Show me the money!
For anyone unfamiliar with UK currency, you're looking at (clockwise from left), a one pound coin, one pence coin and ten pence coin. I shot this with the Olympus OMD EM10 Mark II fitted with the Olympus 60mm Macro lens, and the interesting part is it's actually a composite of 100 focus-bracketed images.
If you were to shoot this close at the lens's maximum aperture of f2.8, you'd have a depth of field measuring roughly 2mm, just covering the cricket-bat shape in the middle of the one pound coin. Close the aperture for a larger depth of field and this band thickens, but even at f22 it doesn't cover the full composition from top to bottom, which isn't even 50mm in depth. Plus at f22 diffraction has resulted in severe softening of the image.
So how do macro-photographers manage to get so much in focus at close distances? The answer is focus stacking, where you capture a bunch of images at fractionally different focusing distances and use software to composite them into one. It allows you to achieve a sufficiently broad depth of field at diffraction-friendly apertures.
What's clever about the OMD EM10 Mark II is it'll automate this process for you - at least on the capture side. The bracketing menu now offers focus bracketing for two to 999 frames at differentials of 1 to 10. You need to experiment for the best results, but after a few attempts I found a differential of two gave sufficient overlap between frames shot at f2.8, and 100 frames covered the desired range from front to back.
To create the composite image you'll need specialist software - I used Helicon Focus here with the default Depth Map option giving the best results. I'm really impressed how easy and effective the process was and I'll go into more detail in my OMD EM10 II review coming soon to Cameralabs. In the meantime though you can download the focus stacked composite plus single frame versions at f2.8 and f22 from my sample images page at the link below.
PS - many thanks to Park Cameras in London for the loan of a 60mm macro lens, a desk and some moral support!
PPS - focus bracketing are coming to the OMD EM5 Mark II and OMD EM1 via a firmware update soon, and the EM1 will additionally offer in-camera focus stacking, albeit only for a small ten frame burst.http://www.cameralabs.com/reviews/Olympus_OMD_EM10_Mark_II/