mckay3d
21-Jun-2013, 15:19
After acquiring a used Tachihara 4x5 field camera I noticed that it just had a plain ground glass focusing screen. So before I shot any film I read up on it and found that Tachiharas came with a ground/matte Fresnel screen and a clear glass cover plate. Ok, I ordered a set ($99) and when I installed it per the directions (matte/GG toward lens and Fresnel toward eye with cover glass on top of that). Two test shots showed that it was focusing sharply on objects closer than what I focused on in the camera! So I checked the film holder with film and it was in spec. at .186". (That specification is .197 plus or minus .007" without a sheet of film.) Then I checked the distance in the camera to the matte surface of the focusing screen and came up with a whopping .049" difference ! ( I used a Brown & Sharpe depth micrometer.) How could this be? So then I noticed that the plastic GG/Fresnel screen bowed in toward the lens and measuring at the sides of the camera back the measurement was still off about .035" off. I know I can shim the focusing screen so that focusing in the center would be within specifications but it does bother me that the screen is not flat. I will contact the seller of the screen to find out if my problem is unique.
So, after that fairly long discourse (or rant, if you prefer) I would like to hear if any other 4x5 field camera users have had similar problems. Any comments or suggestions would be greatly appreciated.
Maurice
So, after that fairly long discourse (or rant, if you prefer) I would like to hear if any other 4x5 field camera users have had similar problems. Any comments or suggestions would be greatly appreciated.
Maurice