Need filter attachment thread specs for M12/CS/C mount lenses from Amazon

Raspberry Pi Cameras
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Hi, I’m hoping someone can help me with a spec question. I’m using Arducam M12/CS/C Mount Lenses (bought via Amazon) and I want to attach a filter in front of the lens. What I really need is the input thread specification for the filter attachment — i.e. the thread size/pitch at the front of the lens where a filter would screw on. Has Arducam published this anywhere?

Some background: the lens worked, but somehow quit working for me, so I’m rethinking my whole setup and I want to get the filter mount right this time. My model number is a bit TBD right now, and honestly I’m not sure of the exact one — but the thread spec is what I’m after. Can you publish the available input thread specification for filter attachment?

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Hi, thanks for reaching out and for posting here.

Quick heads-up: part of what you’re describing sounds like two separate things — (1) a lens that worked and then quit, and (2) a request for the front/input thread spec so you can attach a filter. Those are a bit different, so let’s split them.

For the thread spec, we don’t have a single universal number across the whole range — the M12, CS, and C mount lenses vary, and the front thread depends on the specific lens. To point you at the right spec sheet, could you tell us which model you have? If you’re not sure of the model number, the order number works too — could you please tell us the order number on Amazon? We will check for you. That way we can pull the exact lens and give you its thread specification.

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Order number is TBD on my end right now unfortunately — I’ve got a bunch of lenses and I’m not 100% sure which one this was. But let me clarify what I’m actually asking, because I think my first message wasn’t clear.

I’m not asking only about the one lens I ordered. I’m interested in the thread specification for all your c-mount lenses (and the M12/CS ones too) that have a thread available at the input of the lens, not just the one I ordered. Basically: for each lens model that has front/input threads, what’s the thread spec?

So far I’ve tried: asking here, and digging through the product pages, but the front thread dimensions aren’t listed anywhere I can find. The only thing I’ve confirmed is that the lens worked, then somehow quit working, which is why I’m rebuilding this and need the filter thread info.

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That’s a much clearer ask, thanks — and it changes what I can give you.

Right now, there is no single published table of “input/front thread specification for filter attachment” covering all M12/CS/C mount lenses. The thread specs exist per lens, but they aren’t consolidated into one published document, which is probably why you couldn’t find it. So I can’t hand you one universal spec — but here’s how we can get you there:

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  1. If you can narrow it to a specific model, I can look up that lens’s front thread spec directly (thread diameter + pitch).
  2. If you can’t get the model, the Amazon order number lets me trace it — but you mentioned that’s TBD on your side, so that path is blocked for now.
  3. For “all c-mount lenses with a front thread,” I’d need to go lens by lens; there’s no aggregated sheet to just publish.

A couple of things that would help me:

  • Which mount type are you actually working with on this camera — M12, CS, or C? Those have very different front threads.
  • What filter are you trying to attach (diameter/pitch), so we can check compatibility rather than guess?
  • Any photo of the lens front, if you have one.

The model number, order number, and platform are all showing as TBD on my side, so I don’t have enough to identify the exact lens yet.

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I’ll try to dig up the model and platform for you. For now the answers are still TBD across the board — model TBD, order TBD, platform TBD, and I don’t have an instruction I’ve been following (also TBD). I mainly wanted to know if the input thread spec existed publicly, because my product worked and then somehow quit working, and I’d like to attach a filter to the replacement/front element properly.

So to confirm where we landed: there’s no published input thread specification for the full M12/CS/C mount lens range, correct? And the only way to get the thread spec for my specific lens is to identify the exact model?

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Correct on both points, and let me summarize where this stands so it’s clear:

  • What you’re after: the input/front thread specification on M12/CS/C mount lenses, so you can attach a filter at the front of the lens.
  • What exists: thread specs per lens model only — there is no consolidated published document listing the input thread spec for the entire lens range. That’s the gap.
  • What’s blocking a precise answer: the exact lens isn’t identified. Model number, order number, platform, and the instruction you were following are all still TBD, so I can’t map your request to a specific lens.
  • The “worked, then somehow quit working” detail: it’s noted, but on its own it doesn’t identify the lens either, and it isn’t the same question as the thread spec.

Next step: once you can get me either the model number or the Amazon order number, post it here and I’ll pull the exact front thread specification for that lens. If you want the specs for the whole c-mount range, I can go lens by lens, but I’ll need the specific models you’re considering. I’ll hold this thread open — it’s unresolved until we get that identifier.