HC0 and Tele Converter?
 

What is the best Tele Converter for the HC9?

Is it possible to zoom out while using one and not see the "circular frame" black ring?

What is the larget possible multiplier?

TIA

Pete D.

I don't know about 'best', but I've had excellent results with Sony's own VCL-HG0737C wide angle conversion lens.

It does have the drawback of not having any threads for screwing additional goodies onto the front of it. The flip side is, if it did, you would probably have problems with those additional things intruding into your field of view in ways you did not like.

OP was asking for a TELEconverter.

These are more problematic with vignetting, you'll get it most of the time with a tele lens (they presume you will be zoomed in and not set "wide", so you'll lose about 40-60% of the wide end of the range typically - at least that's what's happened with every lens I tried...). You MIGHT be able to put a much larger lens on with a step up ring and reduce the effect, but then you've got a big chunk of glass on the little camera...

Sony made a HG series lens (the huge VCL-HG2037 around the time of the HG0737Y), that's probably a good choice. You'll probably still see vignette, but you'll want to get quality glass for the best results with HD.

The 2037 is a 2X lens - unless you've got a very stable shooting platform, the more "tele" you get the harder it will be to keep the shot from being a bouncing mess - physics kicks in to make the slightest movement look huge when shot through a high tele lens.

Here's My Telextender Choices for HC9
 

I use a Sony VCL-DH1758 telextender almost constantly on my HC9 and a Raynox HD-2200 on occasions when I need more lens power. The DH1758 is designed primarily for use on Sony digital cameras of the H-Series, but it works very well on many other cameras and camcorders. I mount it with a 37mm to 58mm step-up ring I got from B&H. It has 1.7X and causes vignetting on the HC9 only below 30% zoom. It is very sharp optically, but costs only about $100.(U.S.). Its relatively large size, is what allows it have such a large portion of the zoom range be vignette-free. It weighs 8 oz.

The Raynox HD-2200 (a slightly different model number may be available now, but it's the same lens) gives 2.2X power and mounts directly on the 37mm threads of the HC9. It is at least as optically sharp as the DH1758, but causes vignetting below about 60% zoom on the HC9. It weighs 4 oz.

Here's photos showing the two telextenders on my HC9. I made the butterfly hoods from fiberglass. The mike is a Sony stereo ECM-MS907, a good match for this camcorder. The DH1758 is on the left. I no longer use the internal mike or one mounted on the camcorder's shoe, as the tape mechanism is too noisy. Using a mike on the extended arm is the only way I shoot with this model. With my steady-mount, I have no trouble with camera movement at full zoom. There's more pictures of it a few pages back on my Flickr album and many HC9 videos on my Vimeo album.