Lenses #6 - Fast lenses

[RichardTaylor]

Lenses #6 - Fast Lenses

Fast lenses are those with wide maximum apertures.
F2.8 for a zoom lens is fast.
F2 or faster for lenses from 24mm to 135mm is fast.
F2 for a 200mm lens is very fast and F2.8 is fast.
F2.8 for 300 or 400mm is very fast.

Disadvantages
They can be very expensive.
They can be big & heavy, especially the long telephotos however some of the shorter primes are very small and light.

Advantages
Because of the fast apertures they are great for low light shooting and not just indoors.

(1a) You can even shoot urban scenes hand held, as in this example.


Camera Canon EOS 5D
Exposure 0.04 sec (1/25)
Aperture f/2.0
Focal Length 35 mm
ISO Speed 3200
Exposure Bias 0 EV

(1b) Or indoors without a flash or a tripod.


Camera Canon EOS 40D
Exposure 0.005 sec (1/200)
Aperture f/2.0
Focal Length 135 mm
ISO Speed 3200
Exposure Bias 0 EV
Flash Off, Did not fire

(2) They are capable of achieving very shallow depth of field (DOF), great for isolating subjects from the background or for creative purposes.

(2a) for creative purposes


Camera Canon EOS 40D
Exposure 0.001 sec (1/800)
Aperture f/2.0
Focal Length 135 mm
ISO Speed 100
Exposure Bias 0 EV

(2b) Subject isolation (this case a busy street scene).


Camera Canon EOS 40D
Exposure 0.001 sec (1/1600)
Aperture f/2.0
Focal Length 135 mm
ISO Speed 100
Exposure Bias -2/3 EV
Flash Off, Did not fire

============================

Lenses #1 - Introduction to DSLR lenses.
Lenses #1 - Introduction to DSLR lenses.

Zooms & primes.
For a good introduction to zoom and prime lenses see this post (on this site).
http://www.digital-photography-schoo...which-are-best

(2) "Standard" zooms -
Lenses #2 - Standard lenses

(3) Superzooms:
Lenses #3 - Superzooms.

(5) Wide angle.
Lenses #4 - Wide angle.

(6) Telephoto zooms
Lenses #5 - Telephoto

(7) Fast lenses - This post
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Thanks for looking.
Feel free to ask questions and feedback would be appreciated.

Richard

[STB]

Thank you so much for this info, Richard. Short and clear and filled with just what I needed. The photo examples nailed it for me.

[RichardTaylor]

Thanks.
Glad to help out.

[STB]

I actually just read through your entire series and it helped settle things in my mind as I make some initial purchase decisions. Have bookmarked the series for future reference and gone in search of more educational posts by you. Love the learning and the sharing going on here at DPS.