Focus stacking gone awry

[Ian Watson]

Good evening everyone,

I found this example of hymenoptera on the patio. It was deader than the parrot in a certain Monty Python sketch. So I decided to try stacking focus. One lesson learned is that one has to be more careful with distance. A Micro-Nikkor 105mm f/4 with PN-11 extension tube should have worked closer if I had done so. This image was cropped to compensate.

My main question, though, is what is causing the artefacts you can see? I checked and nothing moved between all 21 frames. Is this a demonstration of the limits of Photoshop for this sort of thing?

[Birna Rørslett]

You need a better stacking software. Zerene or Helicon Focus are better options. Your dead parrot oops fly  should be an easy target.

Do note that stacking mercilessly exposes minor flaws with the individual frames.

[Ian Watson]

Thanks for the advice, Birna. I shall investigate.

[Ian Watson]

Here is the result of running my frames through Zerene Stacker. It was my first time using the software and is a simple PMax output. The artefacts that Photoshop introduced have gone but detail in the body seems less clear. I must tinker further.

[pluton]

Cool shot.  I'm not an expert on Zerene having only used the free trial, but could there have been camera or subject movement between exposures?

[Birna Rørslett]

Many times, the Dmax algorithm provides better results in Zerene .... PMax might exacerbate image noise in the quest for better rendition of overlapping fine details.

[Ian Watson]

Birna, thank you for the tip!

Keith, I am sure that the camera did not move. The subject apparently didn't, as far as I can tell.

Reading some of Zerene's documentation, I had a hunch. The software apparently does not mind whether it stacks from front to back or vice versa. What if a rookie photographed from front to back and then forward some in case he missed a few spots? Would that cause trouble? It turns out that it would! Here is the result using DMax on the frames that start at the front and stop at the back.

[Birna Rørslett]

The retouching tools of Zerene can come in handy .... sometimes the DMax version might be overall better, but  overlapping details can fail to render satisfactorily. Then try brushing in from the PMax version, using a small brush size. 

Never go back and forth with focus in a single stack.

[bobfriedman]

I start with PMAX and then use DMAX for corrections/retouching.. sometimes it is best to use a process called slabbing to isolate certain problematic areas for use in retouching.

generally it is best to isolate the subject relative to the background.. so I would recommend using a pin or needle in the thorax to orient the specimen from the background.

here is an example from years ago.. at 2x mag  https://pbase.com/bobfriedman/image/160249699

[Michael Erlewine]

I have extensively used Zerene Stacker. I alwasy do both PMax and DMax, and then use the DMax image and touch up with PMax for details. Most artifacts can be fixed with a little work. DMax has the color, PMax the finer details. Together, they work well, IMO.

A stacked photo with the NOCT 95.


Grew these indoors myself.

[Ian Watson]

Thank you all for the advice.

I revisited a stack that I did with Photoshop last year. There was some effort involved. Zerene Stacker made short work of it. I wish that I had tried it sooner instead of waiting until I thought I was doing enough stacking.

[bobfriedman]

for flowers I use just PMAX.. 85-stack https://pbase.com/bobfriedman/image/173428368