Anti Glare Plexi in place of ground glass?

[synthetase]

hi-

i'm thinking of building my first 4x5 camera. it occurred to me that anti-glare plexi might be a good option for ground glass. it is acid etched, unbreakable,
and easily attained at any framing shop.

does anyone have any thoughts on this?

thanks

lisa

 

[Dave Parker]

Nothing is unbreakable!

One of the biggest problems with plastic over glass is the ability of the plastic to absorb enviormental contaminents, which in a short time can dim the viewing screen, also plastic is more prone to distortion with heat and cold cycles and the plastic will bow or wave on you in real world usage. Plexi can be a good short term solution, but if you want a good quality screen you should look at glass or one of the enhanced viewing screens, there is stability, ease of cleaning when needed and a predictable light transmission pattern for focusing. Acid etching glass evenly is not easy and the burning characteristics of acid, is very difficult to control on plastic.

Dave

 

[jd callow]

Plastic scratches











By the way...
Satin Snow is inexpensive and by all reports excellent...








By the by...

Welcom to APUG synthetase!

 

[Helen B]

Hi Lisa,

Welcome to APUG.

John has already mentioned the important issues: a Satinsnow ground glass is not only excellent for the job, but also so inexpensive that it's hardly worth considering anything else, unless you want to experiment.

I've just whipped the Satinsnow GG off my old 5-4 and stuck a piece of Acrylite FF P-99 'non-glare' in its place. Here's the problem: the Acrylite as it stands has a very slight texture. It forms a very bright image near the optical axis, but I can also see the 3-D aerial image quite clearly. Because of the presence of the aerial image, I could not focus accurately with ease. I could focus using 'parallax focussing' but that might not be what you want to do. You'd also have a problem in the corners unless you used a fresnel screen as well.

As Dave says, stiffness is an issue. Acrylic needs to be a little thicker than glass for similar stiffness. An eighth of an inch would probably be enough for up to 10-8.

It's good to know that you are thinking of possibilities and alternatives.

Best,
Helen
PS, I only know of 'non-glare' and 'anti-reflective' surfaces. I've assumed that you mean what I know of as 'non-glare'.

 

[Curt]

Buy two Satin Snow ground glasses and keep a spare. They are not that expensive and are the best out there.

Curt

 

[Dave Parker]

I've used polycarbonate screens, one for years, and experienced none of the problems mentioned above.

Jay

Jay,

You were using chlorinated brake clearner to frost your screens if I remember right?

Did you ever experiance any softness in the frosted surface? I am curious and not asking for anyother reason than that, I am just curious, I have used that in a previous job I had in a mechanics shop and we had some difficulties with it on plastic surfaces.

I remember you mentioning it in another thread.

Dave

 

[synthetase]

thanks for the thoughts

the bowing problem occured to me right after i posted.

i appreciate everyone's thoughts. i'll most likely go with glass. esp. since i found the makers of satin snow on this site. i look forward to reading the posts on this site. i don't normally use forums, but this one actually looks useful.

lisa

 

[Helen B]

I've used polycarbonate screens, one for years, and experienced none of the problems mentioned above.

Jay

Just to clarify: I was referring to the use of non-glare acrylic as it comes from the manufacturer, because that's what I thought Lisa was referring to rather than acrylic she would etch herself.

Best,
Helen