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Can't find a Short EOS-M T-Adapter ?

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I'm struggling to find an EOS-M to T-adapter that isn't about 2 inches long .....  😧

I have a mirrorless EOS M5 DSLR which has a lot going for it for Astro use compared to other EOS mirror cameras. 

As well as being much lighter and more compact, the sensor to lens distance is about 25mm shorter than the EOS-EF and EOS range, so it should be easier to attain infinity focus without resorting to a Barlow.

I say "should" because I'm struggling to find an EOS-M bayonet fitting to T-screw adapter that is no longer than the standard EOS T adapter.

The only ones I can find are about 2 inches long, as per these FLO website pics.  I can fully understand the need for that length with the EOS-M to EOS-EF lens adapters, because they have to compensate for the shorter focal path, but why are they so long with the T-Adapters ?  It negates the EOS-M's advantage of having a much shorter focus distance.



Screenshot_2019-07-31 Astro Essentials T Rings First Light Optics(1).png

Screenshot_2019-07-31 Astro Essentials T Rings First Light Optics.png

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I'm having doubts now though, I checked the "Kood" website and their image for their EOS-M T2 adapter is the long type:


...and looking closely at the image on Bristol cameras website of their EOS-M adapter, it is simply marked "for Canon(AF)", so I fear they have just used the wrong image.....   😥

bristol cameras kood-t-mount-canon-eos-main.jpg

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Opticron do one too, the images look like it's short but it's long on their website. 

Doesn't make sense not to market a short one. 

Harrison do a long one for £11, buy one and test your DIY skills in hacksawing a chunk out and rejoining the two halves. 


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59 minutes ago, Starlight 1 said:

But i can not  work out what you are looking for.

If you look at the two images Astro-Geek posted, he needs the long adapter to be more like the short one in length. 

The short one has the wrong size bayonet on the far end so won't fit his camera. 


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Thanks for the replies everyone.

I'm sorry my OP wasn't too clear, but as Michael says, I was searching specifically for a T2 adapter for my EOS M50 camera which has the slightly smaller diameter EF-M bayonet.

I do already have a T2 adapter for it, but the barrel is about 2" long, so it "wastes" inward focus, which is a shame, because the EOS-M cameras have a much shorter infinity focus path than standard EOS cameras because they are "mirrorless".

I am still searching for a T2 adapter ring that is of minimal length, like all of the EOS EF T2 adapters, which are just long enough to accommodate the T2 one end and the EOS bayonet at the other.

I'm not sure how well a plastic 3D printed version would work, with the fine screw T2 thread and the thin EOS bayonet tags.

I guess it would be possible to surgically remove the centre section with a lathe, but the rejoining might be tricky.

I did manage to make a "short" EOS-M adapter for my 2 inch telescope eyepiece drawtubes by following an idea from someone who published it on the Internet somewhere (sorry, I can't remember where).

It was quite a clever idea using an EOS-M to 52mm filter thread adapter and then a step down ring from 52mm to 48mm, then a 48mm extension tube.

DIY short tube EOS-M to 2 inch telescope adapter.jpg

eos_m telescope adapters.jpg

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36 minutes ago, Starlight 1 said:

I do have them 2 parts . So what size have the long  one got to be after cut down.  I look in the shed later and I send and pm on parts with pic if any help.

Thanks Starlight, I've just posted some pics that might explain better what I'm trying to achieve.

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I've just found a solution 🤓

I've ordered an EOS EF-M to "C mount" adapter, (which is nice and short), and a C-Mount to 1.25" telescope adapter.

They look as though they'll give me a minimal length EOS-M to 1.25" telescope adapter when they're screwed together.

I'll update this thread with the result  (whether successful or not !)

Thanks again for the replies and suggestions...

Hybrid EOS M 1.25 adapter.jpg

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19 minutes ago, michael8554 said:

That's a neat solution. 

Though I'd go for a 2" to telescope adapter, 1.25" is asking for vignetting with an APS-C


Yes, I was wondering if it would vignette, the C mount is indeed a tiny opening.

I tried to visualise it by holding my ZWO camera's c -mount adapter up to the front of my EOS M50 in approx the position the narrowest part would be.  The circular hole is indeed  a shade smaller than the diagonal of the APSc sensor, but I'm hoping that the image rays are still diverging as they go past into the camera, so it may even act as a useful extra baffle......   🤓

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  • 1 year later...

Hello, sorry to bring up an old thread but I wondered how you had got on? I’m new to here and just starting out. I’ve been reading up and I’m committed to starting out in both visual and Astro photography. I’ve settled on the Sky watcher explorer 130p as my first telescope. I’m planning to use the canon m3 as my camera as I too figured it would solve the focus issue with reflectors and I couldn’t find an adaptor that didn’t add the back focus which would defeat the object of having the 18mm the mirror less provides. 

I had come up with 2 possible solutions, an eos-m to m39 adaptor with a m39 to m42 stepping ring. Or getting both the eos-m to m39 and to m42 and try to put the threaded ring from the m42 into the m39 adaptor. 

any help would be appreciated. 

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  • 1 month later...

Just to add to this long running thread.

The only solution I found was on ebay: (I have nothing to do with the seller)

If you search ebay for

M42-EOSM Ultra-slim (1mm) adapter For M42 Lens to Canon EOS M EF-M mount Camera

You should see a 1mm thin m42 adaptor for ef-m (also sold on Aliexpress) though cheapest on ebay at £5.50 currently. 

From this I added (from AliExpress) a:

M42 Male to T T2 Female M42(42mm 1mm thread pitch)- T T2(42mm 0.75mm thread pitch) 42mm Coupling Lens Ring Adapter Adaptor

to convert to correct thread pitch (Certain you can buy 2" step up rings if required)

Add a nosepiece adaptor (1.25 / 2") and you are good to go.

Only issue is these adapters are coming from China so you are looking at delivery next year at the time of writing.

Hope that helps.

Edited by _Stuart_B_
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  • 2 weeks later...

Thank you for the reply, I’ve almost convinced myself to go that bit further and get the 150p with a 2” focuser that has a direct camera attachment. 

ive read some people having success with it and others saying it needs a further 1cm inward travel. I hope the ones that had issues still had the older version without the removable extension for Eyepieces. But if I do have problems I will come back to the idea of making the slim eos-m adaptor. 

I took the first step of buying the M3 camera with 18-55 kit lens, witch I’m very happy with. Although I have no tripod or mount I have been practicing with taking 13second exposures when the sky is clear. I can’t wait to get the 150p and try them together. 

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  • 3 months later...

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