Manual Iris

Peter Rush · November 16th, 2011, 10:40 AM

Any tips on overriding Iris ramping on the Z1 or FX1? I've been using these cameras a while now but still unsure how the Iris goes 'auto' even when in manual at the full extent of the zoom

Cheers

Pete

Adam Gold · November 16th, 2011, 01:57 PM

It's a physical property of the lens and can't be overridden. It's physically impossible. The f-number is an actual physical ratio of the iris opening to the focal length. It's not "going auto." As the focal length increases, so does the ratio (f-number), even if the actual iris size stays the same.

Tom Hardwick · November 18th, 2011, 11:06 AM

Peter, if you lock the aperture at f/2.8 or smaller (down to f/11) then there will appear to be no lens ramping. Wherever you are in the zoom range it will be f/4 (or whatever you've selected) at the chips.

It's only when you're shooting at f1.6 to f/2.8 that you'll experience ramping. You can leave the gain on auto to hide the effects but I dislike doing this. We all do. When you talk about 'the iris going auto', is this what's happening?

Remember - if you don't see the iris, gain, shutter or w/bal displayed in the v'finder then that discipline is in auto.

tom.

November 16th, 2011, 10:40 AM	#1
Peter Rush Inner Circle Join Date: Nov 2008 Location: UK/Yorkshire Posts: 2,069	Manual Iris - sometimes not!!! Ramping? Any tips on overriding Iris ramping on the Z1 or FX1? I've been using these cameras a while now but still unsure how the Iris goes 'auto' even when in manual at the full extent of the zoom Cheers Pete

November 16th, 2011, 01:57 PM	#2
Adam Gold Inner Circle Join Date: Jan 2007 Location: Woodinville, WA USA Posts: 3,467	Re: Manual Iris - sometimes not!!! Ramping? It's a physical property of the lens and can't be overridden. It's physically impossible. The f-number is an actual physical ratio of the iris opening to the focal length. It's not "going auto." As the focal length increases, so does the ratio (f-number), even if the actual iris size stays the same. __________________ "It can only be attributable to human error... This sort of thing has cropped up before, and it has always been due to human error."

November 18th, 2011, 11:06 AM	#3
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	Re: Manual Iris - sometimes not!!! Ramping? Peter, if you lock the aperture at f/2.8 or smaller (down to f/11) then there will appear to be no lens ramping. Wherever you are in the zoom range it will be f/4 (or whatever you've selected) at the chips. It's only when you're shooting at f1.6 to f/2.8 that you'll experience ramping. You can leave the gain on auto to hide the effects but I dislike doing this. We all do. When you talk about 'the iris going auto', is this what's happening? Remember - if you don't see the iris, gain, shutter or w/bal displayed in the v'finder then that discipline is in auto. tom.