Why is my aperture changing when zooming? at DVinfo.net

Taj Jackson · August 5th, 2007, 05:41 PM

I don't know if this is normal or not or if there is any way to combat it with the A1. When I am completely zoomed out, I can open up the aperture all the way to 1.6 in manual mode. But as soon as I start zooming in, the aperture also starts closing up and the aperture number begin to slowly increase. Why won't it just stay where its at? I am trying to keep it wide open for my 35mm adapter, which I need to zoom in to.
Thanks in advance.
Taj

Rene Roslev · August 5th, 2007, 05:44 PM

Copy/paste of my answer last time this issue was brought up:

The XH-A1 lens is not a constant aperture lens, which means maximum aperture changes with focal length. The lens is capable of f/1.6 at wide angle, but only f/3.5 at full telephoto. Annoying yes, but that's lens physics - a constant f/1.6 lens would be HUGE.

I've only had my A1 for 2 day, limited experience. But I think the solution is to predict the max. focal length required for the shot, note the maximum aperture associated with that focal length and manually selecting it for use through the entire scene.

Taj Jackson · August 5th, 2007, 05:56 PM

Thank you Rene!!!! that explains it all for me.

August 5th, 2007, 05:41 PM	#1
Taj Jackson Regular Crew Join Date: Sep 2004 Location: United States Posts: 46	Why is my aperture changing when zooming? I don't know if this is normal or not or if there is any way to combat it with the A1. When I am completely zoomed out, I can open up the aperture all the way to 1.6 in manual mode. But as soon as I start zooming in, the aperture also starts closing up and the aperture number begin to slowly increase. Why won't it just stay where its at? I am trying to keep it wide open for my 35mm adapter, which I need to zoom in to. Thanks in advance. Taj

August 5th, 2007, 05:44 PM	#2
Rene Roslev Regular Crew Join Date: Apr 2007 Location: Copenhagen, Denmark Posts: 49	Copy/paste of my answer last time this issue was brought up: The XH-A1 lens is not a constant aperture lens, which means maximum aperture changes with focal length. The lens is capable of f/1.6 at wide angle, but only f/3.5 at full telephoto. Annoying yes, but that's lens physics - a constant f/1.6 lens would be HUGE. I've only had my A1 for 2 day, limited experience. But I think the solution is to predict the max. focal length required for the shot, note the maximum aperture associated with that focal length and manually selecting it for use through the entire scene.

August 5th, 2007, 05:56 PM	#3
Taj Jackson Regular Crew Join Date: Sep 2004 Location: United States Posts: 46	Thank you Rene!!!! that explains it all for me.