Help Quick!

UncleBenji1977

UncleBenji1977

Well-known member
I just received a 2x telephoto lens for my DVX... I screw it on, and I have a big circle vinetteapalooza! I hate it and I want it to go away! Does anyone know how i can get to a normal look???? Please help, I need to shoot soon.



- Uncle Benji
 
I almost have to zoom all the way in, and then focus is an issue.... Is there anything else i can do? I didn't even think i should be seeing this period.
 
The cheap 2x teleconverters from Digital Optics/Crystal Optics/Crystal Vision are completely useless with the DVX.

The only teleconverter that actually works is the Century Optics 1.6x. Even then you can get severe vignetting if you zoom out wider than about Z60.
 
Bill Turner, Century Division, Schneider Optics here:

On a zoom lens with a significant wide angle capability it is somewhere between impossible and impractical to make a tele- attachment of reasonalble power ( 1.5X to 2X) that will not vignette.

The size of the optics that would allow using the wide portion of the lens without vignetting would be huge, which equals very heavy and very expensive.

The normal practice is to design them so that you can use the tele half of the range, maybe a bit more or less. This practice is followed by Canon and Fuji on their teleconverters for broadcast lenses as well.

Making a high quality telecoverter is difficult and the larger and longer the lens it will be used on, the more difficult it is to make. This is the reason that our smaller Tele's for cameras like the Canon GL1/2 and Sony VX2000/2100 , PD150/170 are 2X and those for larger camera lenses like the Panasonic DVX100/100a/100b and Sony HDV camera's are 1.6X.

I have not seen in 2x units that I thought gave satisfactory results on these larger cameras.

The vignetting or "port hole" that occurs as you zoom wide is simply a fact of life, if you need a wider shot you must remove the Tele-converter.

Cheap units are typically too small to avoid vignetting at all but the maximum focal length and even then may show significant darkening (illumination fall off) at the edge as well as limit the speed of the lens (the lens alone is F2.8 but the tele stops it down to 4 or 5.6)

A properly designed unit like our 1.6X maintains the f number of the camera lens telephoto position so that the exposure is the same with and without the unit. This requires making the elements rather large, which makes them much more expensive to manufacture.

Bill Turner
 
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