Need Help With Close Up

You're at around 4-5:1 magnification in this shot. To frame just the "D" you need to be around 10-15:1. You can get there in several ways:

1) Keep adding extensions. To get to 10:1, you will need quite a bit more extension than you have now, total of 340mm. This is not as impractical as it sounds, but it is a lot of extension.

2) Add a 2x or 3x teleconverter between the camera and first extensions. I'd recommend either:
a) 2x: http://www.ebay.com/itm/VIVITAR-AUT...AOSwYlRZKRip
b) 3x: http://www.ebay.com/itm/VIVITAR-cam...AOSwV0RXu0ie

This option will increase your effective aperture by 2x or 3x, so the quality of the image will degrade a bit. But if you downsize the image anyway, it should be OK. The degradation of quality has the advantage of keeping better depth of field.

3) Get a 10x microscope objective, plus a cone-shaped M42-RMS adapter. I'd recommend:
a) http://www.ebay.com/itm/Bausch-Lomb...AOSw32lYsd4L
or
http://www.ebay.com/itm/B-L-Bausch-...AOSwuMZZGHWv
or
http://www.ebay.com/itm/Bausch-Lomb...AOSwImpXpNgn
b) http://www.ebay.com/itm/RMS-Thread-...9wWPAyGvjhLw

This option will give you by far the best image quality, but at the expense of having to do focus stacking to get acceptable depth of field.

Thanks guys, so either way I will have too put out more $$$ :(

With extension tubes, I always had a hard time getting sharp close-up shots. Here's an example, taken with a reversed Micro Nikkor 55mm f/2.8 lens on lots of flimsy improvised extension tubes, with the camera mounted on a tripod:



This is a scanned-in film print (taken decades ago), so you might do somewhat better with a DSLR on a rigid copy stand, etc.

(This is an 1806 overdate half dollar.) I should probably mention that the uncropped photo covers the whole "1806" date.

Another reason it's not sharp is due to focusing problems with old film SLRs. With the lens reversed and on long extension, the effective f ratio is small, so the central split-image rangefinder prism is completely blacked out, as is the surrounding ring of microprisms. This blackout starts around f/8, IIRC. The only way to focus is with the ground glass screen, which is pretty imprecise.

For coin imaging, modern DSLRs have so many advantages over the old film cameras. I wonder if anyone on this forum still uses film?

Yes, you'll need to focus stack.

The Leica Z-stage is fairly precise, so you can do stacking at 10x with it. You won't be able to adjust it in precise steps, so the process will be to focus to the lowest in-focus plane and snap the shot, then move a little higher until the next features are in focus, and keep moving higher, snapping shots at each relevant point where key parts of the coin are in focus. Then use a program to render the stack.

I don't understand what you're asking, please clarify.

The movements you need to make are very small, around 10um for each step. Will be very tough to put in any sort of scale. A dial indicator might work.

You don't really need to make precise focus steps unless you plan to do 3D rendering. It's actually better for 2D rendering to focus on the key areas you want to be in focus in the final image. I often do 2-image or 3-image stacks where I focus on the field, on the top surface of the MM or other feature, and maybe one step in between (especially if the field is not flat). No measurements needed, just decide on the focal planes by eye.