Thank you for posting this table. i'm not really sure how to interpret it.
For example, at:
20 mm, it's a difference of 0.4 stops
30 mm --0.3 stops
50 mm-- 0.5 stops
Is it enough to really make a difference outside a lab? I don't know the answer. And I'm just making my first upgrade from a P&S.
I can post comparison pics if you like.
As for the LBA.. The 10-20 should be here this week, keeping fingers crossed. I'm hoping that the 10-20 will be my main walkabout. and I also got the 35mmDA/2.4 in the marketplace. So 3 lenses total.
And I caved and bought a camera bag.
Originally posted by seventysixersfan I'll be curious what you think. I have a Sigma 18-50 f/2.8 zoom that is pretty good but I admit that there are times I wished it zoomed out to 70mm to get tighter portraits. Plus I think the new 17-70 as well as ver 1 has fairly decent close focus / pseudo-macro ability at 70mm. Anyway, I have often thought about swapping out my f/2.8 constant zoom for a 17-70 range. But I also wonder how much I'll miss having f/2.8 at 50mm.
Here is the aperture range, by the way, of the Sigma 17-70s (copied from the in-depth reviews of these lenses on the PF)
Version 1
17 f/2.8
20 f/3.2
24 f/3.5
40 f/4
70 f/4.5
Version 2 (and presumably same as newest Contemporary version of 17-70)
17 f/2.8
23 f/3.2
34 f/3.5
70 f/4