In my experience, if you want that literal soul in your images without the ASPH price tag, you gotta look at the older Summicrons. I’ve been shooting M-mount for over a decade and honestly, the modern stuff is great, but it can be sooo clinical. For your $1,500 budget, here is what I recommend:

* Leica 50mm Summicron-M f/2 Rigid (Version 2): This is the gold standard for that famous "Leica glow." It has this lower contrast that handles skin tones like a dream! It’s not bitingly sharp like the new ones, but it has a 3D pop that’s just... amazing. It’s perfect for your M4 and M10 setup.
* Leica 90mm Tele-Elmarit-M f/2.8 (Thin): If you want tight headshots, this lens is a total hidden gem. It’s incredibly compact and the bokeh is super smooth. Plus, you can usually find a "user" copy for way under your budget, which basically leaves room for film or more gear!

Honestly, while the 50mm is the classic choice, the 90mm is lowkey the best value play right now. I use my Leica 90mm Elmarit-M f/2.8 for portraits all the time and people always ask how I got that look... it just has this fantastic compression. If you already have a 50mm you like for daily carry, definitely grab a 90mm to round things out. But yeah, if you want one lens to rule them all, the Rigid 50 is just magic. I love mine and wont ever sell it. gl with the choice! 👍

Seconding the recommendation above about older glass having way more soul than the new stuff! I've been shooting an M10 for years and honestly, I'm always a bit cautious about overspending on "mint" gear when a user copy works just as well. I've been super satisfied with my "user" grade lenses as long as the glass is clean.

If you want that glow, you should look at:
- Leica 50mm Summilux f/1.4 Pre-ASPH: This is the "soul" lens. It’s got that dreamy look wide open that’s perfect for skin. You can sometimes snag a scuffed V2 for under $1,500 if you look hard enough.
- Leica 90mm Summicron-M f/2 (Pre-ASPH): This thing is heavy, but the rendering is basically magic for portraits. It's way cheaper than the 50mm version and gives you that classic Mandler look.

tbh, I think the 90mm is the better value play if you're doing tight shots. Just be careful with focus... f/2 at 90mm on a rangefinder can be a nightmare if your M10 isnt perfectly calibrated! Might wanna send it in for a checkup first.

Just catching up on this thread and honestly, I think we sometimes get way too locked into the 'Leica' badge when looking for that vintage glow. I spent a few months doing some heavy market research because I was in the exact same boat—wanted the soul, didnt want to spend $3k. Basically, I realized that the LTM (Leica Thread Mount) market is where the real 'bang for your buck' is hidden. If you want a 50mm that handles skin like a dream, you realy should look at the Canon 50mm f/1.4 LTM. People call it the 'Japanese Lux' and for $400-500, the value is just insane compared to a pre-ASPH Summilux. It has that soft wide-open look but cleans up nicely. Also, for that literal 'glow' you mentioned, the Leica 5cm f/1.5 Summarit LTM is basically the king of character. It’s got these wierd, beautiful flares and a very soft rendering that’s perfect for portraits. On the telephoto side, I found the Minolta 90mm f/4 M-Rokkor to be a total sleeper. It’s tiny, super affordable, and honestly has a very 'Leica-like' rendering since it was a collab anyway. Definitly check out the LTM stuff with an adapter—it opens up so many more 'user' options under that $1,500 limit!!!

Quick question - are you doing tight headshots or environmental portraits? i had issues with 50mm being too wide... check the Leica 75mm f/2.5 Summarit-M? might be too clinical tho.

I spent a good decade thinking only the big brand could give me that specific rendering I wanted for my studio work. It was a total mistake. Honestly, looking back, some of my best portraits were shot on budget alternatives from other brands that just happened to have better flare resistance and smoother bokeh.

• Many vintage Zeiss and high-end Japanese lenses from the 60s actually outperformed my expensive glass for skin transitions.
• Character usually comes from lower contrast, something many third-party brands leaned into back then.
• The current setup I use for portraits cost me half of what I spent on my first M-mount lens, and nobody can tell the difference in the final prints. It took me way too long to learn that the name on the barrel doesnt guarantee soul. If you want value, look at what the competitors were doing during the same era... some of those lenses are absolute gems for portraits and wont break the bank.