If You Can't Beat 'Em, Join 'Em

check out - http://www.klt.co.jp/Nikon/New_Products/index.html - and scroll down to look what they've done with four of their lenses. Nikon must be getting tired of all the white lenses on the sidelines of sporting events.

The above was obtained from the EOS list at eGroups.com.

 

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Dick

Camouflage in snow indeed! Does Nikon know nothing?<br>There is a very

good technical reason for having light coloured barrels on long

lenses, and that's to reflect heat away, and minimise thermal

expansion. This keeps 'focus creep' to a minimum, and helps to keep

all the glass elements in proper relationship to each other. If Nikon

don't realise this, they oughtn't be in the business. They're

certainly not the firm whose system I bought into over 20 years ago.

Now we all know who is copying who!!! Still can't believe that

there's no "VR" in their big glasses and no "S" in their 80-400 lens.

<B>NEWS FLASH!</B> you're 31 years late.<p>

Follow this link to see Nikon's first white lens: <a

href="http://www.cameraquest.com/100063f.htm">http://www.cameraquest.c

om/100063f.htm</a>.

<b>NEWS FLASH!</b><p>

I can't count! ;-)<p>

It's supposed to be 41 years.

"There is a very good technical reason for having light coloured

barrels on long lenses, and that's to reflect heat away, and minimise

thermal expansion. This keeps 'focus creep' to a minimum, and helps

to keep all the glass elements in proper relationship to each other.

If Nikon don't realise this, they oughtn't be in the business"<P>

Does anyone have any evidence that white color have any appreciable

effect on element position? Or is this simply one of those pseudo-

scientific explanations concocted by the marketing department and

propagated by non-critical devotees?

Of course it has an effect. Basic physics tells us that black things

absorb more heat radiation than white things.<br>Touch a white car and

a black car that have been parked in the sun for the same length of

time.<p>As for the f/5.6 Zeiss lens being 'decades' behind Nikon.

Think again. A few years maybe. I can show you many references to the

1000mm f/5.6 Zeiss (Jena) lens from the mid 1960s.

Pete, my link was not a "Nikon is better than Zeiss" taunt, but rather

a comment that white Nikkor lenses have been around for a few

decades.<p>

FWIW, white (well really they're "gray") AF-S Nikkor became a

Japan-only special order item sometime last year. I guess they proved

popular enough to become an "international" product.

It wasn't taken as a taunt Geoff.<br>I really have no special

loyalties to Nikon or Zeiss Jena, they're both legendary optical

companies in decline. :^) I was just refuting the assertion by

whowever wrote the article on the 1000mm mirror Nikkor, that it was

decades before Zeiss came out with a faster lens.<p>In the meantime

I've looked up the expansion co-efficient of Duralumin. A 500mm long

lens barrel will expand by more than 0.17 mm for a change in

temperature between 25 and 40 degrees Celsius. (pretty typical for a

black-painted object sitting in the sun, I think) This is a factor of

20 more than the precision that most lenses are designed to. Or put

another way, a focus shift of 7 metres in 100!

Here in the Midwest, I've long been aware of how alarmingly hot my

black Canon cameras (and any black lenses) can become when for

example, I'm engaged in railroad photography and am waiting for a

freight train to come along, with my camera tripod-mounted on hot,

sunny days. In fact, I keep a white piece of rainfly material with me

to cover my camera in these circumstances. Canon's decision to paint

many of their telephoto lenses in an off-white color makes perfect

sense, and indeed when using my "white" EOS lenses, they are merely

warm to the touch under the above described conditions, while the

black gear may be almost too hot to touch for more than a moment or

two! I believe this heat issue can potentially cause or invite real

problems, especially for expensive lenses. For example, the adhesive

cements that hold certain elements in precise position may soften, or

other components may shift or buckle due to the stresses of thermal

expansion upon heating, and contraction upon cooling. No doubt there

are other potential dangers to extreme heating of lenses.

 

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I've periodically heard complaints from (for example) some nature

photographers who feel that Canon's big white lenses shout "I'm here!"

to wildlife. These individuals may resort to covering these lenses

with camo tape, or even spray painting them. A less invasive but

equally effective solution is to buy or make an elastic camo "sock" to

fit over the lens when needed. Although I've not yet made one myself,

my plan would be to buy some elastic medical/orthopedic-type tubular

sock material from a drugstore or medical supply house, and then

simply dye it in a camo pattern, to be fitted over the lens when

needed.

Pete: I realize that white objects do absorbe radiative heat less

readily then black objects, and therefore tends to acheive lower

themal equalibrium temperatures. I do believe a white lens would be

cooler to the touch under a hot sun than a black one. That could be

an important advantage under many situations. But that is far

different from saying that black lenses are appreciably more effected

optically by the hot sun than white ones. Some say higher

temperature of black lens throws elements out of position. I have

never seen any evidence of detectable optical degradation due to

normal thermal expansion. Some people have claimed that higher

temperature causes debonding of elements or failure of internal

structures. Yet I've never heard of a case where a lens, white or

black, failed due to normal solar heating. <p>

If there is any evidence that white lenses fare appreciably better

under the hot sun than a white one, I like to see it.

The point is Chuck, that it's only a coat of paint. Costs no more,

(probably less in fact) for white paint than black. If it keeps the

lens cooler, then that can only help. Black paint, on the other hand,

if it has any effect at all, will only cause harm. (Unless you're on

night manoeuvres with the SAS!)

Maybe the manufacturers need to consider polished aluminum barrels.

"Costs no more, (probably less in fact) for white paint than black.

If it keeps the lens cooler, then that can only help. Black paint, on

the other hand, if it has any effect at all, will only cause harm.

(Unless you're on night manoeuvres with the SAS!) "<p>

The issue isn't based on whether white paint ought to help based on

glib rationalization. It should be based on whether it can actually

be shown to help in reality.

Perhaps one of you fine gents or ladies can perform a real live

experiment! MTF tests of a quality optic at the same target, f-stops,

controlled lighting etc., with the only difference being the

temperature of the lens barrel (perhaps via the use of a radiant

heater)? It wouldn't matter whether the lens was "L" white or

standard black, as the idea is to see if the heat energy truly has

any discernable impact on optical performance -- not which lens is

actually better under heat situations.

 

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This proposition is to satisfy all of the above posts insisting on

hard data (in fact, I'm surprised it hasn't been done already).

 

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It is a well known fact that metal expands & shrinks under thermal

variation. Since most of the optics are hard mounted in the lens

barrel (except for the floating focus elements/zoom elements), and

optical performance design is all about where to put what shaped lens

where to achieve the desired effect, I find it hard to believe that

there would be no impact on optical performance due to expansion &

shrinkage. Of course, the qualitative differences may only matter to

MTF freaks. :-)

 

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In any case, both Canon & Nikon have many fine professional optics in

their stables, regardless of barrel color.

I have seen a couple tests involving various branded lenses at I

believe 200 or 300mm and one was white and the other black. I don't

remember the link or whether I read it in print and I hope someone

can find it.

Anyway, the study showed that yes, the white did in fact help

minimize shifting of the elements. It varied on the particular lens

if its painted black because of individual build quality and

resistance, however the white lenses still displayed signifigantly

less shift and the test images were sharper.

I guess its hard to say all black lenses will react the same, but

painting it white is an intelligent precautionary measure. None the

less, the black lenses shifted enough to produce visible changes in

sharpness and had varied amounts of shift, I guess depending on the

build quality and how secure lens elements were in that particular

piece. Its safe to say that two of the same model 300 2.8s

experience different amounts of shift if they're painted black, but

experience signifigantly (and a worthwhild difference) less if white.