Originally posted by Gooshin its faster, so techinicaly one could have more depth of field control
its FA, so you can use it on a film camera
it looks cooler (who doesnt want a silver lens on a black camera?)
and it simply has better optics resulting in better images if you're a pixel peeper, altho some will swear that the contrast and colours are out of this world, something that can easily be screwed around with in photoshop.
the resolution however is something that photoshop cannot fix, and technically the 77 will have better sharpness than the 70.
is it worth the price? only if you're making money from photography, or if you're simply rich, then just buy it because its the best.
I own a 77. It happens to be the black version. AFAIK there are very few silver versions available. And yes, it looks nice, and is built exceedingly well.
It has better optics period. No need to pixel peep.
And I don't know about your photoshop skills, but even tho mine are fair, fixing color isn't that easy and why spend the time if you don't have to?
The 77 is sharper than the 70 across the board, no technicalities about it. And it is considerably faster so you can get shots that the 70 is incapable of getting. They might not be perfect, but something decent is better than nothing.
I don't make money from photography and I am DEFINITELY NOT RICH but the money I've spent on the 77 was very well spent and I'd gladly spend it again, if I didn't already have it.
Finally, Mike Johnson of Luminous Landscape fame calls it "one of the best autofocus lenses ever made" and he mostly shoots Nikon!
NaCl(climbs down from the soapbox)H2O