Brighter Ground Glass

Darkroom317 · Mar 2, 2017

With my latest series all of my work is at night. I am having trouble focusing my Cambo's ground glass. I have looked at replacements but all of the information is about 10 years old. I'm looking for recommendations for a brighter ground glass that is currently available and reviews about how well they worked.

Darkroom317 · Mar 2, 2017

Also, I've seen a lot about ground glasses with fresnel lenses. I know this helps with brightness and evenness of light but I've read about some peoples frustrations with the fresnel lines and focus issues. What are the experiences of people here with ground glasses like this.

wiltw · Mar 2, 2017

I have had one of Bill Maxwell's focusing screens in my Horseman 4x5 monorail for about 20 years...love it!!! Incredibly bright. And he still offers screens.

https://www.facebook.com/Maxwell-Precision-Optics-200647716643807/

This phone number still works...
(770) 939-6644

The website doesn't appear to be working correctly, though...
www.maxwellprecisionoptics.com/
but the Google ad phone number (404) 244-0095 is no longer connected.

Do not know if this email address still works...
maxwellprecisionoptics@yahoo.com

Patrick Robert James · Mar 2, 2017

You could try waxing your ground glass. I do this to the older ground glasses and it works great. Big difference in brightness, and you can take it off if you don't like it. Just be careful if you have lines that aren't etched since it may remove them. I use Butcher's wax since I have it, but any carnauba or beeswax will probably work fine. You could probably even use some car waxes. You just need a light coat on the rough side. I have also read before that back in the day some photographers shellacked their ground glass to improve it. I haven't tried that since the wax trick works so well.

Good luck.

Europan · Mar 2, 2017

+1 for wax. Apply very thinly

Darkroom317 · Mar 2, 2017

Patrick Robert James said:
You could try waxing your ground glass. I do this to the older ground glasses and it works great. Big difference in brightness, and you can take it off if you don't like it. Just be careful if you have lines that aren't etched since it may remove them. I use Butcher's wax since I have it, but any carnauba or beeswax will probably work fine. You could probably even use some car waxes. You just need a light coat on the rough side. I have also read before that back in the day some photographers shellacked their ground glass to improve it. I haven't tried that since the wax trick works so well.

Good luck.

I think I'll give this a try before anything else. What kind of cloth do you apply the wax with? I'm afraid of scratching/ or damaging the ground glass.

donkittle · Mar 2, 2017

If you can't get your existing glass bright enough, I second Maxwell glass - picked one up last April and I can't imagine shooting without it now.

Darkroom317 · Mar 2, 2017

Tried the wax and made a bit a mess. It didn't work well either so I took the ground glass out and discovered that the ground glass is not glass but plastic with a fresnel lens and a glass cover. Given this I question how much better the other screens might be after all this is the brightest ground glass I've used so far.

I have been disappointed with the sharpness of some of my images and am trying to track down the cause. I felt that bad focusing might be the cause and as I already use a loupe I figured it might be the ground glass. I feel that the best solution may be to carry a flashlight. Perhaps I am expecting too much

Mainecoonmaniac · Mar 2, 2017

I used a Fresnel page magnifier on my Ansco 8x10 camera. Works great.

https://www.amazon.com/Premium-Page-Magnifier-Fresnel-Reading/dp/B015NR7XGS

Patrick Robert James · Mar 3, 2017

You should probably carry a flashlight with you. Might help.

If you are sure about your focus on the ground glass then it might be possible someone put the fresnel in and it shouldn't be there. If you want to test it, shoot an image wide open of a yardstick or something similar and see if the focus matches. If it doesn't match then try it without the fresnel.

The lack of sharpness could be due to wind during your long exposures. It doesn't take much to screw up an image. If you are having problems with camera movement, there will be nothing sharp in the image vs. a focus problem in which the sharpness just isn't where you want it.

You might want to post an image or two in order to illustrate your concerns.

Hope that helps you.

bernard_L · Mar 3, 2017

Beam a laser onto the subject and focus on the laser spot

Doremus Scudder · Mar 3, 2017

Darkroom317 said:
Tried the wax and made a bit a mess. It didn't work well either so I took the ground glass out and discovered that the ground glass is not glass but plastic with a Fresnel lens and a glass cover. Given this I question how much better the other screens might be after all this is the brightest ground glass I've used so far.

I have been disappointed with the sharpness of some of my images and am trying to track down the cause. I felt that bad focusing might be the cause and as I already use a loupe I figured it might be the ground glass. I feel that the best solution may be to carry a flashlight. Perhaps I am expecting too much

If your ground glass is already a Fresnel/gg sandwich, you are likely working with about as bright a screen as you are likely to find. Make sure it's clean and positioned properly and you should be good to go. If dark focusing is a problem, try carrying a laser pointer or flashlight.

A word about positioning of Fresnel screens: If your Fresnel screen is original equipment with your camera, it is fine. However, if it was added to your camera later, and if it is positioned between the frosted surface of the ground glass and the lens (i.e., not on the eye side), then it may have introduced a focus shift. If you consistently have a discrepancy between focus on the ground glass and what ends up in focus on the film, check this. One easy way is to simply focus wide-open with a longish lens on a detailed horizon (e.g., hills with trees, etc.). Shoot wide open and see if the horizon line is alright. Another is to focus on a middle mark on a ruler laid at an oblique angle to the camera. Use a lens that will get you shallow depth-of-field and shoot wide open. If the focus on the neg doesn't match the focus on the ground glass, then you may have to reposition your Fresnel/gg sandwich. If you're simply having problems focusing because it's too dark, then ignore the above.

Best,

Doremus

AgX · Mar 3, 2017

Waxing a ground glass will reduce the spreading of light and thus highten lateral light fall-off.

A ground glass too underlies the laws of physics. There is no magic screen.

Ai Print · Mar 4, 2017

AgX said:
There is no magic screen.

While true, a top of the line Maxwell screen gave me nearly a two stop advantage over my already good Chamonix fresnel / GG combo.

I got the screen a month ago for my soon to be done Gibellini ACN45.

Something about Maxwell folks are going to find out sooner or later: Bill told me a couple months ago that he has enough material for about 6 more screens in 4x5 and then that could be it. Reason being is that his supplier is no longer offering the material and the place he sourced a replacement from is in Europe so it might make selling the screens difficult due to a considerable price increase.

I'd say if you have been on the fence about getting one of his screens you might want to pony up before either the price rises substantially or he just calls it quits.

BHuij · Mar 7, 2017

Here's perhaps an unorthodox suggestion from someone who has not encountered this problem:

Buy a very bright laser pointer and shine it on what you want to focus on. I figure if it's far away enough that you can't see your laser, you can probably safely assume infinity focus

Heck if you wanted to get really creative, you could figure out some way to stick it on a tiny cheap ballhead attached to the tripod or camera itself, and then it would hold perfectly still for you after you aim it while you focus.

grahamp · Mar 8, 2017

Just don't do it near flight paths, or at least be very careful where it is pointed.

Jarin Blaschke · Mar 9, 2017

I also just purchased Bill Maxwell's screen for a recently purchased Deardorff 8x10. I'm new to the format, so had a very good camera shop install the screen. In the process, they found that the flange depth of the back was off. Luckily they caught this before I started shooting (rather expensive) film but it reminds me that this GG depth error can exist even with the most reputable camera makers.

The new screen is of course very bright; I purchased the brightest version which has a somewhat limited sweet spot to view the whole composition (with a 300mm lens), but in this position it looks beautiful, bright to the very corners. Presumably viewing a 4x5 or 5x7 sized ground glass will be more forgiving as. He also sells a slightly less bright screen that permits more viewing angles. I can easily see a composition indoors without a dark cloth at all. With my slightly too strong 8x loupe, I see the grain but I can still effectively focus at this magnification.

Jarin

Brighter Ground Glass

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