Apertures

We know that the f/2.8 means large aperture but what is the largest aperture you can get, why is it so important while taking photos. as you will gather my knowledge on lens is limited

Thank you

I think the fastest now is f/1.2, but Canon used to make a f/.095
I don't think speed is as important now with the very high ISOs available, since most lenses are sharpest about 2-3X (f-stops) stopped down from wide open. After that, diffraction will start to degrade the image as you get up toward f/16.

If you want to rent a 50mm f/1.0 , then these guys say they have it -> http://www.lensrentals​.com …al-range/canon-50mm-f1.0l

Bob 38 wrote in post #15298890
We know that the f/2.8 means large aperture but what is the largest aperture you can get, why is it so important while taking photos. as you will gather my knowledge on lens is limited

Thank you

It's also not just for exposure, but for depth of field

All f/2.8 means, the aperture is larger than when set at f/4.0, f/5.6 etc, though smaller than f/2.0 by one stop etc....

Assuming you have the "correct" exposure, by increasing the aperture, means you can increase the shutter speed to make sure the exposure is "corrected". You should read something on the exposure triangle, it should help you understand how the aperture, shutter speed and ISO work in relation to one another

The biggest advantage I find in having lenses with large apertures is a brighter viewfinder.

Bob 38 wrote in post #15298890
We know that the f/2.8 means large aperture but what is the largest aperture you can get, why is it so important while taking photos. as you will gather my knowledge on lens is limited

The size of the aperture controls two things,
1. The amount of light entering the camera.
2. The depth of field.

Depth of field is the area in-front and behind the subject that is in focus. The wider the aperture the more light gets in but the narrower the depth of field. Read this article for more on Depth of Field http://www.cambridgein​colour.com/tutorials/d​epth-of-field.htm

Zeiss did a 50mm f/0.7 but there were only 10 made.

PhotosGuy wrote in post #15299428
I think the fastest now is f/1.2, but Canon used to make a f/.095

that front element must've been HUGE!!!!

Bob 38 wrote in post #15298890
We know that the f/2.8 means large aperture

The number represents the size of the iris diameter as a fraction of the focal length. In other words, with a 100mm lens at f/2.8, the iris diameter will be
100 / 2.8 = 36mm (roughly).

The aperture value is the denominator of a fraction, so a larger number equates to a smaller iris opening (less light gets through).

"Fast" lenses (those with a large maximum aperture) require a larger iris mechanism and larger glass elements, making them bigger, heavier and more expensive. And the greater the focal length, the larger those parts need to be. Long lenses with large apertures are big, fat, heavy and really expensive, all due to basic physics.

The other thing to remember about aperture values is that if you double the f/ number, you reduce exposure by a factor of four (and vice-versa). In other words, if you reduce the diameter of a hole from 50mm to 25mm, you reduce the area of the hole to 1/4 the original area, and only 1/4 as much light gets through the hole.

maverick75 wrote in post #15309822

IMAGE LINK: http://www.petapixel.c​om …f0-95-on-an-olympus-e-p1/

there was a typo in the comment i quoted, instead of f/0.95 it was f/.095, so i was throwing some humor at that.

Leica makes a 50 .95 Noctilux

There one for sale on NYC Craigslist right now:
Seller asking for $2700.
http://newyork.craigsl​ist.org/mnh/pho/343950​8788.html