Ultraviolet.

[troutheaven]

Originally Posted by Dunk

UV isn't only found in manufactured materials! Lot's of bird feathers have highlights that reflect in the UV spectrum. Some birds see in Ultraviolet, so that robins' breast isn't only red, it's also got a bit of bling going on.

I remember hearing of this feature in, especially, golden pheasnt feathers, and promptly went over a full skin with an ultra-violet emmitiing lamp ....................................... and nothing. Still, you live and learn and I'm ever open to revising my beliefs or re-iterpretation of my experiences.

[Silver Stoat]

Stan,

If the GP feathers reflect UV you wouldn't be able to see it anyway

I think the only way you may be able to detect it would be to photograph the UV illuminated feathers through a UV 'pass' filter (one that excludes visible light).
From what I have been told, many digital cameras are sensitive, to some degree, to wavelengths below 400 nm - I'm sure someone on here will know more about this and will correct me if I'm wrong


Dave.

[troutheaven]

Originally Posted by Silver Stoat

Stan,

If the GP feathers reflect UV you wouldn't be able to see it anyway

I think the only way you may be able to detect it would be to photograph the UV illuminated feathers through a UV 'pass' filter (one that excludes visible light).
From what I have been told, many digital cameras are sensitive, to some degree, to wavelengths below 400 nm - I'm sure someone on here will know more about this and will correct me if I'm wrong


Dave.

Well, I understand that, and I would suppose that any vaguely reflective surface would reflect uv light, whether the human eye can detect or no.

My point was that there is no evidence of fluoresence from gp feathers when uv light is shone on them.

[Silver Stoat]

Stan,

I understand now.
From the quotation you posted I assumed you were hoping to see reflected UV not fluorescence.

Dave.

[Gander]

Originally Posted by oakham orange

I dont think Kingsmill Moore had too much UV materials in his flies. And they worked just fine.

Kingsmill Moore became very aware of another part of the spectrum in designing his flies. In his book "A man may fish", he descibes carrying out a few basic experiments to see how much infra-red light was reflected by various black materials. His conclusion was that Ostrich herl reflects the least IR and is therefore the best material for a black body, such as in his fly the Kingsmill.

I'm not sure his deduction can be correct because surely it would depend more on the type of dye used rather than the material? He was however, I believe, one of the first tyers thinking along the right lines in giving more regard to how fish see colour as opposed to how we see it. His bumble series is obviously a testimony to this type of thinking.

[Silver Stoat]

Originally Posted by Gander

Kingsmill Moore became very aware of another part of the spectrum in designing his flies. In his book "A man may fish", he descibes carrying out a few basic experiments to see how much infra-red light was reflected by various black materials.

I have not read the book but I am interested in how he attempted to measure the amounts of IR as it's beyond the limit of our vision.
It is also beyond the limit of trout vision so not of any real interest but he would not have known that.

Dave.

[Gander]

Originally Posted by Silver Stoat

I have not read the book but I am interested in how he attempted to measure the amounts of IR as it's beyond the limit of our vision.
It is also beyond the limit of trout vision so not of any real interest but he would not have known that.

He describes getting a scientific friend to photograph flies tied with various materials, on plates sensitive to IR light with IR lighting in place. Most of the materials came out as various shades of grey, except floss and Ostrich herl. The herl especially came out as true black.

KM then extended his experiments to colour photographed in the same way, highlighting that dark blue in particular came out showing much more vividly than lighter shades of the same colour.

He does add that the experiments are inconclusive, as it was only a supposition that trout may be seeing colours in an IR affected way.

[Silver Stoat]

Interesting that, thanks Gander.

Shame it was wasted effort - we now know IR starts at about 900nm but Salmonids vision cuts off at about 800nm - but, as you said, at least he was thinking about how the fish might be viewing his flies rather than just blindly following tradition.

Dave.

[Cap'n Fishy]

Originally Posted by Cap'n Fishy

It is, eh? Kingsmill Moore getting a few 'hits'. Chapter 3 of his book focuses on colour and he speculates on fish seeing colours in the infra-red that are invisible to us. Perhaps he was casting into the wrong end of the spectrum?

Like him, I've always wondered about the lack of claret and hot orange in trout diet versus the success of hot orange and claret in our flies. Maybe a claret spider is just as big an out and out lure as any blob or cat's whisker?

Col

PS: He had a bit of a thing about dyed black ostrich herl, didn't he?...

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