Coin Photo Setup

Forgot to say I'll be out of town til Saturday and will try to answer any questions but I may be slow in responding...Ray

Nothing in my experience gives me the ability to offer a suggestion which could improve what you're showing here.

The only words I can offer: You're running into the same wall (in my opinion) that I have with a nice, dedicated macro lens - the images are beautiful, but not quite enough. The highest-magnification images, about the same as my best with the 100mm Macro, are wonderful to look at but not really more informative than larger whole-face pics.

More magnification is necessary, and I'm exploring both camera-lens-based and microscope-based solutions. Is there anything in your direction which could, say, double the magnification without loss of quality? We have the advantage of being able to throw stupid amounts of lighting on the task, so effective aperture is only relevant in the sense of diffraction, and I'm curious if a setup using bellows/reversing ring (or something) might achieve the 5x-ish number I'm looking for as capably as the $1000+ lens I'm contemplating.

Hhmmmm....so if I were to invest in the purchase of a bellows which provided for the longer extensions I'd be able to get the high magnification using my 18-55mm lens? Basically I'm trying to get a true 1:1 magnification ratio without having to invest in a new (or used) high-priced lens. I can get close right now but no cigar. I doubt I'd often have the need for super macros as shown in your last foto (but I would like to have the option) and at least be able to get the full-face coin shot at 1:1 which will give me the detail and clarity I'm looking for.

That is some silly magnification, rmpsrpms. It becomes relevant to doubling/tripling verification, which is what we're aiming at here. The DOF is far better than I expected, but you'd still want to z-stack for clarity. You're rack-focusing, right?

Here is an example of image stacking. Same Morgan dollar, same Macro Setup with 35mm lens. I took 3 photos, one focused on topmost features of the
date, one focused for best top to bottom balance, and one focused on surface of the coin. For these pictures I opened the aperture to f/5.6
(previous pic was at f/8). I tried f/4 but the sharpness was not as good.

Here is focus on topmost features:



Here is focus on middle features:



Here is focus on surface features:



And finally, the Focus Stacked image:

Thanks for that info Ray. And great pix you're getting with the el cheapo set-up. Sounds like just what the doctor ordered but I think the first order of business for me is getting a decent copy stand. The one I have now is very basic--height adjustment is made by releasing a clamp and then manually adjusting. The process is kinda jerky and getting the height exactly where I want it is hit and miss and imprecise to say the least.

Received my macro extension tube yesterday and haven't come up for air yet trying various set-ups. The results are "fairly" good but it's a bugger getting focused. With the rings in place I no longer have AF and no f/stop control, not even on the camera itself (I'm shooting with camera tethered and I can normally adjust f/stop from the computer) so I assume that lack of control is due to loss of some sort of electrical connection with the rings being placed between the camera and lens.

Another problem I've having with the copy stand is even when it's fully extended, I can't get the entire coin in even if I'm only using one of the 3 rings in the extension tube. I'm talking about Morgans which is what I normally shoot. Smaller coins are no problem.

I managed to find a Canon single rail bellows on the web for about $40 and there were several Vivitar 75mm LU enlarging lenses on ebay but I'm going to hold off on those until I can get on track with a decent copy stand.

This one is with all 3 rings


This is only 1 ring and as close as I could get to having the full face

You're probably losing focus in the peripheries because the lens was not designed for flat field work. On top of this, the lack of aperture control (I assume aperture is wide)is a two-fold problem: first, poor depth of field so any lens field flatness issues are amplified; and second, aberrations that could normally be avoided with a smaller aperture are not removed. Metering won't help this, now will manual focus. You will probably need to figure out how to stop the lens down or use another one.

The copy stand looks fine. It looks like you'll be able to mount a bellows to it, no problem. I am not sure how rigid it is but it is probably OK for Dollar size shots. May not be rigid enough for higher-mag shots, though.