Ebony Focusing (Fresnel) Screen on Chamonix 4x5?

[NewBearings]

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]

Why would you want to? I found the Ebony screen to be a lot like looking through a frosted glass.

[Steve Hamley]

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]

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]

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]

A Maxwell screen would be the best option.

[Steve Hamley]

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!

Cheers, Steve

[NewBearings]

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]

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]

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.