Gene51 Loc: Yonkers, NY, now in LSD (LowerSlowerDelaware)

Though it's not a prime, the Sigma 200-500 F2.8 should be mentioned.

Delderby Loc: Derby UK

Just right for a day's hiking - I guess an appropriate tripod would be about the same weight. Seriously, though, these lenses are really for sports photographers who don't move - just sit on the touch line - and for prying paperazi.

cthahn

f0.85 , 40mm on a aps.c

Architect1776 Loc: In my mind

Canon 200mm f1.8
https://www.ebay.com/p/Canon-EF-200mm-f-1-8-L-USM-Lens/101700379

https://petapixel.com/2017/04/27/canon-300mm-f1-8-yes-monster-lens-exists/

Architect1776 Loc: In my mind

Telephoto? Hmmmmm

crazydaddio Loc: Toronto Ontario Canada

Normally I do....and did in this case but was taking a long time. Figured there might be some quick answers here.....and there was :-)

Thanks to those that responded . Trying to decide if I want an indoor sports lens that gives me some reach that is faster than my 70-200 2.8
100mm sigma at 1.8 looks great but its a crop body lens. I gain in aperature related speed but lose the DR and IQ due to ISO noise using my 70D.

Want something for my 5DmkIV where IQ is much better. 5D with 70-200 and bumped ISO will give me a better image than a 100mm sigma at 1.8 on a 70D body....I am surmising. Also looking at 85mms of which there are plenty to choose from for indoor wedding getting ready shots ...but that is different thread for another day...50mm 1.4 is doing well for now.

crazydaddio Loc: Toronto Ontario Canada

Oohh. 135 sigma is tempting!

amfoto1 Loc: San Jose, Calif. USA

Canon 100mm f/2 is still in production. Also Canon 135mm f/2 and 200mm f/2. And, yes, there are the Canon 85mm f/1.8, f/1.4 and f/1.2. Canon 200mm f/1.8 is a discontinued model.

Lensbaby 85mm f/1.8

Meyer-Optik 75mm f/1.9

Mitakon Zhongyi 85mm f/1.2, 85mm f/2

Nikon 85mm f/1.8, 85mm f.1.4, 105mm f/1.4, 105mm f/2, 135mm f/2, 200mm f/2

Opteka/Yongnuo 85mm f/1.8, 100mm f/2

Pentax 77mm f/1.8

Samyang/Rokinon 85mm f/1.4, 85mm f/1.2, 135mm f/2

Sigma 85mm f/1.8 and 135mm f/1.8
(The Sigma you mention is crop only and also not a prime. It's a zoom... 50-100mm f/1.8 DC.)

Sony 85mm f/1.4, 135mm f/1.8

Tamron 85mm f/1.8

Venus Optics Laowa 105mm f/2

Zeiss 85mm f/1.4, 100mm f/2 and 135mm f/2.

There's a practical limit to what can be built and carried around. The lens aperture and focal length dictate the overall size of the lens. To determine how large an aperture must be, divide the focal length by the max aperture.... for example, a 200mm f/2 lens needs to have a 100mm aperture. That's just the opening size! There also needs to be the mechanisms and lens barrel.

Someone else already mentioned the Canon 1200mm f/5.6:


And the Sigma 200-500mm f/2.8 zoom:
http://www.the-photography-blogger.com/wp-content/uploads/2015/07/TS560x560.jpg

MT Shooter Loc: Montana

It was

wmurnahan Loc: Bloomington IN

Back in the film days, I could see spending that kind of money if I was an indoor sport/event photographer. But with the ability to shoot at high ISO's that film could only dream of and since razor sharpness was less a desire as getting the shot was the function, I can't see spending the money for larger apertures unless the photo just is not doable by increasing the ISO such as astro/milkyway shots.

Architect1776 Loc: In my mind

The 200mm was during the film era and the 300 was a special purpose lens that needed high speed.
It showed Canon could do it with the new EF mount that was large enough to accommodate a long fast lens.

TriX Loc: Raleigh, NC

I typically shoot indoor sports with my 70-200 f2.8L IS on a FF, but this year I’m going to see if my 135 f2L is long enough. It’s a stop faster, sharper, (thankfully) substantially lighter, and I don’t need the IS at the speeds I typically shoot at.

RonVerde

I owned the Nikkor 300mm F/2 ED IF Lens ($6,500 in 1983) sold it to NASA in 1997.

Here's a link for more info about this very unusual lens -
http://www.company7.com/library/nikon/Nikon_0300f2.html

RonVerde

Nikon’s Nikkor 300mm f/2 ED IF is among the most rare of their production lenses with approximately four-hundred forty one (441) being manufactured, including a prototype, between the Summer of 1983 and into 1985. The system incorporates eleven elements arranged in three working groups.

Robert Bailey Loc: Canada

It's not a telephoto, but here's an f 1.0 lens.

http://www.kenrockwell.com/canon/lenses/50mm-f1.htm