Sooo +1 to what was said earlier. I'm just catching up on this thread, and honestly, the K&F stuff is usually fine for M42 glass. But for your Canon FD lenses, you might wanna look at the Urth FD to L-Mount Lens Mount Adapter. I actually tried a super cheap Fotasy FD to L Mount Adapter once and it was basically a nightmare... the locking ring felt loose and I highkey couldn't get infinity focus right on my S5II. Super disappointing. Here's how I'd compare them:
- Urth M42 to L-Mount Lens Mount Adapter vs 7artisans FD to L-Mount Adapter
- Urth: Pros: Really sleek, great build quality. Cons: A bit pricier than K&F.
- 7artisans: Pros: Solid metal, very reliable fit. Cons: Kinda heavy. TL;DR: K&F is decent for M42, but maybe skip the bottom-barrel brands like Fotasy cuz they're hit or miss. Urth is the sweet spot for quality vs price imo. Peace!

I went through this last year. I started with cheap adapters, but I got really worried about mount safety after seeing tiny metal shavings on my sensor—literally my worst nightmare! So I switched it up. For FD glass, I eventually moved to the Metabones Canon FD to L-mount T Adapter. It's pricier than the brands mentioned earlier, but it feels waaaay more solid. The internal baffling is next level for killing reflections that wash out contrast on the S5II. Plus, cheap adapters often have "play" where the lens wobbles, which can actually warp your mount over time. Tip: prioritize build quality for the FD mount because the locking mechanism is more complex than M42. Saving a few bucks isnt worth the risk of metal dust in ur camera body tbh. Gl!

Respectfully, I'd consider another option, especially for the FD glass. While the previous guys like K&F, I've had issues with light leaks and internal reflections on their cheaper units—it literally kills the contrast on my S5II. Not as good as expected for "pro" use. Ngl, the internal baffling on super budget adapters is often just shiny plastic or poorly painted metal. I'd actually suggest looking at the Haoge FD to L-mount Manual Lens Adapter. It’s usually around $30-40 and the machining is way more precise for hitting infinity focus without that annoying "play" in the mount. For M42 glass, I honestly prefer the Fotasy M42 Screw Mount to L-Mount Adapter. It’s like twenty bucks ($20) and the tolerances are actually tighter than some "premium" brands i've tested. Basically, you want that matte finish inside to keep your vintage glass looking "vintage" and not just "blurry." hope that helps! 👍

> I’m curious if it's worth splurging on a Sigma or Novoflex adapter, or if budget brands like K&F Concept are reliable enough... Honestly, K&F Concept M42 to L-Mount Adapter is amazing vs the pricey Novoflex M42 to L-Mount Adapter. Basically, K&F is cheap/reliable, while Novoflex is just luxury. Both hit infinity fine!! sooo good!! gl!

honestly i spent way too much time thinking about this when i first got my s5ii. before you pull the trigger on a specific brand, i have a couple of questions that might help narrow it down for you. are you looking for something that basically stays on the lens forever as a permanent mount, or do you plan on swapping one adapter between a whole kit of glass? also, how much do you care about the mechanical feel? there is usually a massive jump in how the locking rings feel when you move from the budget tier up to the more pro brands, even if they both hit infinity just fine... basically trying to figure out if you want pure utility or a better tactile experience.