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Lacewing eye

 
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Beatsy



Joined: 05 Jul 2013
Posts: 911
Location: Malvern, UK

PostPosted: Tue Nov 07, 2017 2:13 am    Post subject: Lacewing eye Reply with quote

Stacked with a 20x Mitty. The eye appeared much more colourful under a loupe (full rainbow colours like an oil sheen on water) but most of it disappeared under magnification. Oh well - maybe next time...
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svalley



Joined: 03 Dec 2006
Posts: 272
Location: Albany, Oregon

PostPosted: Tue Nov 07, 2017 3:35 pm    Post subject: Reply with quote

Still very nice!
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rjlittlefield
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Joined: 01 Aug 2006
Posts: 18254
Location: Richland, Washington State, USA

PostPosted: Tue Nov 07, 2017 5:49 pm    Post subject: Reply with quote

It is a common issue that interference colors tend to disappear when imaged with wide-aperture lenses. To get the colors that you see with a loupe, you may need to use only the same NA that you get with a loupe.

--Rik
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ChrisR
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Joined: 14 Mar 2009
Posts: 7265
Location: Near London, UK

PostPosted: Wed Nov 08, 2017 11:16 am    Post subject: Reply with quote

I'm going to make a mistake here:
10x 15mm dia loupe.


20mm FL
= f (20/15)= (4/3)

= NA 0.5 x (3/4)

= 0.375

Which is pretty close to the 0.42 of the 20x objective, no?

What's wrong?
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rjlittlefield
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Joined: 01 Aug 2006
Posts: 18254
Location: Richland, Washington State, USA

PostPosted: Wed Nov 08, 2017 7:14 pm    Post subject: Reply with quote

The pupil of your eye stops down the loupe. The calculation needs to use your own pupil diameter instead of 15mm.

--Rik
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Sumguy01



Joined: 28 Jan 2013
Posts: 905
Location: Ketchikan Alaska USA

PostPosted: Wed Nov 08, 2017 8:47 pm    Post subject: Reply with quote

Applause Very nice.
Thanks for sharing.
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anvancy



Joined: 05 Dec 2009
Posts: 309
Location: India

PostPosted: Thu Nov 09, 2017 10:42 pm    Post subject: Reply with quote

Details and colors are magnificent!

Here I am struggling at 4x with light issues and steps and there is this beauty at 20x. Superb!!
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Raynox 150|Raynox 250|Raynox MSN 202|Canon MPE 65mm|Canon 100mm.|Wemacro Rail


Last edited by anvancy on Fri Nov 10, 2017 4:23 am; edited 1 time in total
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vendav



Joined: 31 Jul 2008
Posts: 68

PostPosted: Fri Nov 10, 2017 3:33 am    Post subject: Reply with quote

Hi,
This reminded me of a stack I did some time ago. Searching my records revealed that way back in 2009 I made some images of a common lacewing with a Nikon EPlan 4X and with a Nikon Plan 10X. Both were working way outside their design parameters, each on 185mm bellows extension giving approx. 6X and 16X on the sensor. Ignorance is bliss!
The point of my rambling is that the final stacked images both showed far more colour in the eye than is visible in yours; beginners luck perhaps or maybe the lighting?
My notes show that at that time my lighting set up was fairly primitive, just two "desk lamps" (probably Janso) through a cut down Danone bottle for diffusion.
Kind regards,
David
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Harald



Joined: 13 May 2011
Posts: 398
Location: Steinberg, Norway

PostPosted: Fri Nov 10, 2017 10:15 am    Post subject: Reply with quote

Hi,
The colors, light and details are just great.
Great work as usual Very Happy
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Harald

Lier Fotoklubb / NSFF
AFIAP / CPS
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http://www.500px.com/blender11
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zzffnn



Joined: 22 May 2014
Posts: 1492
Location: Texas USA

PostPosted: Fri Nov 10, 2017 11:27 am    Post subject: Reply with quote

Very nice image, Beatsy!

vendav wrote:
The point of my rambling is that the final stacked images both showed far more colour in the eye than is visible in yours; beginners luck perhaps or maybe the lighting?


I think you were simply lucky in getting a more colorful individual. (The 100 or so) Lacewings that I have found had huge variations in colors. And their colors fade quickly, if one mistreats them (if one puts them directly in alcohol, for example).

I don't mean to be rude or too blunt and I apologize if I sound that way. But many on this web site don't have the skills to do macro/micro lighting as well as Beatsy (myself is an example). Not to mention a beginner.
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vendav



Joined: 31 Jul 2008
Posts: 68

PostPosted: Fri Nov 10, 2017 3:02 pm    Post subject: Reply with quote

Hi,
No offence taken and none meant either.
Apologies if you imagined that I was being boastful, that certainly was not my intention.
I wasn't implying that my skills were in any way superior to Beatsy's - who posts some of the more impressive images on this site - just that I had somehow (beginners luck as I suggested?) managed to capture more colour in the eye.
It was a good while ago, but to the best of my recollection, it was a very fresh specimen with no treatment, fixing etc.
Kind regards,
David Embarassed
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zzffnn



Joined: 22 May 2014
Posts: 1492
Location: Texas USA

PostPosted: Fri Nov 10, 2017 3:44 pm    Post subject: Reply with quote

Sorry, I was not clear. I meant to say that even fresh untreated lacewings from the same collection site can have very different colors. I was surprised myself when I found that.
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ChrisR
Site Admin


Joined: 14 Mar 2009
Posts: 7265
Location: Near London, UK

PostPosted: Fri Nov 10, 2017 5:13 pm    Post subject: Reply with quote

rjlittlefield wrote:
The pupil of your eye stops down the loupe. The calculation needs to use your own pupil diameter instead of 15mm.

--Rik
That occurred to me soon after, at which point I asked myself if I should see with greater acuity in low enough light to open the aperture.. Doesn't seem to happen.
Peak foveal cone density gives approx 3 micron cone width.
(peak density of about 140k/sq mm, though, doesn't tie up with ~0.02 degrees quoted as peak acuity)

Then I wondered how much cross-chanel interference we get and where we'd hit diffraction.
If the eyeball is 25mm and you use a 8x loupe (FL about 25mm) focused with eyes at 200mm ( = approximately infinity), M= 1.
FL becomes 12.5mm. ? (I think)

Eye's pupil dimeter say 5mm, f/2.5, Eff /5

The CoF C is about 2 cone-widths.
That would mean we'd be near a diffraction limit.
Which seems wrong, because if you use a stronger loupe (Mitty 50x) you see a lot more.

Too tired!
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vendav



Joined: 31 Jul 2008
Posts: 68

PostPosted: Mon Nov 13, 2017 2:10 am    Post subject: Reply with quote

Now my head hurts!!!
Kind regards,
David
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rjlittlefield
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Joined: 01 Aug 2006
Posts: 18254
Location: Richland, Washington State, USA

PostPosted: Mon Nov 13, 2017 9:35 am    Post subject: Reply with quote

Yeah, mine too.

The big idea is simple enough: interference colors rely on optical path lengths being such as to cause constructive interference for some wavelengths, destructive for others. The colors are intense when all paths have similar effects. But when the light getting into the lens has come from a wide range of angles, the path lengths have varied widely. Each path length affects the colors differently, so the sum of many path lengths has the colors washed out. The wider the aperture and the more diffuse the illumination, the wider the range of angles and the more washed out the colors become.

As for diffraction and resolution, well, again the details are complicated but the big picture is simple. The objective makes an object that is physically small and close look like a virtual object that is large and far away. Then the eye, regardless of its resolution, forms an image of the virtual object for you to perceive. A higher magnification objective makes the virtual object larger, so your eye can perceive more detail in it, regardless of whether your eye is limited by diffraction (which it's not), or lens/cornea aberrations, or foveal resolution, or something else.

--Rik
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