Thinking of starting to use a daylight balanced compact fluorescent bulb with an adjustable desk lamp for coin photography. I see ones at 45, 85, 105 watts. Anyone use this method? Would like to figure which wattage is ideal without wasting money on trial and error. Thanks!
I assume those are the equivalent wattages you are listing? I use a 5000K spiral CFL, with a wattage of 23 which is the equivalent of 100 watts. It outputs 1600 lumens, which is a lot. I really like this bulb, and I've tried plenty. http://www.amazon.com/Utilitech-4-Pack-23-Watt-Standard-Daylight/dp/B00A9V7RA6 Here is a photo I took last night using 2 of these bulbs:
Don't forget: -- "closeness" of your light source affects reflected light intensity from a coin -- different coin surfaces/metals affect reflected light -- extraneous reflected light from the surroundings affect total light on a coin. These are the sort of things that will drive you crazy trying to account for. Look at this image: See that patch of lightness in front of Liberty's face. I kept getting it on coin image after coin image. FINALLY figured out it was a reflection from the vertical chromed pole of my camera stand. I now have a sleeve that encloses the pole.
@kanga's point about stray light is important. The brighter your desk lamp is, the less other lights around the room will interfere -- but if there are reflections from your stand or camera, a brighter light will just make them brighter, too. Of course, you can compensate for dimmer light with longer exposures, so "ideal wattage" may not be a sensible concept. I think you need to focus more on color rendition index (CRI), color temperature (although you can compensate for that with camera settings or post-processing), and the surface area and direction of your light source. CRI is particularly important if you're trying to shoot toned coins.
If you have a scanner I suggest you try that. Very even image results and a very clear image. And you can edit the image.
There are a few problems with scanners for coin photos, most notable is that the scanned images tend to look very flat, or dead.
Yes, the images are clear and even, but unflattering. They obscure luster, and can obscure toning. On the other hand, scanner images can also obscure signs of cleaning.
Good points about scanners. I have had trouble getting a clear photo of coins so I have had success with the scanner. Your right about the lack of luster or signs of cleaning, but I used the scanner to sell new eagles. No worry about cleaning or lack of luster.
I use a scanner for my less expensive RAW coins. My main gripe about my scanner is that I can't control the lighting. I have to go with what it gives me then tweak the image with Photoshop so that the image looks close to what the coin looks like in hand.
Thanks for the input guys. Based on what @geekpryde said I'm going to try two lamps on opposite sides with the bulbs in the Amazon link (just purchased the 4-pack). The light source will be about a foot above the coin. I'm thinking one angled from the left and one from the right.
