By the way, Chris (R.)—very nice image! Sorry for being so breathless about slabbing that I didn't comment on a superb photograph.
I wouldn't have the patience to routinely combine slabs using Photoshop layer masks. While I often use Photoshop layer masks, Zerene Stacker can stack slabs very well, so I let it do most of the heavy lifting.
I’ve been doing slabs one way or another for some time--it's been cumbersome but often worthwhile. As you demonstrated above, having a slab in which an element is delineated cleanly, but all else is a creamy blur, can help a lot when retouching. And slabs can reduce the interference of things in front of other things.
But a large step forward in my slabbing came a couple of weeks ago, when I asked Rik for advice about a stack I was finding difficult. It was, for me, a shallow stack of 259 frames. But by necessity, the individual frames were dark, fuzzy, and confusing, and my naked eye could barely make heads or tails of them. It was not surprising that the resulting stacks had major artifacts and were hard to retouch. Rik suggested that I make PMax slabs of about 20 images, overlapping each slab with the prior slab by ten frames. Then, he suggested, I should stack the resulting slabs using DMap. And he gave me the tips I needed to create an xml file that could be loaded into the Zerene Stacker batch dialog to do this automatically. I found it tedious to create the first xml file, but thereafter have just edited it for each new job.
Wow, has this approach worked. The difficult stack turned out shockingly better right out of the box. But also notable was how much easier other things were. I could quickly test various DMap settings—which unsurprisingly took an order of magnitude less time to run on 25 slabs than on 259 frames. Since I could test more quickly, I did more testing, and found better combinations—some of which I’ll combine using Photoshop layer masks (right now I’m mostly shooting—will leave the finer points of post-processing until the snow flies). And Zerene Stacker’s retouching tools became much easier to use for this very shallow DOF stack (100x). When a feature is spread across 20 frames, it can be hard to retouch in. When it is contained within a single slab, it’s easy.
So for every stack I’ve shot since (about three per day, the shallowest being 94 images), I’ve used this approach. It’s early to say, but I strongly suspect that slabbing may form a key portion of my workflow for anything other than very shallow, low-magnification, stacks. Definitions of “shallow” and “low-magnification” differ from one photomacrographer to another. The lowest magnification I’ve shot during this period was a 5x stack of 461 images. For this stack, I tried both the slabbing regime described here and a straight (no slabbing) stack. My sense was that Zerene Stacker could handle either approach very well. But the human element—me—found the slabbing approach much easier. Retouching was orders of magnitude easier with the slabs—no confusion about which elements are in front and which behind, and no endless searching for which frame to retouch in. Glorious! And with the slabs, I quickly tried several sets of DMap settings, and (as the tutorials say) found that certain settings worked better for various elements of the image. I’ll retouch the best elements together later. Without the slab approach, trying various DMap settings would have been more onerous, and I’d probably have skipped it.
Sorry for the long post. But I suspect this is paradigm-level issue in photomacrography. A frontier. Thanks, Chris R., for bringing it up.
Ed (“elf”) was generous in sharing his superb generator of xml files for Zerene Stacker batch jobs. His work deserves much more attention than it has gotten. I looked—hard—at it before generating my own xml file, but decided that I needed the learning experience of writing such an xml file myself. And I wasn’t sure, on initial inspection, if Ed’s approach would let me generate the overlapping DMap images that I wanted. (It was partly because of my confusion that I decided I needed the learning experience.) But my sense is that Ed’s application either can, or could with minor modifications, generate an xml file such as I’m using, much more easily than I'm doing it. Ed hasn’t gotten his deserved share of kudos for this contribution, and I think it's because most of us (myself included) are not sufficiently advanced to appreciate what he gave us.
And maybe Rik is cooking up enhancements to facilitate slabbing in Zerene Stacker? While I have no inside information, does anybody care to bet against me?
Anyway, I hope Rik is, because slabbing seems to take focus stacking to a new level.
ChrisR wrote:I imagine that's a front end for batch scripts?
I can't get it to open - it shuts immediately.
The difficulties I find with substacks are more about processing the curves etc in each part and then reintegrating the subs together.
Chris, I can open Ed’s script easily—issue on your machine?
Yes, Ed’s script generates a very nice xml file that can be loaded via the Zerene Stacker batch dialog.
Processing “curves, etc.”—this seems Photoshop specific. Any reason not to stack your slabs with ZS DMap? If you prefer to do it in Photoshop, what’s the problem in processing curves? I use curves layers daily, so this seems like the easy bit. It’s the endless painting in with layers that would kill me.
Cheers,
--Chris (S.)
(Why are so many of us at PMN named "Chris"?)
