In the same lighting, the 35 mm prime ( a brand new lens) set for AV chooses a longer shutter speed than the 24-70 set at 35 mm and same AV. The resulting image from the 35 mm and longer shutter speed makes for the chance of cameral shake and a less sharp picture. Any information would be appreciated. thank you joanlvh
What sort or differences are we talking here? No two lenses will meter exactly the same but there shouldn't be large discrepancies in general. I would have expected the prime to actually have a slightly faster shutter speed than the zoom due to it's much simpler optical design and suffer less transmission loss. Look up t-stops as opposed to f-stops.
Maybe the prime has a faulty aperture? Post the numbers you are getting for the exposures.
to: pixel perfect, no the difference is not great, say aperture with both lenses is f2.8 one shutter speed will be .7, the other .5, however there is a noticeable difference in sharpness, the 24-70 being the sharper, the 35 prime, sometimes blurry. But the kicker is sometimes the 35 prime is very sharp, it sounds like operator error, but I can repeat all the variable results frequently enough that I am still puzzled
joan leslie wrote:
to: pixel perfect, no the difference is not great, say aperture with both lenses is f2.8 one shutter speed will be .7, the other .5, however there is a noticeable difference in sharpness, the 24-70 being the sharper, the 35 prime, sometimes blurry. But the kicker is sometimes the 35 prime is very sharp, it sounds like operator error, but I can repeat all the variable results frequently enough that I am still puzzled
You may find the extra weight of the zoom is helping stabilise the camera and reduce camera shake in this case, the 35 f/2 is a very light weight lens. Those numbers seem reasonable for the difference in exposure for two lenses.
Try a test using a tripod and remote release to test sharpness.
Try shooting some pics using manual focus (if you have LiveView, use it) and autofocus with the 35mm prime. If there are differences (meaning the MF pics come out sharper) than there might be an AF problem.
I'm surprised that the zoom, when wide open at f2.8, can match or better the 35mm f2 at f2.8. My 35 f2 is good to excellent when shot wide open at f2, but is definitely and reliably in the 'very sharp' category when stopped down that one stop to f2.8.
