Lens Construction

[Falcone]

One different between Nikon and Canon lens is that Canon Lens(the High end ones) uses fluorite as one of its elements.

Now fluorite is toxic and there are claims that the process of producing fluorite elements is less environment friendly.

Some say that fluorite is less susceptible to heat and easily fractured, which is one of the reason with Canon High end lens are in white, and why NASA uses Nikon lens.

[Chai]

Originally Posted by Falcone

One different between Nikon and Canon lens is that Canon Lens(the High end ones) uses fluorite as one of its elements.

Now fluorite is toxic and there are claims that the process of producing fluorite elements is less environment friendly.

Some say that fluorite is less susceptible to heat and easily fractured, which is one of the reason with Canon High end lens are in white, and why NASA uses Nikon lens.

I saw that in dpreview forums...

[Falcone]

Originally Posted by Chai

I saw that in dpreview forums...

That's why the 'Some say'

[peaz]

Originally Posted by Falcone

That's why the 'Some say'

Did a quick research over Google.. looks like few things are true here.

Fluorite glass is definitely better than ED glass, but by how much? Might be too little to make a difference for people like us. If you need super high resolution like scoping 10-20 lightyears away... perhaps. But just a 200-400mm FOV, urm... maybe the results almost the same.
Source: http://www.optcorp.com/product.aspx?pid=383-405-1844

However it's also true that fluorite glass cracks much easier than ED glass. But then again, we as general users would probably never get to experience that.
"the expansion rate of optical glass can be low; ie 0.000 001 per degree C.

Flourite is MUCH higher; say 0.000 01 per degree C.

Plastics are WAY WAY (SHOUTING!higher; say 0.000 14 per degree C." - Source: http://photo.net/bboard/q-and-a-fetch-msg?msg_id=00E07w

It might suggest why NASA uses Nikon lens though, in space minus the atmosphere, temp change can be quite extremely crazy.

Perhaps, maybe NASA worked with Nikon to come up with a fluorite replacement? I'm sure Nikon researched on the idea of fluorite glass too, since Carl Zeiss and a few other telescope glass manufacturers also make use of these glass.