Photography Challenge: Reflective Faces

Mineral Matters #431

I have been photographing specimens for the next update of the Illustrated Minerals of Australia in the Monthly Mineral Chronicles.

One of them is jacobsite, a manganese iron oxide, and member of the Spinel Group of minerals.

Some jacobsite crystals are particularly lustrous and reflective. They can be difficult to capture. You can see the finished product below, the result of a stack of 75 images.

Focus stacking is a method to extend your depth of field, very important with macro or micro photography. My tool of choice is Helicon Focus.

There are two stacking methods, Depth Map, and Pyramid. Personally I find that I get the best results with Depth Map, although there can be some issues such as “halos” (Australian photographer Alan Walls has a great article on this). I find that these are usually best fixed by running the Pyramid method and using that output to “retouch” the areas that are an issue on the Depth Map result. The Pyramid method doesn’t tend to suffer so much from it.

I know of some people that prefer the Pyramid method as their primary stacking mode, but for me, there are two major drawbacks. The first is that the Dust Map capability doesn’t appear to be taken into consideration, so you end up with “dust trails”. The second is the flaring that you can get at the edges of reflective faces. This is abundantly clear in the third image below.

This particular stack only had minimal halos, and I was able to fix them with careful retouching using the Pyramid stack result without the flaring interfering. Had I not been able to, I would have reverted to cloning, or retouching from individual photo in the stack. Either of these would have added significant time to complete. Another option is to fix in post-processing, but this can be even more work.

Below: Jacobsite, Iron Monarch, Iron Knob, South Australia. Width of view 6mm. Click on the image for a higher resolution version.

Below: The result of the Depth Map stack. Suffering from minimal halos.

Below: Flaring in the result of the Pyramid Method stack.