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The biggest lens?
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PostPosted: Wed Mar 01, 2017 12:05 am    Post subject: The biggest lens? Reply with quote
I am not sure my question is about manual focus lenses. By that I mean a class of lenses you can hardly operate manually. Still, it is interesting to know which existing lenses are the biggest. That is to know what are physical limits when a several elements construction still works well.


Credit: Wikipedia

Aside a list of 500 to 1200 lenses used for casual cameras, I found a mention of a Canon 14/5200 which is 500mm in diameter and weigts about 100 kilos. When you realize those dimensions, it sounds already huge. Although when you move on the scale you may easily say "nuts!" There are or there were lenses for space satelites such as a Soviet Mezon-2A 6/3000 built in 1972 and shown here in the picture. The lens diameter is 0.6m and it weigts almost 500 kilos. Not really manual. But if you move from space back to earth, in modern observatories you may find even larger devices with glass optics. Such as a Canon correctional lens of 7 elements with 1m diameter placed on a 870Mp camera weighting 3000 kilos.

Well, the question follows: a Planar with 1m lens diameter is the biggest lens possible?

And an easier question: what is the biggest lens you happened to use?


PostPosted: Wed Mar 01, 2017 2:42 am    Post subject: Reply with quote
Of course the astro guys really go big but they use mirrors. The VLT is currently operational with 4 scopes each 8.2meters in diameter. the E-ELT is under constructon with a thirty nine meter aperture! My own current is a 1200mm celestron (5inch) SCT. But I also have a rubinar 1000 and my largest refractor is a Meyer Gorlits 500mm (It is far more unwieldy than the Celsestron as it is very very heavy.


PostPosted: Wed Mar 01, 2017 3:12 am    Post subject: Reply with quote
I owned a Meade 10" SCT for several years. Front element diameter was 10" (254mm). It was an f/10 scope, so its focal length was 100 inches, or 2540mm. It took great shots of the moon, the Andromeda galaxy and other interesting deep sky objects. I even dabbled in terrestrial photography with it. But it was pretty unwieldy, requiring a huge tripod.


image borrowed from cloudynights.com


PostPosted: Wed Mar 01, 2017 3:18 pm    Post subject: Reply with quote
Wow, thanks for sharing! You use great equipment, in both meanings of the term "great".

It's true that telescopes use huge mirrors. What is more intriguing is a huge lens. If I remember correctly, glass has a quality that is called something like fluidity or viscosity which leads to deformations and to a natural limit in production of huge lenses. So, a mirror lens may be anyway bigger than a glass one.

My experience is limited to a near-kilo Quantaray 75-205 zoom. Which is already too much for a subtle Nex!


PostPosted: Wed Mar 01, 2017 8:06 pm    Post subject: Reply with quote
Cooltouch I have telescope envy.

As far as casting giant glass optics mirrors also bump up against physical limits. They have a casting facility at University of AZ that cast some of these giant things they have to carefully analyze where to put reinforcing ribs on the underside. Even so most of the larger ones are made with multiple optical elements. The largest refractor ever cast was installed at the Yerkes observatory in Wisconsin and measures 40 inches in diameter and dates to the 1890's.


PostPosted: Wed Mar 01, 2017 9:42 pm    Post subject: Reply with quote
There are big lenses listed in the message thread:

http://forum.mflenses.com/whats-your-biggest-lens-t64369.html


PostPosted: Wed Mar 01, 2017 11:14 pm    Post subject: Reply with quote
That thread was a lot of fun, sad that so many of the images were lost.


PostPosted: Wed Mar 01, 2017 11:31 pm    Post subject: Reply with quote
jamaeolus wrote:
That thread was a lot of fun, sad that so many of the images were lost.


Was that the tread that had the picture of Klauss sat on a throne of humungous glass? That was a classic picture.


PostPosted: Thu Mar 02, 2017 12:19 am    Post subject: Reply with quote
Lloydy wrote:
jamaeolus wrote:
That thread was a lot of fun, sad that so many of the images were lost.


Was that the tread that had the picture of Klauss sat on a throne of humungous glass? That was a classic picture.


That photo was in a later thread iirc...I couldn't find it -- may be in the Cafe which Google can't see. Sad


PostPosted: Thu Mar 02, 2017 1:52 am    Post subject: Reply with quote
alex ph wrote:
Wow, thanks for sharing! You use great equipment, in both meanings of the term "great".

It's true that telescopes use huge mirrors. What is more intriguing is a huge lens. If I remember correctly, glass has a quality that is called something like fluidity or viscosity which leads to deformations and to a natural limit in production of huge lenses.

The word I believe you're looking for is plasticity, the weight causes the lens to deform.


PostPosted: Thu Mar 02, 2017 12:00 pm    Post subject: Reply with quote
My biggest lens is Canon FD 800mm 5.6L - Sometimes use it when shooting animals and well the moon & play with it just for fun.


Maybe I should start private investigator work and spy people as there are people hiring and paying for spying (adultery, corporate espionage) Very Happy
Hmm... interesting business idea.


PostPosted: Thu Mar 02, 2017 2:30 pm    Post subject: Reply with quote
Thank you, Lightshow! That is the correct term, plasticity.

Visualopsins, I missed this thread. You are right folks, it's much of fun to watch and discuss big things in this attractive lens realm where one of the main virtues is compactness.


PostPosted: Fri Mar 03, 2017 12:20 am    Post subject: Reply with quote
tanheis wrote:
My biggest lens is Canon FD 800mm 5.6L - Sometimes use it when shooting animals and well the moon & play with it just for fun.


Maybe I should start private investigator work and spy people as there are people hiring and paying for spying (adultery, corporate espionage) Very Happy
Hmm... interesting business idea.


I am immensely jealous Razz


PostPosted: Fri Mar 03, 2017 3:48 am    Post subject: Reply with quote
Glass has no crystalline structure so it is technically considered to be a fluid that just happens to be stable at a range of temperatures we would consider to be normal. But it does flow, so yeah, that was the big problem with refractors and the reason why mirrors supplanted them for deep-sky astronomy. I recall reading years ago that the casting for the Mt. Palomar mirror, which was the world's largest for many years, took an exceptionally long time to cool -- like years? Maybe that's an exaggeration, but it took a long time before it had reached an equilibrium such that it could be ground to its final shape.


PostPosted: Fri Mar 03, 2017 7:49 am    Post subject: Reply with quote
tanheis wrote:
My biggest lens is Canon FD 800mm 5.6L - Sometimes use it when shooting animals and well the moon & play with it just for fun.


Maybe I should start private investigator work and spy people as there are people hiring and paying for spying (adultery, corporate espionage) Very Happy
Hmm... interesting business idea.


Holy Bazookas Batman, that is a serious piece of lens kit.
Too big for what I shoot but.....
It is the panzerfaust of lenses Smile
T


PostPosted: Fri Mar 03, 2017 7:52 am    Post subject: Reply with quote
cooltouch wrote:
Glass has no crystalline structure so it is technically considered to be a fluid that just happens to be stable at a range of temperatures we would consider to be normal. But it does flow, so yeah, that was the big problem with refractors and the reason why mirrors supplanted them for deep-sky astronomy. I recall reading years ago that the casting for the Mt. Palomar mirror, which was the world's largest for many years, took an exceptionally long time to cool -- like years? Maybe that's an exaggeration, but it took a long time before it had reached an equilibrium such that it could be ground to its final shape.


Yes Michael, I can believe that.
Window glass gets thicker at the bottom and thinner at the top over an extended period of time due to the influence of gravity.
Fluid indeed.
Maybe we should rotate our lenses through ninety degrees each day to maintain uniformity Smile
T


PostPosted: Fri Mar 03, 2017 8:32 am    Post subject: Reply with quote
Oldhand wrote:

Maybe we should rotate our lenses through ninety degrees each day to maintain uniformity Smile
T


lol! What a novel idea! Just one more thing to worry about, oh my!


PostPosted: Fri Mar 03, 2017 8:58 am    Post subject: Reply with quote
Frankly, I had the same idea on the spot, and I don't understand why it is not done. With a refractor the image plate is straight behind it and could rotate with it ..

Perhaps there are other issues with glass, such as having to grind at least 6 surfaces to exactness, versus one (and easier conditions, since it can rest on the ground) for mirrors.


As to Big Lenses:

There was one large litho lens for sale here, I cannot find the thread, maybe deleted?

Astro-Berlin had some Forum member-sized teles too. These were actual photography lenses, not some gizmo ripped from a russian tracker. They were just extremly large.

Sigma and Canon made some teles that require an elephant and motor zoom, 200-500/4 or whatever it was.

One pretty large pipe is the Sigma 400/5.6 in various mounts, AF and stuff.. It is not really large but pretty common.


Largest pipe I personally handled, Sun/whatever relabel 300/4.5


PostPosted: Sat Mar 04, 2017 12:16 am    Post subject: Reply with quote
buerokratiehasser wrote:

Sigma and Canon made some teles that require an elephant and motor zoom, 200-500/4 or whatever it was.


I remember seeing ads for the Canon 150-600mm f/5.6 in the photo mags back in the 80s. It sold for 880,000 yen back then, which was a huge amount back in those days. Roughly $7,700 at today's exchange rate. But that was 1980s dollars.

http://global.canon/en/c-museum/product/nfd258.html


The old Century Precision Optics folks in Hollywood would convert those big zooms for 35mm movie camera use.



Sigma makes a 200-500mm f/2.8, which has to be some sort of record.


PostPosted: Sat Mar 04, 2017 3:29 am    Post subject: Reply with quote
Turning lenses over during storage also helps maintain lubricant distribution. Also good for mechanical cameras, at least as important as occasional working of mechanism imho.

My biggest:







PostPosted: Sat Mar 04, 2017 12:12 pm    Post subject: Reply with quote
Glass remaining liquid resulting in windows thickening at the bottom over time has to be up there in the truthiest truthinesses of all time.


PostPosted: Sat Mar 04, 2017 12:20 pm    Post subject: Reply with quote
Oldhand wrote:

Window glass gets thicker at the bottom and thinner at the top over an extended period of time due to the influence of gravity.
T


This is an oft quoted 'fact' that is somewhat misleading.
Glass production in the past did not have the current option of float finishing, so tended to be much less uniform than todays window glass. Given the distinct thickness differences in the glass being fitted it made sense to install the thicker end at the bottom. The plasticity of glass is nowhere near enough to account for the early windows.


PostPosted: Sat Mar 04, 2017 12:40 pm    Post subject: Reply with quote
DConvert wrote:

This is an oft quoted 'fact' that is somewhat misleading.
Glass production in the past did not have the current option of float finishing, so tended to be much less uniform than todays window glass. Given the distinct thickness differences in the glass being fitted it made sense to install the thicker end at the bottom. The plasticity of glass is nowhere near enough to account for the early windows.


Well there's that, and that every google search you run on it says the same down til you get to the timecube level, but then there's the fact that it feels like it ought to be true Very Happy


PostPosted: Sun Mar 05, 2017 11:38 pm    Post subject: Reply with quote
Thanks to all! It's a pure joy to watch and to read about those curious things.


PostPosted: Mon Mar 06, 2017 5:20 pm    Post subject: Reply with quote

Photosonics 100 inch lens


Jonel 100 2540mm F/8 Mirror Lens for Photosonics (currently offered on ebay for $33.500)
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