Lots Of Gear Don't Know How To Use It

Here is the setup. a Nikon d90 with a 50 mm f1.8 dx refurb lens. I paid $99.00 for the lens 4 yrs ago and it was never used. a cheapo $20 copy stand that wont fit a DSLR. A focus rail from ebay to allow a DSLR to fit. a jury rigged hot shoe extension to stabilize the vertical arm. one Ikea light, and a cheapo hot shoe flexible light that doesn't connect electrically to the camera.

Ha! I love it. I may not be reading this right since I'm on my phone, but it looks like the vertical arm has enough downward travel - and the camera enough upward - so it could become a load-bearing element. That would stiffen things, and frankly you're now working in a realm where little gains like that are important.

So how large are your originals? Are you autofocusing?

I'm thinking the focus rail can slide downward so the bottom actually touches the table and holds weight.

Custom white balance is a capability of all dSLR's. I don't know the specific steps for your camera, but it will involve setting white or gray paper (they make a bespoke 18% gray shaded card for the purpose) where the coin will be, with the lighting set as for the shot. You take a picture of the card and (via some setting) tell the camera that is "baseline." It is then able to correct color in-camera.

The tiny light position adjustments you make for each individual coin won't matter for this, as long as you're close to their final position to begin with.

My Canon is perfectly happy doing this with white printer paper. I don't know about your Nikon, but Ray (rmpsrpms) knows Nikons and will hopefully poke his nose in.

1) Always use the camera's maximum image size and quality. You're going to depend on postprocessing software to downsize the image later. In fact, if you want to go that far eventually, we'll teach you to use RAW files in your shooting. They're raw photographic data straight from the sensor, with no in-camera processing at all.

The reason for this is that cameras are very weak computers. It's preferable to do as much processing as possible on your much more capable desktop computer. Your goal is to do all processing at your computer, and directly upload a completed file.

2) Use only monochromatic shades for background. Preferably black or gray to minimize light reflected back into the lens. Reflected light is a problem in macro photography, moreso than other specialties. Work hard to minimize external light and surfaces that can reflect light back into the lens. Reflected light costs you contrast, and you are going to be adding a little contrast in most postprocessing operations anyway.

There isn't enough wrong with that Quarter image for me to offer any critique here. You're well ahead of the power curve in terms of quality - you seem to have the feel for how the coin needs to look which is a big help. That's teachable but difficult.

Find a well-worn and darker Lincoln - or something similar in your collection - and see what differences it requires for lighting and exposure.

so I tried the WB reading a out of focus white card, but had trouble. So I just took a series of photos with different K numbers with silver coins and pennies. I went with what I thought was the best 3450K. Here is an example

Coin flips are very nearly perfectly white. The flip your coin is in reads (typically, depends on where you take it) 139,138,133 so it is pretty close to being a perfect setting. You might try just a little "cooler" at perhaps 3500-3600 or try skewing the WB a bit toward blue, maybe B1. Or just leave it alone since you are only off by -4% in Blue.

I don't know how Ray does it but I use this:

http://instant-eyedropper.com

The reversing ring disconnected your electronic connection between lens and camera, preventing the camera from setting aperture. It has to be set at the lens now. In the absence of electronic signal some digital cameras default to aperture fully closed, and others are fully open. Makes setting the shot up a bit complex because you have to artificially reset some parameter - I use ISO - brighter to see what you're doing on the screen, and then back to snap the shot.

or some other workaround