So I've posted before about my struggles to get good images of Culicidae eyes . I think Rik suggested that the eyes might be held "inflated" by some kind of hydrostatic pressure. I thought I'd just physically damaged them while mounting.
These two images were shot 12 hours apart - subject stayed pinned (yes I finally managed it ! ) on my desk overnight. So the eye colour goes and the eye starts to collapse inwards. The other thing I've noticed is that if you try and pin a Culicidae, after it is dead more than a few hours, you are just pinning an empty husk.
Image is with a Nikon 20x PLAN ELWD objective. Lighting by Nikon flashes. The purple colouration on the antennae setae (if that is the right word) is interesting as well - not sure if it is real or an optical (diffraction ?) artifact.
Aging Culicidae eyes ...
Moderators: rjlittlefield, ChrisR, Chris S., Pau
Aging Culicidae eyes ...
rgds, Andrew
"Is that an accurate dictionary ? Charlie Eppes
"Is that an accurate dictionary ? Charlie Eppes
- rjlittlefield
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Nice images!
About the purple, you might check the original stack and see if perhaps each bit of antenna changes color as you focus through it. Something like green to gray to purple, perhaps. I've seen color changes like that with some lenses. I presume they are due to longitudinal CA -- different colors focusing at slightly different depths.
If you do see color shifting like that, then perhaps what's happening in these stacked results is that the point of sharpest focus happens to be a purplish one, so that's what gets picked out by the software and appears in the stacked result. Only one of many possible explanations, of course.
--Rik
About the purple, you might check the original stack and see if perhaps each bit of antenna changes color as you focus through it. Something like green to gray to purple, perhaps. I've seen color changes like that with some lenses. I presume they are due to longitudinal CA -- different colors focusing at slightly different depths.
If you do see color shifting like that, then perhaps what's happening in these stacked results is that the point of sharpest focus happens to be a purplish one, so that's what gets picked out by the software and appears in the stacked result. Only one of many possible explanations, of course.
--Rik
- Charles Krebs
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I don't think the blue/magenta is natural color. Longitudinal (axial) CA is a likely reason, but fortunately the detail is surprisingly well rendered.
Unfortunately axial CA is extremely common in microscope objectives. I get way too much of it with the achromats I use with my vertical illuminator. At least with digital you can do some "correction". Must have been brutal working with film if you were hypersensitive to this sort of thing.
Here are two links I've read over several times in the past. Both good references.
http://toothwalker.org/optics/chromatic.html
http://www.microscopyu.com/tutorials/ja ... chromatic/
Andrew... you just said in a different post:
If you know the color is "false" you can quickly make it look a little more "natural". The difference below is subtle but it "allows" the viewers attention to stay with the details in the photo instead of wondering about the color in parts of the feathery antenna. (However, I think I'm overly sensitive to this sort of thing.... but Rik is too! )
Unfortunately axial CA is extremely common in microscope objectives. I get way too much of it with the achromats I use with my vertical illuminator. At least with digital you can do some "correction". Must have been brutal working with film if you were hypersensitive to this sort of thing.
Here are two links I've read over several times in the past. Both good references.
http://toothwalker.org/optics/chromatic.html
http://www.microscopyu.com/tutorials/ja ... chromatic/
Andrew... you just said in a different post:
So...ps: thanks for looking, I welcome constructive criticism (and even energetic discussion !) and have no problems if people want to edit and repost some of my images.
If you know the color is "false" you can quickly make it look a little more "natural". The difference below is subtle but it "allows" the viewers attention to stay with the details in the photo instead of wondering about the color in parts of the feathery antenna. (However, I think I'm overly sensitive to this sort of thing.... but Rik is too! )
- rjlittlefield
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Harrumph! I think of myself as "exquisitely sensitive". "Overly sensitive" would be a description of other people.Charles Krebs wrote:(However, I think I'm overly sensitive to this sort of thing.... but Rik is too! )
About the color, it's an interesting question whether better results could be obtained by separating the channels, stacking separately, then putting the results back together. When I've tried that approach at lower magnifications, it was more likely to introduce color shifts than to get rid of them. But perhaps at these higher magnifications it would be a better tradeoff.
--Rik
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Interesting! I'm seeing some yellow fringing around a purple fiber, but I'm not seeing the shift from yellow to purple that I would expect at the focus point if this were simple longitudinal CA. I don't know what's going on here, but I don't think that processing the RGB bands separately would make much difference.
--Rik
--Rik
Good question, the first stack was started 30minutes after it shuffled off this mortal coil. So I think that's what they look like. I'll catch another live one and check it under a stereo scope if it stops still long enough.ChrisR wrote:Back at the mossie's eye, is the pushed-in shape in the first image they way they are in vivo, or has it already collapsed?
Andrew
rgds, Andrew
"Is that an accurate dictionary ? Charlie Eppes
"Is that an accurate dictionary ? Charlie Eppes
Andrew, this one I shot a while ago doesn't seem to have the 'dent' so I suspect your mossie has just started to deflate. They are tricky buggers aren't they!
Could well be, but different species might have different morphology ? The trouble with deflating eyes, is when you shoot very high mag and as the head structure gradually changes, the angle of the antennae magnifies it. I've been going barmy trying to shoot some 20x stacks of another specimen today. At least my stage does all the hard work for me - my heart goes out to those who have to twiddle knobs for each slice.lauriek wrote:Andrew, this one I shot a while ago doesn't seem to have the 'dent' so I suspect your mossie has just started to deflate. They are tricky buggers aren't they!
Tell you what, if I get a fresh and juicy one at the right time, I might try shooting a whole series of stacks a T=0, 15mins, 30mins, 60mins, 2 hours, 4 hours, etc.
rgds, Andrew
"Is that an accurate dictionary ? Charlie Eppes
"Is that an accurate dictionary ? Charlie Eppes