50mm is normal because it is what came on the camera, and specifically because that was what Barnnack (sp?) used on the original Leica.
The reason a lens of about the diagonal of the film is usually chosen as the normal lens is simply because that is the most cost effective focal length to use. IMNSHO, all the other quasi-technical reasons are simply BS. Ciao, graywolf [EMAIL PROTECTED] ----- Original Message ----- From: Frantisek Vlcek <[EMAIL PROTECTED]> To: Mike Johnston <[EMAIL PROTECTED]> Sent: Thursday, January 17, 2002 5:27 PM Subject: Re: Magnification > Thursday, January 17, 2002, 5:16:37 AM, Mike wrote: > >> I was sitting in my spare bedroom the > >> other nite, camera and FA 28-70 1:4 lens (that my coworkers got me for > >> Christmas!) just kind of zooming in and out, when I noticed that my "field > >> of view" in my free eye matched that of the lens at about 65mm. It's pretty > >> close to normal, but not too close. > > > MJ> Chris, > MJ> That depends entirely on finder magnification. It doesn't really have > MJ> anything to do with the field of view you find most comfortable. > > To elaborate: finder magnification of newer bodies is about 0.75x so > 0.75x65mm=49mm, pretty close to "normal" 50mm. With older bodies, > which had higher magnification, around 0.85x-0.9x was the norm I think in > the good old days, notice that Exakta's normal prime lens (first cine > SLR I think) was 58mm, to allow easy viewing with both eyes open. That > would mean Exakta had 0.85x magnification. The abundant 55mm (Pentax > too) is meant for the K series with 0.9x magnification. > > Now somebody can elaborate on why 50mm is considered normal ;-) > > (I think there are two reasons - 1) technical: eyes have 20 diopter > vision normally, that means the little lens we have, when at ease, has > 20 D=50mm focal length; 2) experimental: we see most easily about the > same FOV as 43-50mm lenses do on 24x36 frame /very roughly/. Of > course, I could easily be wrong.) > > Good light, > Frantisek Vlcek > - > This message is from the Pentax-Discuss Mail List. To unsubscribe, > go to http://www.pdml.net and follow the directions. Don't forget to > visit the Pentax Users' Gallery at http://pug.komkon.org . - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
