[Digitalis]

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As well as having a higher refractive index than air leading to a more compact lens.

But this compactness is massively offset by the fact that glass has significantly more weight than air.

[ThorSanchez]

But this compactness is massively offset by the fact that glass has significantly more weight than air.

After my morning hit of LSD, I went and Googled refractive indices of various substances. It seems that carbon tetrachloride has an index nearly that of glass, but it weighs half as much. It's a liquid at room temperature, was once used in fire extinguishers, and is highly toxic to the liver and kidneys. I also found a scientific paper indicating that it has a slightly higher refractive index when pressurized to 1000 atmospheres.


So maybe Pentax can innovate by filling a mirror lens with highly pressurized carbon tetrachloride. It would be slightly lighter than the glass-filled one and almost as small, while having the ancillary use as a kind of fire extinguisher.


Plus, it might win this thread.

[savoche]

It would be slightly lighter than the glass-filled one and almost as small,

...and considerably more toxic than any thorium glass lens ever was. What's not to like?

[Na Horuk]

So maybe Pentax can innovate by filling a mirror lens with highly pressurized carbon tetrachloride.

That had to be more than just LSD, buddy Just a tube of highly pressurized toxic liquids with glass on the two ends haha

[UncleVanya]

Carbon-tet... I haven't been around that stuff since High School. Fun stuff. It was used as a degreaser for years and then ultimately pulled due to toxicity. We used it in chemistry classes.

[Digitalis]

carbon tetrachloride has an index nearly that of glass, but it weighs half as much

Pentax can innovate by filling a mirror lens with highly pressurized carbon tetrachloride

Forget traveling with that on an airline, or traveling with it at all: at 760000 Torr that amount of pressure would be rearing to come back out at you should the containment vessel fail. And the additional thickness of the lens barrel required to contain that kind of pressure would completely offset the weight saved. Solid cat is the way to go.

[Kerrowdown]

Working distance can be a problem for some

Aye and the green fringing too...

[angerdan]

what's the strangest thing I could wish for?
I thought we could maybe discuss the most bizarre, illogical, how-did-a-company-signoff-on-building-this-stuff lenses you've ever seen here.

Canon 5600mm F14
Ginormous 5200mm Canon Lens on eBay

You Tube

You Tube

Canon PE 300mm F1.8
This is the Canon 300mm f/1.8 -- Yes, Such a Monster Lens Exists
Canon EF 300mm lens - Wikipedia

Zeiss Apo Sonnar T* 1700 mm F4
Zeiss Apo Sonnar T* 1700 mm F4 lens: Digital Photography Review

Nikkor 1200-1700mm F5.6-8 P IF ED
The Insane Zoom Of The Nikkor 1200-1700mm | Popular Photography
http://www./2012/07/06/nikon-1200-1700mm-f5-6-8p-if-ed-lens-a-look-back-at-this-massive-lens/

Leica APO-Telyt-R 1600mm F5.6
World's Most Expensive Camera Lens
1600mm Leica Lens Is World's Most Expensive At $2 Million | Popular Photography

[Fogel70]

Is there a Q adapter available for that 5200mm Canon lens?

[bdery]

Some entries are pretty out of this world, but when reading the topic I immediately thought of this one:

Zeiss Apo Sonnar T* 1700 mm F4 lens: Digital Photography Review

[SGOMMO7]

Came across this thread again, and thought I should post the 2 lenses I originally thought about, (but was too lazy to look up at the time).

Sorry I’m not posting pictures but instead supplying links, I need to increase the amount of photos that I can post here on the forums. I should have more space and be a site supporter as I used a forum link when I bought my 20–40mm, (but for whatever reason, it didn’t work).

Anyways there are liquid lenses which use a drop of oil in lieu of glass optics, by putting in electric current through the oil droplet it can make the oil take on different curvatures. So instead of having a bunch of optical elements, the oil simply gets formed into one perfect element tailored for the exact shot you are taking. They have lots of advantages, like being very shock and wear resistant, and can focus so quickly that you would keep track of their focusing time in milliseconds.

Their big drawback is that they can only produced with a very small circumference, about the size of a droplet, it is just too difficult to get enough milliliters, of fluid to be suspended, that would be needed to cover C–crop/full frame or anything like that.

Right now these lenses are only used for more industrial purposes, but here’s an article of them trying to put this technology into smart phone cameras.

Exclusive - Future iPhones to feature global shutter, liquid lens and optical zoom - EOSHD

And here’s a link speaking more about their attributes.

Electrowetting for liquid lens - Display Plus

The other one, and in my opinion even more interesting as this actually has the possibility of replacing just not smart phone cameras lenses, (like the aforementioned) but all lenses!

This, “lens” is flat and extremely thin, and picks up the images akin to a radio antenna. Supposedly the performance potential for this technology, when fully developed, compared to our standard optics would have them obsoleted.

Lightweight, distortion-free flat lens uses antennae, not glass, to focus light | Harvard Magazine

[angerdan]

2540mm F/8 lens used by NASA - only $28,000 (instead of $32,000 in 2015):
Huge NASA lens (2540 mm) for sale on ebay. - PentaxForums.com
This Jonel 100 Mirror Lens Used by NASA Now Costs $28,000
Massive 2540mm f/8 NASA Lens Shows Up on eBay
Huge NASA mirror tele lens Jonel 100 ( 2540mm F/8 for 6x6 and more ) | eBay