Old ground glass...how to brighten?

[Robbie Bedell]

The original ground glass on my 100-year-old speed graphic is very coarse (and dark). I have read in earlier posts that some people have used furniture wax or other substances on the ground side to brighten it. Has anyone ever used anything that really works? I would get a new glass but the one in my camera is really screwed in with old, very set screws so I would rather just keep it there at this point. Thanks in advance, Robbie Bedell

http://robbiebedell.photoshelter.com

[Jim C.]

Not that familar with Speed Graphics but if the screws aren't rusted out
it may be worth removing them to give the gg a good cleaning with
one of the purple cleaners and running water. You'd be surprised at how
much brighter a OEM gg will be after cleaning off 100 years of grime, tobbaco
smoke residue.

[BetterSense]

I reground mine with 400 grit silicon carbide powder.

[Liam:]

I had the same problem, so I ground my own using these links...

http://www.apug.org/forums/forum216/...us-screen.html

http://www.dokasphotos.com/techniques/ground_glass/

http://www.largeformatphotography.in...luminium+oxide

[rdenney]

The original ground glass on my 100-year-old speed graphic is very coarse (and dark).

Applying wax will brighten it, but it reduces diffusion and becomes more sensitive to the central spot issue. So, its brighter in the middle but less bright elsewhere.

Buying one of those plastic Fresnel lenses for 4x5 cameras on eBay is a way to brighten the corners, but at the expense of adding more stuff to look through. The Graflex Fresnel (which I suspect came later than your camera) mounted in front of the ground glass, but this is unusual. The accessory no-name Fresnels can just be taped to the back of the ground glass.

Most of the work you'd have to do to make the screen work better will require removal in any case. If you can get over that hurdle, then consider just replacing the ground glass with something newer. Steve Hopf makes nice screens that are not expensive.

Any ground screen will be more difficult to see through using a loupe than an acid-etched screen, just because of the shape of the scratches. A finer grind minimizes this. But the finer the grind, the more you lose brightness in the corners, just like using wax.

If you really want it bright and don't mind spending more than the camera is worth, replace the screen with a Maxwell screen. That will transform your life in ways other options will not. It uses a Fresnel and is bright across the screen, but the Fresnel is so fine and the pattern of the frosting so microscopically smooth that you can look at the screen through a 10X loupe even at small apertures and not have the surface treatment overwhelm the scenery.

You might also be able to replace the whole back, assuming (dangerously, perhaps) that later Speed Graphics have the same box as earlier ones. If so, put the back from a later Speed junker on your camera. Find one with the Kodak Ektalite Fresnel. The back is held to the body with six screws, and those might be easier to remove than those holding the ground glass.

Rick "not afraid to modify a Speed Graphic" Denney

[Martin Miksch]

"...You might also be able to replace the whole back, assuming (dangerously, perhaps) that later Speed Graphics have the same box as earlier ones. If so, put the back from a later Speed junker on your camera. Find one with the Kodak Ektalite Fresnel..."
btw with this modification you can use any modern filmholder
Regards
Martin

[IanG]

This dilemma is not uncommon, personally I'd remove the screen and re-grind it which is in fact what I've done now with a number of pre-WWII screens. The grits used then were nothing like as good (fine) as today's and the improvement in brightness & use-ability is quite surprising.

Liam's posted a link to my screen making. I make my own new screens and have also supplied a few to others, however I've no intention at the moment of making them on a commercial basis.

Ian

[Liam:]

Applying wax will brighten it, but it reduces diffusion and becomes more sensitive to the central spot issue. So, its brighter in the middle but less bright elsewhere.

Buying one of those plastic Fresnel lenses for 4x5 cameras on eBay is a way to brighten the corners, but at the expense of adding more stuff to look through. The Graflex Fresnel (which I suspect came later than your camera) mounted in front of the ground glass, but this is unusual. The accessory no-name Fresnels can just be taped to the back of the ground glass.

Most of the work you'd have to do to make the screen work better will require removal in any case. If you can get over that hurdle, then consider just replacing the ground glass with something newer. Steve Hopf makes nice screens that are not expensive.

Any ground screen will be more difficult to see through using a loupe than an acid-etched screen, just because of the shape of the scratches. A finer grind minimizes this. But the finer the grind, the more you lose brightness in the corners, just like using wax.

If you really want it bright and don't mind spending more than the camera is worth, replace the screen with a Maxwell screen. That will transform your life in ways other options will not. It uses a Fresnel and is bright across the screen, but the Fresnel is so fine and the pattern of the frosting so microscopically smooth that you can look at the screen through a 10X loupe even at small apertures and not have the surface treatment overwhelm the scenery.

You might also be able to replace the whole back, assuming (dangerously, perhaps) that later Speed Graphics have the same box as earlier ones. If so, put the back from a later Speed junker on your camera. Find one with the Kodak Ektalite Fresnel. The back is held to the body with six screws, and those might be easier to remove than those holding the ground glass.

Rick "not afraid to modify a Speed Graphic" Denney

Adding a fresnel to a graphic will shift the plane of focus by a few mm.

This dilemma is not uncommon, personally I'd remove the screen and re-grind it which is in fact what I've done now with a number of pre-WWII screens. The grits used then were nothing like as good (fine) as today's and the improvement in brightness & use-ability is quite surprising.

Liam's posted a link to my screen making. I make my own new screens and have also supplied a few to others, however I've no intention at the moment of making them on a commercial basis.

Ian

Thanks for the tips, helped me a lot

[rfesk]

I had an old screen and washed it with dish detergent. Made a huge difference for me.

[rdenney]

Adding a fresnel to a graphic will shift the plane of focus by a few mm.

Not if you add it between the screen and the user, the way accessory Fresnels are installed on most other cameras. What matters for focus accuracy is the location of the frosted surface, and adding a generic Fresnel between the screen and the user doesn't change that.

Rick "who thought he was clear about that" Denney