Understanding the bellows factor - mamiya C330

J Rollinger · Apr 22, 2009

My Mamiya C330f has a focus screen with markings and a needle so you can adjust the exposure for the bellows extension but i dont know how to make the correction. The marks are as follows - 1.5 - 2 - 2.5 - 3 I know this cannot mean 1.5 stops and up to 3 stops, can anyone help me understand how to adjust the exposure using those numbers?

Smudger · Apr 22, 2009

The numbers translate thus :
1.5 = +1/2 f
2 = +1 f
2.5= +1.5f
3 = +2 f

paul ron · Apr 22, 2009

Get the manual here...

http://www.butkus.org/chinon/mamiya/mamiya_c330s/mamiya_c330s.htm

J Rollinger · Apr 22, 2009

Smudger, Paul Ron, Thank you both for the info and the link to the manual!

Q.G. · Apr 23, 2009

Smudger said:
The numbers translate thus :
1.5 = +1/2 f
2 = +1 f
2.5= +1.5f
3 = +2 f

The steps are in 1/3 stops:

1.5x = +0.6 stop
2x = +1 stop
2.5x = +1.3 stop
and 3x = +1.6 stop

But when you can't set 1/3 stops, it indeed (almost) translates to the 1/2 stop list above.
Almost, because it would be 'closer' to round 1.6 down to 1.5, not up to 2.

grahamp · Apr 24, 2009

Bear in mind that on the C330 models you have to 'program' the lens focal length using the ring on the side control, otherwise the moving index marker will be off. It's a neat enough idea, but I sometimes think the basic scales on the 'simpler' models are just as effective.

benjiboy · Apr 24, 2009

There is also a plastic paralax correction plate that fits under the focusing hood to give correct index marks for the 55 and 65mmwide angle lenses

Understanding the bellows factor - mamiya C330

J Rollinger

Smudger

paul ron

J Rollinger

Q.G.

grahamp

benjiboy

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