Stupid question about f stops

i tried googleing it and searching on this forum but couldnt find an answer.

im trying to find a new lens for my Mark II and am running into he same dilemma im sure alot of people have.

i want a wide angle lens but am unsure which to to get.

24-105mm 4.0
24-70mm 2.8
35mm 1.4

I rented the 35 1.4 and am enjoying it but am looking into something wider but they dont have the others in stock to test.

ANYWAY.. my question is with my 35mm 1.4 if i stop it down to 2.8 or 4.0 and try out some pics like that... will the other lenses preform in a similar way at the same aperture and MM?

the main difference is of coarse prices.. which is why im debating this

At the same aperture, they'll be similar, but not exactly the same. Lenses tend to sharpen up when you stop them down 1-2 stops from wide open. The 35mm at f/4 is stopped down 3 stops while the 24-105 is wide open at f/4. Also, prime lenses have less glass to absorb or reflect light so all else being equal, the prime will produce a slightly brighter image.

Depth of field will be the same, but you cant cant judge the IQ of 2 zooms using a prime. The prime should be sharper, especially stopped down a couple of stops.

Stopped down, the prime will be sharper than the 2 zooms wide open.

crn3371 wrote in post #9617169
Stopped down, the prime will be sharper than the 2 zooms wide open.

Classic statement true of film camera lenses and the early days of zoom lens design. With computer design, it is possible to get zooms that rival or even surpass prime lenses. Examination of the MTF scores listed in the www.photozone.de web site will prove my statement, that all zooms are NOT inferior to all fixed focal length lenses.\


[edit] I re-read this, and have to rescind...a stopped down prime will most probably be better than wide open zooms.

You can do a side-by-side comparison of different lenses' performance shooting test targets here (this one compares the 35 f/1.4 to the 24-105, but you can use the dropdown lens list on each side to select any lenses in their database):
http://the-digital-picture.com …&FLI=0&API=0&Le​nsComp=355