I'm still surprised it doesn't support Av and Tv, but it sure doesn't. There is a version of CHDK that supports it: http://chdk.wikia.com/wiki/SD1200IS ... but you'd have to decide whether you want to tackle it; I don't know how hard it is to install and use (never tried it myself, only a very early hacked firmware for an original Canon Digital Rebel).
Thanks for the link Jeff but after doing a little reading I don't think I want to (as you say) tackle it.
I have a Nikon D50 with a gargantuan Tamron on it, leaving precius little lighting angle for me to work with, and I've got to believe I can still improve my images substantially by making an equipment change (can be seen on toughcoins.com). Right now, I just can't see how well I'm focusing when the coins are small. To leave plenty of room for my lighting while maximizing the size of the viewed coin as I focus, I just bought a Nikon mount Vivitar micro teleconverter, and plan to buy a Nikkor 50mm F2 to go on it. I figure I'll be able to see the detail far better when focusing, and not have to guess at how I'm doing. Is this the right direction for me, or should I cut my losses and change directions? - Mike
If you read further up into the thread, this started with my using a Vivitar micro converter ($14.99). For a penny more, I purchased a 50mm f3.5 micro-Nikkor ($15). If you look at the post starting the thread, that was shot with a 18-55 kit lens with the macro converter on. Honestly, it isn't very useful for coin photography. I should be receiving the lens tomorrow, since it takes a full day for the USPS to get my packages from the airport sorting facility to my local post office. Once I get that in, I'll take comparison photos between the kit lens with the converter and the micro-Nikkor. Honestly, given how cheap the micro-Nikkor lenses are (which I didn't realize beforehand), just get that.
I'm not a fan of teleconverters for macro use. A teleconverter works by taking a crop from the center of the image created by the lens and then expanding that crop to once again fill the frame. They work best with longer lenses, which is why Nikon designs its current teleconverters to only allow mounting of a handful of lenses. Other brands of teleconverters don't have this restriction, but still recommend against using them on lenses shorter than about 100mm. I haven't used the Vivitar you purchased, but the 2x teleconverters I used from that era are of indifferent quality. I hate to be the bearer of bad news, but I honestly feel this is a "buy once/cry once" situation. With a D50 or a D3x000, you can spend ~$200 and get a 105mm f/4 AI and a cheap set of extension tubes from eBay. That'll give you some nice optics that require a fully manual workflow including exposure. Or you can spend ~$450-$550 on one of several excellent lenses (Nikon 60mm f/2.8, Nikon 85mm f/3.5 VR, Tamron 60mm f/2, Tamron 90mm f/2.8, Tokina 100mm f/2.8, Sigma 70mm f/2.8). Not only are each of these lenses far easier to use, but they come with a warranty and are great when you want to photograph things which move faster than coins .
If you're going to spend the money, don't bother with Tamron/Sigma or any Nikon shorter than 100mm for macro photography of moving stuff. Some sites actually recommend a minimum of 150mm/200mm for macro photography of plants/animals. The Tamron/Sigma side of the argument is always the "cost of ownership" one. When you resell lenses, Nikkor-ED tends to get closer to the original "used" price no matter when you end up selling.