Will a telephoto lens adapter ... at DVinfo.net

Maureen Futtner · May 17th, 2004, 12:38 PM

give me less depth of field and better ability to select focus? I realize adjust the aperture (less light, wider aperture), and zooming in helps make dof more shallow, but with my TRV-950, at full zoom, I haven't found a whole lot less dof. My idea is if I buy a tele-extender, I might have some more playroom along these lines. Is this true?

All thoughts welcome. Thanks.

Tom Hardwick · May 19th, 2004, 01:30 PM

When you add a teleconverter you are actually increasing the focal length of the zoom, but you're not decreasing its maximum aperture. Well, you are a bit because those three elements do absorb and scatter some light, but it's not really noticeable on such a low res 720 x 576 raster.

So say you fit a 2x converter to your TRV950. You now have an 86.4mm focal length with an f2.8 maximum aperture. You will indeed get noticeably less depth of field, but only if you move in tighter to your subject. Whereas before you might frame a head and see the background was ''too sharp'', now you can zoom in even tighter and get the background much softer.

But the big problem is the tiny size of those 1/5" chips, and in reality it means that it's pretty difficult to get small DOF. The best way is to use max aperture (but you're not told where this is with the silly bar chart in the v/f), max telephoto, closest focus and have the background as far away as possible. A bit restrictive, yes?

tom.

May 17th, 2004, 12:38 PM	#1
Maureen Futtner New Boot Join Date: Feb 2004 Location: San Francisco, CA Posts: 11	Will a telephoto lens adapter ... give me less depth of field and better ability to select focus? I realize adjust the aperture (less light, wider aperture), and zooming in helps make dof more shallow, but with my TRV-950, at full zoom, I haven't found a whole lot less dof. My idea is if I buy a tele-extender, I might have some more playroom along these lines. Is this true? All thoughts welcome. Thanks.

May 19th, 2004, 01:30 PM	#2
Tom Hardwick Inner Circle Join Date: Mar 2003 Location: Billericay, England UK Posts: 4,711	When you add a teleconverter you are actually increasing the focal length of the zoom, but you're not decreasing its maximum aperture. Well, you are a bit because those three elements do absorb and scatter some light, but it's not really noticeable on such a low res 720 x 576 raster. So say you fit a 2x converter to your TRV950. You now have an 86.4mm focal length with an f2.8 maximum aperture. You will indeed get noticeably less depth of field, but only if you move in tighter to your subject. Whereas before you might frame a head and see the background was ''too sharp'', now you can zoom in even tighter and get the background much softer. But the big problem is the tiny size of those 1/5" chips, and in reality it means that it's pretty difficult to get small DOF. The best way is to use max aperture (but you're not told where this is with the silly bar chart in the v/f), max telephoto, closest focus and have the background as far away as possible. A bit restrictive, yes? tom.