Fast Autofocus Camera Lens Selection Guide

Are Faster Lenses Better?
Faster lenses cost more than slower ones. But are they better?
In one area, they obviously are: They transmit more light. A faster lens provides a brighter viewfinder image for easier composing in dim light and allows you to shoot at a lower ISO for better image quality, or at a faster shutter speed to minimize blur due to camera and subject movement.

And faster lenses often outperform slower ones. For instance, Canon’s EF 300mm ƒ/2.8L IS USM pro telephoto is superior to its EF 300mm ƒ/4L IS USM pro telephoto not only in lens speed, but also in optical performance, AF performance and weatherproofing.

But you pay a price for those benefits. That ƒ/2.8 costs more than three times as much as the ƒ/4 and is much bulkier.

A fast lens is one that has a large minimum aperture (smaller f-stop numbers). The minimum aperture might be f/1.4 f/1.8, f/2 or f/2.8 in comparison to other lenses with the same focal length. The larger minimum aperture requires larger glass elements and is subsequently heavier and usually bulkier than a lens one or two slops slower. They are often higher quality as a side-effect of the lens maker justifying the extra expense. Most lenses do not perform very well wide open (shooting at their maximum aperture). You need to stop it down to get best result out of the lens. A fast f2.8 lens stopped down to 4 or 5.6 will give great results, where the slow 5.6 lens would need to be to be wide open and will not be as great a picture.  Always Best Prices for the fastest lens you can afford, or that you want to afford.  A professional zoom lens is already two stops slower than a f/1.4 prime lens.

Some of the fastest camera lenses ever made are:

• Carl Zeiss 50mm f/0.7 (Limited production lens built for the NASA space program, used on 35mm movie cameras by Stanley Kubrick for some candlelit scenes in Barry Lyndon)
• Tokyo Kogaku Toko 5cm f/0.7 (WWII) and Simlar 5cm f/0.7 (1951)
• Rodenstock TV-Heligon 50mm f/0.75
• Nikon TV-Nikkor 35mm f/0.9-Fastest Nikkon ever made[2]
• Leica Noctilux-M 50 mm f/0.95 ASPH, announced on September 15, 2008, it is the fastest Aspherical lens to have ever reached mass production.[3]
• Canon 50mm f/0.95 (Available in TV and Canon 7 Rangefinder Version)
• Schneider Kreuznach 50mm f/0.95 'Xenon' (Available with C mount)
• Leica Noctilux 50mm f/1.0 (Leica M mount, discontinued and replaced 2008 with a new Noctilux, see above)
• Canon EF 50mm f/1.0 (for Canon autofocus SLR, now out of production)