Orthogonality Of My Camera Sensor To The Coin

Any ideas on how best to make sure my camera is completely orthagonal (flat) to my camera sensor?

I'm using a few different methods in my current set-up (portable), my heavy duty copy stand (in storage) doesn't have an issue that I've ever noticed before. Now I'm shooting with a tripod only.

I use a level on the camera and another one mounted in the hot shoe. then I try to shoot a flat printed paper, looking for focus at all edges.

Trouble might be the camera is flexing over time on my tripod head (all Bogen/Manfrotto gear) I've noticed that the cork on one of my quick release plates was an issue, so I removed that, but still have trouble getting it exactly orthogonal. Maybe it's just not possible to do on a portable set-up like I'm using now. Even a single millimeter off can throw things out of whack pretty quick.

On my telescope rigs I understand this and I have really heavy duty connectors that screw EVERYTHING together in my imaging train, rather than using the set screws and compression rings that come standard on most telescopes. (you don't want to know the cost of all those connectors either)!

Then again maybe it's my coin that isn't as flat as I thought, (I Just thought of that in the equation). I noticed that Ray is using the plate from a microscope to shoot on, I use a cork to elevate the coin to get it off the background and throw anything not on the coin out of focus.

My shots aren't too bad at the moment, just not where I'd want to be currently. I may have to suffice with where I'm at now until I find a permanent place to set up my big copy stand again. I'm staying with a friend temporarily, and can't really leave something set up longer than I'm using it.

Any and all ideas are appreciated. - For examples see my last few posts in the "classic coin grading" forum. I'm using Canon DSLRs (various bodies 1Ds, 20D, 7D, 5D, and usually my 100mm f/2.8L macro lens). Shooting at f3.2 or f/4, ISO 200 between 1/60 & 1/500 second always with mirror lock up enabled, with a pair of Jansjo LED lights. I pretty much quit shooting the 1Ds as it is just too heavy and big for my tripod to handle without flexing.

I'm really missing the copystand now!

It's not a huge issue right now, but will be when I bring the super macro back into play with a bellows set-up.