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View Full Version : Ebony Focusing (Fresnel) Screen on Chamonix 4x5?



NewBearings
10-Sep-2009, 18:14
Hugo told me someone had success using the Ebony focusing screen in place of the OEM Chamonix GG (without the OEM Chamonix Fresnel).

Anyone else try this successfully?

Doug Dolde
10-Sep-2009, 18:55
Why would you want to? I found the Ebony screen to be a lot like looking through a frosted glass.

Steve Hamley
10-Sep-2009, 18:57
It should work because it's a fresnel that's frosted one the side that faces the lens, then a cover glass goes over it to protect the fresnel grooves. So the image forming surface is in the same plane as a normal GG.

This would fix the problem as I understand it. A Maxwell is or can be made the same way.

Cheers, Steve

NewBearings
10-Sep-2009, 19:12
Why would you want to? I found the Ebony screen to be a lot like looking through a frosted glass.

I've only had one opportunity to focus with an Ebony. It was the regular fresnel/GG.
It was fine to my eyes.

I need a fresnel, and the Chamonix fresnel throws the focus off with WA (as has been beaten to death on previous threads). So I can either place the Chamonix fresnel in front of the GG or go with another. The Ebony is apparently the same size.

Placing the Chamonix fresnel in front of the GG requires some adaptation, and the plastic fresnel wears quickly.

Have you got another option, Doug?

shadowleaves
10-Sep-2009, 19:13
Hugo told me someone had success using the Ebony focusing screen in place of the OEM Chamonix GG (without the OEM Chamonix Fresnel).

Anyone else try this successfully?

I tried and it works. No focus shift, apparently because the ground side is facing the lens and fresnel side facing the user. However, Ebony screen is very coarse, and it shows a huge hot spot in the center with wide-angle lense. that makes the focusing not so pleasing.

Another thing, you need to add some shims under the 4 screws that hold the ground glass, since now you will need to put both the ebony screen and ebony protective glass at the place where the original GG was. The ebony screen plus protective glass is much thicker, and so you need to add some shims under the screw to make sure they hold the screen/glass firmly. This should be the same in the case of fitting a Maxwell screen to Chamonix.

Doug Dolde
10-Sep-2009, 19:20
A Maxwell screen would be the best option.

Steve Hamley
10-Sep-2009, 19:32
I found the Ebony screen to be a lot like looking through a frosted glass.

And here I thought that's what they all were! :D

Cheers, Steve

NewBearings
10-Sep-2009, 19:46
I tried and it works. No focus shift, apparently because the ground side is facing the lens and fresnel side facing the user. However, Ebony screen is very coarse, and it shows a huge hot spot in the center with wide-angle lense. that makes the focusing not so pleasing.

Another thing, you need to add some shims under the 4 screws that hold the ground glass, since now you will need to put both the ebony screen and ebony protective glass at the place where the original GG was. The ebony screen plus protective glass is much thicker, and so you need to add some shims under the screw to make sure they hold the screen/glass firmly. This should be the same in the case of fitting a Maxwell screen to Chamonix.

Have you tried the Ebony WA Focusing screen?

Steve Hamley
10-Sep-2009, 20:04
The Ebony wide-angle focusing screen is a second, "unfrosted" fresnel that is installed WITH the standard screen, "groove-to-groove" then the cover glass is over all.

It works fine.

Cheers, Steve

Brian Ellis
11-Sep-2009, 07:59
The Ebony screens that came with my Ebony 45 SVe and SVi cameras were probably the most difficult to focus of any screen I've owned. Unless they've improved in the 8 or so years since I owned these cameras an Ebony screen would be the last screen I'd choose as a replacement. Maxwell would be the best IMHO, after that I'm not sure what I'd choose since BosScreens are apparently no longer made but it wouldn't be an Ebony screen.

shadowleaves
11-Sep-2009, 09:57
The Ebony wide-angle focusing screen is a second, "unfrosted" fresnel that is installed WITH the standard screen, "groove-to-groove" then the cover glass is over all.

It works fine.

Cheers, Steve

Interesting. Maybe I'll try this one. Thank you!

Steve Hamley
11-Sep-2009, 14:51
The Ebony screen is the cheap way out compared to Maxwell or other "premium" screens. I find the Ebony about a stop less bright than a Maxwell, but the coarser grain of the image "pops" into focus more easily than the Maxwell.

I've thought that people really want a LCD out of their screen, but the purpose of a screen is to help you focus, it isn't an end in itself.

Lest the flames begin, let me add that in any fresnel system. there are three lenses at work, the camera lens, the fresnel, and your eye. Different people want different things, but what I want is to be able to focus critically. Brightness or "beauty" of the GG image is not a consideration beyond the focusing and composition aspects.

Cheers, Steve

Brian Ellis
11-Sep-2009, 20:38
The Ebony screen is the cheap way out compared to Maxwell or other "premium" screens. I find the Ebony about a stop less bright than a Maxwell, but the coarser grain of the image "pops" into focus more easily than the Maxwell.

I've thought that people really want a LCD out of their screen, but the purpose of a screen is to help you focus, it isn't an end in itself.

Lest the flames begin, let me add that in any fresnel system. there are three lenses at work, the camera lens, the fresnel, and your eye. Different people want different things, but what I want is to be able to focus critically. Brightness or "beauty" of the GG image is not a consideration beyond the focusing and composition aspects.

Cheers, Steve

No flame, just a comment. It's difficult to completely separate focus from brightness (not "beauty") since you can't focus on something you can't see. With a plain ground glass I found it difficult to see the entire image at one time because areas on the edges and in the corners of the screen were very dark, especially with wide angle lenses.

That was one of the reasons I liked my Maxwell screens so much - even with an 80mm lens (my widest) the corners and edges of the screen were so bright they were almost indistinguishable from the center, which for me made it very easy to focus. With the 4x5 ground glass screens I've used only the part of the image in the center of the glass was visible unless I moved my head up, down, and all around and viewed different parts of the image separately.

I should mention that the plain ground glass screens I've used haven't been the ones made by Satin Snow and similar places, they've been screens that came with the camera. Maybe Satin Snow and similar screens would be better.

NewBearings
11-Sep-2009, 22:34
Steve,

Keep in mind, user experience (joy) is also an important part of what we do - aside from focus.