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Don't like the WHITE on your L?
- Thread starter Tbedna1
- Start date
...and don't you tell me you tried to gauge the temperatures by touch?
I'll tell you what. The rubber will always feel warmer than metal even if both are same temperature and colder than your hand. It's reversed if they are hotter than your hand. There will be difference in the situation you mention, but you need a thermometer to say anything accurate about it.
Your skin "measures" heat transfer, not temperature, so your brain is tricked. Even a metal that is hotter than rubber can feel colder in low temperatures. LOL!
(thermal conductivity of metals are orders of magnitude higher than rubber's as you should already know)
Eh, did you even read the article yourself?
If your white or whatever lens barrel lets drops of water into your fluorite element, return it, or let independent observer check how you use it.
The brittlenes without water shock cooling is said to come in temperatures above 250F, that is 120 degrees Celsius. Happy shooting! LOL
Man you're incredible! Rather than just firing out whatever comes to your mind, stop and think for a while.
thecameraguy
Senior Member
at being mugged for an 18-55 lens!..lol
--
~ Being over-exposed can get you arrested ~
http://ramsden.smugmug.com/
--
~ Being over-exposed can get you arrested ~
http://ramsden.smugmug.com/
I assume you might have ben thinking of 18-55 mkII, but there is
by far better candidate: 28-80 mkIII,
jpr2
Token,
thank you very much for this informative and actually very interesting
post, so much unlike than many other such coming from the
pro-white camp The pro-white at it's best and objective too !
ones, and also more slowly - thus, any expansion of fluorite aill be
lagging behind it's metalic mount;
and anyway the real danger is not as much associated with heat, but
rather with extreme colds and increased brittleness of fluorite at such
temperatures:
with your's thermal images, there are some questions about cooling rates of
white surfaces of 70-200/4L as compared to the vivitar's 600mm - perhaps
that mirror lens was covered with black paints of entirely different heat
dissipating properties (that is both as to it's reaction to heat and esp. as to
it's cooling rates), that is much more in line with behavior of plastic parts
of 70-200 which both heated most and cooled the slowest - in short a
"plastic paint" with very poor and not optimized thermal properties?
another interesting bunch of facts concerns 70-200's rubber bands, which
have stayed at much lower temperature (that is if these thermal photos
were calibrated to measure everything "equally": plastic, rubber, and paint
covered metals - but I'm sure they were), compared to both canon's and
vivitar's metal elements - and as these were measured, and not felt by
hand, it can not be said those were subjective observations
thank you again,
best,
jpr2
thank you very much for this informative and actually very interesting
post, so much unlike than many other such coming from the
pro-white camp
The pro-white at it's best and objective too !but certainly fluorite elements would not expand more than the metal
ones, and also more slowly - thus, any expansion of fluorite aill be
lagging behind it's metalic mount;
and anyway the real danger is not as much associated with heat, but
rather with extreme colds and increased brittleness of fluorite at such
temperatures:
your's past experiences are even more interesting. However, in connection
with your's thermal images, there are some questions about cooling rates of
white surfaces of 70-200/4L as compared to the vivitar's 600mm - perhaps
that mirror lens was covered with black paints of entirely different heat
dissipating properties (that is both as to it's reaction to heat and esp. as to
it's cooling rates), that is much more in line with behavior of plastic parts
of 70-200 which both heated most and cooled the slowest - in short a
"plastic paint" with very poor and not optimized thermal properties?
another interesting bunch of facts concerns 70-200's rubber bands, which
have stayed at much lower temperature (that is if these thermal photos
were calibrated to measure everything "equally": plastic, rubber, and paint
covered metals - but I'm sure they were), compared to both canon's and
vivitar's metal elements - and as these were measured, and not felt by
hand, it can not be said those were subjective observations
thank you again,
best,
jpr2
wilfredmrand
Senior Member
Light reflection is indeed the reason Canon (and Sony) make their long lenses white.
--
Wilfred M Rand
http://www.pbase.com/wilfredmrand/
--
Wilfred M Rand
http://www.pbase.com/wilfredmrand/
wilfredmrand
Senior Member
Their 70-200, 300, and a couple TC's are white. Whiter than Canon's, even.
http://www.sonystyle.com/webapp/wcs/stores/servlet/CategoryDisplay?catalogId=10551&storeId=10151&langId=-1&categoryId=32335
--
Wilfred M Rand
http://www.pbase.com/wilfredmrand/
http://www.sonystyle.com/webapp/wcs/stores/servlet/CategoryDisplay?catalogId=10551&storeId=10151&langId=-1&categoryId=32335
--
Wilfred M Rand
http://www.pbase.com/wilfredmrand/
LOL indeeed
) IF THIS IS TRUE (i'm not so sure about your's reference points, although some sources and pointers as to where you are finding
most of your's arguments are rather easy to trace
) then you've just dealt a heavy blow to the heat related danger of destroying fluorite
elements,
jpr2
ph0t0h1ker
Forum Enthusiast
If this white/beige color is such a positive design feature, why is Canon essentially crippling their other products by continuing to make them black? Seems like Canon could implement a color change pretty easily. My thought, though, is that white is 99% marketing.
sneakerpimp
Senior Member
that would diminish the value of white/L lenses.
...and color is there for purely practical reasons - being pro-choice myself
I do not care much what is the color of my fellow photogs. lenses as long
i'd be able to get mine with no problems and as little hassle as possible
in... black
)jpr2
I'm finding it hard to understand your english here, but the above data is from a reference provided by YOU that you thought is important, but it seems that you didn't read or understand it yourself... you are hopeless...LOL indeeed
points, although some sources and pointers as to where you are finding
most of your's arguments are rather easy to trace
I intended to do so. I've never claimed heat caused lens shattering being a problem in photographic lenses...
I've had the impression that Canon has stated they're worried about optical properties changing and performance degradation by uneven expansion, not catastrophic shattering. I don't have a reference here though and I'm too lazy to search it for you.
On the other hand, I've HAD my 100-400L reflection prevention ring, or whatever the plastic bit is called come loose inside lens barrel because of sunlight. That was at high altitude with really chilly temperatude in shadows but torching sunlight. Local repair fixed it, no problem, but shows that the problem is real. The repair man said he's fixed a couple of these, so it's likely that it's a kind of manufacturing flaw in at least some of 100-400L's. Maybe it was wrong kind of glue that didn't allow any flex with uneven expansion?
mmullen
Senior Member
On a telephoto lens there are two ways that radiant heat energy can degrade image quality. One, as you mention, is thermal expansion of the lens body.
The other, and I believe the more problematic of the two, are the thermal air currents in the optical path. Telescopes have the same problem (in reverse) as the scope is brought outside. It requires time to cool to the ambient temperature. It's not uncommon for telescopes to have small fans inside the optical tube assebly to blow the air around so it is all of uniform temperature. If you recall Physics 101, air of different temperatures has different densities and therefore different refractive qualities. You can see how the metal body of a black telephoto lens heating up to 180 degrees F will cause thermal air currents to form inside. On a hot day, the diffractive qualities of the hot air rising from a blacktop road or parking lot is clearly visible in the viewfinder when looking through a telephoto lens. The last thing a photographer wants to contend with on a sunny day is these same type of currents INSIDE the lens! A white body will minimize, not eliminate, these currents.
The appearance of a white lens may or may not help sell more telephotos. Judging by the complaints in this forum about white lenses leads me to think the white appearance is a slight disincentive to purchase. On the otherhand, the final result (the image) will be of higher quality if the lens is not full of convective air currents. High quality images make photographers happy, increase the reputation of a lens and help sell more lenses. So, ultimately, it is a marketing decision. It would be like saying Canon's use of ED and flourite elements is only for marketing purposes. Well, of course it is, how many lenses would they be able to sell if all their telephoto lenses created images with purple fringing?
In the end it's all about IQ and those who believe a white telephoto does not have significantly more resistance to IQ degradation caused by thermal absorption of solar energy have little to no appreciation for the physics involved. This is not about a pie-in-the-sky theoretical advantage or style points, these are physical principles that come into play under real world photographic situations.
--
Mike Mullen
Some doubts:
effects?
ever operate in a cosmic environment of extra-terrestial spaces, where
Sun irradiation might heat surfaces to extreme temp. and yet environs
are at about zero Kelvin), and seems to neglect not only extreme cold,
but also a plethora of other circumstances (like some dark-loving interiors of
opera houses - I'm yet to see a single advice as to how hide a 200/2.8 IS from
ushers in a simple, at yet elegant way);
might be affecting (relatively short and small, if compared to gigantic astro
refractors) performance?
If one is looking at the IR pictures of Sun heated: the white 70-200, and the
black 600mm vivitar:
as provided by:
http://forums.dpreview.com/forums/read.asp?forum=1029&message=12671815
one thing is immediately obvious,
there are areas on 70-200 which are as hot, as black spaces on Vivitar,
and thus differences in temperature in their vicinity as opposed to areas
shaded by rubber bands are much higher than on (unprotected by white
paint) Vivitar lens. So, the zebra pattern of white and black bands is serving
a very bad, and actually a counter-purpose if we would to follow your's
line of arguments
kind regards,
jpr2
- how it is that all other manufacturers seems to posses a magic formula
effects?
- why all arguments of pro-white camp are gravitating towards extreme heat
ever operate in a cosmic environment of extra-terrestial spaces, where
Sun irradiation might heat surfaces to extreme temp. and yet environs
are at about zero Kelvin), and seems to neglect not only extreme cold,
but also a plethora of other circumstances (like some dark-loving interiors of
opera houses - I'm yet to see a single advice as to how hide a 200/2.8 IS from
ushers in a simple, at yet elegant way);
- all what you are saying is perhaps true, and these lines of arguments are
might be affecting (relatively short and small, if compared to gigantic astro
refractors) performance?
If one is looking at the IR pictures of Sun heated: the white 70-200, and the
black 600mm vivitar:
as provided by:
http://forums.dpreview.com/forums/read.asp?forum=1029&message=12671815
one thing is immediately obvious,
there are areas on 70-200 which are as hot, as black spaces on Vivitar,
and thus differences in temperature in their vicinity as opposed to areas
shaded by rubber bands are much higher than on (unprotected by white
paint) Vivitar lens. So, the zebra pattern of white and black bands is serving
a very bad, and actually a counter-purpose if we would to follow your's
line of arguments
kind regards,
jpr2
mmullen
Senior Member
Other manufacturer's black telephotos are not immune from the effects, the free market offers a variety of choices. When I was a young child I preferred a toothbrush with stiff bristles. My mother told me that dentists say a soft bristle brush works the best. It ran counter to my intuition and I refused to believe it. "Mom, why do they make stiff-bristled brushes if the soft bristled ones work better?" I asked triumphantly. The wind was somewhat taken out of my sails when my mom replied "Because someone will buy them."
It's not extreme heat that is the problem, it's the temperature differentials. Solar radiation is not limited to extreme heat, it's probably worse on a nice spring day at 23,000 feet in the Himalayas. The effect would be at it worse with increasing differences in the temperature of the air inside the lens and the temperature of the lens body.
I have a Televue Pronto, a small refractor that has a shorter focal length than some Canon telephoto lenses. The effects of thermal currents in the optical tube are visible on a cold night before the scope has reached thermal equalibrium. Obviously, with shorter focal length lenses the problem is minimised as there is less air inside the lens and the magnifications are not as high. I don't know where it ceases to be a practical problem, it would certainly depend upon the conditions. My guess is the worst possible conditions are tripod mounted on a cool day with intense solar radiation coming from a direction perpendicular to the optical tube.
I wouldn't draw too many conclusions from those photos as they indicate thermal energy that is radiated, not the actual temperature of the area. Some materials have a higher emmisivity factor which must be taken into account. Also, the photos were taken of the exterior of the lenses some time after they were removed from the sun and the insulating properties of the rubber focus bands are probably making the "zebra" effect look more pronounced. What matters from the perspective of themal air currents inside the lens is the temperature of the inside surfaces in relation to the air temperature inside the lens. White simply minimizes this difference and costs nothing to implement.one thing is immediately obvious,
there are areas on 70-200 which are as hot, as black spaces on Vivitar,
and thus differences in temperature in their vicinity as opposed to
areas
shaded by rubber bands are much higher than on (unprotected by white
paint) Vivitar lens. So, the zebra pattern of white and black bands
is serving a very bad, and actually a counter-purpose if we would to follow your's
line of arguments
--
Mike Mullen
Thanks for support
Pretty much all these have been covered earlier, but jpr2 just digs them out again and again, like:
http://forums.dpreview.com/forums/read.asp?forum=1029&message=26879399
http://forums.dpreview.com/forums/read.asp?forum=1029&message=26864909
His empirical and theoretical knowlege about black vs white is questionable. See this "classic" post he made a few days ago:
http://forums.dpreview.com/forums/read.asp?forum=1029&message=26851187
By the way, in this post he rightly said that "it is not as much important to dwell on such surface temperatures" and now he's just doing that with the IR photo thing, that a layer of black rubber with poor conducting abilities on top of metal barrel matters so much...
I think I'm ready to give up with him. He never acknowleges one proof, just stops commenting it, only to dig out the same song again a few days later for somebody else...
Thanks for your input about air currents inside the lens.
Pretty much all these have been covered earlier, but jpr2 just digs them out again and again, like:
Already argued multiple times...
No we are NOT! Already covered here:
http://forums.dpreview.com/forums/read.asp?forum=1029&message=26879399
Rubber/magnesium properties differences already covered. Heat conductivity etc.shaded by rubber bands are much higher than on (unprotected by white
paint) Vivitar lens. So, the zebra pattern of white and black bands
is serving a very bad, and actually a counter-purpose if we would to follow your's > line of arguments
http://forums.dpreview.com/forums/read.asp?forum=1029&message=26864909
His empirical and theoretical knowlege about black vs white is questionable. See this "classic" post he made a few days ago:
http://forums.dpreview.com/forums/read.asp?forum=1029&message=26851187
By the way, in this post he rightly said that "it is not as much important to dwell on such surface temperatures" and now he's just doing that with the IR photo thing, that a layer of black rubber with poor conducting abilities on top of metal barrel matters so much...
I think I'm ready to give up with him. He never acknowleges one proof, just stops commenting it, only to dig out the same song again a few days later for somebody else...
Thanks for your input about air currents inside the lens.
rsn48
Veteran Member
The story goes that when Cadillacs were first introduced to the public, the motors were designed to run on standard gas. But the folks who bought them wanted the "best" gas for their cars. Now if you know anything about the "best" gas, it is the gas to be used that your motor was designed to burn. So in those days, the best gas would have been "standard" gas.
But the new owners would have none of this, they had the best cars - in their mind - and the best car should have the "best" (premium) gas; after all, everyone knows the "best" always costs more. So eventually the folks at the Cadillac division caught on and designed motors for Cadillacs that required premium gas.
Apparently Canon's original intention for white lenses is that they would absorb less heat than black ones. Test have never confirmed this reality, though scientifically it makes sense. However Canon did discover that the white lenses carried a certain 'mystic' to the buying public, so why mess with a good thing.
--
Rationally I have no hope, irrationally I believe in miracles.
Joni Mitchell
But the new owners would have none of this, they had the best cars - in their mind - and the best car should have the "best" (premium) gas; after all, everyone knows the "best" always costs more. So eventually the folks at the Cadillac division caught on and designed motors for Cadillacs that required premium gas.
Apparently Canon's original intention for white lenses is that they would absorb less heat than black ones. Test have never confirmed this reality, though scientifically it makes sense. However Canon did discover that the white lenses carried a certain 'mystic' to the buying public, so why mess with a good thing.
--
Rationally I have no hope, irrationally I believe in miracles.
Joni Mitchell
it is a very tiny minority here... who would ever be willing to suffer sweltering
heat, strong enough to even start to give reason for any substantial concerns,
and yet many pro-whities are ready to discuss phoney reasons until they are
blue in faces... just to wave somewhat puny "victory flags" - the problem is
that neither myself personally, nor \i believe most of a real pro-choice users do
care WHO is right, but rather about WHAT might be an actual truth
jpr2
What planet are you living on? Does it have a Sun? Are there primary schools?
Check this lab experiment: (already posted)
http://www.iapht.unito.it/fsis/lauree-scientifiche/girep_107-modelling.doc
Notice that it begins:
"A very simple experiment often programmed already in primary schools is to observe the temperature rise of a black object exposed to solar radiation and to compare it with the temperature rise of an identical white object exposed in similar conditions."
Please pay attention to figure 2 which shows how big the difference really is that even a lamplight caused in the test. The white can temperature rise was just 15C while the black went up 35C all the way from 20C ambient temperature to 55C. The temperature rise was more than doubled because of the can being black!
There's no scientific argument why lenses would behave differently, so the burden of proof lies on the one that says there will be no difference when it's a "lens" not just a "can".
You may be right or you may be wrong. Guessing motives is guesswork, and there could be even many "truths" there...
There could even be conflicting sides inside Canon personnel about this, so Canon might actually be collectively schizophrenic!
Yeah "the truth is out there" but as long as it's just out there, keeping in sound physics gives more solid answers than guessing motives or nursing conspiracy theories.
I bought a white L because i wanted a white lens. A marketing ploy that worked on me =)
Also scientific reasoning to it as well. these white L's are all outdoor lenses so makes sense to try to keep the temps and rise/rate of temps low as possible to avoid moisture/condensation bulid up.
So..... a bit of both maybe. Would be stupid to assume Canon's reasoning to one thing only.
Also scientific reasoning to it as well. these white L's are all outdoor lenses so makes sense to try to keep the temps and rise/rate of temps low as possible to avoid moisture/condensation bulid up.
So..... a bit of both maybe. Would be stupid to assume Canon's reasoning to one thing only.
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