|With all the discussion about what trout see, light attenuation, etc., etc., it might be easier to look at a couple of pictures. |
The caddisfly pupa is a few inches under the surface in bright sunny conditions. In your hand it is an amber color, from a trout's perspective it is a silhouette. If it were swimming over a bright reflective surface such as sand, the true colors would be vivid.
Two shots of Goblins tied in various colors. One picture is one foot under the surface and the next is at ten feet. These were taken in Lake Davis when the water looks very clear from a boat. At ten feet the white takes on the color of the ambient light, the purple turns brown, the hot orange is sienna and the green is still pretty much green. At 20 feet the orange is brown (identical to the purple) and the white and green look the same.
Not only is depth attenuating the light, but the amount of water between the fly and the fish's eyeball have to be added. A fish chasing down a streamer from 10 feet away in 10 feet of water will see the fly as if it were under 20 feet of water.
Flash will catch a fish's eye from much greater distance than the same fly tied without flash; however, there are times when fish will spook from a flashy fly once it gets close enough to see the fly in detail. It often pays to use a flashy attractor fly followed by a fly without flash as a dropper. . . hmm - those two pictures won't load.
[click here to display pictures]