Super fast lens

[Alex]

Did anyone see the documentary on Kubrik last night on SBS? He used (for one of his movies) a Zeiss lens (custom made for NASA) which had an aperture of 0.7! Now, even Birdie can't get that! Or can he???

Alex

[endymion]

Did anyone see the documentary on Kubrik last night on SBS? He used (for one of his movies) a Zeiss lens (custom made for NASA) which had an aperture of 0.7! Now, even Birdie can't get that! Or can he???

Alex

Don't tempt him!

[mudder]

Wow, someone was telling me about a lens made by NASA with a .7 aperture today, no I know where he got that from...

I have no idea how the aperture is measured, how do you get less than 1?

Missed the show though, rats!

[Glen]

I know Birddy has his eye out for the 85mm Repro f1

[digitor]

Wow, someone was telling me about a lens made by NASA with a .7 aperture today, no I know where he got that from...

I have no idea how the aperture is measured, how do you get less than 1?
.............

When the objective diameter is bigger than the focal length.

I suspect this lens was f 0.707, because that would make the objective diameter = root 2 x the focal length, and it's a well known fact that optical designers seem to like roots.

Cheers

[johndec]

I suspect this lens was f 0.707, because that would make the objective diameter = root 2 x the focal length, and it's a well known fact that optical designers seem to like roots.

Cheers

I wouldn't know about such things, I'm married

[birddog114]

I suspect this lens was f 0.707, because that would make the objective diameter = root 2 x the focal length, and it's a well known fact that optical designers seem to like roots.

Cheers

I wouldn't know about such things, I'm married

John,
What's the difference in between the married and unmarried man?

[Matt. K]

I'm no lens expert...my understanding, unless someone shoots me down with some facts, is that a lens of f/0 allows the same amount of light throught the glass as there is in the original scene. A lens of F1 allows half the amount of light throught. The other half is lost as it passes through the glass. As you add more optical elements...or focal length, then more light is lost. Is that everyone elses understanding?

Disregard the above! It is clearly wrong! I was thinking of something totally different. I was wondering what the light falloff would be at F/0, theoretically, through the glass, and somehow my befuddled brain dragged in mechanical f/stops...which obviously reduce the light by reducing their physical size. Damn $2.50 vintage wine!

[phillipb]

That's great Matt, I'm going to fit a lens mount on my lens shade and call it a nikkor f0 ... now if only I can figure out how to focus it onto the sensor.

[johndec]

I suspect this lens was f 0.707, because that would make the objective diameter = root 2 x the focal length, and it's a well known fact that optical designers seem to like roots.

Cheers

I wouldn't know about such things, I'm married

John,
What's the difference in between the married and unmarried man?

Maybe you should ask a married optical designer

[Alex]

I though aperture, f/0.7 in this instance, is literally focal lens (f) divided by the aperture in mm.. So if it is 28 mm lens, then the aperture is 28/0.7 = 40 mm. I hope someone corrects me if my understanding is wrong.

Alex

[digitor]

I'm no lens expert...my understanding, unless someone shoots me down with some facts, is that a lens of f/0 allows the same amount of light throught the glass as there is in the original scene. A lens of F1 allows half the amount of light throught. The other half is lost as it passes through the glass. As you add more optical elements...or focal length, then more light is lost. Is that everyone elses understanding?

The aperture (or more correctly, the relative aperture) of a lens is a measure of its light gathering ability, and the f number used to describe it is the ratio of the diameter to the focal length. So, for example, a 100mm f2.0 lens has an objective diameter (which is effectively the maximum aperture) of 50mm. Nowhere near half the light is absorbed or reflected by the glass elements - only a few percent in total, with modern coatings.

An f0 lens, as you can see from the above, would have an infinite diameter, which is one reason why they're not too common

Cheers

[SoCal Steve]

Alex and Digitor are both on the right track.

If you do happen to find one of those illusive f/0.000 lenses, bring it over I'd like to see the truck that can haul that big sucker!! Great for shooting available darkness though, huh?!.