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View Full Version : What did Hopf and Satin Snow do differently during ground glass production?



williaty
8-Mar-2018, 22:40
As part of getting my new Eastman 2D back into fighting trim, I had to come up with a ground glass. Initially, I followed some online directions that suggested using 5um white aluminum oxide followed by 3um white aluminum oxide and the results were HORRIBLE (absurd hot spot, hard to know exactly when it was in focus, could see the lens aperture through the GG). I then found some 600 grit silicon carbide at a local rock shop and that produced a much better screen. This got me to thinking, is a 600 grit silicon carbide screen as good as it gets (for me)? That led me to wondering about what the manufacturers who produced straight ground glass (no fresnel or other add-ons) who are so loved by the community actually did to produce the results so many people love.

Does anyone know what the production process for the old Satin Snow ground glass or the more recent Steve Hopf ground glass was? From reading old threads on here, I know Hopf's old website had a DIY page but it's long gone. I'd be interested in making a few in either of their methods to compare to the other two I've made and see what I prefer.

Randy Moe
9-Mar-2018, 06:41
There are more ways to make a GG than grinding. Etching by media or chemistry. Coatings like a KMV. Tape which falls into film layers. Heck dirt and glue might work.

There are also many differences in ground glass over history. I have a very course ground Linhof OE 4x5. Different.

Also Aerial Focusing. Read this thread. Lots of good info. http://www.largeformatphotography.info/forum/showthread.php?45251-aerial-focusing&p=433645&viewfull=1#post433645

goamules
9-Mar-2018, 06:46
I've used 5 micron Alum Oxide to great success. It may be your technique was wrong.

Ron Stowell
9-Mar-2018, 08:08
I've used 5 micron Alum Oxide to great success. It may be your technique was wrong.
Holgamods listed on E-Bay can produce custom size ground glass, reasonable priced and good quality.

Alan9940
9-Mar-2018, 08:14
Wasn't there someone on these boards that recently posted a thread about him making gg? And, at reasonable prices, too, IIRC. I'd suggest doing a search here, if you're not going to make it yourself.

Willie
9-Mar-2018, 08:16
My Uncle has made a number of them in various sizes up to 12x20. Sand blasting was the method used. Sand from a commercial glass blaster that was being dumped as it was at the end of the cycle and worn down into smaller grains. made nice ground glass for a number of cameras.

DrTang
9-Mar-2018, 08:30
I've used wax paper

BradS
9-Mar-2018, 09:12
I was under the impression that Steve Hopf was still making focusing screens.

Dave Parker (satin snow) was a member here. He was a craftsman who took great pride in his product. He made excellent ground glass focusing screens and although he occasionally hinted at his methods and tools, he was fairly quiet about the details. It was my impression that Dave had developed a machine to facilitate production.

John Layton
9-Mar-2018, 09:27
Super cheep: stretch magic tape across film plane of gg frame. Works (until it doesn't)

Cheap: oversized plate glass, 500 grit carborundum, picture glass (sized to gg dimensions), a teaspoon of grit on the plate glass, a few drops of water, picture glass placed on the grit/water slurry, move picture glass in a circular motion (wear rubber gloves for friction) until grit gets distributed into a thin layer under the entirety of the picture glass. Do this for a couple of minutes. Rinse and repeat two or three times, rinse and look for any unevenness - repeat grinding if necessary. Use this glass by itself...or slap a page magnifier over it to increase evenness of image and increased brightness. Works.

OH...and don't clean off the plate glass - but instead let it dry in a vertical orientation...the resulting dendritic patterns will blow your mind! (you may want to make a photo of this!)

Lots of other commercially available options. (I prefer Maxwell by a long shot - worth the cost of a lens...and why shouldn't it be?)

As for "out of the box" DIY-ing...I've heard of a technique - applying something like thinned out polyurethane to the ground surface of a diy glass to make it brighter, but I'd imagine it would need to float low enough to allow some texture to rise above the dried poly...otherwise the glass would pretty much go back to useless (be really bright though!).

Gotta get back to shoveling snow (sigh).

Ray Van Nes
9-Mar-2018, 09:34
I posted several ground glasses on the Classified which I cannot find myself but in there I have an 8 x 10 ground glass which is exactly 8 x10 in. May save you a lot of grief.
Cheers
Ray

Bob Salomon
9-Mar-2018, 09:38
I know somebody who used to take existing gg from mf and lf camera’s and would polish the ground side with toothpaste! Ended up with remarkably good gg screens!
But only with ground glass screens, not plastic ones!

Luis-F-S
9-Mar-2018, 09:48
That's why they charge the big bucks! Unfortunately, knowledge and technique costs. I've bought several GG's from Hopf up to 11x14 and they're great! L

LabRat
9-Mar-2018, 11:33
Quik/EZ way (with a slight hot spot) is to spray clear glass with window frosting spray (from the home store spray paint dept)... It is slightly delicate, but on the inside of the camera, nothing should scrape it...

Light, even, two layer application is fine...

Steve K

williaty
9-Mar-2018, 11:49
I'm fairly sure there's a lot of people posting in this thread who didn't actually read the topic starter carefully.

I've already made 2 screens using 2 different methods, one of which works acceptably well. I'm not looking for basic info about how to make a ground glass or significantly unusual methods of making a ground glass substitute.

I'm asking if anyone knows how either of two well-regarded screens were made in hopes that the info would provide helpful leads for further experimentation with making more screens for myself.

Paul Ron
9-Mar-2018, 12:26
theres a video in this thread you may find helpful...

https://www.photrio.com/forum/threads/looking-for-thick-ground-glass.157982/


ive made gg screens using wet dry paper from autobody supply stores and an orbital sander.

Jac@stafford.net
9-Mar-2018, 14:16
[...] I'm asking if anyone knows how either of two well-regarded screens were made in hopes that the info would provide helpful leads for further experimentation with making more screens for myself.

Oh, the Chinese method of R&D - reverse engineering. Ask them!
OTOH, innovation is hard word. Best of luck.
.

williaty
9-Mar-2018, 14:17
Oh, the Chinese method of R&D - reverse engineering. Ask them!
OTOH, innovation is hard word. Best of luck.
.

Isn't trying to make good things by yourself in the best spirit of LF photography?

chris_4622
9-Mar-2018, 14:30
I can't answer what Satin Snow did or anyone else for that matter but I can tell you starting with the 5 micron is too fine and takes too long. I made a number of them and I had good results starting with 25 micron then moving down (I can't remember if it's ??) then down to 5. On one I did go to 3.

My advice is to get some coarser powder and then work your way down.

williaty
9-Mar-2018, 14:33
OK. That's kind of what I was planning on. With the 600 grit silicon carbide (which is roughly 11um), I got a serviceable screen. However, I'm cursed by wondering if things could be better. Since the silicon carbide grinds via fracturing, I think I'm going to order some 25um, 15um, and 9um white aluminum oxide (which grinds by planing/cutting) and give that a whirl. The good thing is that small quantities of abrasive are cheap. It'll just take me a while to grind a bunch of screens. Hence asking around to see if I could avoid re-inventing the wheel.

Jac@stafford.net
9-Mar-2018, 14:37
Isn't trying to make good things by yourself in the best spirit of LF photography?

Yes, Sir, it is, however asking how two of our most successful entrepreneurs/inventors make their product is too much like an intellectual property short-cut. If you could improve upon their product, do you not suspect that they could or have already, possibly deciding not to do so for financial reasons?

Search well and you can find how Satin Snow had considered a new method before a tragedy having nothing to do with his product intervened. It's in this site.
.

williaty
9-Mar-2018, 15:28
Yes, Sir, it is, however asking how two of our most successful entrepreneurs/inventors make their product is too much like an intellectual property short-cut. If you could improve upon their product, do you not suspect that they could or have already, possibly deciding not to do so for financial reasons?
I want to make it myself because I like making things for myself. That's a big part of the reason why I work in LF. I am not concerned with improving on *their* products. What I'm curious about is whether what I've come up with is in the same ballpark as what many on this forum have recommended as the best simple ground glasses ever offered. All of the other ground glasses I have to compared to are factory produced with integrated fresnels.

Satin Snow is long gone and Hopf hasn't replied to several attempts to contact him before I gave up and started experimenting with making them myself. It's not like I'm taking money out of some kid's mouth by trying to make my own screens.

I really don't get why you're so hostile and acting like I'm a bad person just because I want to make a couple of good screens for cameras.

Bob Salomon
9-Mar-2018, 15:44
I want to make it myself because I like making things for myself. That's a big part of the reason why I work in LF. I am not concerned with improving on *their* products. What I'm curious about is whether what I've come up with is in the same ballpark as what many on this forum have recommended as the best simple ground glasses ever offered. All of the other ground glasses I have to compared to are factory produced with integrated fresnels.

Satin Snow is long gone and Hopf hasn't replied to several attempts to contact him before I gave up and started experimenting with making them myself. It's not like I'm taking money out of some kid's mouth by trying to make my own screens.

I really don't get why you're so hostile and acting like I'm a bad person just because I want to make a couple of good screens for cameras.

There are no ground glass screens with an integrated fresnel. All glass screens either are sandwiched with a fresnel, for instance some Wista screens, or the fresnel is an add on extra.
Except for the parifin wax sandwich Boss Screen that didn’t need a fresnel the plastic screens like the Super Screen or the Beattie Screen were frosted acrylic on one side with a fresnel on the back side.
Most of these, including the two named, were made in a Rochester, NY by Fresnel Optics. In fact, Beattie was owned by them.

jnantz
9-Mar-2018, 15:45
Wasn't there someone on these boards that recently posted a thread about him making gg? And, at reasonable prices, too, IIRC. I'd suggest doing a search here, if you're not going to make it yourself.

hello alan
it was barry young
http://www.largeformatphotography.info/forum/showthread.php?144632-Ground-Glass-focusing-screens-including-custom-sizes-from-Young-Camera-Company



I've used wax paper
me too !
and sheets of thin plexiglass that i used an orbital sander on ...

Bob Salomon
9-Mar-2018, 15:51
hello alan
it was barry young
http://www.largeformatphotography.info/forum/showthread.php?144632-Ground-Glass-focusing-screens-including-custom-sizes-from-Young-Camera-Company



me too !
and sheets of thin plexiglass that i used an orbital sander on ...

The old trick was to use a thin layer of shellac on the grain side of a gg (not plastic). It really made a difference, but had to be removed and reapplied every year or so.

williaty
9-Mar-2018, 15:57
There are no ground glass screens with an integrated fresnel. All glass screens either are sandwiched with a fresnel, for instance some Wista screens, or the fresnel is an add on extra.
Except for the parifin wax sandwich Boss Screen that didn’t need a fresnel the plastic screens like the Super Screen or the Beattie Screen were frosted acrylic on one side with a fresnel on the back side.
Most of these, including the two named, were made in a Rochester, NY by Fresnel Optics. In fact, Beattie was owned by them.

In both my Wista and my Toyo, the ground glass is inseparable from the fresnel; they are single monolithic chunk of plastic. Counts as integrated in my book.

Bob Salomon
9-Mar-2018, 15:58
In both my Wista and my Toyo, the ground glass is inseparable from the fresnel; they are single monolithic chunk of plastic. Counts as integrated in my book.

Wista has several ground glass screens for 45.

jnantz
9-Mar-2018, 18:51
The old trick was to use a thin layer of shellac on the grain side of a gg (not plastic). It really made a difference, but had to be removed and reapplied every year or so.

i wonder what happens when you say shelac 3x ?
i gotta find me a haunted house and a beetle farm :)

Peter De Smidt
9-Mar-2018, 21:45
I've made a number of glass screens using aluminum oxide powder. It really isn't very hard. It just takes a bit of time.

williaty
9-Mar-2018, 21:47
I've made a number of glass screens using aluminum oxide powder. It really isn't very hard. It just takes a bit of time.
What abrasive size did you use? Did you see different results through trying different sizes or techniques?

As I said, I've made a perfectly functional ground glass. I'm trying to learn if I can make a better than perfectly functional one now.

Robert Brazile
10-Mar-2018, 05:03
OK. That's kind of what I was planning on. With the 600 grit silicon carbide (which is roughly 11um), I got a serviceable screen. However, I'm cursed by wondering if things could be better. Since the silicon carbide grinds via fracturing, I think I'm going to order some 25um, 15um, and 9um white aluminum oxide (which grinds by planing/cutting) and give that a whirl. The good thing is that small quantities of abrasive are cheap. It'll just take me a while to grind a bunch of screens. Hence asking around to see if I could avoid re-inventing the wheel.

That is what I did on my 11x14 ground glass and I'm satisfied with the results.

Robert

c.d.ewen
10-Mar-2018, 07:26
I don't see that anyone has yet mentioned it, but I've made GG's from diamond abrasives. Using diamond abrasives is way faster than any other abrasive, and not expensive. That was years ago, and I don't remember the supplier or the grit used.

I made a couple of 12x20 and several 4x5 glass plates by gluing the 4x5 plates to the bottom of an orbital sander and using them to grind the 12x20's.

Charley

Colin Graham
10-Mar-2018, 10:02
I was always curious about this too, so last year I finally just cut a screen blank in half and ground each half with progressively finer aluminum oxide grits up to 3 micron until I found the one I liked the most. I installed both halves in the camera at the same time to compare different grits, flipping the back 180° just to make sure there was no dominant eye bias skewing the results. I liked the 9 micron screen, but ground the other half through to 3 micron just to make sure. I didn't like the finer grits at all.

For what it's worth, I bought a Satin Snow screen from Dave back in 2006 or so, and can't tell much difference between it and the 9 micron screen viewed under a loupe on light box.

Most glass isn't very flat, so I usually lap it with 320 silicone carbide first. I use an flat-bottomed element from a cheap telephoto lens to grind with. It's kind of a slog, even on a small screen- I need try Charley's orbital sander/diamond grit trick.

Peter De Smidt
10-Mar-2018, 10:29
Generally, the coarser the ground glass, the less diffusion there will be, and the brighter the hot spot will be. Conversely the finer the grind, the more diffusion, the dimmer the hotspot will be, but there will be less brightness dropoff outside of the hotspot. As others have said, experimenting with different grits is useful to find what works best for you. This depends on the lenses you use. Longer lenses have less of a bright spot effect on the ground glass. Thus, a coarser screen/brighter screen might be best. Wide angle lenses have inherent fall off which can make the corners of the screen really dark. A screen with finer granularity might help. And all this depends on whether you are using a fresnel, as they allow a brighter screen while still keeping the corners bright. Finally, you can experiment with a coarser screen with a coating of something like Renaissance Wax.