Help me understand Apertures

Discussion in 'Lens Lust' started by bradNYC, Sep 11, 2008.

  1. bradNYC


    Mar 28, 2008
    I have 17-55 2.8 and a 50 1.8, if I was to take the same picture using both pieces of glass @ 50 2.8, should I get the EXACT same image?
  2. Absolutely not. The amount of light entering should be the same but each lens renders colors a little differently as well as sharpness. The 50 1.8 stopped down to 2.8 will probably be sharper if your a pixel peeper. The 17-55 tends to be soft wide open. This is just my two cents worth.
  3. bradNYC


    Mar 28, 2008
    let's throw this into the mix 24-70 2.8...same scenario
  4. loudtiger


    Sep 6, 2007
    very similar image.
  5. Depth of field should be identical.

    In general, lenses are sharpest when stopped down at least 1 stop from widest aperture. So the 50 f1.8 will probably be sharper at f2.8 than virtually any other f2.8 lens wide open.

    The 24-70 (which I do not have, unfortunately) does extremely well wide open when tested and at f2.8 has less CA and is as sharp as the 50 f1.8. Of course you are comparing a lens that is $1800 to one that is $100.

    In practice I suspect you would have a very hard time telling one from the other.
  6. there are also several threads talking about skin rendering differences between the 24-70 and the 28-70