With and without light tent

[pittendrigh]

Two fishing flies photographed much the same way with and without a light tent.

In both shots the fly is on top of a raised 1/8" inch thick semi-translucent white plastic (Plexiglass) sheet with a slave flash underneath, pointing up, set at its lowest intensity. Two umbrella strobes left and right, slightly in front. Stackshot rail and Zerene Stacker. 140 (or so) focus stack.

The sequence shot without the light tent shows shadow-like anomalies inside the bend of the hook, plus a spurious chaotic black border at the edges of the image. The brighter the strobes were the worse this effect was. But with the strobes turned down low enough to avoid the anomalies there wasn't enough light for a good photo.

The same pose with lights turned up brightly, but with a light tent (synthetic wedding gown material from the sewing store) the shadow-like anomalies do not appear.

So I'm curious to hear a technical explanation. Knowing why chaos happens seems to help avoid in the future, in a greater and wider set of circumstances.

[rjlittlefield]

First, check your source images. The dark border indicates that at least one source image in that stack was quite dark. I would not be surprised if alignment also got screwed up at that point, which would explain the shadow-like anomalies and several other stacking artifacts that I see in other parts of that first image.

When you find the bad image(s), just restack the other good ones and see what result you get.

Expected differences with and without a light tent would be much more subtle than the pair of output images that you've shown here. You'll see significant differences in the appearance of shiny parts, like the eye of the hook and the bead just behind it, but I expect that most of this subject will look almost exactly the same.

--Rik