Building my own lens Mine's Bigger than Yours

[Mt Spokane Photography]

I wanted a large aperture lens, so my first task was to find out how large of a front element I could find. This one is about 14 inches across, and actually consists of two elements.

Great Start eh, and only $200.

I will post more info about it when I get time, it has quite a history.

 

[IglooEater]

Haha, pretty sweet!! Looking forward to your updates. What focal length are you looking to make? Good luck!

 

[Mikehit]

Lens? That is a bass cone from a speaker with some glass in front of it!
For a more 'focussed' sound no doubt.

 

[AlanF]

Haha, pretty sweet!! Looking forward to your updates. What focal length are you looking to make? Good luck!

If it's a 50mm, then if would be f/0.14. Hate to think what the field curvature and depth of field would be.

 

[rs]

Assuming you can make the aperture match that front element diameter, a 400/1.1 would be quite nice. What was it part of before?

 

[Alex_M]

part of this, likely? 8)

Assuming you can make the aperture match that front element diameter, a 400/1.1 would be quite nice. What was it part of before?

 

[DominoDude]

The colour kind of gives it away. I'd bet it has been part of some military equipment.
It might have been part of a door peephole at NORAD operations center. :

 

[Khufu]

Cooool... have you tried holding it near a wall at a dark end of a room to see what its as-is focal length/flange distance is, and how large the projected image is?! Go do aaaall the tests and report back to us, trooper!

 

[Mikehit]

I'd return it if I were you. It is obviously crippled by a poor focus mechanism.

 

[Maximilian]

I wanted a large aperture lens, so my first task was to find out how large of a front element I could find.
...

If I were to choose something for this task and I wasn't fixated on glass I'd go the mirror optics way
But $200 is a though price.

Enjoy and post your progress

 

[AlanF]

Assuming you can make the aperture match that front element diameter, a 400/1.1 would be quite nice. What was it part of before?

Solved the puzzle. 14" diameter is the minimum size of the front element for a 1000mm f/2.8.