What's A Fast Lens?

[Brackish]

I saw a cam for sale that had an f1.3. Is this considered pretty fast?
Is this about the fastest lens normally found around?
Seems like most lenses are f1.8. What commonly available cams have even faster lenses? Isn't f1.2 about the limit?

[Actor]

You'd be hard pressed to find a lens faster than f/1.2 on any commercially available camera but theoretically there is no limit. When filming Barry Lyndon, Stanley Kubrick had a Mitchell modified to accept a set of three f/0.7 primes.

[jean]

f/0.9 should qualify. At $25 it also qualifies as low budget lens. Ebay sometime is a very fun place

[Brackish]

Jean,
What brand of lens is that? And which camera is it from?
How's the image quality?

[christoph]

I saw a cam for sale that had an f1.3. Is this considered pretty fast?
Is this about the fastest lens normally found around?
Seems like most lenses are f1.8. What commonly available cams have even faster lenses? Isn't f1.2 about the limit?

it depends a lot on the format you're shooting... the bigger the more difficult it is to design a fast lens with good optical qualities. zooms are harder than primes as well.

for super8, a f1.2 zoom is pretty fast.. there are some cameras with f1.0 and some c-mount primes with f0.95.

on 16mm f1.3 is considered a high speed lens, with normal lenses around f2.2 and zooms f2.0 to f2.8. again you might find special lenses with f1.0 or slightly below, but they are not common..

on 35 cine lenses f1.3 is called high speed.. anything below are usually special adapted lenses. zooms are 2.8 or higher

on 35 photo a f1.4 is pretty high speed.. you can buy f1.2 or f1.0 50mm lenses, but they are big an expensive... it's very hard to design tele and wideangle (and zooms) lenses with high speed that cover this format and more.

medium format lenses usually start with f2.8.. you can find some f2.0 lenses, but again only on normal focal lenght.

You'd be hard pressed to find a lens faster than f/1.2 on any commercially available camera but theoretically there is no limit.

as far as i know it's teoretically not possible to design a lens with more than f0.5.. so f0.7 might well be the the practical limit.

++ christoph ++

[jean]

Jean,
What brand of lens is that? And which camera is it from?
How's the image quality?

It's a c-mount Schneider-Kreuznach Xenon, 0.95 50mm (sorry, I typed 0.9 above). On ebay usually they sell for $20- $30, a 25mm version is also often available. Image quality is OK, DOF wide open is SHALLOW, so you have to focus very accurately and mak sure the victim dousn't move t o much.

I've seen similar lenses from Angenieux, but evidently they are sought after by collectors and hard to get under $100.

I figure these lenses must have costed like a car back in the 70's 8O

[tr0x]

as far as i know it's teoretically not possible to design a lens with more than f0.5.. so f0.7 might well be the the practical limit.

Carl Zeiss 40mm f/0.33 "Super-Q-Gigantar" with a Contarex.
This lens was only a "joke" and the maybe the 0.33 value is invented... however it's interesting...


bye.

tr0x

[Basstruc]

I got a few 42mm opened at 0.75. I'm still waiting for someone would could convert the mounts to M42 for tests. Anyone ?
Matt

[christoph]

as far as i know it's teoretically not possible to design a lens with more than f0.5.. so f0.7 might well be the the practical limit.

Carl Zeiss 40mm f/0.33 "Super-Q-Gigantar" with a Contarex.
This lens was only a "joke" and the maybe the 0.33 value is invented... however it's interesting...

well, i only got this info (f0.5) from a few web searches, so one never knows... but the sources seemed to be quite plausible...

here is one:

>>The maximum theoretical aperture of an aplanatic lens amounts
>>to f/0.5. The designation aplanatic means that the lens is free
>>from spherical and comatic aberrations.
>
>I'm just curious what the math for calculating this is (any good
>books on lens design you can recommend? I'm quite curious about the
>subject now)

The maximum possible aperture is restricted by the so-called
sine rule. Difficult to explain without schemes.

Books on lens design?

General optics:
Eugene Hecht, Optics, 3rd ed., Addison Wesley, 1998.

Photographic optics:
Sidney F. Ray, Applied photographic optics, 2nd ed.,
Focal Press, 1997.

Engineering:
Warren J. Smith, Modern optical engineering, McGraw-Hill, 1966.

Applied optics and optical engineering, edited by Rudolf Kingslake,
Academic Press.

or like this:

...not to be actively unpleasant or anything, but f/0.5 is the limit in air. f/0.7 lenses have been used by cinematographers. And as I mentioned Canon made thousands of 8.5-25.5/1.0 zoom lenses for relatively inexpensive S8 cameras. There are indeed lenses faster than f/0.5, e.g., oil immersion objectives for microscopes, but for general photographic purposes I don't think filling the space between the front of the lens and the subject with high index of refraction oil is practical. It certainly wouldn't be easy.

http://micro.magnet.fsu.edu/primer/anat ... rture.html

++ christoph ++

[JGrube]

I've got one of those F1.0 Canons (a 310xl); good little camera, it will render an image in very low light, I've been amazed at the conditions under which I've been able to shoot. It has only automatic exposure, but when using it strictly as my "low-light" camera, it's served me very well.

Boy, I'd sure love to get one of Stanley's Mitchell cameras with the f0.75 lens. They were able to shoot under CANDLE LIGHT with that fella. How cool would that be?

Ah well, maybe down the road. I'll have to live with f1.0 for now.

Jason

[Wells]

F-stop is the result of dividing the focal length of a lens by the diameter of the effective aperture. Therefore a 0.5 lens will have an aperture twice the diameter of the focal length. At these extremes, light coming from the edge of the lens must bend around 45 degrees. Very hard to keep all colors in line at this point, the lens wants to act like a prism, throwing colors through different angles (see dark side of the moon cover). Thus, chromatic abberration...

Theoretically the limit approaches zero, with a lens of infinite aperture. A 15mm f 0.0001 lens would be 150 meters across.

Sorry, broken ankle, too much coffee and time on my hands...

[christoph]

Boy, I'd sure love to get one of Stanley's Mitchell cameras with the f0.75 lens. They were able to shoot under CANDLE LIGHT with that fella. How cool would that be?

yeah, but don't underestimate how MANY candles they needed... think of hundreds here as film stocks were quite slow at that time.

++ christoph ++

[Brackish]

Hi JGrube,
What kind of light have you been able to shoot in with that
Canon f/1.0?

[JGrube]

"JGrube wrote:
Boy, I'd sure love to get one of Stanley's Mitchell cameras with the f0.75 lens. They were able to shoot under CANDLE LIGHT with that fella. How cool would that be?"

Christoph:
"yeah, but don't underestimate how MANY candles they needed... think of hundreds here as film stocks were quite slow at that time."

I'll give you that, my friend, I also heard they used special, extra-bright candles. I think I'm feeling jealous because I spent 2 weekends in November shooting interior shots, in a house with no electricity, lit with about 50 candles, on Kodachrome 40, with a max aperture of f1.8 (which definitely does not fall into the truly "fast" category of lenses) How, you might ask! Well, all that was really necessary was a big portable generator, a huge amount of gasoline, a 1000-watt spotlight, three 500-watt fill lights, and two 150-watt mini spots. Good God!

Using a similarly slow filmstock and trying to give the APPEARANCE of only candlelight would definitely have been less hassle and a little more authentic with one of those wonderful super-fast lenses.

Anyway....just dreaming.

Jason

[christoph]

I think I'm feeling jealous because I spent 2 weekends in November shooting interior shots, in a house with no electricity, lit with about 50 candles, on Kodachrome 40, with a max aperture of f1.8 (which definitely does not fall into the truly "fast" category of lenses) How, you might ask! Well, all that was really necessary was a big portable generator, a huge amount of gasoline, a 1000-watt spotlight, three 500-watt fill lights, and two 150-watt mini spots. Good God!

lol.. i know how you feel... i just spent some cold dark days shooting in a unheated house with broken windows and no electricity... about 8000W HMI lights and a whole lot of heaters.

that was with 5274 Vision 200T and T 2.8 though

and man those generators are noisy (well, the one we could afford anyway)

++ christoph ++