8/31    Does it make sense to buy a nice 70-200mm f/4L lens and mount it on a
        cheap Canon Rebel XSi with 12MP? I'd hate to upgrade the body
        because bodies get outdated quickly, and I don't care about how fast
        auto-focus is. I just care about image quality for non-sports pics. I'd
        love to have a sharper lens than my cheapo 55-250mm and don't care
        about the body, but I'm wondering if there are severe disadvantages
        for going with a consumer body + pro lens combo. Thanks.
        \_ There may be better lenses to consider depending on what your
           photo priorities are, but I dont think you're making the mistake
           of "too much lens for the body". As you imply, most amateurs
           make the opposite problem: too much body for their lenses.
           An issue may be the FOV multiplier ... which makes that quite
           a long lens [I assume the 70-200 is calibrated to 35mm, so really
           that's 110 at the short end ... that may still be useable indoors
           but it starts getting impossible when you get a little longer ...
           rooms arent big enough to get more than a headshot].
           \_ The 70-200mm f/4 IS is SHARPER than 70-200mm f/2.8 IS at all aperture
              except for 2.8, which of course the f/4 cannot get to. But
              at f/4 and beyond, the f/4 IS beats the f/2.8 IS version
              hands down. How important is that one extra stop? I'd say,
              for outdoors and birds and weddings such, the f/4 is a better buy.
        \_ The XSi is a fine camera; if you're not at the cutting edge of
           photography, it will do just fine.  A 70-200mm will be quite long
           on the APS-C sized sensor, but that might be what you want if
           you're doing wildlife photography or something.  It'll certainly
           give you better pictures than a cheap megazoom.  -tom
           \_ I saw a 1:1 picture from 50D at 800 ISO and it was surprisingly
              noisy. I just don't see how a better (more megapixel) camera
              is supposed to be better when it looks ugly at only 800 ISO.
              \_ For a given sensor size, the more megapixels the camera
                 has, the noisier images will be, if all else is equal
                 (which is rare).  -tom
                 \_ So newer cameras are crappier since they have higher MP?
                    \_ It's not so simple.  A sensor using the same technology
                       will have more resolution and more noise at 15MP than
                       12MP.  Whether that matters depends on what you're
                       shooting.  And newer, and more expensive cameras
                       often have different/better sensor technology.
                       In any case, we do seem to be reaching the point
                       of diminishing returns on megapixel count.  -tom