About the stock lens at DVinfo.net

Melvin Torrens · October 2nd, 2006, 04:05 AM

I have the JVC GY-HD101E with the Fujinon lens that comes with the cam.

I'm new to cameras and so on and i've been wondering if there's some problem with my lens... When I adjust the focus ring my framing changes (slightly zooms in and out) is this normal ?

Antony Michael Wilson · October 2nd, 2006, 04:22 AM

Yes, it's annoying but also normal. It's called 'breathing' and is common/more obvious with lower cost zoom lenses. It's pretty bad with the stock 16x lens on the HD100.

I'm more of an editor than a camera person so perhaps someone else could give a proper explanation of why breathing occurs etc, etc...

Stephan Ahonen · October 2nd, 2006, 05:45 AM

It's the same thing that happens when you take a magnifying glass and move it closer and further from your face to get something in focus. At the same time the subject gets bigger and smaller in the glass, because the focal length is changing. A zoom lens is just a very complicated magnifying glass, the focus is basically moving the "image" backwards and forwards relative to the focal plane to get whatever you want in focus and the focal length changes as a result.

Burk Webb · October 2nd, 2006, 12:32 PM

A trick to get around this is to use the macro focus ring for rack focus stuff.

Melvin Torrens · October 2nd, 2006, 01:06 PM

Thanks alot for the quick and helpfull reply.

October 2nd, 2006, 04:05 AM	#1
Melvin Torrens Regular Crew Join Date: Apr 2006 Location: Spain Posts: 46	About the stock lens I have the JVC GY-HD101E with the Fujinon lens that comes with the cam. I'm new to cameras and so on and i've been wondering if there's some problem with my lens... When I adjust the focus ring my framing changes (slightly zooms in and out) is this normal ?

October 2nd, 2006, 04:22 AM	#2
Antony Michael Wilson Major Player Join Date: Sep 2005 Location: London, UK Posts: 343	Yes, it's annoying but also normal. It's called 'breathing' and is common/more obvious with lower cost zoom lenses. It's pretty bad with the stock 16x lens on the HD100. I'm more of an editor than a camera person so perhaps someone else could give a proper explanation of why breathing occurs etc, etc...

October 2nd, 2006, 05:45 AM	#3
Stephan Ahonen Major Player Join Date: Apr 2005 Posts: 512	It's the same thing that happens when you take a magnifying glass and move it closer and further from your face to get something in focus. At the same time the subject gets bigger and smaller in the glass, because the focal length is changing. A zoom lens is just a very complicated magnifying glass, the focus is basically moving the "image" backwards and forwards relative to the focal plane to get whatever you want in focus and the focal length changes as a result.

October 2nd, 2006, 12:32 PM	#4
Burk Webb Major Player Join Date: Mar 2005 Location: Portland, Oregon Posts: 249	A trick to get around this is to use the macro focus ring for rack focus stuff.

October 2nd, 2006, 01:06 PM	#5
Melvin Torrens Regular Crew Join Date: Apr 2006 Location: Spain Posts: 46	Thanks alot for the quick and helpfull reply.