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Archive 2009 · What does fluorite actually do?

Fred Lindsey
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p.4 #1 · What does fluorite actually do?

Yeh it does, just the 70-200 2.8 Non and IS that don't

Nov 09, 2009 at 02:00 AM

BigStuart
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p.4 #2 · What does fluorite actually do?

This is a very interesting discussion!

If you're getting into the optical properties of CaF2, you'll want to google "Intrinsic Birefringence"... Not much of an issue for photography, but it gave the semiconductor photolithography manufacturers a bit of a sore head a few years back!

Nov 09, 2009 at 02:12 AM

PetKal
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p.4 #3 · What does fluorite actually do?

White and bright smile goes a long way towards social acceptance and success.

Edited on Nov 29, 2009 at 10:17 PM · View previous versions

Nov 09, 2009 at 02:27 AM

skibum5
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p.4 #4 · What does fluorite actually do?

Fred Lindsey wrote:
skibum5 wrote:
Fred Lindsey wrote:
So why is it so transparent then?

the atoms in that arrangement are able toand the structure is very uniform so you get lots of phase reinforcement in the forward direction and don't lose lots of it to scattering

I don't understand what you mean here.

Funnily enough, my teacher has said she finds my arguement that I quoted plausible and will accept it

well classically with waves look at the some classical optics books, but that isn't the way you seem to be trying to get at it.

otherwise, errrr, maybe you need to think of it like a sum of all possible paths of a photon through a certain configuation of atoms bound together in complex ways that give many sorts of interaction possibilities for the photons and all the electrons in the material.

Most possible paths through have the photon not interact at all but since it is not a vaccum some paths would have the photon interact. Most would be single interactions.

actually this will get too long for me to feel like typing all out but the photon has a phase and as time goes on it cycles around and different frequency photons it cycles around at different rate. you say why this way why does that spit it out or off that way, well let's say it doesn't, say it spits it back out in any possible direction and it travels along any possible way from one side to a point straight across on the other side of the flat sheet of fluorite. Now some interactions could send it back to where it came from, each of those interactions takes a bit of time and adds pretty much the same phase change (and they mostly with an incident hit would go straight back up since that is the shortest path from source to fluorite back to source which means that any other nearby path will be less of a distance change than the distance change between other nearby paths not along that straight line and each photon goes all the ways but since the length and thus time it takes along the paths close to up and down are mosty similar those phases are all pretty close while once you get farther out and since the frequency cycles around so fast they come back to the source with all sorts of phases and taken all together they pretty much cancel out any probability for it to go but straight back up) for whatever reason some materials are more reflective and some send more back up ok forget about that and deal with whatever goes in and doesn't head back up reflected off any internal electrons either, granted all sorts of other options for how it could go, but lets just say they cancel and ignore why something might reflect more and transmit less

anyway some go down and interact and keep heading down to the point on teh far side, again the path where the phases don't cancel out is the line straight down.

now if the material had imperfections and junk suddenly the paths through might start giving unexpected phases and the cancellations might not work out to make it mostly go straight through and you might get more scattering.

also with something only partially transparent some interactions would result in absorbtion without re-admission i guess and get enough of that and these terms add up enough to cancel out getting through term.

one others dont get absorbed but just get a phase change from the interaction

but you have to think of all paths being taken at once so the thicker it is the more chances it had to have that sort of interaction so the more the phase is changed. I guess a low index of refraction would have each interaction apply less of a phase change than one with higher index of refraction

i guess something like fluorite might have things arrange so the blue end is getting closer to some resonant frequency and so it might hit the spike where you can get a dissporotionately large jump in index of refraction change from green to blue than from red to green where regular glass may be more even change from red to green to blue frequencies.

ss you'd have lots of interactions where there is an electron in some shared each interaction randomly different phase inducing than the next possibility and probably a random one and the path straight through would almost entirely cancel out.

If it is transparent first you'd and it would seem that this would need to be the most likely outcome and in other cases, where it does interact, if there is a very regular structure maybe you could assume that most of the interactions would have a similar probability and induce the same phase change it might interact would be very similar in the phase change they gave and that each possible interaction would just build the magnitude of that given phase change and of a type that would not cancel out much amplitude (certain phase that would not reduce the total amplitude much but just change the phase a bit and the thicker the piece of fluorite the more electrons in the sea of bound atoms that it could act with so the more interaction terms you need to add in and the greater the phase change.

trying to say exactly how the structure of Fluorite would cause a certain amount of reflection vs. transmission and the exact index of refraction for eah frequency and unusual dispersion characteristics is way beyond just saying it looks like so and so shape and all that at that level i think is ridiculous difficult, actually applying low level stuff to even basic processes can quickly become all but impossibly complex. i think virtually nothing along those lines has been calculated from elementary particle interaction principles I think they just go and measure the indices in the lab

. I guess you could say the uniform crystalline structue in the general sense helps cut down scattering though.

anyway there would be at least a few interaction terms contributing enough to the sum to be relevant and they would cause a phase shift. you can use lenses to focuses stuff since where they are thicker there is more time for the phase to cycle around then where it is thin and you can then get stuff from various points to hit the target focal point in sync.

anyway i'm babblig and don't feel like typing more and it would take a lot more typing to have any chance for it to come out sensibly which this has not (and that assumes it would given enough typing and maybe it would not

) so yeah bye

Nov 09, 2009 at 02:36 AM

skibum5
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p.4 #5 · What does fluorite actually do?

Ed Sawyer wrote:
Canon is not the only lens manufacturer to use Fluorite - Minolta did back in the day, and a few others as well. None marketed it like canon did though.

You should also pick up a glass map - fluorite is on it, and it gives a nice graphical representation of the relationship between index of refraction and dispersion , along with abbe #, etc.

-Ed

are you sure they didnt just use very heavily doped glass?

i thought only canon had made SLR lenses out of solid crystals of fluorite

Nov 09, 2009 at 02:37 AM

skibum5
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p.4 #6 · What does fluorite actually do?

Mauro Moretti wrote:
I think the only Canon lens with fluorite are:

70-200 4L
70-200 4L IS
100-400 L

200 2L IS
300 2.8L IS
400 4 DO IS
400 2.8L IS
500 4L IS
600 4L IS
800 5.6L IS

I didn´t knew the 70-200 4L had a fluorite element.

and the old EOS 100-300L and original version EOS super-teles I think (but not the original 200mm), no clue which FD had it

Nov 09, 2009 at 02:38 AM

skibum5
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p.4 #7 · What does fluorite actually do?

PetKal wrote:
White and bright smile goes a long way towards social acceptance and success.

yeah why not just toss quotes off the crest box and get your A and forget about all this physics nonsense! and get a bold rush of cinnamoniny goodness while you are at it!!!!

Nov 09, 2009 at 02:40 AM

Fred Lindsey
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p.4 #8 · What does fluorite actually do?

No, I understand it much better now, call me a simpleton for understanding your 'babble'.

The reason I like the net is because I'm handing in my presentation slides tommorow at 4PM
And I'm at school from 8, with no real breaks to do proper work in.

Nov 09, 2009 at 02:41 AM

Fred Lindsey
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p.4 #9 · What does fluorite actually do?

I'll put some colgate in my 70-200 2.8 IS then and see if that makes it as supposedly sharp as the 70-200 F4 IS

Nov 09, 2009 at 02:42 AM

skibum5
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p.4 #10 · What does fluorite actually do?

Fred Lindsey wrote:
I'll put some colgate in my 70-200 2.8 IS then and see if that makes it as supposedly sharp as the 70-200 F4 IS

make sure to squeeze out a full tubes worth and mind the expiration date!
it'll perform like no lens you've ever owned before, guaranteed

Nov 09, 2009 at 03:03 AM

kakomu
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p.4 #11 · What does fluorite actually do?

Fred Lindsey wrote:
No, I understand it much better now, call me a simpleton for understanding your 'babble'.

The reason I like the net is because I'm handing in my presentation slides tommorow at 4PM
And I'm at school from 8, with no real breaks to do proper work in.

When was it assigned? Is this college or high school?

As much fun as discussion is, why didn't you just hit a library or another source of information? Maybe I'm just a little more anal about quality sourcing of information.

Nov 09, 2009 at 04:40 AM

FSJ_Guy
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p.4 #12 · What does fluorite actually do?

Fred Lindsey wrote:
Apart from that obviously

That is a social/economic issue I will write about in my piece don't worry about that.

Exactly! What fluorite does is suck huge amounts of money from my wallet. And it keeps on trying to this very day.

Nov 09, 2009 at 04:44 AM

Fred Lindsey
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p.4 #13 · What does fluorite actually do?

Over here I'm in the penultimate year before university.

Yes and it was assigned..........

I much prefer hammering through internet sites for hours on end than going to a library and finding no books - where I live our libraries aren't all that expansive.

Nov 09, 2009 at 07:28 AM

kakomu
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p.4 #14 · What does fluorite actually do?

Fred Lindsey wrote:
I much prefer hammering through internet sites for hours on end than going to a library and finding no books - where I live our libraries aren't all that expansive.

Regardless of your preference, you're going to find internet research is going to be turned down in most (if not all) forms of academia.

Nov 09, 2009 at 01:02 PM

Will Patterson
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p.4 #15 · What does fluorite actually do?

dirb9 wrote:
Fred Lindsey wrote:
Does the fact that they are artificially grown affect the structure at all?

What exactly is standard optical glass made of, for my research?

Optical glass is generally a blend of many different elements at precise amounts to get the proper refractive index for a given lens. One of the keys is that there isn't any iron. If you look at a piece of regular glass from the side, it looks green. This is from excess iron in the glass. Beyond that, all glass is mainly silica (except for special quartz crystal glass for IR/UV photography), with lead (phased out), boron, fluorine, potassium, tantalum, or many other elements. Ohara, Schott, and Hoya are the main companies for glass, you could contact them for more details. They usually also put their glass catalogs online, and I'd bet you could contact them for information about why certain elements are used. FYI, Ohara is what Canon uses for glass. I wouldn't think the fluorite being artificially grown would affect its structure, beyond making it even throughout, though I'd suggest contacting Canon, once again, and asking to be put in contact with an engineer. As for why it transmits at certain wavelengths, a physicist would be the best resource. I know the University of Rochester has an optics division.

Hey, the U of R is right by me

The hospital side is one of our customers.

Nov 09, 2009 at 01:29 PM

SoundHound
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p.4 #16 · What does fluorite actually do?

The highest quality spotting scopes of many makes use Flourite lenses. I have a Zeiss 85mm objective spotting scope with a Flourite element.

Nov 10, 2009 at 02:47 AM

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