Newbie Question: What Are You Looking For When You Photograph A Coin?

I think I got what luster is, thanks to @coinphotofan It is that radial shiny/dark pattern.

right, @mrwhatisit, I finally got it

And here is 5x magnification of those patterns causing luster. But not all coins will have it, even new, I guess due to different strike process.

thanks @coinphotofan.

thanks for another example. I think I now have a good grasp about what luster is

I do not think all coins have luster, for example, this one does not seem to have it, it does have anti-counterfeit marks.

Another questions from a newbie like me is if details matter much? Here is a 2x image of Year of Dog coin, lots of details, does it matter to coin people?

8081x8081 Images Here

I agree, your images are outstanding. Getting a tack sharp image is always important, but for some purposes, like selling coins for example, focus stacking is probably overkill. For uncirculated coins, getting an accurate depiction of luster, color, and brightness are just as important.

Luster depends mostly on lighting. Typically, having lights at 45-60 degree angle vs horizontal will produce the best luster. Above 60 degrees luster starts to diminish, and of course at 90-deg (ie axial) it is completely gone as we've been discussing. I prefer high angle lighting as it brings the colors out on toned coins, so I usually have to find an angle that is a compromise between showing color and luster, and this is usually 75-80 degrees.

I wouldn't worry about monitor calibration. Just make sure your colors are accurate with proper white balancing. You never know who will view the image or the quality of their monitor, so best is just to make the image technically accurate.

Problem is, if you start adjusting color to try and match what you see in-hand, you run into a few problems. First, very few monitors can be calibrated well, so you will only be able to get within a certain accuracy window. Second, even if your monitor is perfectly calibrated, human visual memory is not particularly good. To compare color, you must view in exactly the same lighting as you took the photo, and then compare that to what you see on the monitor. The accuracy of this process is not very high. And finally, if you go messing around with color, and assuming you did an accurate white balance, you are actually making the color inaccurate according to the factors mentioned above. Most accurate is objective white balance, and if you shift away from that due to perception of color on your monitor, it is guaranteed to be wrong.

I am not disagreeing that having a calibrated monitor is a good thing. What I am saying is if you adjust your images based on your calibrated monitor, you are skewing the color away from reality, assuming you did a decent job of white balancing. When your client gets the image, it won't be as accurate as if you just used white balance, and if her monitor is not calibrated, with worst case a shift in opposite direction of your adjustments, the color may appear way off.