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View Full Version : Old ground glass...how to brighten?



Robbie Bedell
23-Nov-2010, 18:04
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.
23-Nov-2010, 21:03
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
24-Nov-2010, 05:57
I reground mine with 400 grit silicon carbide powder.

Liam:
24-Nov-2010, 09:15
I had the same problem, so I ground my own using these links...

http://www.apug.org/forums/forum216/78392-making-ground-glass-focus-screen.html

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

http://www.largeformatphotography.info/forum/showthread.php?t=41718&page=2&highlight=aluminium+oxide

rdenney
24-Nov-2010, 09:24
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
24-Nov-2010, 11:31
"...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
24-Nov-2010, 16:23
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:
24-Nov-2010, 16:46
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 :D

rfesk
24-Nov-2010, 17:46
I had an old screen and washed it with dish detergent. Made a huge difference for me.

rdenney
24-Nov-2010, 19:29
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

Robbie Bedell
24-Nov-2010, 20:24
Thanks to all of you for your insight. The good thing here is that this is not an emergency situation. The camera is just one hundred years old this month. The patent date is Nov. 10, 1010. It was given to me by a good friend in New York in 1980 and it was well-worn when I got it. It must have been a working newsman's camera and I would love to know the photographs it made. I am familiar with the bright screens as I have a Beattie Intensescreen for my Wisner, which I switch off with its original ground glass from time to time. I am thinking that I might try to find the screws and loosen them. If I can I might go toward the Steve Hopff route as I like the acid-etched glass of the original Wisner. Again, thanks to all! Robbie

http://robbiebedell.photoshelter.com

Liam:
25-Nov-2010, 07:18
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

Sorry I didn't realise you could get accessory Fresnels, are they expensive?

IanG
25-Nov-2010, 08:51
They aren't cheap in the UK, "lens2shutter" have some at a reasonable price in the US. The reading type are used by some for 10x8 cameras.

Adding a fresnel makes another significant difference, but the best are the all in one super screens like Beattie but very expensive. Wista make one (screen/fresnel combination) that's much cheaper and usually standard on their cameras.

Ian

rdenney
25-Nov-2010, 11:56
Sorry I didn't realise you could get accessory Fresnels, are they expensive?

Look on eBay. I see generic 4x5 Fresnels routinely, usually advertised for cameras like Cambo and Toyo. They are all the same--just a 4x5 sheet of plastic with a Fresnel pattern. These can just be taped to the back of the glass. I bought one of these for my Cambo before switching to Sinar, and though I had to trim it slightly to fit, it does what a Fresnel is supposed to do.

Rick "which is brighten the corners" Denney

IanG
25-Nov-2010, 14:24
Liam, you might look at this one (http://cgi.ebay.co.uk/3S-Kangrinpoche-Fresnel-Screen-4-5-LF-Cameras-/110522819448?pt=LH_DefaultDomain_0&hash=item19bbac6378). If they are OK tart's an exceptionally good price.

Those example photo's aren't hype, I shot similar when I fitted a Fresnel to a Crown Graphic 18 months ago. It's overall screen brightness that's improved making composition and focussing far easier.

Ian

Liam:
25-Nov-2010, 16:31
Wow that is a lot brighter, if I where to attach it to a crown graphic would it sit my side of the ground glass, as opposed to the lens side? But 25, sucks being a student...

Robbie Bedell
25-Nov-2010, 19:23
Update...So today I sat down and got the screws loose to free the old ground glass. I put some Noxon metal polish on a separate peice of glass and squshed it around for about three minutes. Then I put the glass back into the back and started screwing in the tiny screws. Well, I did not have the glass seated properly and as I tightened one screw I heard a noise. The glass cracked. Not all the way, just about and inch and a half. Live and learn! I started all over again and got everything in place and it seems to work fine. The crack does not bother me, but how long it will last before it travels all the way is anyone's guess. And all of you are correct. The glass is brighter, but it is uneven with the center being quite "hot". This is with my 135 lens. It looks like a 90 or wider now with the hot spot. Down the road I will try and get a fresnel for it. Despite the crack, I am happy with it. Again thanks to all. Robbie

http://robbiebedell.photoshelter.com

rdenney
25-Nov-2010, 21:20
Wow that is a lot brighter, if I where to attach it to a crown graphic would it sit my side of the ground glass, as opposed to the lens side? But 25, sucks being a student...

Yes, this one would be place on the user side of the focus screen, with the Fresnel ridges touching the glass.

Sinar makes their accessory Fresnels in a frame that snaps into place in the ground-glass holder. That's why they are all rather scratched--they are vulnerable to loupe abuse. Preventing that abuse is probably why Graflex, for their cameras with the Fresnel installed at the factory, put them on the lens side. But they had to adjust the ground glass position to do it.

Edmund Scientific sells general-purpose 5x5 Fresnels for less money, but you have to cut it down yourself.

Rick "who paid about that for the one for the Cambo" Denney

IanG
26-Nov-2010, 04:07
Wow that is a lot brighter, if I where to attach it to a crown graphic would it sit my side of the ground glass, as opposed to the lens side? But 25, sucks being a student...

When I added a fresnel to my Crown Graphic (rear of the glass screen) I found that I needed to add spacers (card) under the fittings that hold the glass in place otherwise the focus hood wouldn't attach properly. It was simple to do.

The Edmund Optics fresnels (http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productID=2040&search=1) are more expensive than the Chinese screens.

Ian