Customer Reviews
Good, but a couple of things would make it a lot better. 
2008-09-07
Maybe it can't be done, or maybe there isn't enough money in it, because if it could be done or if there were enough money in it, surely the Canon lens development engineers would have already done it to complement and enhance their very exceptional peerless point-and-shoot digital camera, the G9.
The Canon G9...used by photographic novices like myself who want more than only simple point-and-shoot good-but-not-great pictures, yet still want a digital camera of much better quality with more features and capabilities that takes great-not-good exceptionally high-resolution pictures, but want a camera is still relatively small and relatively light and relatively inexpensive, but aren't ready or willing to take the big step into the heavy-duty big league digital cameras used by serious professional photographers with seriously deep pockets or credit card balances) is not a good camera...it is a great camera.
The Canon TC-DC58C Teleconverter lens is a good quality accessory lens with very nice optics for the Canon G9 Digital Camera, and, yes, it does what a teleconverter lens is supposed to do - allow you to zoom even closer and take very nice high-resolution pictures when attached to the G9 of subjects and views that are far away.
The teleconverter lens attaches to the G9 via a required lens adapter. Canon offers a plastic lens adapter - the LA-DC58H, but don't buy it...it's plastic for crying out loud. Lensmate makes a much more durable aluminum Canon G9/G7 58mm lens adapter that is of MUCH better quality - [...]
So, that's all good, but there are two somewhat annoying things about this teleconverter lens:
[1] Why are there no threads on the business end of the lens to accomodate attachment of a UV filter to protect the lens? It certainly can't be a difficult thing to engineer. The absence of threads on the lens body so owners can put on a UV filter - my gosh, that has to be an inexpensive and simple beyond description thing to do - is a seriously glaring design deficiency.
[2] With the teleconverter lens attached and the G9 zoom pulled back it looks like you are looking down a black tube with the subject or view you want to get a shot of showing up as a circle in the center of the view - which, or course, you are looking down a black tube. To be fair, the reason you attach a teleconverter lens is so that you can use the zoom to get even closer to the subject or view you want to get a picture of, and the black tube effect does go away when you use the G9 zoom to get closer to what you want a shot of. And for that, the teleconverter lens works as it should and gives you really nice pictures of further way subjects and views that you can't get with the G9 alone. However, it would sure be handy and nice and appreciated if the creative and very smart Canon lens engineers would bring a teleconverter lens that would allow G9 users who have the teleconverter lens attached to have the flexibility to take full-field-of-view pictures with the zoom pulled all the way back, and then be able to use the lens for its real purpose of extending the G9's zoom for those further-away shots.
Maybe solving the looking-down-a-black-tube thing is too much to expect, maybe it is optically and physically impossible to resolve. And it that's the case, fine...if it is becomse so annoying that a G9 owner can't get past it then there is always the bigger camera - bigger bucks - bigger lens path to take.
All in all, and mainly because of these two things, this teleconverter lens is just sorta ok for an add-on lens for a "tweener" digital camera like the G9 that is easily the best of the point-and-shoot digitals but doesn't reach the level of the big-time digital SLR's.
But I am just sure there are a lot of creative and really smart engineers at Canon, and if the MBA bean-counters would let them, they could come up with a much better and more elegant solution to solve these two annoying things about their teleconverter lens and still extend the optical reach of the otherwise exceptionally excellent Canon G9 digital camera and show the MBA bean-counters at Canon that their overly conservative sales and revenue estimates for G9 teleconverter lens were way too low.
Strap this on and shoot the moon 
2008-07-11
I was a little skeptical when I purchased this lens for my G9. Partly because the camera is about the same size, if not smaller and also because I have a very capable DSLR with great lenses too.
In the end, I'm very happy with it. It's easy to put on and take off... just screws right onto the necessary converter. It looks a little funny connected to the camera but no more than the pros look with their 800MM lenses at the super bowl (just a much smaller scale).
You need to know that this basically just extends the focal lenth by 2X at the high end. It doesn't make the wide angle half as wide (like making a 35MM a 70mm). So at the wider angles it's like looking through a tunnel with the image in the center of a dark tube. But once you get toward the telephoto range you "zoom out" of the tunnel and get the full effect of the lens.
It works great...no complaints and gives you a 400MM capability on the G9.
TC-DC58C - Excellent Lens 
2008-07-10
Just purchased this lens a month or so ago, and used it on vacation and a few other events. Overall, very happy with the lens. Sturdy and good weight to it - just what you would expect from a Canon lens. As I had read in other reviews prior to my purchase, the built in flash of my G9 cannot be used with the lens due to the shadows produced, so this is really limited to outdoor use (or a large indoor space with good lighting). Due to the weight of the lens, a tripod is helpful in keeping the camera still. I have used the tripod and some of the pictures have been amazing (sunrises, swim meet, baseball game). Would recommend to others.
Excellent add-on 2008-06-15
This teleconverter works great with my Canon G9. However, with this lens added to the G9 lens, you do not have a fast low-light combo. Be sure to use it with bright sunlight, or use a tripod. Also, if you intend to use flash, realize it will be blocked by this lens. Use an external flash if you must use flash. I may have to break down and get one for myself now.
Good item 2008-05-28
The lens is a great accessory for my Canon G9. Also, I ordered the conversion lens adapter, but amazon did not have it on stock. They took almost twenty days to send my order!
Except for the problem of slow delivery, I'm happy with my purchase.
Canon TC-DC58C Tele-Converter Lens 2008-05-27
Requires Conversion Lens Adapter LA-DC58H / Used to enlarge the central part of an image from an objective lens
GREAT LENS FOR THE CANON A650 IS 2008-05-21
After a lot of reading and investigating this is the best lens for the money. Don't be fooled by the cheaper lenses. If you have the Canon A650 IS then a Canon teleconverter lens is the only way to go. Also, remember to purchase the converter tube by Canon for a perfect fit.
Don't forget to set your camera on CONVERTER so that you get clear crip shots with no interferance. This lens works best with good lighting conditions. Great for zoo photography.
If you are on the fence about what lens to get for the CANON A650 IS look no more - this is the one!
Great for Outdoors but terrible for indoor photos 2008-04-27
This lens works very well outdoors or when there is a lot of light but is terrible indoors and takes very dark grainy photos. The photos taken outside with full sun exposure were very good though. Another problem is that for closer subjects you will see a circle in the center of your photo until you zoom out enough to move past this circle.
Good resolution, handling so-so 2008-02-16
This tele-converter produced very good resolution on my G9. If you want a field-of-view equivalent to a 420mm lens on 35mm film cameras, but not all the time, this is a good choice, assuming you already have a G7 or G9. If you are a frequent user of such long focal lengths, you will likely prefer a camera that has it built in, or better still, a digital SLR. There are two main reasons I say this:
(1) this add-on lens completely obscures the view through the optical viewfinder, so you have to rely on the LCD screen for framing your shots. You will need good light to be using a shutter speed that is fast enough to hold the camera at arm's length, like you need to do to see the screen, and the visibility of the screen in bright sunlight can be less than ideal. It can be done. A tripod or monopod would work better, provided your subject doesn't move too quickly or erratically. My percentage of keepers shooting birds in flight, for example, was pretty low.
(2) While the G7/G9 lens zooms from 35mm to 210mm (equivalent in 35mm terms), and this 2x converter gets you out to 420mm at the long end, you can't use it down to the 70mm (=2x35mm)you might expect, as you will run into severe vignetting. I *think* you can use it for all or most of the range above 210mm.
Having said all this, the G9 plus this converter makes for a very small and light long-lens package, for those who already have a G7/G9 or who only require the added reach from time to time.
Excellent extension of g7 capabilities 2008-01-04
I have used the teleconverter for a G7 camera for some time and am extremely pleased with the results. It balances very nicely on the camera and allows one hand shooting without a tripod. To me the additional coverage is stunning. For example, I was able to get a close up of a pitcher on the mound at a major league game from the upper deck of the stadium. The picture was very clean. Please note that there is a menu setting which should be used with the teleconverter or wide angle lens. If the menu is set correctly, you will not get the black circle effect that one of the reviewers mentioned. It is explained in the G7 manual.
