"The heavens declare the glory of God"...
So this cabbie says: "Know who I had in this cab last week? Bertrand Russell! Wisest man in the Western World. And I says to him 'Bertie, what's it all about?' And do you know, he couldn't tell me..." Kenneth Williams
Leica 8x20; Nikon Action 7x35; Vixen Apex Pro 8x42; Orion 15x63; Docter Nobilem 15x60
WO Megrez II 80 FD / APM 107mm f/6.5 / Mewlon 210 on DM-6 + Berlebach Planet
Quote: Why worry about the edge of field in an Action? It'snot worth much anyway is it? Ron
Binoculars: Miyauchi Saturn III - 33/39/50/71/150x100, WO 22x70ED, Fujinon 16x70 FMT-SX Pentax 10x50 PCF-V, 10x43 DCF-SP, 6.5x21 Papilio
Nikon 10x35 EII, 7x35 E, 8x30 EII, 8x23CF AS Diplomat
B&L 7x26 Custom
Scopes: C9.25, TMB130SS/FT, SV80S-LOMO 80/480
Quote:deal Ron! I like birding with the FMT anyway, masochist that I am.
The night sky is the canvas....
My optics are the brush....
The Milky Way is the masterpiece
reductio ad absurdum of epistomology is solipsism....
Quote:Quote:deal Ron! I like birding with the FMT anyway, masochist that I am. Rich,How's the depth of focus, on the Fujinon 10x50, when it comes to birding? (under 100m) Stan
Quote:depth of focus on the 10x50 FMT is reasonable Stan. Forget the thing for close focus birding obviously, but I had great fun watching buzzards and eagles in Scotland a while back with them.
Quote:I must admit after reading your first post Jon, that I had never seen such noticeable vignetting in any binocular before, going by your description. I have looked, and I have owned some "budget" models in the past believe me.
Quote:depth of focus on the 10x50 FMT is reasonable Stan.Forget the thing for close focus birding obviously....
Quote:I definitely saw it but it had to have been something I was doing... Jon
Quote:Quote:I definitely saw it but it had to have been something I was doing... Jon Jon, Next time be sure and remove the right lens cap. Stan
Quote: --do you really want to pay for and carry around the honking prisms, etc, that an unvignetted system would demand? For example, Leicas, although of very high build quality, are quite bad in this way.Why worry about the edge of field in an Action? It's not worth much anyway is it?Ron
Quote:Quote:depth of focus on the 10x50 FMT is reasonable Stan. Forget the thing for close focus birding obviously, but I had great fun watching buzzards and eagles in Scotland a while back with them.
According to the Eagle Optics website, the close focus on the 10 x 50 FMTs-SX's is 35 feet, there's a lot of birding to be done at distances closer to 35 feet.
But... I have to add another WOW and HUMM to this thread. Last night I spent about 3 hours at an Elementary School star party. Conditions were perfect, not a cloud in the sky, seeing rock solid.. Lots of people. Long Lines at my two scopes.. I must say I was amazed at how few people knew the Pleiades or even seemed to have heard the name before.
Anyway, when I got home, I had to unload everything and when I was done, I spent about 10 minutes with the 10 x 50 Nikon Actions. This time, I did not see the serious vignetting I had seen the night before. I tried the same tests, I tried to mess with the inter-ocular separation, the eye cups, I could not duplicate what I had previously seen. There was minor vignetting but it was acceptable and I could pick M93 out of the light pollution essentially all the way to the edge.
I can only figure that the first night, somehow I was not seeing the entire field of view with both eyes so when I reached a certain point, I was only viewing with one eye and the image dimmed.
Quote: Jon,the Nikon Actions I tested had dramatically imbalanced vignette, far more on one side of the barrel than on the other side. And both 8x40s and 10x50s had more vignette than the Nikon Action Extremes of same size and were more out-of-balance.
Quote:Jon, the Nikon Actions I tested had dramatically imbalanced vignette, far more on one side of the barrel than on the other side of that barrel. And both 8x40s and 10x50s had more vignette than the Nikon Action Extremes of same size and were more out-of-balance.
Of course, if the observer's pupils are smaller than the exit pupil, binocular is stopped down and the light fall-off gradient is reduced. If the eye's pupil is smaller than the minimal minor axis of the truncated exit pupil, the illumination fall-off is near zero. It's not expected to be truly zero, because of the normal change in transmission of light as it traverses the optical elements at angles varying with field angle.
If one wanted a very good measurement of illumination fall-off, a light meter which could sample the full exit pupil from some fixed distance while swing through the requisite angle would integrate both the area and the transmission efficiency. The result would be the fall-off with field angle corresponding the worst case scenario, where the eye's pupil is at least as large as the exit pupil.
Quote:Ed:Thanks for that information. I will spend some time this evening with them and see if I see the difference in the sides using one eye at a time.Jon