canon-300mm f1.8, Exotic or what

[magarity]

My guess it's an autofocus lens. If not, than I cannot for the life of me figure out why they'd have a focus limit switch on the body. Style? Looks? Took the body from another lens, but was too lazy to just cover that area up with a blank plate?

Because such a limited run specialty product (with associated price tag) was almost certainly handed to the engineers to do with a fair amount of leeway to "do it right". Being engineers, they were psychologically incapable of NOT including the focus limiting switch, etc.

 

[privatebydesign]

My guess it's an autofocus lens. If not, than I cannot for the life of me figure out why they'd have a focus limit switch on the body. Style? Looks? Took the body from another lens, but was too lazy to just cover that area up with a blank plate?

Because such a limited run specialty product (with associated price tag) was almost certainly handed to the engineers to do with a fair amount of leeway to "do it right". Being engineers, they were psychologically incapable of NOT including the focus limiting switch, etc.

Looking at it it is based on the EF 200mm f1.8. Certainly externally from the rubber focusing ring to the body are from the 200 f1.8, like the one behind it. You can tell this because only the non IS super teles had the pre focus distance ring closer to the camera than the actual focus ring, and the 200 was the only version of those teles that looks remotely like it. So even if it was manual focus, it would still have those switches and covers even if there was nothing behind them. Though bearing in mind all those lenses are internal focus lenses I see no reason why it wouldn't be AF capable.

Indeed looking at the block diagram of the non IS 300 f2.8 and 200 f1.8 it would seem the 200 has a lot more potential for customization than the 300, just replace the front four elements that are the only relevant thing forwards of that focus ring with lots of potential for adjustments within the 200mm f1.8 barrel. The focus group and motor and the aperture are all contained in that 'borrowed' section.

Mind you that does mean if it is AF it is a focus by wire lens and would need power to focus even manually, also if the motor were to die the lens would be unusable even in manual focus.

P.S. It also has the later 200mm f1.8 focus switch on it, the earlier ones had AF/M on them the later ones AF/MF. I thought I remember reading that was the last few years of production so it potentially dates the lens to around the late 1990's.

P.P.S. The front element is going to be around 166mm, so a decent bit bigger than the 600mm f4 at around 155mm, but much smaller than the 1200mm f5.6 which would be around 214mm!

 

[Sharlin]

I believe NASA are building a 134 meter focal length f20 right now! 8)
Wonder if my 1DX11 will work on it

Yeah, but it's a reflector so the bokeh will be horrible

 

[IglooEater]

I believe NASA are building a 134 meter focal length f20 right now! 8)
Wonder if my 1DX11 will work on it

Yeah, but it's a reflector so the bokeh will be horrible

I'd also be guessing that its minimum focus distance might not allow it to have anything on earth in focus...

 

[rs]

I believe NASA are building a 134 meter focal length f20 right now! 8)
Wonder if my 1DX11 will work on it

Yeah, but it's a reflector so the bokeh will be horrible

I'd also be guessing that its minimum focus distance might not allow it to have anything on earth in focus...

I guess it can focus down to 1.5 million kilometres:

Orbit: 1.5 million km from Earth orbiting the L2 Point

source: https://jwst.nasa.gov/facts.html

 

[jolyonralph]

That would really be pushing the limits for infinity focus!

 

[IglooEater]

I believe NASA are building a 134 meter focal length f20 right now! 8)
Wonder if my 1DX11 will work on it

Yeah, but it's a reflector so the bokeh will be horrible

I'd also be guessing that its minimum focus distance might not allow it to have anything on earth in focus...

I guess it can focus down to 1.5 million kilometres:

Orbit: 1.5 million km from Earth orbiting the L2 Point

source: https://jwst.nasa.gov/facts.html

True enough. Forgot it would be in orbit... :-\