Bumblebee Foot

Images taken in a controlled environment or with a posed subject. All subject types.

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cube-tube
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Bumblebee Foot

Post by cube-tube »

Nikon plan 10x/0.25, Raynox 150, Canon 6D, Stacked in Helicon Focus, touchups in lightroom.

Just getting back into macro photography after a long hiatus. I like the image, but I'd like to fix the strange halos and chromatic aberrations near the top of the subject. Better diffusion? Dirty objective? Not sure. It's something I'll work on.

Image

apt403
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Post by apt403 »

Nice shot!

The haloing is one of the most difficult problems I've encountered so far. Tough to deal w/ in camera - Seems to be careful framing is the only way to minimize it, short of building a light scanning rig (which I suppose wouldn't remove the problem entirely, but dark OOF haze is probably better than bright):

http://www.photomacrography.net/forum/v ... hp?p=54698

Here's a decent post processing method I've been experimenting with (post #11):

http://www.photomacrography.net/forum/v ... p?p=166043

I've resorted to making heavy use of ACR in PS (or Lightroom), using the retouching brush with the clarity and dehaze options. Never perfect, but usable. After running my images through Topaz Sharpen AI, there seems to be enough data under the haze I can remove most of it w/ those filters.

cube-tube
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Post by cube-tube »

Thanks for the advice, apt403! That's very helpful.

Funny that you mention light scanning. I love the idea of building a light sheet rig. In the lab where I work I get to use this beast of a lattice light sheet:

Image

apt403
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Post by apt403 »

:shock: Yeah, 'beast' is a highly appropriate adjective there. What's that setup used for?!

cube-tube
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Post by cube-tube »

apt403 wrote:What's that setup used for?!
Pretty much any live imaging where a spinning disk confocal doesn't cut it. When people need better resolution, lower phototoxicity, or very long acquisition times. I know that there is a group using it for fruitfly morphogenesis. Another group has plans to do really long timecourses of root growth. Really cool stuff. Love it.

But I swear the photographers on this forum produce cleaner images with $20 lenses from eBay :roll:

rjlittlefield
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Post by rjlittlefield »

cube-tube wrote:But I swear the photographers on this forum produce cleaner images with $20 lenses from eBay :roll:
Yes, it seems like magic sometimes. But most everybody here is willing to share incantations, so it makes a nice place to learn from each other.

Regarding your image, I agree it looks less crisp than I'd expect. But at this scale I can't tell exactly what's going wrong.

Can you post an actual-pixels crop, marked up to indicate the chromatic aberrations and halos that you're concerned about?

Also, exactly what settings and stacking methods did you use in Helicon?

--Rik

cube-tube
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Post by cube-tube »

Sure!

Helicon Focus method C (Pyramid), 0% scale, 1% X adjustment, 1% Y adjustment.

Here is a single image from the stack:
https://photos.smugmug.com/Portfolio/Ph ... PRK-X4.jpg

Here is the unprocessed stack:
https://photos.smugmug.com/Portfolio/Ph ... 2FX-X4.jpg

Top crop, showing some green fringing around the high-contrast scaly bits.
Image

Middle crop:
Image

Bottom crop:
Image

I was also surprised by how low-contrast the raw image is. I have noticed that I get better contrast against a black background, so I think it might be internal reflections in the tube. I ordered some better flocking. But I don't think that's the whole story.

Olympusman
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Haloing

Post by Olympusman »

I have tested Helicon Focus and Zerene on the same stack series and found Helicon had haloing where Zerene did not.

Mike
Michael Reese Much FRMS EMS Bethlehem, Pennsylvania, USA

cube-tube
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Post by cube-tube »

Good to know thanks. I'll try out Zerene.

rjlittlefield
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Post by rjlittlefield »

cube-tube, thanks for the closeups.

The whole frame images appear to have gotten shrunk by SmugMug. It let me download, but the images came down as 2048x1365.

Looking at your crops, the CA does not look excessive to me. If you need less false color than this, as shot, I expect you'll have to move up to an apochromat, typically the Mitutoyo 10X NA 0.28 M Plan Apo. That's an expensive lens, but in good condition it's very sharp and has little or no false color. The working distance is also great, 33.5 mm. Green fringing on a brown subject can probably be fixed by a defringe filter in post-processing, but other people can advise you better than I can on that topic.

Your middle and bottom crops look good to me. They look soft from diffraction blur, but that can be helped a lot with some aggressive sharpening as discussed recently in apt403's thread at http://www.photomacrography.net/forum/v ... 084#250084 . In Lightroom, I'd suggest something like Amount 100 and Radius 1.5, but just play with it to see what you like. Note that such hard sharpening will also bring up the noise levels, which is why it's important with deep stacks to shoot at the lowest possible ISO.

Back to the top crop, two issues do catch my attention.

First is that the rear claw looks quite murky, especially near its base. But that also looks like normal behavior, caused by the large amount of out-of-focus light contributed by foreground areas that are seen by the wide aperture of the NA 0.25 microscope objective. See http://www.photomacrography.net/forum/v ... 042#135042 for some discussion and illustration of that issue. As mentioned by apt403, some of the detail in that region can probably be restored by filtering, but there are limits even to that approach. It may sound fatalistic, but my recommendation is to just get used to the idea that it's tough to see much detail through small gaps and bristle mats, especially when the detail that you're trying to see is dark and the foreground structures are light.

Second issue with the top crop is that the big foreground claw has a large featureless area on its upper left surface, around the area of that big bend. To go with that, there's a brighter band around the edge next to the dark background, extending down the claw as a narrower band. Given the rich texturing elsewhere on the claw, part of my head is screaming that that looks like a stacking problem. But on careful study, I suspect that the claw really is featureless in that area, and the bright band is just a reflection of some illumination coming in at an unexpected angle, something like a rim light component in what is otherwise frontal illumination.

--Rik

rjlittlefield
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Post by rjlittlefield »

BTW, I'm still unclear what "strange halos" you're talking about. Can you maybe post a crop that's marked up to point graphically to some of those? Thanks!

--Rik

cube-tube
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Post by cube-tube »

Sure here are some annotations:

Image

I guess I was just using "halos" as a catch-all for a few different kinds of artifacts.

To me, #1 looks kind of smudged, like the highlights are bleeding over into darker areas even though the surface is fairly flat. The kind of muddiness that you tend to see with dirty optics. There is the same kind of thing near the base of the claw, near the top of the image, where the image is hazy and contrast is very low.
#2 might just be a stacking error, but there is also some strong purple fringing. That area is kind of confusing
#3 looks like halo due to out of focus light obscuring the background, like you mentioned.

Thank you for your detailed reply. It is very helpful to know which artifacts are normal, and which are worth chasing after.

The out of focus light issue is something that I am familiar with. I know there are a few simple deconvolution/deblurring algorithms used in life science, like "nearest neighbor" deblurring, but I'm surprised that there is nothing like that available for macro photography. Maybe things get more complicated with opaque subjects.

rjlittlefield
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Post by rjlittlefield »

Thanks for the annotations.

General rule: in case of doubt, check your source images. A lot of times some appearance that initially makes no sense in the final image becomes clear when you look at the sequence of source images that produced it. This happens especially often in cases of overlap, for example foreground and background bristles that are nearly lined up.

I agree that the things you've noted here probably have several causes.

#1 looks pretty normal to me. Could be a dirty lens, could be some spherical aberration, could be a bit of OOF blur leaking into the stacked result. If this area is clear in one of your source images, then see if another stacking method does a better job. Typically a depth map method will give cleaner edges in areas of simple geometry like that part of the claw.

#2 looks to me like there's a second bright hair on the back side of the claw, that might not ever have been fully focused because the stack didn't go back far enough. Definitely check the source images on this one.

#3 is a bit of puzzlement. If you had lots of those bright "echo" type halos, then I would suspect a glitch in alignment. But since it's just here, I'm wondering if there's a background bristle in play. Again, check the source images.
Good to know thanks. I'll try out Zerene.
I'm the fellow who wrote Zerene Stacker, so I'll be happy to answer any questions you have about that one.

--Rik

cube-tube
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Post by cube-tube »

rjlittlefield wrote: I'm the fellow who wrote Zerene Stacker
Nice to see that student discount 8)

I tried being much more aggressive with the sharpening/clarity/dehaze and I think it does look better.

Image

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