Mamiya 645 Question

Folks,

I've recently started using a Mamiya 645
w/ 80mm f/2.8 for piggyback photos. I
was surprised to find a fair amount of
coma with the lens working at f/4.0

Does anyone have experience with this?
Has anyone used the (faster) 80mm f/1.9 lens?

I'd prefer not to stop down higher than f/4.5
as that's where my prime focus refractor works.

Any experienced opinions on these lenses would
be welcome.

Thanks
Todd

Hi Todd,

I have both 80/2.8 and 80/1.9. It's true that 80/2.8 has noticable coma at F4. At F4, 80/1.9 does much better than 80/2.8. For me, the coma of 80/1.9 at F4 is negligible. Sometimes I even use 80/1.9 at F3.5.

Two pictures for your reference:
http://www.ifa.hawaii.edu/~wang/gallery/picutres/cassiopeia.html
http://www.ifa.hawaii.edu/~wang/gallery/picutres/scorpius-2003.htm
The first one is at F4 and the second one is at F3.5. There is a large picture in the second link. You can see how the coma is at F3.5.

Hope this helps.

Wei-Hao