C-Mount CCTV Micro Four Thirds Lens Review – Digital toycam funtimes!


Two of the most common arguments used against mirrorless cameras (vs. DSLRs) is that there are less lenses and the sensor is smaller.  While both of these are true, one of my favourite accessories for my E-P5 addresses both of these complaints in one fell swoop.  As you’ve probably guessed from the title, I’m talking about the somewhat obscure C-Mount lenses.  These lenses, designed for CCTV (closed circuit television) have a flange distance that is way too short to be adapted for any current DSLRs comfortably (that I’m aware of).  That’s where the mirrorless cameras come in!  To cut a long story short, the compact nature of mirrorless cameras means that the C-mount lenses can be adapted, which is a good thing.  

I’ve own 3 different C-mounts:  a 25mm f/1.4, a 35mm f/1.7 and a 50mm f/1.4.  These are equivalent to a 50mm, 70mm and 100mm respectively, on a standard 35mm sensor.

Image quality:

I’ll start with this, because that’s why we’re all here after all.  If you’re looking for lenses that give you crystal clear, sharp photos, then look elsewhere.  If you’re after some lenses that are super fun to use and give you some really interesting photos, then these are the droids you’re looking for.  Given my obsession with toy cams, the first thing I looked for was a fun toy-like lens.  After lots and lots of research, I came across these C-Mount lenses.


As you can see (click for a larger version), these lenses take some really funky-looking photos.  The centre will turn out relatively sharp, but you lose that as you move to the periphery.  Interestingly, you also get this cool circular blur effect that I just can’t get enough of.  Finally, while the micro four-thirds sensor is close to the required size, it doesn’t match up to the lens 100%, so you will get some vignetting (but I love that too).  While you can get some more sharpness if you close up the aperture, that kind of defeats the purpose of even using these lenses.  The optical effects are most pronounced when the aperture is wide open, so that’s how I always shoot with these.

I haven’t even gotten to the best part of these lenses yet – the glorious bokeh blobs.  Here, let Lumpy Space Princess demonstrate:


Okay, so what I’ve been calling bokeh blobs are apparently called ‘circles of confusion’.  It’s an apt name really, because… what?  Anyway, these cctv lenses produce perfectly round circles of confusion, which are beautiful.  In the above photo, you can once again see that you get the circular swirly action towards the periphery.  Here’s another photo which probably does a better job of highlighting the distortion around the corners.


Using the things:

Getting the C-mount lenses onto your mirrorless camera is a breeze.  The adapter is that silver ring thing you see in the above photo.  You mount the adapter onto the body of the camera (as with any other lens/adapter), and the C-mount lenses screw into the middle of the mount.  I actually really like the threaded screwing mechanism, as it means that you can switch between C-mount lenses quickly and with minimal fuss.

One thing to note is that these lenses are fully manual.  Whilst I don’t personally find that to be an issue, I can definitely see why it isn’t for everyone.  Each of these lenses has two rings, which predictably control the focus and aperture.  One small annoyance I’ve noticed is that there is a general lack of consistency with the rings, both in terms of which ring controls what parameter and the direction of turning.  On my 25mm, for example, the closer ring controls focus, and you turn anti-clockwise to focus to infinity.  My 50mm, on the other hand, has the further ring as focus, and clockwise focuses to infinity.  It’s a minor thing, but does mean additional adjustments are often necessary.

I should probably mention build quality here.  These lenses are surprisingly constructed of fairly solid-feeling metal and rubber.  I was suitably impressed, but my 35mm has since started falling apart.  The focus ring kind of just keeps turning and turning until it comes right off the lens.  It’s technically still usable, but I’m currently trying to figure out how to secure it properaly again.

Most importantly, though, these lenses are pure joy to use.  It might just be me, but I guess it brings back all the joy of using toycams – it’s just as experimental, but far less expensive when you end up with a failed picture.  I think my toycam obsession is showing again.  Besides, these lenses also match the styling of my E-P5 very well.


I haven’t even gotten to the best part: Price

This part really seals the deal – these lenses are dirt cheap.  My three lenses + the adapter only cost me a grand total off US$74 from eBay.  I actually bought the three separately – the 25mm bundled with the adapter only cost US$22!  All of my lenses are either unbranded or made by Fujian.

Now, there’s actually a similar product out there by a company called SLR Magic.  Essentially, they’ve made c-mount equivalent lenses with built-in mirrorless adapters, then started charging US$100-150 for them.  Admittedly, their lenses are probably better built and look better, but I’d rather save the money.

So which focal length should you buy?

I struggled with this question for a very long time when I first found out about C-Mounts, so I thought I’d throw this in.  I find that I use the 25mm more than the others, by quite some margin.  I think that its equivalent 50mm focal length is the most flexible for everyday shooting.  Plus, the optical distortions are the most pronounced on it too.  That said, if you can afford it, consider picking up all of the lenses as they all have their place.  If you look around, you can find some more premium C-Mount lenses out there, but I haven’t had the time or funds to explore myself.

Finally, here’s a bonus photo, because duck:
50mm f/1.4

2 thoughts on “C-Mount CCTV Micro Four Thirds Lens Review – Digital toycam funtimes!

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