Help With Coin Photography, Most Of My Equipment Has Arrived

Now you see why we push this stuff so hard.

I don't think you can stop the picture popup; I just leave it up the first time (minimized) and close it once at the end of the session.

A twoshot of both faces at once is nice for presentation, but no good for grading. You have to halve the size of the individual coins and still probably have to host offsite for an image of any real size. For grading purposes, what you posted here is perfect.

To create that in the Gimp, you'll be opening both faces in individual windows. Change the Canvas Size to double the size of one single shot you have open. You can then copy/paste the second face of the coin into that window.

The farther you extend the lens from the camera, the higher the magnification. If the total extension equals the FL of the lens, magnification is "0", ie you focus at infinity. If the extension equals twice the FL of the lens, then magnification is 1, ie you get lifesize images on the sensor. The equation is: M = (EXT - FL)/FL. Solving this for EXT you get: EXT = FL*(M + 1). If you want to frame a Dollar, which is 38mm diameter, on a 15mm APS-C sensor, you need a magnification of 15/38=0.39. Your total extension, for a 75mm lens, would need to be 75*(0.39 + 1) = 104.25mm. Note that magnification changes rapidly in this range as extension is varied. If you are at 102mm your magnification is 0.36, while for 106mm magnification is 0.41. Mag of 0.41 will over-fill your sensor with the dollar, while 0.36 will only fill 91% of the sensor, so it's important to get this set precisely. This is where the fine focus helicoid comes in for the <$400 setup, or a bellows in other setups. IMPORTANT...total extension includes the camera "register" distance, ie distance from lens mounting plane to the sensor. For Canon this is an extra 44mm.

Working distance is sort of inverted from extension. As magnification increases, working distance decreases. For example, when M = 1, working distance equals twice the FL of the lens, which is the same as the extension. So when you're at M = 1, the lens is exactly centered between the sensor and the coin. When M = 0, by definition working distance is infinity! On the other end of the scale, WD never becomes shorter than the FL of the lens. This is not strictly true, because these distances we are calculating assume the lens is very thin, but it's generally close enough for what we're doing. If you know your magnification you can calculate the working distance: WD = FL * (1 + 1/M). So for the Dollar example, WD = 75 * (1 + 1/0.39) = 267mm or about 10.5". Again though, WD is very sensitive in this range. When M=0.36, WD is 283mm, while when M=0.41, WD is 258mm. So a couple mm of extension plus or minus makes a much bigger change in WD.

So...Magnification is proportional to extension, and working distance is inversely proportional to magnification. Longer Extension --> Higher Magnification --> Shorter Working Distance.

Here are my ASE pictures, any comments on the quality, what I can do better or try, would be appreciated.
The 87 was pretty reflective, and the 95 has more of a matte finish.

Thanks, the lights were near the lens, I will try moving them out. More of an angle to the coin, instead of directly down, correct?

I had to grab the coin and look at those scratches, didn't notice them until I took this picture.

Yes, I think my pictures of my wheat cents (brown) look really good, so I tried the same settings on a 2013 straight out of a mint set. Not happy at all. Same hotspot problems, and the color was not representative. I am having fun learning though. Anyone have a picture of a new cent they are happy with? That would give me a goal to shoot for.

It's better than any Lincoln Cent shot I've done, so far.

Looks pretty good. I'd recommend reducing exposure by 0.5EV to eliminate the hotspot highlights.

And also...rotate the coin a little CCW to make LIBERTY horizontal...Ray