Spanik
Well-known
I have a Mamiya 65/6.3 in Seikosha-S shutter, 5-digit serial number, made on the 29 may 1967 according to the garantee card. It had a frozen shutter (mechanism ran but blades didn't move) that I managed to free with some patience and alcohol.
But my problem is the diaphragm. I doesn't seem to open completely but covers about half of the lens opening when at f/6.3. Otherwise it is smooth.
Now I looked on the net and found examples of both diaphragms that are half-closed and those that are fully open when set at f/6.3. Can someone enlighten me?
How can I check if it is OK without taking it apart? Tought of using the ground glass and a lighted background and then meter (using a spot meter) on the glass with the 65 set at f/6.3 and the 90 set at f/6.3. My take was that if both give the same reading the diaphragm is ok. Sound reasoning?
But my problem is the diaphragm. I doesn't seem to open completely but covers about half of the lens opening when at f/6.3. Otherwise it is smooth.
Now I looked on the net and found examples of both diaphragms that are half-closed and those that are fully open when set at f/6.3. Can someone enlighten me?
How can I check if it is OK without taking it apart? Tought of using the ground glass and a lighted background and then meter (using a spot meter) on the glass with the 65 set at f/6.3 and the 90 set at f/6.3. My take was that if both give the same reading the diaphragm is ok. Sound reasoning?
oftheherd
Veteran
I have never seen but two, and both are as you describe.
charjohncarter
Veteran
My 65mm does not open all the way either.
Spanik
Well-known
Thanks! Feel relieved I don't have to delve deeper into it. Going to try it out this weekend then.
oftheherd
Veteran
Hope you will show us some photos.
Spanik
Well-known
I'll try if there is something to be shown 
The idea was to also develop for the first time myself without anyone around to hold my hand.
The idea was to also develop for the first time myself without anyone around to hold my hand.
oftheherd
Veteran
I'll try if there is something to be shown
Easier than you think. If you do run into difficulties and don't know what happened, don't hesitate to ask questions.
ColSebastianMoran
( IRL Richard Karash )
The 65mm lens is known for the iris not opening all the way.
I read someplace of a guy who modified his lens to open further, trying for a faster lens, but it's probably the way it is for a reason.
I read someplace of a guy who modified his lens to open further, trying for a faster lens, but it's probably the way it is for a reason.
RBruceCR
Well-known
My 65/6.3 Mamiya Sekor doesn't open all the way! And it's an awesome lens too!
https://www.flickr.com/photos/rbruce63/14981456842/
And
https://www.flickr.com/photos/rbruce63/14978719241/in/photostream/lightbox/
And
https://www.flickr.com/photos/rbruce63/14981477212/in/photostream/
And
https://www.flickr.com/photos/rbruce63/14795131460/in/photostream/
This one with a small light leak which is from the lens release button. I thought it was repaired, but the leak is solved with black tape. I wanted to include the road signs as per Walker Evans delight! But the Edificio Solera is very nice despite all the telephone and electrical wires!
The film is Rollei Retro 80S shot as 6 X 9.
Enjoy your lens! I wish I knew how to paste the pictures here!
https://www.flickr.com/photos/rbruce63/14981456842/
And
https://www.flickr.com/photos/rbruce63/14978719241/in/photostream/lightbox/
And
https://www.flickr.com/photos/rbruce63/14981477212/in/photostream/
And
https://www.flickr.com/photos/rbruce63/14795131460/in/photostream/
This one with a small light leak which is from the lens release button. I thought it was repaired, but the leak is solved with black tape. I wanted to include the road signs as per Walker Evans delight! But the Edificio Solera is very nice despite all the telephone and electrical wires!
The film is Rollei Retro 80S shot as 6 X 9.
Enjoy your lens! I wish I knew how to paste the pictures here!