Borosilicate ground glass screens?

[Kirk Gittings]

The wind today at the Bisti won a battle with me and my camera. Of course I didn't have my spare with me which is highly unusual. Time to look at replacements. Anyone here have any experience with Steve Hopf's Borosilicate screens?

https://scontent-dfw1-1.xx.fbcdn.net/hphotos-xpl1/v/t1.0-9/12718376_10209092167251295_6399327944993212939_n.jpg?oh=4b791f1c55d59e9bf4dd13e240e1dcd2&oe=5787EBAA

[RSalles]

Kirk,

I have, and highly recommend you. Maybe it's also a good idea for you to get + one as spare, never know,

Cheers,

Renato

[David Karp]

I have one too. Excellent. It is not a bright screen. Just groundglass. I had him put a silver grid on mine. You can see it when you need it. It sort of disappears when you are not looking for it. Steve is easy to deal with and quite responsive in my experience.

[pjd]

I've got one, the borosilicate is good - and beyond that Steve is definitely a decent guy to deal with. I messed up the details of an order once, and he did a lot more than I expected to help me out.

[RichardRitter]

Borosilicate is 3 to 6 % brighter then regular soda lime ground glass.

The bad side of brosilicate is it harder and breaks a lot easier.

[N Dhananjay]

I have the Steve Hopf borosilicate glass - he does very good work and was very good to deal with. The borosilicate has a slightly warm cast to it - sort of pale straw yellow tone unlike normal glass that tends to lean towards green. The grind seems to be a very good balance between fineness (for detail) while avoiding a hot spot. Cheers, DJ

[Kirk Gittings]

Borosilicate is 3 to 6 % brighter then regular soda lime ground glass.

The bad side of brosilicate is it harder and breaks a lot easier.

Darn, I thought it was less prone to breakage.

[Paul Cunningham]

Darn, I thought it was less prone to breakage.

Me too. If it is indeed the glass of Pyrex, it has a lower expansion coefficient, which is why it is good for hot materials. I think a previous poster mentioned that a thin(ner) version is used for ground glass, which makes it more fragile in practice, (but perhaps not in theory).

[Sal Santamaura]

Your fractured glazing looks like a clear cover over what's probably a plastic screen with integral fresnel. If that's the case, I suggest merely replacing the cover glass. In my 4x5 and 5x7 cameras, which have Maxwell screens of that type, I replaced the clear cover glasses with AR-coated versions made by the manufacturer of Intenscreens. One can order those (separately, without the Intenscreen itself) through B&H.

[Dave Wooten]

Steve Hopf: yes! I had Steve make a 5x7 for my DD. I highly recommend.

[Jim Graves]

Borosilicate is 3 to 6 % brighter then regular soda lime ground glass.

The bad side of brosilicate is it harder and breaks a lot easier.

I'd be interested in seeing the source of this opinion.

[RichardRitter]

I'd be interested in seeing the source of this opinion.

Just look up the transmission rate of each type of glass. Bososilcate is about 99% which is about the same of optical grade glass. Soda lime is 96% or less it's window glass if you look at the edge of the glass it will see a blue /green color to it. Not good for UV printing acts as a ND filter.

[Sean Mac]

Borosilicate glass was apparently first produced by the famous Schott company in Jena.

Otto Schott, Ernst Abbe and Carl Zeiss founded the company.:)

[Richard Wasserman]

You can read what Steve Hopf has to say— http://hopfglass.com/borosilicate.htm

He shows how it is not tinted and claims that it is stronger and more difficult to break. I have one and have been very happy with it, and as others have said, Steve is great to work with.

[Wayne]

Just look up the transmission rate of each type of glass. Bososilcate is about 99% which is about the same of optical grade glass. Soda lime is 96% or less it's window glass if you look at the edge of the glass it will see a blue /green color to it. Not good for UV printing acts as a ND filter.

I thought he was asking about it's breakability, but could be wrong.

[HMG]

Me too. If it is indeed the glass of Pyrex, it has a lower expansion coefficient, which is why it is good for hot materials. I think a previous poster mentioned that a thin(ner) version is used for ground glass, which makes it more fragile in practice, (but perhaps not in theory).

Actually, Pyrex used to be made with borosilicate glass, which did provide great thermal properties. Now it's made with tempered glass which has poorer thermal properties, supposedly slightly better resistance to breakage, and is cheaper to produce.

[Tin Can]

I have considered tempered glass for GG, but also imagined it may be hard to grind...

Gorilla glass is very tough, which uses a chemical treatment.

http://www.corninggorillaglass.com/en/glass-types/gorilla-glass-4

[Drew Wiley]

Tempered is a pain in the butt to grind, and tricky even to cut unless you have the correct gear (most glass shops do, and I do too). I'd rule it out. I don't think borosilicate has much advantage either. What might be interesting is a new offering by TruVue which is scratch-resistant optically coated acrylic one side only, which means the other side could be ground, and with higher transmission rate than any glass. But my precaution is that, treated in this manner, could it be trusted not to differentially hydration-bow due to unequal surfaces? Might be OK for up to 4x5.

[Peter De Smidt]

Whatever glass Kirk gets, he might want to have an acrylic one in his kit as a spare. Wehman 8x10s used to come with an acrylic screen. If they were rigid enough for that, they should work fine for 4x5, especially as a backup.

[Jerry Bodine]

Whatever glass Kirk gets, he might want to have an acrylic one in his kit as a spare...

Good idea. And don't forget a tiny screwdriver for the clips holding the gg in place. If the screws are a magnetic metal, then a magnetic screwdriver would be useful to prevent losing the screws once removed.

I'm certainly not a expert on glasses, but I do know that tempered glass is made by a process that creates a very thin layer of compressive stress at the surface of the glass which is counteracted by tensile stresses in the interior material. Since normal glass is sensitive to breakage as a result of surface scratches or edge knicks (stress concentrations), the tempering process makes it less sensitive to breakage under a load. But if that compression layer is ground away that would defeat the purpose of tempering and break-resistance.

BTW, this is the same strategy used for pre-stressed concrete; concrete suffers under tensile stresses, so steel rebar under tension is imbedded in the material and creates compression in the concrete; so if the tension load on the composite is great enough to overcome the pre-compression the composite will start to crack and finally rupture.

[Drew Wiley]

Tempered glass tends to spall rather than grind. Voodoo.

[austin granger]

Another recommendation here for Hopf's borosilicate glass. It might just be my mind making it so, but I swear I noticed an improvement in brightness over the original screen (Deardorff plain ground glass). And it seems to really "pop" into focus nicely, especially with a bright standard lens. One thing I would say though is that I ordered mine with a clear grid and it's tough to see it under the dark cloth. Steve warned me about this so that's not on him. If I ever get another one, I'd probably go with a black grid if that's available.

Sorry about your camera Kirk, but at least it'll be exciting to put a new ground glass on it.

[Kirk Gittings]

Your fractured glazing looks like a clear cover over what's probably a plastic screen with integral fresnel. If that's the case, I suggest merely replacing the cover glass. In my 4x5 and 5x7 cameras, which have Maxwell screens of that type, I replaced the clear cover glasses with AR-coated versions made by the manufacturer of Intenscreens. One can order those (separately, without the Intenscreen itself) through B&H.

True but the fresnel is very scratched by the broken glass cover and while it is usable it very distracting. So I am looking at what is out there.

[Sal Santamaura]

Your fractured glazing looks like a clear cover over what's probably a plastic screen with integral fresnel. If that's the case, I suggest merely replacing the cover glass...


True but the fresnel is very scratched by the broken glass cover and while it is usable it very distracting. So I am looking at what is out there.I found this thread from almost three years ago


http://www.largeformatphotography.info/forum/showthread.php?106274-Installing-Beattie-screen-on-my-Phillips-4x5

that identifies your scratched screen as a Beattie Intenscreen. Back then, you didn't say whether you'd ever tried a Maxwell screen. If you still haven't, I'd once again suggest getting one (with cover glass) from Bill Maxwell. Then, obtain a Horseman folding focusing hood. The combination will liberate you from focusing cloths/tubes and, as a bonus, serve as built-in screen damage protection. That's the configuration I use on my Phillips 4x5.

[Drew Wiley]

My own Phillips (8x10) is still equipped with the original Satin Snow glass, which is bright enough to make a fresnel redundant, though I can understand the value
of one for interior use with very wide angle lenses. Ironic how the least expensive and lowest-tech GG out there was also functionally the best. I haven't needed
anything new since this fellow quit grinding glass, but his method should be repeatable in a simple shop environment.

[Kirk Gittings]

I am looking at the Maxwell screens. Haven't heard back with a price yet-but I know it will be pricy. I want to protect it from the same mishap that scratched the heck out of my Boss Screen. Does anyone make an acrylic (ie unbreakable) cover screen with a grid?

[Drew Wiley]

Double layers? I know you shoot a lot in the desert, but in damper situations that can be an ingredient for condensation between the elements. Learned that the
hard way.

[Kirk Gittings]

I have used double layers for the last maybe 20 years and never had that problem. If i ever go to shoot in in humid areas like your tropical CA :) I will keep that in mind.

[Drew Wiley]

Tropical????????? Wet and foggy, sure. But no alligators or humid swamps here. Some strange people. The bigger problem would be those cold mornings in the mountains where even your breath will create hoarfrost on a groundglass. If I want my gear sandblasted instead, a rare beach day might do it; but generally it takes about a four hour drive from here to the edge of the Great Basin. One reason why I refuse to shoot alongside dirt roads unless they are exceptionally quiet.
The Monster Truck types love nothing better than to leave a roadside photographer drowned in a dust cloud.

[Kirk Gittings]

Tropical????????? Wet and foggy, sure. But no alligators or humid swamps here. Some strange people. The bigger problem would be those cold mornings in the mountains where even your breath will create hoarfrost on a groundglass. If I want my gear sandblasted instead, a rare beach day might do it; but generally it takes about a four hour drive from here to the edge of the Great Basin. One reason why I refuse to shoot alongside dirt roads unless they are exceptionally quiet.
The Monster Truck types love nothing better than to leave a roadside photographer drowned in a dust cloud.

Did you forget what a smiley face emoji means?

[Jim Graves]

I thought he was asking about it's breakability, but could be wrong.

I was asking about Richard Ritter's statement that borosilicate glass breaks easier than regular glass ... I haven't found anything that supports that opinion ... but maybe Richard has.

[carylee2002]

Well I just emailed Steve and get a final quote for ebony rw45 with grid. He says he has a brighter glass but it reduces diffusion and may create hot spots....anyone tried the brighter glass?