How to make your own DIY ground glass focusing screens for large format cameras
These days, if you want to shoot large format, you might have difficulty finding replacement parts. Large format cameras aren’t exactly as common as they used to be, and there aren’t many companies making spare parts for older ones these days, or creating custom pieces for odd-sized cameras.
In this video, though, photographer Markus Hofstätter walks us through how we can make our own ground glass focusing screens at whatever size we need.
It’s quite a simple process, once you know how and it’s made easier by using two sheets of glass. One is the one which will become the focusing screen and the other is what you’ll use to actually grind it. But first, you need to cut your glass to size so that it actually fits inside the ground glass holder of your camera. This is fairly simple to do with your standard diamond glass cutting tool.
Then it’s just a case of rubbing 400-500 grit silicon carbide powder in between the two sheets of glass to create an even grind across the entire surface. And once it’s all done, rinse it off and then finish grinding with some 600 grit silicon carbide powder to get it smoother for a sharper view once placed into the camera.
The only problem I found when grinding mine was that some of the silicon carbide powder would get underneath the glass I was grinding, and onto the other side – the side that I wanted to remain pristine. You can still see the image projected by the lens just fine, but it still annoys me that I scratched the other side.
Placing the glass onto paper towels, as shown in Markus’ video helps, but it can still get under there sometimes. If you’re worried, cover the side you want to protect with masking tape during the grinding process, and then peel it off when you’re done. That’s my plan for the next one I make.
So, if you’ve got a large format camera that needs a new focusing screen, or you decide to build a camera for yourself, now you know how to make your own – which is significantly cheaper than buying already made ones these days.
John Aldred is a photographer with over 20 years of experience in the portrait and commercial worlds. He is based in Scotland and has been an early adopter – and occasional beta tester – of almost every digital imaging technology in that time. As well as his creative visual work, John uses 3D printing, electronics and programming to create his own photography and filmmaking tools and consults for a number of brands across the industry.