My wife is having coffee and my girls are asleep. What else is there to do than to make a relatively pointless lens comparison and blog about it? Since purchasing my Canon 17-40 f/4 L and the Canon 40mm STM I've been curious how the two compare at the 40mm focal length on my Canon 6D. Why? Great question. Many of my photography outings have me thinking about weight, especially when I'm in the backcountry on technical terrain. Obviously, the two lens' purposes are very different, however, there have been several times when I've decided to bring one lens and my choice ultimately comes down to these lenses. Each lens has its advantages and disadvantages. Obviously, the 17-40 f/4 L is a wide angle zoom, which opens up a number of creative possibilities. The 40mm STM is a prime lens, but its biggest advantage is its maximum aperture of f/2.8, which also allows some creative flexibility that the 17-40 f/4 L doesn't. When the light fades, the f/2.8 definitely comes in handy, something an f/4 aperture doesn't give you.
So where did I start with this comparison? Like I said, a lot of my photography outings are in the backcountry, so it would make sense to make a comparison outdoors, right? How about at my dinner table? Yep, it's the best I could do for this comparison. Here's the scene (full size image here - https://www.flickr.com/photos/dinger/15521313550/sizes/o/):
And here is the same series, but with crops to show the detail between the two lenses at given apertures (full size image here - https://www.flickr.com/photos/dinger/15707833112/sizes/o/):
Thoughts? In my opinion, the differences are negligible. You have to really be pixel peeping to see any differences. One observation that I'll make, albeit a very subjective one, is that the 17-40 f/4 L seems to give a slightly more natural look to the images (again, when really pixel peeping). All in all, a rather pointless lens comparison, but one that answers the question I've wondered for a while now: which 40mm focal length gives the best results.