C100: Example of "fine" iris adjustment

A

aly324

Well-known member
I'm curious about how "fine" the 1/8th-stop iris adjustment on EF lenses is, but haven't been able to find a video explicitly of such. If someone could point me to one I'd be much obliged.
 
Well since there doesn't seem to be any thing already out there I shot a little test for you.

https://vimeo.com/68558850

The first one is going from f4 to f22 click by click using the little iris wheel on the grip. Now one thing I noticed is that between the changes that you can actually see there are 1-2 extra clicks that don't seem to actually do anything to the iris. So it looks like every 3 clicks of the iris wheel on the grip makes a change of the iris (if that makes sense).

The second test is a Rack Iris. Basically I quickly raked my finger across the iris wheel. I guess my fingers are very long because I can't go from wide open to closed in one pass. I can get down to about f16 before I run out of finger haha.

Hopefully this helps at all. If there is anything you want to see specifically just let me know.
 
Thank you very much Tim! Exactly what I needed. It's quite smooth but still noticeably stepped.
 
I assigned the auto iris to the focus push auto button. A nice setting when you don't have your right hand on the grip.
This way you can focus and set the exposure with the same hand...almost at the same time.
 
Ive never found these lenses to have a usable iris adjustment through a shot. A manual iris with an aperture pull will be far cleaner.
 
Of course I never adjust the iris during the shot, i set my exposure before to shoot.
That is the problem with the C100 (and DSLRs) , the stepped iris. That's the thing I miss from my Z5...With the C100, impossible to film someone you interview in a car and pan from the road to the face. Unless you have a convertible.
 
There's still the option to use a Vari-ND to 'ride the iris' in situations like 'partly cloudy' conditions. Cheaper than getting your lenses de-clicked.
 
De-clicking a lens is sort of like 'taking it to the vet...' - the lens is taken apart, the spring and ratchet mechanism that makes the iris click into certain f-stops is removed or modified, so you get a smooth iris progression from wide open to almost closed. Usually there's a 'damping' mechanism fitted so the iris requires a little effort to turn, rather than just spinning round. Sublime feel and control, but the camera will not be able to control it, the lens becomes 'fully manual'.

The chap I've used is Eddie Houston, aka 'The Lens Doctor' - http://www.thelensdoctor.co.uk/
 
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