Macros of New Zealand Coins – P365 Feb13

I was browsing through Strobist’s favourites on Flickr, as I often do, and I was inspired by this photo of an American penny to try taking a macro photo of a coin again. I tried shooting a coin with my macro tubes the very first day they arrived. I’ve learned a lot since then, so I put that to use when shooting the following pictures. These are a couple of New Zealand coins, which we brought back from our holiday a couple of years ago,

There are a number of considerations I had to take into account when shooting these photos. I used a similar lighting setup to the one I used very successfully to photograph the fossilised shrimp. This worked particularly well on the copper 10c piece. For some reason, copper really “glows” when lit in this way, as can be seen in the above photos and the American penny I linked to above. The wrap-around light highlighted the texture dramatically.

To get the whole coin in focus, I shot with the lens set to f/11, and pointed the camera straight down to keep the focal plane parallel to the coin itself.

When I shot the silver 20c piece in the same way, I discovered it to be flat and boring, so I thought I’d apply some of the lessons I’d learned from reading the fantastic book Light: Science and Magic. Getting metallic surfaces to look interesting and lively is all about controlling reflections. Silver surfaces have no colour of their own, they only reflect the light that’s around them. When I was shooting straight down, the coin was reflecting the dark lens of the camera. The light was coming from a low angle to the side, so it looked like a black disk with thin white lines at the detail.

This looked fine with the copper coin, but it was simply ugly with the silver. If I was going to get any light on the shot, I’d have to angle the camera, so I rolled the tripod down and looked across the coin. Have a look at the setup shot below. A test shot revealed it was reflecting the wrap-around white paper diffuser beautifully, but whereas before it was all black, now it was all white. The detail was again flat and boring. I needed something black to reflect in the coin, and I needed to position it precisely in the “family of angles”. That wasy it would be reflected just enough, but not too much in the coin. I grabbed the closest handy black object, the lens cap.

Using my ever-useful “helping hands” (which I’ll return to in a future blog post), I suspended the lens cap such that the reflection appeared to cover half the coin. The fact that the lens cap is circular added a nice shape to the reflection: curved, rather than straight across the middle. The effect would have been nicer with a new, unscratched coin. Here the dark half is distinctly grey due to the scratches scattering the light.

Lighting wasn’t the only problem affected by the change in viewing angle. Now that the coin is tilted with respect to the plane of focus, parts of the coin would be out of focus. I stopped down the aperture two stops to f/22 to widen the depth of field, and spent a long time manually focusing the lens to place the focal point where it looked best.

In Lightroom, I noticed that none of the photos escaped without some parts being over or under exposed. So I cheated slightly. I processed the RAW file into three separate TIFF files, one exposed for highlights, one for shadows and one in the middle. I then merged the three with Enfuse GUI and then played with the fused file in Photoshop, bringing in and manually blending the various layers a bit to have more control over the exposure. I also selected and brightened the background to make it mostly white, but keeping the shadow.

Don’t you just love the designs of the New Zealand coins? The fearsome faces are very cool.