The Canon EOS and Photography Forums

This may sound silly but I had this question since long time in my mind. What/which kind of application requires wide angle lenses with fast apeartures? Generally, as per my knowledge, wide angle lenses are being used for capturing landscape which requires huge depth of field and so need slow (small) apearture. Why do we need f1.2 or f1.4 on say 24mm/28mm or so?

I can think of low light tight indoor space for one reason.

Photo journalist and snapshot/street photographers need ones I guess.

Not all landscapes are brightly lit by the sun!  After all, the best time to take them is at magic hour, when the light is fading fast.

And small apertures don't limit DOF by that much on this page:
http://www.bobatkins.com/photography/technical/depth_of_field.html

Bob has a chart that lists a 24 mm lens at f/1.4, the hyperfocal distance is 16 m.  16 m is pretty far away, but not unreasonable for a landscape, and you might want to blur out that coke can 5 m in front of you.  Why not have the option?  Also, note that aperture is a *ratio*:  for shorter lenses, the aperture diameter required for a given focal length is smaller and therefore cheaper and lighter.

I'd say the main application for fast wides would be indoor photography in low light where there's not enough room to back up and use a longer lens and perhaps street photography and photojournalism.

But you are right in that most wideangles are probably used stopped down most of the time for landscape work. That's one reason I've never bought a fast wideangle. My fastest wide lens is the EF 24/2.8, an excellent and very useful lens on both a full frame and crop sensor body. I review it briefly here:

http://www.bobatkins.com/photography/reviews/24mm_lenses.html

Nowadays F/2.4 is pretty fast! 8^)

Thank you guys, Thanks for the reply.