What is the minimum aperature for a portrait lens? 4.5? 2? I'm debating getting a zoom vs. a prime at 100mm. If I get a prime, then I would consider a 100mm macro, which has a smaller maximum aperature than the non-macro. Important to my decision, is what aperture is required to throw the backgrounds out of focus.

-- Pat Lehnherr (lehnherr@isd.net), June 04, 2000

Answers

i think you mean max aperature. my portrait lenses are 85mm f1.8 and 80-200 f2.8. imho, anything slower than a 2.8 is too slow for portraits. also need to take in consideration your work space... distance to the model, distance to background etc...

-- howard shen (hshen@lsm.org), June 04, 2000.

Depth-of-field depends on focal length and aperture. Portrait lenses are "typically" 75mm to 200mm. Portrait lenses generally have apertures among the fastest for their length -- 85/1.4 or 85/1.8, 100/2, 200/2.8.

Generating background blur is dependent on physical aperture size. Longer, faster lenses have larger apertures available, which will allow you to blur backgrounds more.

Close focus limitations may also be a problem for portraits. If you find out you really like frame-filling portraits of just your subject's eyes to mouth, you'll need a macro lens or some tubes.

I would look for at least the same size aperture you get in a 50/1.4 lens in order to do portraits, ~35mm.

(To get the approximate size of an aperture for a given lens, divide the focal length by the aperture).

-- John O'Connell (boywonderiloveyou@hotmail.com), June 05, 2000.