I know the 20 mm is faster lens. Since I do not own the 20mm, I have a more practical question. I realized on recent trip that 14-42 is not fast enough in low light conditions during low light situation. eg. Taking family pictures in moderately lit room. I had high percentage of blurry photos without flash requiring me to retake multiple times. In real world can someone compare the shutter speed of the two lenses in low light situation in auto or p mode? How much of the faster shutter speed is gained by the 20mm in same situation? P.S. i know the lighting situation can vary but i would like to know the lens relative to each other when in auto settings are used so all other parameters are the same. Btw I have e-pl1. Taking family pictures in general low lighting is important to me because that is lighting situation I tend to end up in during family gatherings. If this lens helps me get those shots easier then I'll consider buying this lens.
F1.7 to 3.5 is, what 2 stops? Or is it 3? Anyway, for every stop, you can cut the shutterspeed in half. So, if at 3.5, you metered a 1/50 shutterspeed, with a 1.7, you could be at 1/200 at the same ISO setting! Fast lenses are where its at. I have been amazed at the pictures I can take without flash using the 20/1.7
1.5 + 2/3 aka 2-1/6. Also: "Doubling the f-number increases the necessary exposure time by a factor of four."
The 20/1.7 is a great low light lens - and the price has dropped considerably. Even more so it is just a good, sharp, quality lens over all well worth having for general shooting. I think you will be well pleased.
I have that lens. Great one, but be careful when you use it at f/1.7... Shallow DOF can be deadly if you don't know where to focus.
