(For those of you too young to know, the TV show was "Have gun - will travel"
reversed El Nikkor 50/2.8 @ f/5.6; minimum and full bellows extensions, some cropping; ZS PMax.
Another Green Lacewing
Moderators: rjlittlefield, ChrisR, Chris S., Pau
Another Green Lacewing
Hardly any insect activity in this part of the world so was glad to see this Green Lacewing at my blacklight last night. There are several lacewing images here already so I apologize for posting another - but to paraphrase an old western TV show "have camera - must shoot".
(For those of you too young to know, the TV show was "Have gun - will travel"
reversed El Nikkor 50/2.8 @ f/5.6; minimum and full bellows extensions, some cropping; ZS PMax.
(For those of you too young to know, the TV show was "Have gun - will travel"
reversed El Nikkor 50/2.8 @ f/5.6; minimum and full bellows extensions, some cropping; ZS PMax.
Last edited by NikonUser on Tue Sep 22, 2009 7:18 am, edited 1 time in total.
NU.
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.
Nikon camera, lenses and objectives
Olympus microscope and objectives
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.
Nikon camera, lenses and objectives
Olympus microscope and objectives
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Harold Gough
- Posts: 5786
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Re: Another Green Lacewing
I don't recall any from this viewpoint. Refreshing!NikonUser wrote:There are several lacewing images here already so I apologize for posting another.
harold
My images are a medium for sharing some of my experiences: they are not me.
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Charles Krebs
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rjlittlefield
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His world looks rather like yours, seen through a fisheye lens.
The retina structure of an insect's compound eye is closely analogous to a human retina. In both cases there is an warped 2D array of photoreceptors, interconnected with their neighbors, on which is projected an optical image of the world. In the human eye, that projection is accomplished by a single large wide-angle lens. In the insect eye, the projection is accomplished by an array of small narrow-angle lenses aimed outward along the radii of a sphere.
It's an interesting observation that these two eyes have different sizes. My first thought was that it might be an illusion due to perspective. On second thought that's not possible, given the sizes and distances involved.
However, it's clear that we're not looking at the head from perfectly straight above. If you layer two copies of this image -- one normal and one flipped horizontally -- then flashing between the two shows a clear rotation of the head. So it could be that the eyes are not perfectly spherical and the apparent difference in size is actually a matter of exactly which part of the periphery we're seeing. Or it could be that the eyes really are different sizes. That would not be surprising. Given the different corrections between the lenses on my glasses, I would not be surprised to find that the images presented to my eyes are 2% different in size.
--Rik
The retina structure of an insect's compound eye is closely analogous to a human retina. In both cases there is an warped 2D array of photoreceptors, interconnected with their neighbors, on which is projected an optical image of the world. In the human eye, that projection is accomplished by a single large wide-angle lens. In the insect eye, the projection is accomplished by an array of small narrow-angle lenses aimed outward along the radii of a sphere.
It's an interesting observation that these two eyes have different sizes. My first thought was that it might be an illusion due to perspective. On second thought that's not possible, given the sizes and distances involved.
However, it's clear that we're not looking at the head from perfectly straight above. If you layer two copies of this image -- one normal and one flipped horizontally -- then flashing between the two shows a clear rotation of the head. So it could be that the eyes are not perfectly spherical and the apparent difference in size is actually a matter of exactly which part of the periphery we're seeing. Or it could be that the eyes really are different sizes. That would not be surprising. Given the different corrections between the lenses on my glasses, I would not be surprised to find that the images presented to my eyes are 2% different in size.
--Rik
ChrisR
Longitudinal bilateral symmetry is a very common feature of most animals; there are some exceptions. However, perfect bilateral symmetry is rare - looked at your face recently?
Longitudinal bilateral symmetry is a very common feature of most animals; there are some exceptions. However, perfect bilateral symmetry is rare - looked at your face recently?
NU.
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.
Nikon camera, lenses and objectives
Olympus microscope and objectives
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.
Nikon camera, lenses and objectives
Olympus microscope and objectives
Chris:
I wasn't trying to be a smart a***, also I'm not clairvoyant.
The emphasis on your post appeared to be that one eye was bigger than the other, I saw no indication that the emphasis was on the spherical nature of the eyes.
I wasn't trying to be a smart a***, also I'm not clairvoyant.
The emphasis on your post appeared to be that one eye was bigger than the other, I saw no indication that the emphasis was on the spherical nature of the eyes.
NU.
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.
Nikon camera, lenses and objectives
Olympus microscope and objectives
student of entomology
Quote – Holmes on ‘Entomology’
” I suppose you are an entomologist ? “
” Not quite so ambitious as that, sir. I should like to put my eyes on the individual entitled to that name.
No man can be truly called an entomologist,
sir; the subject is too vast for any single human intelligence to grasp.”
Oliver Wendell Holmes, Sr
The Poet at the Breakfast Table.
Nikon camera, lenses and objectives
Olympus microscope and objectives
-
Charles Krebs
- Posts: 5865
- Joined: Tue Aug 01, 2006 8:02 pm
- Location: Issaquah, WA USA
- Contact:
These eyes look pretty spherical from the side as well.They may only appear circular from this direction of course.
So they do.
WIkipedia has some fairly general info, but doesn't mention a retina, but a rhabdom
http://en.wikipedia.org/wiki/Rhabdom.
It seems that there's a 3 dimensional array (for this insect, it's suggesting hemispherical, about as thick as half the radius)) of three dimensional structures (conical, in each of the ommatidia), within which are "microvilli" where the photosensing molecules live.
Most of the references on structure which I found, were pay-to-access. This old article has some structural info (though its subject is about electro responses), http://www.pubmedcentral.nih.gov/picren ... obtype=pdf
(It also comments that dissecting the eyes of 3-day old larvae is difficult - geddaway!)
It seems there's a "retinula cell" which is peculiar to compound eyes, and not a lot like a retina as in a human eye.
Human eye structure is explained in what I thought a nice level of detail , here:
http://thalamus.wustl.edu/course/eyeret.html
There's not much stereo vision going on with these eyes; a band from above, down to frontal, but only about the same angle as coverage of a 110mm lens on 35mm.
You have to wonder how it knows what it's eating.
WIkipedia has some fairly general info, but doesn't mention a retina, but a rhabdom
http://en.wikipedia.org/wiki/Rhabdom.
It seems that there's a 3 dimensional array (for this insect, it's suggesting hemispherical, about as thick as half the radius)) of three dimensional structures (conical, in each of the ommatidia), within which are "microvilli" where the photosensing molecules live.
Most of the references on structure which I found, were pay-to-access. This old article has some structural info (though its subject is about electro responses), http://www.pubmedcentral.nih.gov/picren ... obtype=pdf
(It also comments that dissecting the eyes of 3-day old larvae is difficult - geddaway!)
It seems there's a "retinula cell" which is peculiar to compound eyes, and not a lot like a retina as in a human eye.
Human eye structure is explained in what I thought a nice level of detail , here:
http://thalamus.wustl.edu/course/eyeret.html
There's not much stereo vision going on with these eyes; a band from above, down to frontal, but only about the same angle as coverage of a 110mm lens on 35mm.
You have to wonder how it knows what it's eating.
Last edited by ChrisR on Thu Jun 13, 2013 1:16 pm, edited 1 time in total.
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rjlittlefield
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See http://books.google.com/books?id=09XPAA ... &lpg=PA515. "The anatomy, physiology, morphology and development of the blow-fly", Benjamin Thompson Lowne, 1895.
Quoting from page 517,
With this picture in mind, one immediately asks "How does the fly integrate so many tiny images?"
The answer is that it doesn't have to. There are no tiny images. What the fly sees is just a fuzzy picture of the world, broken up into roughly hexagonal pixels, each of which represents intensity integrated over the small angular area that is sampled by one ommatidium.
--Rik
Quoting from page 517,
Many people imagine that each facet of the compound eye sees an image of the world. This leads to classic cartoons of "the last thing a fly sees", showing a hexagonal grid of hundreds of tiny flyswatters.The Retina (Pl. XXXVI., Fig I, rt). --- The term 'retina' has been applied by me to a layer of nervous elements and pigment cells which lies internally to the basilar membrane, and which is connected with the optic ganglion by the decussating fibres, already described as the optic nerve.
As this layer consists of rod-like elements, identical with those of the simple eye, in which the nerve-fibres obviously end, and upon which a dioptric picture can be shown to fall, this term is not only appropriate but necessary, unless it is to be entirely discarded in relation to the invertebrate eye.
With this picture in mind, one immediately asks "How does the fly integrate so many tiny images?"
The answer is that it doesn't have to. There are no tiny images. What the fly sees is just a fuzzy picture of the world, broken up into roughly hexagonal pixels, each of which represents intensity integrated over the small angular area that is sampled by one ommatidium.
--Rik
A couple of (slightly more recent!) papers which would be interesting to read more from...
http://arjournals.annualreviews.org/doi ... o.42.1.147
http://www.springerlink.com/content/rx488815177664ku/
There's certainly variation in the terms authors use.
Ah I see how to find bits from books now - some good stuff here, around page 28
http://books.google.com/books?id=AiLtc5 ... na&f=false
http://arjournals.annualreviews.org/doi ... o.42.1.147
http://www.springerlink.com/content/rx488815177664ku/
There's certainly variation in the terms authors use.
Ah I see how to find bits from books now - some good stuff here, around page 28
http://books.google.com/books?id=AiLtc5 ... na&f=false
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rjlittlefield
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There is also a lot of variation in the level of structure that's being talked about.ChrisR wrote:There's certainly variation in the terms various papers use.
The page you linked shows a diagram of a small part of the human retina, that part consisting of a single photoreceptor talking to a nerve cell. Each of those photoreceptors would be either a rod or a cone cell. The photoreceptor senses light intensity from a small area of the world, sampling from a large image projected by the cornea and lens. The retina is a large structure comprising millions of these photoreceptors, which in the aggregate produce a single image of the world.
The rhabdom described by Wikipedia is an even smaller part of the insect eye. The rhabdom is a part of one ommatidium. For purposes of image formation, each ommatidium is a single multispectral photoreceptor, roughly equivalent to a small cluster of rod and cone cells in a vertebrate eye.
So talking about rhabdom versus retina in an insect eye is already crossing several orders of magnitude, and going down to the microvilli and photosensing molecules is adding several more.
To see the analogy between insect and vertebrate eyes, one needs to stay at a much coarser level of detail. To repeat what I wrote before,
In the human eye, that single large wide-angle lens projects an image of the world onto an array of photoreceptors (rods and cones) that are arranged in a single layer. The layer of photoreceptors then talks to other layers of nerves, some of which connect to their neighbors to do a certain amount of feature detection before signals are sent to the brain.In both cases there is an warped 2D array of photoreceptors, interconnected with their neighbors, on which is projected an optical image of the world. In the human eye, that projection is accomplished by a single large wide-angle lens. In the insect eye, the projection is accomplished by an array of small narrow-angle lenses aimed outward along the radii of a sphere.
In the insect eye, an array of small narrow-angle lenses projects an image of the world onto an array of photoreceptors (rhabdoms and associated structures) that are arranged in a single layer. The layer of photoreceptors then talks to other layers of nerves, some of which connect to their neighbors to do a certain amount of feature detection before signals are sent to the brain.
The parallel language in the preceding two paragraphs is not an accident. It represents the analogy that I was speaking of between the retina structures of insects and humans. In both cases a single image of the world is projected onto a single layer of photoreceptors, with points that are close in the world mapping onto photoreceptors that are close in the eye.
When I used the phrase "warped 2D array", I was speaking of a single layer (2D = "two-dimensional") spread across a larger structure that is roughly spherical ("warped", as in not planar). Certainly the layer has thickness, and in the insect eye that thickness is pretty large compared to the radius of the sphere. This relative thickness is primarily due to the much smaller radius of the insect eye. In absolute thickness, the retina of a human varies from roughly 0.15 to 0.30 mm. [ref] Map that to the radius of an insect's eye, and you'll get a structure that looks not much different from figure 2.1 A of the butterfly eye shown on page 29 of the link you gave.
--Rik