Ground Glass alternatives?

harlequin · Oct 20, 2017

Dear Apug Analog Users,

After the 3rd ground glass breakage on my Omega45 D and Toyo, I am questioning the sanity
of spending dearly on a piece of frosted glass..... My immediate questions are:

a) does anybody have a source for generic ground glass 4x5, at this point I do not need the silkscreened
grid marks or the 6x9 reference points.
b) would it be possible to get one that is acrylic or some other material that is more durable.
c) The cameras are transported in the factory cases and am very careful, like a windshield they crack
in the corner and spread diagonally across the glass, still useable but probably dangerous.
d) could one get a picture frame glass and have it cut to size and use a Krylon Frosted Glass
aerosol or simply get a jitterbug sander and some wet 250 grit and go to town...

e) If any members have suggestions, I would love to hear them. One visit to Death Valley CA
I saw a Wista 4x5 with what looked like frosted coke bottle glass, definite aqua/green tint to that glass.

There has to be a APUG DIY solution to this problem, I am all ears....

Thanks

Harlequin

E. von Hoegh · Oct 20, 2017

Stop breaking them.
Seriously, I've been using 4x5 since the mid 1980s and 8x10 since the late 1980s, carrying the cameras in a backpack miles back in the woods, camera bag, etc. and I've never so much as scratched a groundglass. There has to be a reason they are breaking, either the handling or the mounting.
If I wanted to make a groundglass I would get good quality (read: flat) single weight glass cut to dimension, smooth the sharp edges, and grind it with 360 or 400 grit aluminum oxide or silicon carbide and water, using a 2x2 piece of double weight glass (you could glue a drawer pull on as a handle) as a 'grinder'. You can experiment with finer or coarser grits to get the texture you like.
But there's a reason they keep breaking.

tedr1 · Oct 20, 2017

There is a reason glass remains popular, it is strong hard and inexpensive. Acrylic scratches very easily and is probably weaker than glass of the same thickness, I would forget acrylic. The polymer Polycarbonate however is much stronger almost unbreakable, however it also is very soft compared to glass.

Perhaps it might be worth investigating the camera backs for the cause of the cracked glass, it seems unusual for normal transport in cases to fracture glass, I wonder is there some defect in the back that is putting excess stress on the glass?

Yes, the matt surface can be produced by grinding. Power sanding is recommended. 250 grit seems too fine, I would try 120 or even 80.

The matt surface of "magic" adhesive tape performs well as a focus screen. Perhaps it might be found in sheet sizes for laminating to plain glass. These folks do a lot of business in laminating films, it is possible they have a matt surface product that would work perhaps? http://www.solargraphicshome.com/

E. von Hoegh · Oct 20, 2017

tedr1 said:
There is a reason glass remains popular, it is strong hard and inexpensive. Acrylic scratches very easily and is probably weaker than glass of the same thickness, I would forget acrylic. The polymer Polycarbonate however is much stronger almost unbreakable, however it also is very soft compared to glass.

Perhaps it might be worth investigating the camera backs for the cause of the cracked glass, it seems unusual for normal transport in cases to fracture glass, I wonder is there some defect in the back that is putting excess stress on the glass?

Yes, the matt surface can be produced by grinding. Power sanding is recommended. 250 grit seems too fine, I would try 120 or even 80.

The matt surface of "magic" adhesive tape performs well as a focus screen. Perhaps it might be found in sheet sizes for laminating to plain glass. These folks do a lot of business in laminating films, it is possible they have a matt surface product that would work perhaps? http://www.solargraphicshome.com/

"Power sanding is recommended"
Good luck with that.

darkroommike · Oct 20, 2017

If your back has a removable folding hood put it back on, if it does not or it's missing, invest in a GG protector. You can make ground glass with polishing compound and two sheets of glass.

tedr1 · Oct 20, 2017

E. von Hoegh said:
"Power sanding is recommended"
Good luck with that.

When I wrote that I had an orbital sander in mind. Having attempted grinding by hand I only recommend it for those with a lot of time on their hands and lots of stamina (as in elbow grease) and no worries about painful fatigue in the arm next day

E. von Hoegh · Oct 20, 2017

tedr1 said:
When I wrote that I had an orbital sander in mind. Having attempted grinding by hand I only recommend it for those with a lot of time on their hands and lots of stamina (as in elbow grease) and no worries about painful fatigue in the arm next day

An orbital sander can leave a pattern. It can also crack the glass.
If using the method and abrasives I mentioned above, grinding in circular or figure-eight pattern and moving the pattern around i.e. no two patterns in the same place the grinding proceeds rapidly and leaves a fine and uniform matte surface.

removed account4 · Oct 20, 2017

i think canham or phillips were made / sold with plastic ground glass.
you can make your own, its not hard. measure the thickness of the glass you currently have that is broken
and get a piece of plexiglass the same thickness and grind it the same way you would grind the glass. there is also
an adhesive film you can tape on one side of the glass / plexiglass that does the same thing. its sold through glass tinting shops.

good luck !
john

Reinhold · Oct 20, 2017

Make a ground glass cover...

Like this...

Some plans are on on my DIY page here...
http://re-inventedphotoequip.com/DIY.html

Reinhold

Ian Grant · Oct 20, 2017

I quietly make over 100+ GG screens a year for various cameras, the usual reason they break is the glass is to thin 1.5mm if it's Boro-Silicate (Pyrex) that's a lot stronger but far more expensive. In Europe we can't buy anything less than 2mm class, not even in picture frames

One customer broke 2 new 2mm screens, not immediately, due to not noticing the GG screen back needed clipped corners (which he adn't asked for). I now own the cameras

Ian

AgX · Oct 20, 2017

jnanian said:
i think canham or phillips were made / sold with plastic ground glass.
you can make your own, its not hard.

Grinding plexiglass or polycarbonate will likely give different results optically from mineral glass.

John Koehrer · Oct 20, 2017

Easy enough to do it by hand to wet sand random patterns. I'd get enough glass for a couple of spares.
The way it works for me is that if I have a spare, I'll never break another one.

bdial · Oct 20, 2017

Try Richard Ritter for a plastic one.

DREW WILEY · Oct 20, 2017

Use acrylic or polycarbonate for a GG protective cover (removable), not as a substitute for actual ground glass. Plastic can bow or warp. I've never broken a glass, despite decades of view camera use in rough mtn and desert terrain.

removed account4 · Oct 21, 2017

AgX said:
Grinding plexiglass or polycarbonate will likely give different results optically from mineral glass.

i guess ..
i used a sander and ground 2 of them, 1 8x10 and 1 11x14 ..
they work great !
i also use a sheet of waxed paper sometimes that works OK too if you have nothing else ..

Alan Gales · Oct 21, 2017

The Wehman came with both glass and plastic ground glasses. I bought my Wehman used and the original glass ground glass is all scratched up. A really nice new gridded one came with the camera though along with the original plastic ground glass. The plastic ground glass has worked fine for me.

Alan Gales · Oct 21, 2017

jnanian said:
i also use a sheet of waxed paper sometimes that works OK too if you have nothing else ..

Wax paper. The po man's ground glass. I love it!

I guess if you did break your ground glass you could always go to the grocery store for wax paper and at least finish the shoot. Nice tip, John!

Gerald C Koch · Oct 21, 2017

AgX said:
Grinding plexiglass or polycarbonate will likely give different results optically from mineral glass.

This is true. The coarseness of the surface is a compromise between brilliance of the image and the degree of resolution of fine detail. If the surface is too fine then the image will be rather dim and hard to see.

Gerald C Koch · Oct 21, 2017

Alan Gales said:
The Wehman came with both glass and plastic ground glasses. I bought my Wehman used and the original glass ground glass is all scratched up. A really nice new gridded one came with the camera though along with the original plastic ground glass. The plastic ground glass has worked fine for me.

I wonder how the previous owner managed to scratch the glass.

Actually the 'ground' glass is not ground but sand blasted. A grinder would leave marks mostly in one direction something you don't want.

It is also important the glass be the correct thickness or the focus will be off.

Alan Gales · Oct 21, 2017

Gerald C Koch said:
I wonder how the previous owner managed to scratch the glass.

I wondered that myself. I assume that he scratched it with his loupe? It was badly scratched all over. I've never seen anything like it.

AgX · Oct 22, 2017

Gerald C Koch said:
This is true. The coarseness of the surface is a compromise between brilliance of the image and the degree of resolution of fine detail. If the surface is too fine then the image will be rather dim and hard to see.

The other way round: a fine surface (mineral glass) has a high transmission in the line of the incoming ray, but strong fall-off at an angle to to it.

A good groundglass is always a complex compromise between coarseness and even brightness distribution, depending on the lens and the viewer's eye position. Something typically not understood when talking on ground glasses.

Gerald C Koch · Oct 22, 2017

AgX said:
The other way round: a fine surface (mineral glass) has a high transmission in the line of the incoming ray, but strong fall-off at an angle to to it.

A good groundglass is always a complex compromise between coarseness and even brightness distribution, depending on the lens and the viewer's eye position. Something typically not understood when talking on ground glasses.

Yes the falloff can be quite pronounced as one approaches the edge of the glass. I was thinking of the overall brightness. A fairly coarse surface gives better edge to edge coverage.

chris77 · Oct 22, 2017

all i can add is that since i have used aluminium oxide - which took me maybe 30 min for 5x7 - to make my gg, i wont go back using anything else.
its the finest and makes a big difference in brightness and clarity. id say its perfect. but wear gloves and a mask when handling the powder, i havent used gloves for the first glass i did and the irritations were unpleasant (but didnt last longer than a day).

Patrick Robert James · Oct 22, 2017

Who even makes ground glass anymore? I am pretty sure Satin Snow is defunct (nice glass) and Hopf is gone. Maxwell seems to maybe still be around, but hard to get a hold of.

Just curious.

DREW WILEY · Oct 23, 2017

My Phillips 8X10 camera came with Satin Snow glass, and then I put the same on my 4x5's. Really like it. Allegedly someone else is now grinding something equivalent, but I personally haven't had the need to specifically look.

Ground Glass alternatives?

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