I didn't mean to leave everyone hanging in regard to the results of my test shoot using the Voigtlander Nokton Classic 50mm f1.1 versus the 40mm f1.4. The questions was, is it worth paying twice the price and doubling the size and weight of your lens for that extra stop?
The magic settings for the unevenly lit, dark stage in Kemah seemed to be:
f1.1 1/250s ISO 640
f1.4 1/125s ISO 640
Even at 1/125s, the performers were tending to blur as they moved around the stage, so that extra stop did make a difference.
Here's a couple from the f1.1:
And from f1.4:
As you can see, in this extreme situation, the 50mm f1.1 is a bit sharper with less ghosting and motion blur. The extra size and cost isn't just hype. I also found the focusing ring on the f1.1 smoother, more natural and much faster than the focusing tab on the f1.4 despite having had practiced with the f1.4 for a couple weeks.
The two lenses had about 13mm difference in range, but neither was really wide enough to catch the entire stage and the signage without being too far away, so the slightly wider focal range of the f1.4 wasn't any help.
In average guy, average budget terms, I still have to say the 40mm f1.4 is the better value for the money. I got mine used for just under $400. If you shopped smart and watched the deals on eBay, you could probably get the Voigtlander Nokton Classic 40mm f1.4 along with a used Voigtlander Ultron 28mm f2.0 and a used Leica Hektor Wetzlar 135mm f4.5 for the cost of one Voigtlander Nokton Classic 50mm f1.1.
However, in Leica terms, the 50mm f1.1 is an amazing deal. It's sharper than the 40mm, it's faster than the 40mm, and the only new lens currently in the same category is Leica's Noctilux 50mm f.95, which runs $10,000.
In other words, if you have the money to spend, do it.
I'll leave you with my favorite shot of the night from the 50mm f1.1.
Note: None of these guys were actually wearing purple. Like all good bands, they were in black, but the M8 is especially sensitive to infrared light, so if you don't have an infrared filter, black clothes come out purple. Yes, I'll be buying an infrared filter this week.