and examined with a loupe/magnifier to confirm focus.

A cheap and simple tip which helped get my Lubitel sorted and confirmed that my FED was in order.
Click to expand...

(y) Top tip, I've got a Lubitel sitting in my cupboard that has the same problem, it's not been right since I took it all apart to give it a good clean and tighten everything up :bang:
 
Tracing paper also works, although it's obviously harder to keep absolutely flat, and I don't think the image is quite as strong as through the plastic.
 
Jakska said:
Tracing paper also works, although it's obviously harder to keep absolutely flat, and I don't think the image is quite as strong as through the plastic.
Click to expand...

I tried it with tracing paper and you're right keeping it in place and flat on the film plane is really difficult. I gave up in the end :bang:
 
True, I tried tracing paper with frustrating results initially, that's why I moved onto this method. Much easier IMHO, you can either hold it place yourself or secure it with a pair of elastic bands and be guaranteed of a flat focussing plane.
 
I didn't even think about using elastic bands! When I tried with tracing paper I spent about 20 minutes trying to stick it to the camera using all sorts of things from blu-tac to masking tape to strips of gum from rolling papers...
 
I got a piece of plain frosted glass cut from our local glass place, cost me a pound!
 
I use tracing paper (about 120gm/sq.m weight) and adhere it to the film plane with a smear of Pritt adhesive (solid glue in a stick, I pinch my 10 year old daughter's!). Tracing paper is easy to cut to size for different cameras and the glue simply wipes off with your hanky.
 
This is really useful - I'm vaguely planning to make a 'large format' camera where you use a digital camera to photograph the resultant image cast on the ground glass, but I couldn't figure out where to get any!
 
I thought about doing a similar thing with a pinhole camera onto frosted glass mounted in an old desktop scanner with the internal lamp disabled. The project for that has now been canned but it might work ok if you are looking for ideas.
 
Thanks Ben...........but I needed three hands checking a 35mm camera:- one for holding the shutter button at "B", one to hold the plastic in place, and one to use a magnifying glass ;)
Anyway I needed more powerful magnification as I have three lenses giving poor results on a camera that gives correct exposure at all shutter speeds, so it's either the lenses or the lens mount has moved away from the film plane.....I reckon it's the carp Yashica lenses
 
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