Making a Ground Glass Focus Screen

[chrisf]

I just made two 5x7 ground glass focusing screens using this glass: Dead Link Removed

It took about 10 minutes using a 5 micron powder.

The glass doesn't have any green cast when looking through the edge.

chris

 

[spoolman]

Hello Ian:I just finished your article on making a new ground glass.Excellent work.I noticed in the final image of the finished product that the corners are clipped.Is this specific to the camera it is used on or is it standard practice?.

Thanks,

Doug

 

[Ian Grant]

That was some-one else's GG ground finer & also brighter No names of who'd just made it . . . . . . .

Clipped corners are usually added so you can check lens coverage, the idea is that you look through the gap and can see through the lens to see it's not vignetting.

I use both, I have at least 15 LF cameras.

Ian

 

[alanrockwood]

Does bead blasting or sand blasting work?

 

[33dollars]

I to was just thinking about bead blasting also alanrockwood. We have one at work with fine silica powder. Most times when blasting metal from a distance of 2½"-70mm. I think with glass it would have to be farther back to get an even spread. Plus you will need to factor in the nozzle of the blaster. Grinding by hand with a paste will give lots more control of the finish product. So I believe hand grinding will be better.

 

[rulnacco]

There was a very good article on this subject published some time back in Photo Techniques magazine. It's available, from the original author, here:

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

You can obtain the aluminum oxide grinding powder mentioned in the article from Willman Bell. It's available here (scroll down a bit):

http://www.willbell.com/ATMSupplies/ATM_Supplies.htm

 

[daemon]

For the lazy at heart, you can always go to someone like Bill Maxwell and get a fancy one made. He will add grid lines or split focus, whatever you ask. Helluva good guy, too. He made me a nifty HI-LUX one for my Autocord. But I appreciate the article and think the end result looks pretty damn neat. Definitely appreciate the DIY spirit. (I did do my own DIY when it came to replacing the mirror. Ordered the proper product from Edmund optics, cut it down and installed it into the Minolta. End result + the Maxwell screen = about a million times better focusing ability than the original.)

 

[Sal Santamaura]

Can you use this method to make a quasi-ANR neg carrier top glass?

...No because the grain of the ground glass will be an issue...

Since anti-newton-rings (ANR) top glasses are readily available, it doesn't seem worthwhile, but I'm not sure it couldn't be done effectively. One would need to put an absolute minimum of texture on the glass, nowhere near as much as what's necessary for a focus screen.

I'm considering something similar for a negative carrier's bottom glass. With TMAX 100 and Acros, the emulsion side is sufficiently shiny to create rings in glass carriers. Does anyone have experience with grit size to ever-so-slightly grind the glass so it resembles plain glass with ANR powder on it? ANR powder was used by spraying it into the air and then passing a transparency or negative through the powder cloud.

The glass surface would need to be almost indistinguishable from how it looked before "grinding." In other words, ground just enough to break the gloss. All suggestions welcome!

 

[michaelbsc]

Can you use this method to make a quasi-ANR neg carrier top glass?

...No because the grain of the ground glass will be an issue...

Since anti-newton-rings (ANR) top glasses are readily available, it doesn't seem worthwhile, but I'm not sure it couldn't be done effectively. One would need to put an absolute minimum of texture on the glass, nowhere near as much as what's necessary for a focus screen.

I'm considering something similar for a negative carrier's bottom glass. With TMAX 100 and Acros, the emulsion side is sufficiently shiny to create rings in glass carriers. Does anyone have experience with grit size to ever-so-slightly grind the glass so it resembles plain glass with ANR powder on it? ANR powder was used by spraying it into the air and then passing a transparency or negative through the powder cloud.

The glass surface would need to be almost indistinguishable from how it looked before "grinding." In other words, ground just enough to break the gloss. All suggestions welcome!

You might try an acid etching bath due just a few seconds if the grinding doesn't work.

 

[Jay Abbas]

I;m breakin out my diamond dust on this one !

 

[holmburgers]

I might give this method a try - last one was acid etched, seemed simple enough and I didn't lose an eye - the method you outline seems possibly a bit more earth friendly however ...

I was thinking of grinding/etching some museum glass one day (or the cheaper AR Reflection-Free®)- might be a bit of extra work getting through the coating properly but I thought that at least with one side still coated with less reflection that maybe a GG could be used sans dark cloth in a few more situations than normally ... Your thoughts ?

Did you ever do this? Anyone ever do this?

I noticed for the first time how pronounced the reflection off my G.G. was, and if you've ever seen a quality museum glass (or didn't!) then you know what a difference it would make. That coupled with a fresnel would be huge.

Also, 3M makes a product called Vikuiti; which is a protective AR film. I wonder how effective these would be? Do any of these "screen protectors" make the reflective image a dark red/green/blue color? That's the key to an AR coating...

 

[twalsh341]

Being a bit new to this side of photography, What is ground glass used for?

 

[Ian Grant]

Being a bit new to this side of photography, What is ground glass used for?

The focus screens on view cameras - any camera where the lens focuses directly on a ground glass screen. Also older SLR's and TLR's but modern SLR & TLR cameras tend to use thinner glass and/or combination fresnel screens.

Ian

 

[twalsh341]

that helps a bit. Thanks.

 

[aaronmichael]

I'm living in Southern California (Long Beach) right now - would anyone happen to know of any local places I'd have a good chance of finding the silicone carbide at? I've seen a couple people mention that they used the valve grinding compound, which seems easy to access and fairly cheap.

 

[Ian Grant]

Valve grinding paste is far to coarse so isn't suitable.

Try checking your Yellow pages there's 13 potential suppliers near you. Search "lapidary"

Ian

 

[aaronmichael]

Is a new grinding blank required every time a new piece of ground glass is made? I gave it a go this weekend but because I was anxious to try it out, I had a large piece of glass with a smaller (but still large, maybe 5x5 inches) piece of glass on top. I put some grit in between, added a few drops of water, and started going at it. The piece that I was using as a grinding blank (the two pieces of glass were equal in thickness), got ground before the piece that I intended to grind got ground. This may just be because of the size of the bottom piece though that I was trying to grind. I need to get my hands on a thick 3x3 piece or just cut a piece myself. Does the thickness of the grinding blank matter or is the only reason for its thickness is to make it easier to handle?

 

[Ian Grant]

Yes keep using the same grinding blank, and it will get ground faste as it's a smaller area that's one reason why I get blanks made from thicker glass, the other as you've realised is a thicker piece is far easier to work with.

Ian

 

[derwent]

I've made these for focus checking on 35mm and 6x6 but I did two at a time in those sizes and it worked fine.
I got the grit from an optical bloke, and a ground up to 1000 grit although that was maybe overkill...

 

[andy_k]

just got a 4x5 view camera, and within two days of ownership broke the glass. for less than $25 canadian I've got three make-work replacements, and I feel in short order I'll be able to make any number of format/application specific focus screens.
the screens I ground with 600 SiC look dimmer than the original Sinar piece when laid down on a piece of newspaper; if I stumble onto some AlO powder I shall try that as well.

amazing thread, thank you.

 

[rorye]

Great article, thanks Ian.
Any ideas how one would etch a permanent grid?

 

[paul_c5x4]

Any ideas how one would etch a permanent grid?

For my Wista, which uses a fresnel and a plain glass screen, I cheated. Printed a grid on to a sheet of plastic (Over Head Projector sheet) and sandwiched it between the two screens.

 

[rorye]

For my Wista, which uses a fresnel and a plain glass screen, I cheated. Printed a grid on to a sheet of plastic (Over Head Projector sheet) and sandwiched it between the two screens.

Nice, I like the idea that you could switch that out. Sometimes I just don't want a grid, other times I need it.

 

[baachitraka]

I thinking to do with 5 and 3 micron, to replace the screen in Rolleicord. But, I have no idea whether it will bring any improvement in comparing with original screen.

 

[Randy Moe]

A big thank you Ian Grant!

I had fooled with acrylic with a DA sander and made junk. I bought a pound each of 320 and 500 silicon carbide from http://www.gotgrit.com/ this stuff. http://gotgrit.com/index.php/cPath/2_6

I learned today how to break/cut glass, then made a couple 1/4" pucks for grinding. Made nice cut corners on Home Depot 11x14 glass. All new skills for me.

Then using small amounts of 320 grit made an wonderful 11x14" GG first time out. It looks better than my store bought ones. I'm just getting into 11x14 and renewing an old studio camera.

I finished an hour ago. This is great, it did take me a couple hours, but it was my first time. I am excited!

Do this. Buy grit from the above. 2 pounds delivered was $15 and a $3 sheet of glass. I don't know the seller, but he sells tiny amounts for less and delivers ASAP.

I am never buying a GG again, and I have bought 3. No complaints with them, but this is more fun and way cheaper. I can watch a movie and do it.

Thanks again, Ian Grant!