1.6x factor with portraits

[BJL]

"Big nose distortion" depends only on subject distance, so in that respect using a 50mm lens combined with 1.6 crop factor means that by standing 1.6 times further away than with that lens on 35mm format, you are at the same distance with the same field of view and the same distortion as with 80mm in 35mm format.

However, depth of field changes at the same aperture ratio; you need to open up about one stop to maintain the same DOF.

More precisely, for the same DOF, reduce the aperture ratio by the crop factor of 1.6. For example, to reproduce the extreme shallow DOF of an 80mm at F/1.8, you would need to use a 50mm at about F/1.2.

[sc21]

Hey Everyone -

I just got on the internet, it's my first forum (always wanted to be a debutante), and I need some help.

I have a Canon EOS-1, and would like to upgrade to the 10D, but how exactly do your usual portrait lenses work with cameras with the 1.6x crop/magnification factor?

I usually use my 100mm macro with bounce flash, but how much further will I have to back up?  For a 2' high portrait, I need to stand back 6 1/2 feet.  How much further back would I have to stand for the same lens and 2' high subject on the 10D?

Also, a 50mm will now be cropped in to an 80mm view, but won't it still have the usual 50mm portrait distortion of big noses and small ears?  You'll be further back, of course, but how exactly does it look?

Thanks for your help,
Steve