Stock Wisner screen

[Jim Rice]

Okay, so I don't have any problems focusing with my stock Wisner focusing screen (4x5 Tech, s/n 120x). Composing with the 90/6.8 Grandagon could be easier. I also aspire toward a 65/8 SA. So, should I just leave well enough alone, or go for an enhanced screen? If I were to try an enhanced screen, the leading canidates would be the Maxwell and Bosscreen. This seems to be the most voodoo laden subject on the planet. If anyone has any direct experience with these options I would appreciate your input.

[Gem Singer]

Hi Jim,

When I owned a 4x5 Wisner Tech, several years ago, I asked Ron Wisner about adding a Fresnel. He stated that he did not believe that a Fresnel could improve my focusing ability. However, at my insistance, he did send me an expensive removable plastic Fresnel. It attached on the top of the ground glass with brass clips. After using it, I began to agree with Ron. It did not solve my focusing problems. Eventually, the removable plastic Fresnel self- destructed, and I tossed it.

If was attempting to improve on my Wisner focusing screen today, I would replace the groundglass with an inexpensive Satin Glass screen. I would also use a Harrison Silver Classic dark cloth, and a high quality focusing loupe.

[Gem Singer]

Sorry Jim, that's a Satin Snow groundglass.

[Brian Vuillemenot]

Hi Jim,

I have to disagree with Eugene. I had a lot of difficulty focusing on my Wisner 4X5 TF with just the ground glass. I obtained a permanent fresnel from Wisner, that screws in place, and it is a vast improvement- much more evenly lit. The "hot spot" on a ground glass drives me crazy! The fresnel does have the problem of annoying rings if you look at it from an angle, but I greatly prefer it to just the ground glass. I haven't tried bossceens, maxwell screens, or any of the other devices, so I can't comment on them, but an inexpensive fresnel will lead to a much more evenly illuminated image on the ground glass.

[Gem Singer]

Hello again Jim,

Perhaps I should add that since the time I owned a Wisner Tech field, I have owned six other cameras. Each one came equipped with a factory installed Fresnel brightening screen. The Fresnel on both Toyo field cameras is installed between the lens and the groundglass (under). The Fresnel on the Ebony and all three Tachiharas is installed on top of the groundglass, with a thin gridded cover glass for protection. No problems. I enjoy using with them. They make composing and focusing a lot easier.

However, if you are planning on replacing your standard Wisner groundglass with a Maxwell or Bosscreen, you need to be careful to make certain that the focal plane ends up in the same place as it did with the original groundglass. That may require shimming or shaving the groundglass frame. That's why I recommended the Satinsnow. As long as the ground surface of the Satinsnow is placed in the same plane as the Wisner's ground surface, the installation is simple to do yourself.

[Brian Ellis]

I've used Fresnels (the ones that came as original equipment with Ebony and Tachihara cameras), add-on Fresnels (a Beatttie), a Linhof plain ground glass, and the BosScreen . My personal preference is the BosScreen. It isn't technically a "bright" screen in the sense that it doesn't actually make the image brighter on the ground glass but it spreads the image out evenly across the entire ground glass so that it appears brighter and makes it a lot easier to compose, especially with wide angle lenses, than a plain ground glass. In addition, because it doesn't have the lines of a Fresnel I find it much easier to focus than a Fresnel, very similar to a plain ground glass in that respect. It seems to me to combine the best of both a Fresnel and a plain ground glass. Since there is a layer of wax inside I'm told that there can be problems with the BosScreen in extreme heat or cold. I never used mine in extreme cold but I never had a problem using it in the heat and humidity of Florida summers.