Why are the lenses White...?

It probably has been discussed to death, if so, point me there... If not, I ask, why are the long L lenses white...?

My understanding is that the "white" finish keeps temperature-sensitive lens elements cooler than a black finish.

White reflects more solar energy so the lenses don't heat up as much. HEat can cause issues for lenses.

Google is your friend.

This:

Larger sized L-lenses, such as the 70-200 mm and 100-400 mm zooms and longer focal length primes (300 mm+), usually have an off-white barrel (sometimes referred to as the color "putty") to reduce heat absorption under the sun that may otherwise affect the performance of the lens, as well as to identify Canon's lenses (for example at sporting events)

ErnieT wrote in post #10832741
as well as to identify Canon's lenses (for example at sporting events)

^ this is all it really is, imo

Also note that Canon is not the only company making lenses in this color.

bindabinjo wrote in post #10832764
^ this is all it really is, imo

Uh huh, and which is why companies like Mamiya make their larger telephotos in white, right? Lots of 645 film shooters on the sidelines at NFL games...

mguffin wrote in post #10832717
It probably has been discussed to death, if so, point me there... If not, I ask, why are the long L lenses white...?

Due to thermal expansion. White absorbs far less heat than black. With all the various components in a lens (magnesium, aluminum, glass, plastics) all having different coefficients of thermal expansion, having a lens that remains cooler in direct sunlight means more stable performance and less chance of parts binding. My old Vivitar 120-600 zoom (which indeed was black) used to get so hot in the sun that it was hard to hold. My big "L" zooms remain fairly cool overall.

Canon themselves discuss this in a few places... I think in "Lens Work", for example.

They say it's primarily done to reduce thermal expansion.... Which can be a problem with longer telephotos in particular, expecially ones using fluorite elements (which many Canon do).

Canon was not the first to paint their lenses white or a light color, and they aren't the only ones even today. Leica has sold a lot of silver lenses over the years. Tamron has sold gray and olive colored lenses in the past. Many "cat" lenses (aka "mirror" lenses or "catadioptric" lenses) are painted light colors, too, since they are particularly sensitive to the optical formula changing due to heat expansion. I recall Konica 2000mm f11 and 1000mm f8 "cats" were both painted white, way back in the mid-1970s. There have even been some medium format lenses painted white or off-white, from Pentax and Mamiya I think.

But Canon has taken it to a whole new level to make their lenses stand out in a crowd. So I suspect it now has as much to do with marketing as anything. They like to be able to brag about all those white lenses in the hands of pros shooting at major sporting events and relish it when the TV cameras pan and show them. It's probably now become enough of a Canon "trademark" that I suspect other manufacturers would think twice before painting their lenses white, even if they'd benefit from it.

amfoto1 wrote in post #10833028
...I suspect other manufacturers would think twice before painting their lenses white, even if they'd benefit from it.

Minolta was the first to use white and Sony continues the tradition. Even Nikon has at least one or two white lenses in the lineup.

krb wrote in post #10832773
Uh huh, and which is why companies like Mamiya make their larger telephotos in white, right? Lots of 645 film shooters on the sidelines at NFL games...

Uh huh, smack dab in tha middle, brother sir!

Temperature. Sometimes when outside shooting under sunlight the black lenses and bodies really get hot to the touch. I can imagine it would change the parameters of the glass in the larger lenses by a noticeable amount in right conditions.

It's also white cause it looks cool

Besides reflecting light, it's good marketing. When you look at a white lens, you know it's Canon.

xcel730 wrote in post #10834000
When you look at a white lens, you know it's Canon.

http://www.bhphotovide​o.com …to_AF_S_Nikkor_​300mm.html

http://www.bhphotovide​o.com …F28G_300mm_f_2_​8_APO.html

http://www.bhphotovide​o.com …300mm_f_4_5_APO​_LENS.html

http://www.bhphotovide​o.com …m_f_6_3_Manual_​Focus.html

krb wrote in post #10832765
Also note that Canon is not the only company making lenses in this color.

Negative.
Pentax wants to be cool too.