CA and extenders at DVinfo.net

Paul Gale · November 11th, 2007, 07:42 AM

I'm still pondering what lens I should be getting with my eventual purchase of an F355. Not simple as I also have remote focus and zoom for some conference work (which would also need upgrading if changing from my current Fuji to Canon lens).

I currently use a 570 with a cheaper Fuji A13x6.3BERM-SD. At full zoom and in high contrast situations (like a conference stage with presenter against projector screen etc), I notice fairly extreme CA. This is all without the extender in. TBH I rarely use the extender as the DOF is so shallow, it makes focussing very difficult with my remote focus control.

So my question is - I've heard people say that CA is more likely/apparent with extenders - but is this true when using AND not using the extender?

I'm also wondering what kind of difference I will notice between my current camera and lens and the F355 and a good quality lens like the KH21ex5.7 IRSE?

Thanks,

Paul.

Alister Chapman · November 11th, 2007, 07:59 AM

CA is usually much more pronounced when using an extender. When the extender is not used there is normally less CA. Most lenses are optimised for use without the extender. I don't really like extenders, they are useful for increasing the focal length but the loss of light and other optical abberations they introduce can be harsh. HD is unforgiving of lenses and will show up any issues much more quickly than SD.

Paul Gale · November 11th, 2007, 08:00 AM

Thanks Alister.

What lens(s) do you have for your XDCAM camera?

November 11th, 2007, 07:42 AM	#1
Paul Gale Major Player Join Date: Feb 2004 Location: Oxfordshire, UK Posts: 425	CA and extenders I'm still pondering what lens I should be getting with my eventual purchase of an F355. Not simple as I also have remote focus and zoom for some conference work (which would also need upgrading if changing from my current Fuji to Canon lens). I currently use a 570 with a cheaper Fuji A13x6.3BERM-SD. At full zoom and in high contrast situations (like a conference stage with presenter against projector screen etc), I notice fairly extreme CA. This is all without the extender in. TBH I rarely use the extender as the DOF is so shallow, it makes focussing very difficult with my remote focus control. So my question is - I've heard people say that CA is more likely/apparent with extenders - but is this true when using AND not using the extender? I'm also wondering what kind of difference I will notice between my current camera and lens and the F355 and a good quality lens like the KH21ex5.7 IRSE? Thanks, Paul.

November 11th, 2007, 07:59 AM	#2
Alister Chapman Inner Circle Join Date: Dec 2005 Location: Bracknell, Berkshire, UK Posts: 4,957	CA is usually much more pronounced when using an extender. When the extender is not used there is normally less CA. Most lenses are optimised for use without the extender. I don't really like extenders, they are useful for increasing the focal length but the loss of light and other optical abberations they introduce can be harsh. HD is unforgiving of lenses and will show up any issues much more quickly than SD. __________________ Alister Chapman, Film-Maker/Stormchaser http://www.xdcam-user.com/alisters-blog/ My XDCAM site and blog. http://www.hurricane-rig.com

November 11th, 2007, 08:00 AM	#3
Paul Gale Major Player Join Date: Feb 2004 Location: Oxfordshire, UK Posts: 425	Thanks Alister. What lens(s) do you have for your XDCAM camera?