View Full Version : reflex viewer problem

Mark Muse
28-Sep-2003, 08:44
I recently purchased an Ebony 23S, which is a wonderful camera. I also bought a Horseman monocular reflex viewer, adapted by Ebony to work with their hinged GG and fresnel. The lenses I am using are a Rodenstock AR-S 135mm (5.6) and a Schneider SA 65mm (5.6).

The problem is the degree of light falloff in the viewer. It is extreme! With the 135mm lens under brilliant light it is workable but far from satisfactory. With the 65mm lens it is not usable.

I know I can get an Ebony WA fresnel that would help with the 65mm. And Andrew Ito recommended Bill Maxwell focusing screens.

Does anyone have a solution specific to a viewer like this, particularly one that would work well with either lens (this is a field camera and I am trying to keep my kit weight and bulk to a minimum)? I occurs to me that a second lens, on the viewer side of the GG, to bend the light to the objective might be what is needed.

28-Sep-2003, 09:09

I have an Ebony with Horseman *binocular* reflex viewer, and I'm extremely pleased with it. I haven't seen the monocular version, but I'm guessing that it must be differently constructed as far as light transmission/direction. The bino version is very bright, i.e. about the same as looking directly at the GG. Currently I use a Maxwell screen, but before acquiring this, the default Ebony screen seemed just as bright. I don't consider the Maxwell screen to offer a lot of overall brightening, but instead evens out the brightness and eliminates the hot spot to a great extent.

This would unfortunately be an expensive solution, but I think the bino version would solve your problem; I don't know if it's available to fit a 2x3 camera, however. Does your viewer have a knob to change the mirror's angle in relation to your position? If so, try adjusting that if you haven't already done so. If you have any specific questions re: construction of the bino version, feel free to email me.

Regards, Danny www.dannyburk.com

Ernest Purdum
28-Sep-2003, 09:33
The problem is inherent in viewing from 90 degrees to the groundglass as a viewer like this does. The wider the angle of the lens, the greater the problem will be. Different screens and fresnels can help, but they can't eliminate the problem. The best answer is to use the viewer for a first overall look, then remove it, and use a loupe with half of the base cut at an angle, so that it can be held at an angle when looking at or near the corners.

Mark Windom
28-Sep-2003, 09:36
Not that this will help your specific problem but I have an Arca-Swiss binocular viewer that I use on my A-S 69 and the image is very bright with a 65mm lens. Can you rent or borrow a binocular viewer to see if this would solve your problem?

John Cook
28-Sep-2003, 09:50
Without a fresnel, you need to "look at the back of the lens" to see anything on the ground glass. This means to see an image in the corner of the ground glass you need to move your eye over to that corner, so your eye will still be pointed at the lens. Hard to describe without a diagram. But if your eye is behind the lower left corner of the ground glass and you are looking at the upper right corner, if the ground glass were clear you would not see the back of the lens but the right inside of the bellows.

In short, without a fresnel you need to move your head around a lot to see various parts of the ground glass image. (A lot of walking going on behind an 8x10. A reguar hike behind ULF!) A reflex viewer keeps your eye in a fixed position, so you can't do this. I don't think a reflex viewer of any type or brand is of much use without a fresnel lens on the ground glass. It has been my experience that they really do go together.

James Driscoll
28-Sep-2003, 10:39
ditto what John Cook says....Sinar basically tells you that their "Bino-Reflex" is almost useless without a fresnel lens....and it is.

After using a fresnel for 3 years, I can't fathom going back to NOT using one. The sinar one clips behind the GG so you can remove it if you have to (sometimes it is hard to focus with one).

Michael J. Kravit
28-Sep-2003, 10:49
The problem you are having has nothing to do with the camera. I owned the monocular viewer and sold it for the exact same reason. As someone else mentioned, the mirror and eyepiece are set up at a 90 degree angle to the ground glass. If you owned a binoculat viewer you would experience the same problem if you were to tilt it up to a 90 degree position.

The Arca and Horseman binocular viewers are adjustable for viewing angle and may offer you an acceptable solution.

I own an Ebony 45SU and don't fine that I need a viewer at all with the Ebony Fresnel. In fact, when shooting with the 6x9 back, I rarely even need a dark cloth.

Bert Otten
28-Sep-2003, 10:54
Hello Mark,

I had the same problem with the reflex viewer on a Horseman 6x9 camera and a 65 mm lens. The following solution worked very well: I bought a plexiglass magnifying glass with a focal length of about 15 cm. The glass was thick and rectangular. I sawed a piece out of it with the inside dimensions of the ground glass carrier of the reflex viewer then clamped it in this carrier after removing the cap with turnable eyepiece. This produced an enormous increase of uniformity of the image and made the 65 mm usable. Naturally it does not change the accuracy of focussing, since the plexiglass lens is behind the groundglass. The cone of scattered peripheral light rays is bent more in the direction of the eyepiece and the uniform plexiglass lens does not produce extra ridges in the image, like a fresnel lens does. Only one disadvantage: a slight increase in weight, but the lens being plexiglass, the increase is tolerable.

Hope this is of use to you Mark.

Massimo Squillace
28-Sep-2003, 16:23

I have two of Bill Maxwell's replacement screens for my Horseman Angle Viewer and they work beautifully.

The "standard" version is better (more contrasty) for longish lenses, but the "special" version I ordered for my wide angles is truly outstanding!

I use it for my Rodenstock 55mm and it's great, and it only gets better with my 75mm and 100mm - the illumination is so even!

It has virtually the same performance as the "standard" version on my 150mm, and only from 210mm upward I see a definite improvement with the "standard" screen.

Given your lens setup I'd simply get one of the "special" versions, specifying the intended usage so Bill will optimally tune the screen for a 65mm/135mm combo.

It won't be cheap nor fast, but the results will be worth it.

One last thing ... I asked Bill to cut a 6x9 frame out of a 4x5 "special" screen instead of crafting directly a 6x9 one, since this last option (his default) leaves dark corners and I wanted to be able to see the full frame clearly.

Mark Muse
28-Sep-2003, 18:39
The last sentence in my original post seems to have mislead a number of you. There is an Ebony fresnel lens in use in this arrangement. I assumed, perhaps wrongly, that the fresnel lens is on the bellows side of the GG, hence my comment about a second lens on the viewer side of the GG.

Burt, I don't quite follow you. Can you post a diagram?

Massimo, I keep hearing good things about Maxwell's screens. I would like to call him. Would you be so kind as to send some contact info directly to me via email?

Thanks to everyone so far!

Herb Cunningham
11-Oct-2003, 07:44
I too, have thought the reflex viewer was the way to go. I am 67, bifocals and the rest, and find that reflex viewers, bino or mono, don't really do it. The problem is that us old guys can't get the right distance to the ground glass-Steve Simmons told me to get some cheap reading glasses, 2.5+ or 3.0+ at Wal Mart ($2), and that was the solution. Now I use either a lightweight dark cloth or the fancy BTZ shroud and those glasses, and I will be selling my reflex viewer on ebay. The bright screen is also a plus.