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-   -   zoom-through? (https://www.dvinfo.net/forum/sony-trv950-pdx10-companion/23130-zoom-through.html)

Jim Schweer March 18th, 2004 12:26 PM

zoom-through?
 
Please help me understand "zoom-through" as regards wide-angle converters. I assume it means that the image stays in focus as the camera's lens is actively zoomed in or out. Would a converter that is not zoom-through, such as the .56 Tiffen favored in previous threads by Frank Granovski, produce a focused image at all fixed points along the camera lens's zoom range?

Thanks.

Jim S.

Frank Granovski March 21st, 2004 10:05 PM

Tom Hardwick would be the best to answer those.

For the 37mm thread size, the 2 best wides out there are the Raynox HD5000 and the Tiffen (37mm).

Jeff Donald March 21st, 2004 10:11 PM

Different manufactures apply different meanings to the term zoom through. Visually inspecting the product and testing it will insure if it meets your needs and expectations or not. Zoom through generally means that you can attach the adapter to your lens and zoom from the wide angle setting through the telephoto position. Non-zoom through adapter need to be set to the wide angle or telephoto position (on the camera) and then not zoomed by the camera controls.

Tom Hardwick March 22nd, 2004 01:42 AM

If I may add my interpretation of the ''zoom-through'' term. Fit a zoom through and you alter the focal lengths of the zoom. So if you have a 4 to 48mm 12x zoom and then you fit a 0.5x zoom through, you now still have a 12x zoom, but the focal length has been halved to 2 to 24mm.

I have a non zoom through 0.5X and when fitted to the above lens will give me a 2 to 10mm zoom, after which the image suddenly blurrs hopelessly, so much so that it can almost be used as an instant focus dissolve. Camcorders work with single element nonzoom throughs by using their very powerful close focusing abilities, and the closer focusing the camcorder, the more you can zoom with these 'non zoom throughs'.

Make sense? Know anyone who is pretty short-sighted? Ask to borrow their (negative element) eye-glasses, hold one lens in front of your cam, zoom to the wide-angle end and see what you see.

tom.


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