Heh. I've done this quick intro two dozen times here, and I'll do it with enjoyment another hundred times if it helps to create more happy coin photographers.
Your G7 is an excellent camera, and once you figure it out it should me more than adequate for the task. Did you get the included software with it? This camera can do tethered shooting.
1. Solid mount for the camera. A tripod will do fine if a copystand isn't available.
2. Make sure the lens plane and the coin are parallel. Macro shooting enjoys very little depth of field, and it's easy to get some of the coin in focus while the rest is not, if the coin and the camera aren't parallel. With a tripod, this is best done by having the coin on a flat surface and the camera pointed straight down on it.
3. Delayed or remote shutter. You don't want your finger snapping the shutter - too much chance of wiggling the camera.
4. The farther you can get from the coin and still shoot an image of adequate size, the better-off you are. Generally speaking, the lighting wants to be as close to the lens, vertical above the coin, as you can get it. If you can get the camera 12" or more from the coin and still get clearly-focused images of 700 pixels or larger, you're in the driver's seat. Try the zoom with the Macro setting - some cameras will, some won't, and you might not need the macro setting anyways with a 10MP camera.
5. Fewer lights are generally better, and the smaller the bulb, the easier it'll be to get the light exactly where you want it. I use MR16 Halogens which are only 2" across. However, a cheap gooseneck table lamp with a standard bulb will work fine. Shoot in the darkest room you can, trying to make the light you're deliberately putting on the coin be the only light it gets; this will make color balancing much easier.
6. Learn about White Balance settings, and how to adjust them with your specific camera. You'll be a lot happier if you can get the color right with the camera, rather than tweaking it afterwards in postprocessing.
Start with your settings around f/5.0, ISO200 and an initial exposure of around 1/160. That'll depend on how much light you're using, of course. You really don't need to mess much with anything except exposure - use the numerically-lowest aperture (the f-number) that will keep the whole surface of the coin in focus as that will allow the maximum-possible amount of light to register on the sensor. Similarly, use the lowest ISO number that will allow you to set your exposure in the 1/80 or 1/100 range - with a solidly-mounted camera and remote shooting, you can go as low as 1/4, 1/2 or even slower and get good results, but you'll be happier with the amount of adjustability available if your setup will let you shoot 1/160 and get a good shot.
What works for copper is not what works for nickel, and what works for lustrous silver is not what works for worn silver. The differences are small, though - a few degrees of angle on the light, 1/80 instead of 1/200. Play, play, play. Experiment. Shoot lots of pics. You'll soon find that you can glance at a coin, you'll know what the initial shot will need to be, and you'll probably get it right on the first or second shot.
If I've been speaking down to your level of knowledge, please forgive me; if there's any clarification you'd like, don't hesitate to ask.
Posted 10/01/2009 9:06 pm
