| Author |
Message |
    
Wernerjb
Tinkerer
Username: Wernerjb
Post Number: 180
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 14, 2007 - 09:25 am: | 
|
On restoring run down SRTs (as usual I prefer the banged-up ones) I discovered differences in the flange-film distance of various specimen of Minolta SLRs (usually it is 43.7mm). I have not taken any photos with any of these cameras, but I know that misalignment inevitably results in sharpness problems. If prism and mirror in the viewfinder are properly adjusted you won't probably even notice that when focussing.
In my understanding all cameras of one manufacturer should be identical, otherwise interchangeable lenses could not be used, so the question is if it was possible that those SLRs were produced like that or are those different distances (in the order of 0,05mm!) due to heavy use perhaps (although alignment screws were tight and still looked like new, no scratches or worn-out crossheads)? |
Don
Tinkerer
Username: Don
Post Number: 22
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 14, 2007 - 10:18 am: |
|
Minolta made 2 different lens mt. flanges - 1 was 4.1 mm thick & the other was 3.9. You are correct in the flange/focal distance of 43.7mm. There are 4 adj. screws accessible thru the front plate. A 10 deg . rotation will raise/lower approx. 0.03mm. Don't touch the screw next to the mirror lock button as you can distort the front plate.
Don |
Wernerjb
Tinkerer
Username: Wernerjb
Post Number: 192
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 24, 2007 - 04:28 am: |
|
I'm a bit "out of focus" at the moment, as I have been trying to follow Rick Oleson and Mick Feuerbacher's infinity focus alignment method, but ...
... the camera although properly aligned according to what the dial gauge says does not show sharp pictures on a translucent ground glass in the film window.
Is there any reasonable explanation for this? |
Wernerjb
Tinkerer
Username: Wernerjb
Post Number: 193
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, October 01, 2007 - 12:13 am: |
|
Has anybody here ever gathered experience in adjusting both prism AND focal distance (which is a must after a complete overhaul) and is willing to share their knowledge? |
Hovaness
Tinkerer
Username: Hovaness
Post Number: 45
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, October 01, 2007 - 07:14 pm: |
|
Are you sure that the lense with which you are testing is properly set for infinity focus? You need to test with a known good lens. |
Wernerjb
Tinkerer
Username: Wernerjb
Post Number: 194
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, October 02, 2007 - 03:38 am: |
|
Yes, the lens on the camera to be tested and the one on the testing camera are both fine, and I have excluded all other distorting factors, thanks for your input though, W.
Problem is that the camera actually is a "compilation model" made from surplus junkers' parts. What is called "body back adjustment" in the repair manual (of the SR-T 101 etc.) is a bit tricky in practice as there are four adjustment screws on the lens carrier plate for the flange-film distance and another one for parallelism of that plate. I have all the necessary tools, but only theoretically everything is just fine. It is either the measured distance that is o.k. or the picture on that makeshift ground glass. What troubles me is that both should produce identical results, namely a sharp image, but unfortunately that is not the case, and I do not know why. |
Wernerjb
Tinkerer
Username: Wernerjb
Post Number: 197
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 04, 2007 - 11:07 am: |
|
Problem solved with the help of Don and Glenn, cf the other SRT thread, thanks, W. |
