Totally agree! For safety, I use Hoya 39mm HD3 UV Filter. It’s super strong glass. Maybe ask your local shop about hardened filters? Just be careful cleaning it so you dont scratch it! gl!

Sooo, in my experience, I've spent way too much time testing this cuz that 35mm Summicron glass is literally legendary. I feel u on the micro-contrast worry—you dont wanna ruin that look! Here is what I recommend: - Leica E39 UVa II Filter: This is the "purest" option. Since the coatings are designed by the same engineers, you get zero color shift. It's pricey, but it maintains the look PERFECTLY.
- B+W 39mm XS-Pro Clear MRC-Nano 010M: Seriously amazing flare resistance. The MRC-Nano coating makes it sooo easy to clean. Honestly, i think it's basically indistinguishable from the Leica glass.
- Heliopan 39mm Protection Filter SH-PMC: These use high-end Schott glass and brass rings. Very sturdy, though maybe? i noticed a tiny bit more flare in extreme backlit situations compared to the others. Basically, grab the Leica if you want peace of mind, but the B+W is highkey the best value without ruining the image quality iirc. Anyway, gl with the new lens! 👍

tbh I'm not 100% sure if B+W coatings perfectly match Leica's tech, but iirc their multi-coated glass is the standard for a reason. I think the nano versions help a lot with flare, tho some say they add a tiny warm tint? Idk, I've used them on my own glass and barely noticed a difference. Just dont go cheap or you'll lose that micro-contrast for sure. good luck!

To add to the point above: Janny is right that DIY testing is essential, tho I would suggest being very careful with your light source calibration. One might want to consider how easily these tests can spiral out of control. It reminds me of a colleague who got way too deep into testing his own 35mm glass and it turned into a huge mess.

• He actually bought a used spectrophotometer to measure light transmission curves for every piece of glass in his kit.
• He spent weeks building a custom light box to avoid any external interference or ambient light pollution.
• He ended up getting so bogged down in the raw math that he eventually forgot which filter was which in his unmarked storage case. It was a whole ordeal and tbh he still hasn't figured out which one performed best because he lost his original spreadsheet during a hard drive crash. Just goes to show that even with the best intentions, the technical data can get away from you if you dont stay organized from the start...

I get the worry about contrast! Honestly, Leica filters are crazy expensive and unfortunately, I was pretty disappointed with the value. I agree that B+W is a great middle ground, but if youre on a budget, just hunt for used brass filters from top brands. Theyre basically the same glass without the brand tax. That's my go-to for keeping the look without overspending. gl!

Honestly, after messing around with M-mount glass for like ten years, I have realized that maintaining that Leica look is as much about how you test and maintain your gear yourself as it is the brand on the ring. Instead of sending stuff off for professional testing or just trusting the marketing, you can do a lot of DIY checks. One thing I always do is a basic flare test. Put your 35mm on a tripod, point it at a bright desk lamp in a dark room, and see exactly how the micro-contrast drops with the filter on vs off. I have been using the Breakthrough Photography X4 UV lately and it is SO impressive. It uses Schott B270 glass and the neutrality is basically perfect. From a DIY perspective, I also recommend checking the internal threading of the filter. If the inner ring is too reflective, you get internal ghosting that kills your micro-contrast. I have actually had to DIY a bit of matte black paint on the inside of some filter rings to fix this myself. It is basically about being your own quality control.

• Check for internal ring reflections
• Test against a single harsh light source
• Use high-quality brass frames for easier self-service Anyway, you dont always need the Leica brand tax to get the results, you just need to be diligent with your own testing.