Photographing coins is often an unnerving process for those who need to sell one or just have an image to share. They're small and hard to photograph well because the camera has a hard time focusing so close or the light won't cooperate or the color looks awful or maybe all of those. It sure took me a long time to stop pulling my hair and get to the point where I could be proud of my efforts. And today I start all over again with my first dip into photomicrography; the art and science of imaging under the magnification of a microscope. The results I'm about to share below will to my own eyes someday, I'm sure, rank as an embarrassment but all the same I'm eager to explore virgin territory. And despite a lot of Googling I can't find any good photos of coins taken under a microscope. Sure, lots of pennies with big dates and so on but nothing you wouldn't see under a cheap magnifier yourself. Nothing to really show you what it's like down there at the level you can wave hello at a paramecium. That was my goal today.
So anyway, let's start off on our journey into making an old, ahem ancient, coin really big on screen! I've selected this siliqua of Constantius II mainly because it has low relief and being of shiny silver will pose fewer lighting headaches since as you increase magnification the available light at any given power reduces proportionally so that under high magnification you need a very strong light and/or long exposure times to properly expose the image. And, because of difficult to dampen micro vibrations, long exposures are the bane of a photographer looking for sharp detail.
Here for our first image is this coin at lifesize, 1x and our starting point for reference. Depending on your monitor it might look a little smaller than a coin should be but this is likely because we're accustomed to seeing coins on the internet blown up. At 20mm in circumference it's a smidge smaller than an American nickel. Overlay a coin of this size on your monitor to make sure we're all working with the same scale.
Now let's turn up the juice.
Here we see the coin now at about 15x, a big enlargement that has made this coin almost the size of a dinner plate. At this size we clearly begin to see the tortured topography of this ancient metal... but I've cheated. This magnification did not come from a microscope but from the raw resolving power of the camera and lens alone.
Here is our first bona fide picture under a microscope.
Blow up the coin forty times its normal size and the surface appears very rough and pitted but the lettering is still tidy and recognizable overall. At this scale a coin of this size would be bigger than a giant New York-style pizza. Let's make it bigger still.
The tiny letter V in the actual-size image at top, the one that is virile and elegant at 15x and faded at 40x, is now appearing like an angry metal jungle cratered nearly beyond recognition. At this scale you would need a 12ft screen long to see the whole coin. Now for our last image...
Our final stop sees me crank the power up to about 200x. I can't be sure for certain given a number of different factors to consider but it's in the ballpark. And the valley of that V has now become a moonscape with deep craters and metallic glints blurred by cheap Chinese optics that in sum render an abstract image which brings to mind anything other than a coin!
And if you thought likening that image to the moon was accurate, this section below from a gold solidus should resemble a Martian landscape. What do you think?