View Full Version : Ground glass / fresnel configuration in Cambo

29-Dec-2006, 04:27
Hi. I recently bought a Cambo 4x5 (SC I believe) so I thought I'd join this forum. Think it could be very helpful. Short intro of myself: My name is Willem, I live in the Netherlands (but will move to Montreal in two months.) I am a photography student and will graduate in february. WIth my newly acquired Cambo I would love to take architecture and 'city-scapes'.

My first question to the experts here. I am looking at the foucussing screen of my Cambo and I see three layers of glass. The one closest to the lens has the well knows fresnel structure. The actual focussing screen says 'Bosscreen' which explains the other two layers of glass. I was thinking a Bosscreen was not supposed to be resting on a fresnel? So my next thought was: is a Cambo designed to have a frensel between the ground glass and the lens?
Also, when I take out the fresnel, the sheet of glass of the Bosscreen which is closest to the lens, is not small enough to fit in "the hole" of the back, so the tape of the Bosscreen is not resting on anything. But then, this may be the right configuration if the Cambo was designed to have that fresnel between the focussing screen and the lens, because then the small sheet of the Bosscreen is replacing the thickness of the fresnel (assuming it actually is of the same thinckness....)

I find all these things rather confusing...

29-Dec-2006, 04:43
Oops, I should have played a bit more before asking! I didn;t actually take the screen out. I was just looking at the screen and seeing that the Bosscreen was resting on the fresnel. But I just took the screen out and saw that it was not! On the sides of the screen where the tape is, the holder has two rims for the tape to rest on. The fresnel is slightly shorter and fits between these rims. So all is well. No need to worry about my Cambo anymore.
But still it was a usefull experience finding out anbout these two rims. Because it meant that I could take out the fresnel without moving the position of the Bosscreen. I did take out the fresnel and guess what? The screen became a million times as bright, sharp and easy to focus!