Hey, I am thinking of a little desk light -- LED light or maybe a nice Green Bankers light -- for my desk so I have lighting closer to me when I look at coins with my eye or through a lens (my regular room lamp is a few feet away to the side). Should I get something for a traditional incandescent, CFL, or LED light -- or maybe it doesn't matter ? I'll assume the best choice(s) for naked eye viewing are also best for photgraphing (though that's secondary for me).
These may not be the best for pleasure viewing, but my middle aged eyes like these for spotting problems. They are bright. Also you can really play with different angles when photographing. Some cover the lens with a ping pong ball or some other material to diffuse the light for photography.
I use incandescent at my desk, only because that's what I have used most of my life and before all the options we have today. I'll sometimes walk a coin around the house and view it under different lighting. When it comes to imaging, you can use several types of lighting but you need to be able to control the white balance with the camera or with software. Giant topic.
It matters. The reason it matters is because different kinds of light do different things. Some will show you one thing and not show you another. So what you want is the kind of light that will show you what you need to see when judging a coin. And it is and always has been recommended in countless books and articles on the subject that incandescent light is the best for this. That's because it shows you everything you need to see when judging a coin. And the same thing is true for taking pics of coins.
Those Jansjo LED lamps from Ikea have about a 2500K color to them. I bought three for coin photography and while they will work (you do have to do a white balance on your camera for the colors to come out correct), I find they are a little weak. But they are useful sometimes since the heads are so small you can position them easily. I think mine cost about $13 each last year. I wouldn't use CFLs for photography and I don't like them for coin viewing. Also, it's hard (or impossible) to find the color temperature range you might want. For general viewing, most people like the 2500K color temperature since it's easy on the eyes but I think if your primary purpose is viewing coins you want something that is about 5000K to 5500K color temperature. While incandescent works, they can get hot. You can find LED bulbs in this color range pretty much everywhere nowadays (all the big box hardware and general merchandise stores) for about $10-$13 for a pack of three. They run very cool, are much more efficient and last pretty much forever.
In order to control your whitebalance you need to control, or overpower, or restrict the different types of lights and different color of lights that are in the room. As @Publius2 reviews the different color of lights, if you have a room with windows, that lets in light from the outside (one color of light), if you then use different LCD or LED bulbs each particular bulb could be a different color. You could end up with many different colors of lights. LCD bulbs also flicker, which leads to other problems. To your eyes they just blend, to a camera it creates havoc in relation to the subject's true color. ==> https://www.cambridgeincolour.com/tutorials/white-balance.htm These different type of lighting situations can cause White Balance issues. Even colored walls can cause color problems in relation to bounced/reflected light. For instance in my bathroom I have two LED bulbs of different colors. And this is the result (notice the black band across the light bulb to the right which isn't there if I take a pic of just that bulb): In photography one learns to control light. Or to overpower multiple different color light sources; use of flash photography; or just be careful about the limiting the different types of lighting. (in a nutshell).
Way too many folks miss all of this, aren't even aware of it ! To make everything easy, your best bet when taking coin pics is to make sure there is no other light in the room - other than the specific lights you're using to light the coin. In other words, the only light in the room should be coming from those lights. And if you have the right kind of lights, and get them positioned correctly, then you're all set. Of course if you have the wrong kind of light, you're still gonna have problems.
