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Old Aug 5, 2011, 7:16 PM   #1
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Default Why white is a good color for a telephoto lens

I figured y'all aren't physicists so you might not realize why white is a good color for a telephoto lens. My idea for this thread arose from Harj's comment that he didn't want any Canon telephoto lenses because they are white. Emotionally I support his anti-Canon view but reality is not that simple.

There really is a lens IQ issue if the lens is getting superheated by bright sunlight. The lens body, glass elements, and air cavities expand at different rates and surely you must realize this affects the overall lens element alignment and therefore the IQ. The longer the lens, the more air cavities there are and the more temperature differences are an issue. I came into this issue with the very long focal lenghts of my astronomical telescopes but it's an issue with long FL terrestrial cameras.

So there really is a good reason for a long lens to be white.

Ted
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Old Aug 5, 2011, 7:39 PM   #2
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.....never thought about it this way, so is this a/the reason for the 'white' lenses? It seems to me that if it were then more makers would be building light colored camera lenses.
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Old Aug 5, 2011, 9:30 PM   #3
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Bob, I don't know if that's why they make the lenses white. But that's why they should, at least the long ones.

Edit: When you plan to observe with a telescope you have to set it up outside some time before you plan to use it, so it can come to thermal equilibrium with the night time air temperature. Otherwise you can't observe squat - just blurred, dancing images of stars due to air currents inside the scope. The greater the magnification and the more air a lens has in it, the more this is an issue. And the content of long telephotos is mostly air.

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Old Aug 6, 2011, 7:13 PM   #4
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Hey Ted

Thanks for the explanation.. I knew it had something to do with heat but I never really looked into it so kudos for passing on that bit of info!

Still.. white lenses.. ewwwwwwwwwww pap's instantly pop into mind......

I'm surprised that Oly never made a white ZD and also Nikon . I think I remember seeing one white body OM lens a while back.

Cheers

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Old Aug 6, 2011, 8:30 PM   #5
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I like the white lenses! I could never afford one... But they're nice to look at!
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Old Aug 7, 2011, 11:41 AM   #6
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Ever notice that at sports shows and TV wild life shows that the "real" togs use white lenses? That's because they're the pros, the real deal, real photographers who know what they're doing. Not like the rest of the lemmings like us.


Besides they get theirs free from the sponsors...
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Old Aug 7, 2011, 1:06 PM   #7
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Free lenses would be awesome!
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Old Aug 8, 2011, 7:04 AM   #8
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I, too, had a hunch it was something to do with heat although for a reason other than air currents and distortion issues. I thought it might have something to do with the electronics. Heat can't be good for those tiny, l'il focusing motors/servos.
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Old Aug 8, 2011, 11:16 AM   #9
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As I said, I don't know for a fact that that's the reason Canon does white. I suppose if heat was a big issue Nikon would also do white and they don't, so I guess it's just a brand thing. But years ago I had the venerable Vivitar Series 1 70-210 and when I spent a sunny day at a car racing track, that lens got HOT - almost too hot to touch. So I used to bring an old white t-shirt to put over it.

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Old Aug 8, 2011, 1:30 PM   #10
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I always come in on the tail end of things. When I got my 70 300 I should have ordered it in a lighter shade of black. Oh well crap happens.
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