DV Info Net - Review of Sony VCL-HG1758 Telex Lens

From five minutes after the FedEx guy came by, I spent the rest of the afternoon playing with my new toy. It is a Sony VCL-HG1758 telextender lens for my VX2100. It has 58mm mounting threads that match this camera, as well as the VX2000 and PD150/170. It weighs about 14 oz. (395 gms.) and has an outer barrel 90mm wide.

It is impressive in its sturdiness and its optical sharpness. It's by far the best telextender I've used. There was no distortion at the edges I could see and the autofocus worked quickly and accurately with it installed.

It has a couple of extra mounting threads when put on the VX2100, compared to others I've used. It requires a few more seconds to mount, but it's less likely to strip the plastic threads on the camera.

I got flawless clarity on closer subjects with it and the footage looks as good as that shot without it. When the camera was on full zoom, I had to back off to a distance of 18 ft. (5.5 meters), to get a sharp focus with it. There were no soft focus zones anywhere in the non-vignetted part of the zoom range, outside of that one situation.

I spent a lot of time experimenting and calculating, regarding the big issue of vignetting.
With the HG1758, in sunlight and no filters used, the VX2100 started vignetting at the upper left corner at a point 45% from the low or wide end of the zoom range. This was equal as seen on both the viewfinder and viewscreen. When I clicked it to the ND1 filter position, the vignetting began at 50% zoom and with ND2, it appeared at 53% zoom.
This difference is due to the iris opening wider with the neutral-density filters reducing the light. This brings the barrel of the extender into the field of view at an earlier point when backing-off on the zoom. This problem could be lessened by turning down the exposure manually, instead of using an ND filter, when a telextender is attached. This would also increase the depth of focus, but this is getting into another complicated subject.

This level of vignetting is such that I can live with it and leave the extender on during much of my outdoor shooting. My Raynox DCR-2020PRO telex gives me 6X more magnification, but vignettes at about 85% zoom. My Canon TL-55 gives 16.8X total zoom and starts vignetting at 38% zoom. The threads of the 55mm Canon lens are fitted inside the 58mm threads of the VX2100's lens and attached with thin rubber tubing. When mounted with a 58mm-55mm step-down ring, it is pushed a full centimeter farther out and vignettes at 50% zoom.

But, there's more to the vignetting calculations.
When I played my camera tape and viewed it on my 35-inch Mitsubishi and 24-inch Toshiba CRT monitors and on the LCD screen of my GV-D1000 mini-VTR, the vignetting was somewhat less. It showed at points about 5% farther back on the zoom than on the camera's viewfinders. Apparently, the VX2100 screens show some overscan area at the edges that aren't displayed on many video monitors. So, on my TV screens, at least, the HG1758 caused vignetting in only about the bottom 40% of the zoom range, with good sunlight and no ND filter. Your mileage may differ.

All in all, I really like this lens. The 20.4X it gives me is enough to do a trackmeet adequately, although my 30X Canon L1 is very nice for such quickly-varying long and medium-range shooting.
With its 2X extender under the lens, there's no vignetting at all. But, it's no VX2100.
Too bad the HG1758 doesn't come with a mount to fit the GL2, as it would produce 34X.

It comes with snug plastic end caps and a nice, padded, drawstring pouch. It cost $269.95, mailorder. I would definitely buy it again and even pay more, if necessary.

Steve McDonald