Since I am in my late 50s and my eyesight isn’t as good as it once was, I have read with great interest all of the many discussions in this forum (and the other LF forum on a different server) concerning using specialized focusing screens.
It seemed to me while I read through these comments that there were three basic types of focusing screens being discussed – Fresnels, screens from manufacturers that create special kinds of frosted or ground glass surfaces, and “sandwich” types that put wax or a wax-like substance between two pieces of glass. There were also variations in which, for example, a special frosted glass screen was combined with a Fresnel lens.
It also seemed to me that there were basically three sources of such screens – those made by third party manufacturers such as Maxwell and Satin Snow, those sold with cameras or by camera manufacturers such as the Linhof Super Screen or Wisner Fresnels, and those created by individual photographers using a variety of techniques, but very often by purchasing Fresnel lenses not made specifically for use with a camera and adapting them. (This is not to mention those intrepid photographers who grind, sand blast, acid etch, or Vaseline their own!)
To assist newcomers to LFP like me who may be interested in learning more about this kind of product, I’ve pasted some URLs below as a starting point. (I am quite sure that these are not exhaustive of the field.)
There is no URL for the Velveteen View Screen so I’ve left the inventor’s email address instead with his permission. He has indicated he'd be happy to send anyone who is interested more information about his product. I’ve also posted the email address of Bill Maxwell because the Maxwell URL listed is “unofficial.” I am not sure if “BossScreen” is the same product as “BosScreen” but I suspect it is. Both are mentioned in comments on this forum but I couldn’t find a URL for “BossScreen,” only for “BosScreen.”
If you know of a good source of focusing screens that I’ve left out please add it in your comments.
FOCUSING SCREENS MADE BY THIRD PARTY MANUFACTURERS
Maxwell Precision Optics UNOFFICIAL website
Maxwell Precision Optics
Contact Bill Maxwell <email@example.com>
Velveteen View screen
Contact Greg Garret <firstname.lastname@example.org>
EXAMPLES OF FOCUSING SCREENS MADE/SOLD BY MANUFACTURERS FOR THEIR CAMERA
Ebony Fresnel Lenses
Canham Fresnel Lenses
Linhof Super Screen
Sinar Fresnel Lenses
Wisner Fresnel Lenses
Wista Fresnel Lenses
EXAMPLES OF GENERIC FRESNEL LENS THAT CAN BE ADAPTED FOR USE AS A FOCUSING SCREEN WITH A CAMERA
One final comment: In reading the various reviews, opinions and comments about these products I found a lot of concern about how their use would effect focus. Since I ended up buying a Maxwell based on what I saw as a slight preponderance of positive reviews for his screen, I thought I should check with Bill Maxwell about this issue. He wrote back:
“The focusing surface of your new screen faces the lens of the camera. The Fresnel is on the backside of the screen and therefore has absolutely no effect on the original focus. That reference that you mentioned is only valid if there is a Fresnel (or other clear element) in front of the focusing surface (on the lens side), which would change the optical path length. A compensation would have to be made if a classic 'ground glass / Fresnel sandwich' was used as a focus screen. My screen is a modern 'one piece' focus screen with a clear cover glass on the backside and focuses at exactly the same focus plane as a plain ground glass. You may want to pass this information on to some of the groups to correct this misinformation that passes for knowledge on the Internet.”