Wista Focus Screen Orientation

BillMar · Post by **BillMar** » Fri Feb 13, 2009 9:14 am Etc/GMT-1+01:00

Hi All,
I have a Wista DX III that I bought second hand about 12 months ago.
I have not been totally happy with sharpness even in landscapes but recently I did some still life shots that were decidedly fuzzy even though I used a loupe to focus. The lens was a 150 mm Symmar S that gives sharp images on my Arca Swiss monorail.
Last night I was reading up on film holders and now understand that the 'standard' depth is 5 mm with a small tolerance. I checked my focus screen and it is 5 mm from the camera back face BUT to the Fresnel side not the ground side. I understand that you focus on the ground side of the screen. That would put it out by the thickness of the screen.
Looking closely at the screws holding the screen in place it looks like they have been removed at some stage, small scratches on them and one missing.
I am now wondering if the ground glass has been out at some stage and replaced the wrong way round by the previous owner.
If anybody has one of these cameras can you please tell me if the ground glass side or the Fresnel side faces the lens? My thoughts are that it should be the ground side.

Any comments or help appreciated.

IanG · Post by **IanG** » Fri Feb 13, 2009 12:02 pm Etc/GMT-1+01:00

My Wista 45 DX has an all in one screen/fresnel, it's very bright and accurate.

If you remove the screen mine has a thinner protective clear acetate or similar piece on the outside with the grid lines on, then the all in one sreen/fresnel.

It's possible someone has replaced the screen etc on your Wista, the best people to ask are Teamwork, in Foley Street, London as they are the importers.

Ian

BillMar · Post by **BillMar** » Fri Feb 13, 2009 1:43 pm Etc/GMT-1+01:00

Thanks Ian.

Mine appears to be an All-in-one so if I turn it over the Fresnel will be exposed. One thing to consider is possible damage, however compared to fuzzy images that is a small problem.

BillMar · Post by **BillMar** » Fri Feb 13, 2009 6:42 pm Etc/GMT-1+01:00

Just an update. I turned the screen over and used a piece of unexposed but processed film to protect the Fresnel in the short term.
I shot a sheet of newspaper before and after turning. To the naked eye there is no difference but when enlarged to 16" x 20"in the enlarger there is a marked difference in sharpness and clarity especially in the small print.
So it looks like I have been using an incorrectly assembled camera for the last 12 months.
That's another excuse blown for producing unsharp images.