If you have used the Beattie Intenscreen, or other "improved" focusing screen ki ndly post your thoughts. I have found that retailers will special order the scr een for me but will not be happy if I want to give it back to them. Thanks
If you have used the Beattie Intenscreen, or other "improved" focusing screen ki ndly post your thoughts. I have found that retailers will special order the scr een for me but will not be happy if I want to give it back to them. Thanks
Midwest Photo was running a special on Linhof's latest bright screen, so I got one for my Technika. It's much brighter than the old Fresnel, but the one centimeter square grid on the glass overlay drive me crazy, and I'm not so sure that it's easier to focus.
The Intenscreen is just a fresnel lens with the characteristics of a fresnel exaggerated. I have used a fresnel lens and was unhappy with it because it makes focusing in the corners difficult. When I moved the loupe to a corner, the image would go dark. This should be even worse with the Intenscreen. An Interscreen should be good with a medium or small format camera, when one's eye is always looking at the screen from the center.
About a year ago I put a Maxwell Optics Fresnel screen in combination with a Boss screen. I always liked the Boss screen for it's nearly grainless aspects, but it's not very bright especially with wide angle lenses. With a Boss screen you can effectively use a much more powerful loupe for focusing. The resulting combination is great! because I placed the fresnel between the Boss screen and the lens, I had to adjust the depth placement of the Boss screen in order to maintain proper focus.
It might be useful to know more about what exacty you will do with the screen. Is this to replace an existing one? What camera? Was that camera designed to use a Fresnel? Will you be installing this in front of or behind the gg? These are all important things to know if you want to add a Fresnel and still get sharp negatives!
Putting a fresnel between the lens and ground glass will cause a curvature of field that cannot be corrected by adjusting the distance of the ground glass. Light is displaced 1/3 the thickness of the fresnel. When light passes through the fresnel at an angle (which occurs with all lenses, but especially with wide angles), there is a curvature of field. The light that passes through at a steep angle goes through a greater thickness of the fresnel and is, therefore, displaced more than light that passes straight through the fresnel. This curvature of field is slight enough to go unnoticed, but critical people may want to place the fresnel over the ground glass or not use one at all.
Arnold, Although I have not used one, Ebony offer a wide angle fresnel screen that fits most makes, and is supposed to be a great improvement. I know someone who replaced the screen on his new Wisner 54 expedition with one and he is very pleased with it. Regards Paul
Arnold I use the Ebony WA fresnel that Paul has just mentioned. I've sandwiched it between the focusing screen and protective glass and it rearly delivers excel lent viewing with even very wide angle lenses such as the 35 Apo Grandagon. I wa s told it is only usable up to the 90m focal length but I've used it with a 135m m lens and its fine. I purchased this fresnel from Robert White UK for #50( about $75). Trevor.
Arnold,
I recently compared four screens in my Linhof Technikardan 4x5: 1) originl ground glass, 2) Linhof Superscreen, 3) Boss screen, and 4) Beattie Intenscreen. The Superscreen was quite bright and snappy overall, but I found it difficult to check corners with a loupe on 90mm views because of fresnel ring interference, and the standard ground glass was very dark, somewhat grainy and had a prominent hot spot with wide angles. Initially, the Beattie seduced me with it's incredible brightness--no dark cloth needed much of the time, and the easiest viewing in low light. I bought it, used it, then returned it because of three problems: 1) critical focusing was very, very dificult because of a lack of fine detail--focusing with a loupe revealed a mushy image with no snap, 2) moving my eye off-axis quickly blackened out the image, and 3) after getting several soft chromes I tested further and discovered the Beattie was 2mm off in correct plane alignment in my TK when compared to the original ground glass. The Boss screen did not impress me on first viewing, but after having used one now for 3 months I can say that my search for a good screen is over. The Boss is not super bright, but plenty bright enough when used with a decent darkcloth, but the best qualities are evenness of illumination across the screen, and the finest resolution of detail I have ever seen on a 4x5, making it an absolute joy to precisely focus any lens with a georgeous 5x Mamiya loupe. I am now getting the sharpest chromes ever from my Rodenstock APO-Ronar 480mm because of the accuracy and resolution of this screen.
Just my own personal experience, but hope it helps.
Regards, Ross
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