extension tubes

[michaelnotar]

i have an 150mm lens for my mamiya 645. i am considering extension tubes for closer focus, i would like to know which one to purchase, 12, 20 ,36mm.

if you can point me to any online caculators or know of any ways to calculate this, let me know.

any help appreciated.
thx

[MarkKay]

I am not sure about Mamiya but Hasselblad has a pamphlet that gives the exact information you want for each of the extension tubes individually or in groups for each lens. I would suspect Mamiya has something similar

[AndrewCassino]

Michael, The information you're looking for used to be on the Mamiya website but appears to be gone. You're lucky - I printed it out over 10 years ago and have kept it handy! Here are the close focusing distances for the 150mm lenses for each of the extension tubes:

#1 from 85.9" to 35.4" (.08 to .21 magnification)

#2 from 45.7" to 27.5" (.15 to .28 magnification)

#3S from 32.6" to 22.9" (.23 to .36 magnitication)

There is a note that says with the #3 "some vignetting may occur".

I have only needed the #1 for head and shoulders work.

Andrew

[michaelnotar]

much thanks andrew!