Minimum working distance of Angenieux 10mm

[Guest Owen Parker]

Does anyone know the minimum working distance of an Angenieux 10mm Retrofocus?

Or the min focus distance in C mount?

 

It's a 60 year old cine lens you could get for the Filmo so the data for the lens is hard to come by.

I've trawled the internet to no avail.

 

Any thoughts?

[Dom Jaeger]

It depends on the stop, and whether the back-focus of the particular lens is still correctly set. Normally a fixed-focus wide angle like that has the back-focus set so that the lens focuses close to the hyperfocal distance (about 10 feet) to give the maximum depth of field. I don't have the depth of field table but wide open your minimum is probably around 5 feet, getting closer as you stop down. If the back-focus is slightly out it will shift the depth of field range either closer or further away.

 

It actually also depends on your circle of confusion figure, which is simply a way of determining when something could be considered 'out of focus', ie how critical focus will be when the final image is viewed. A video destined for youtube for example needs a far less critical CoC than something that will be projected on a large screen. If you come across a depth of field table for the Angenieux 10mm it will most likely use the traditional CoC figure for 16mm format of 0.0005" or 0.015mm. Check out http://www.dofmaster.com/cinematography.html

 

In a pinch, simply unscrewing the lens a quarter turn (or more properly shimming it out a little) will shift the minimum focus closer.

 

[Guest Owen Parker]

Dom, much obliged.

 

Very useful link, thanks for that.