What is a “fast” lens?
What is a "fast" lens anyway?
Applied to a lens, the term "fast" refers to faster shutter speeds made possible by the superior light gathering power of a lens.
A fast lens is always larger heavier and more expensive than a slower one. For example, a 50mm f/1.2 lens might cost $1600 compared to $300 for a 50mm f/1.4 lens and $100 for a 50/1.8.
Each f-stop represents a full shutter speed. So an f/1.4 lens allow one faster shutter speed than an f/2 lens, and two faster shutter speeds than an f/2.8 lens. That's a very big deal at dusk, or indoors.
Most consumer zooms are in the f/3.5 - f/5.6 range, meaning that they lose 2-3 shutter speeds, a huge difference leading to blurred images when the light levels drop (which requires a lower shutter speed).
An aperture which is 1.4 times the previous one is half as bright eg f/2 is half as bright as f/1.4. Faster apertures (e.g. f/1.4 or f/1.2 or even f/0.95) are far more challenging to design and build to achieve high quality.
|Focal length range
(for 35mm format)
|12mm - 21mm||f/1.4, f/2|
|22mm - 35mm||f/1.4, f/2|
|50m||f/0.95, f/1, f/1.2, f/1.4|
|100mm, 135mm||f/1.8, f/2|
|180mm, 200mm||f/2, f/2.8|
Top recommendations for fast lenses
Lenses I've used and/or own, and can heartily recommend.
Click on links to each lens for reviews.
Zeiss for Nikon or Canon
- 21mm f/2.8 Distagon (not so fast, but oustanding at f/2.8)
- 28mm f/2 Distagon
- 35mm f/2 Distagon
- 50mm f/1.4 Planar
- 50mm f/2 Makro-Planar
- 85mm f/1.4 Planar
- 100mm f/2 Makro-Planar
Canon's f/1.2 lenses are unique. Nikon does not offer f/1.2 lenses as of 2010.
- 21mm f/1.4 Summilux-M ASPH
- 24mm f/1.4 Summilux-M ASPH
- 28mm f/2 Summicron-M ASPH
- 35mm f/1.4 Summilux-M ASPH
- 50mm f/0.95 Noctilux-M ASPH
- 75mm f/2 APO-Summicron-M ASPH
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