Questions about Mamiya Press 65mm lens

[Barry S]

I just received a Mamiya Press 65mm lens and if any of you have experience with this lens--I have a couple of questions. Does the aperture open completely when the lens is wide open? On my lens, when the aperture is opened to f/6.3, the iris blades don't open to the full round diameter of the lens elements--they stop short and form a pentagon--is this normal?

The helical is also very stiff. I imagine the grease has dried out and needs to be replaced. Has anyone ever disassembled the 65mm (or other) helical, cleaned, relubed, and successfully reassembled it? Thanks.

Barry

 

[hpulley]

I've noticed on some of my Mamiya RB67 lenses that wide open is actually stopped down a bit when I press the DOF preview lever or dry fire them. I thought this a bit odd but never asked anyone about it... I have a 65mm but the old RB67 65mm Sekor may be a completely different beast to the Press version.

 

[j_landecker]

Yes, this is normal. Although the aperture can potentially open wider, Mamiya apparently deemed the performance wider open than f6.3 not up to par, so the opening is limited by a stop on the aperture mechanism.

 

[Barry S]

Thank you both. I've been having less than stellar luck with my used equipment purchases lately and that's one less problem to worry about.

 

[j_landecker]

Enjoy it - I find the 65mm to be a very nice lens!