Wednesday, April 9, 2014

Focus Stacks v Straight Shooting: Tuesday at the Arboretum

I paid a visit to the Raulston Arboretum Tuesday, with one aim being to experiment with focus stacking. This is a technique that can enable shooting high magnification subjects (small objects shot from very close) with the whole subject, front to rear, in focus. Before digital photography permitted the blending of multiple exposures, the limitations of optics meant that only things which were pretty close to flat could be rendered fully sharp when the camera was really close. Think of stamp or coin photography compared to very tiny insects or flowers, which could be tack sharp in the areas closest to the lens but had to be allowed to "go soft" as their shapes bent just fractions of an inch further from the lens. Ah, the wonderful days of film photography!

Well, as often happens when I set out with one goal in mind, I became diverted to other pursuits along the way. However, my first image of the day did indeed involve focus stacking, though not of the sort I might do with a single tiny object. Instead, I found nice shapes and light at the top of a flowering bush, and wanted to capture that part of the plant with clarity, but wanted the background as soft as possible. I used the long end of a 100-400 zoom, near its closest focusing distance and widest aperture. This gave the desired background effect, but would not have come close to getting all of the nearby twigs and flowers in focus. Depth of field is very limited with such a long focus lens. So, I made three exposures (on a tripod), with each focused slightly differently. In Photoshop®, I then combined them to get the areas of clarity I wanted, a reasonable transition to softness, and the soft wash of color behind it all.

Lower in the same bush, bees were active. I couldn't resist sticking my nose in there and getting a few shots. No focus stacking possible with living, moving creatures!

These bee photos stand up to cropping and enlargement pretty well. Here's a version taken from the shot above.

Next I tried some of those tiny flowers that sometimes seem to call for heroic efforts to get them in focus. I did a stacking experiment, but in terms of artistic effect I decided I preferred these two straight shots (i.e. single exposures), with limited portions emphasized by their clarity while others were left blurred and highlighted the translucency and delicacy of structure.

The next flower was above my eye level, but a nearby staircase let me get a view from above. Here too, I tried a stack of shots to let me render the whole bloom sharp, but I like this version with detail and texture in the front and softness in the back.

To round out my journey, I studied a plant that became dormant over the winter and may or may not spring back from its geophyte. Here too, the idea of stacking shots to get every bit of detail in focus occurred to me, but I think that the gradual softening as leaves curve further away from the plane of focus helps to strengthen the feeling of depth and solidity.

I did make use of a bit of supplemental illumination from an off-camera flash, to emphasize the textures that were so much a part of what intrigued me. Here are three successively closer compositions:

[first photo Canon EF 100-400/4.5-5.6 L @ 400mm,
other shots EF 100/2.8 L IS macro]


  1. You continue to amaze and impress me with your talent for seeing beauty in what most of the passing world considers mundane. Gorgeous pictures, as always!

    PS: I made the Play with the Pros cut again this year. I'll try not to embarrass you next month! :-)


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