Instructables

Does A Mechanical Iris's Cam Wheel Size Matter?

I would like to know if a Mechanical Iris's Cam Wheel Size dictates how much the shutters close.  Please and thanks.

frollard3 years ago
A bit:

If the cam section doesn't allow the shutters to move outside the outer diameter of the assembly, you're limited by the number of shutters and the ratio of the inside to the outside diameter of the cam area.

If the iris is free to move outside that area, then you can have shutters whatever size/shape you need to have the iris close completely or open completely.
iceng3 years ago
I make several assumptions here ;
  • You are talking about a camera lens
  • Diameter is what you mean with Size
  • Mechanical Cam is a euphemism for manual adjust.
  • shutters does not mean the actual focal plane light shutter
The size does not determine the smallest closure ( biggest F/Stop value ).
The larger opening diameter can be a good determination of the lens speed.
This may put you on track after you read and understand.

A