ZWO 183 mm pro and Canon Lens adapter! Struggling with focus.

[Spacetrace82]

Hello. 

I really need some help. Has anyone managed to successfully use a canon lens with a zwo asi 183 mono pro camera. I have conflicting info and regardless no matter what number of combinations I use I do not get focus. 

 

Method of madness below: 

 

I purchased the following ZWO adapter 

 

https://www.firstlightoptics.com/zwo-accessories/zwo-adjustable-eos-lens-to-t2-adapter-for-all-asi-cameras.html 

 

on the website is says that for the 183 camera I should not use the 5mm extender provided...but.... on the asi 183 mono cam site it shows a diagram of adapter connected straight to the cam!  

Great, except you can’t actually connect the two that way as it is Male to Male in that set up. 

 

so I asked around and was told to use it with the11mm adapter that comes with the ASI cam and nope again...no focus. 

I have attaches some pics soyou can try and seethe fitting, the different combinations tried and those suggested by ZWO.

 

I’ve even gone to extending out further just in case and again no avail. Seems to me I need to get it closer not further away. Apparently I read somewhere that canon lenses need<44mm to focus? 

 

I am confused because it should just work and I shouldn’t be trying to fiddle about with every combination under the sun, or I’m doing something fundamentally stupid which is perfectly possible but I just have not figured out what. 

P.s I’ve tried different canon lenses just in case and same scenario. I’m sure someone has it figured. 

 

Thank you all 

Edited January 11, 2019 by Spacetrace82
Clarity

[wetwalker]

Hi, I used the TS-Optics CCD Adapter for Canon EOS lenses to T2 - 26-33 mm it worked well with the ZWO183mm pro tec and my canon lenses with the 5mm spacer with a little adjustment on the ts-optics adapter.

Sorry I cant give you further details I sold them a few months back.

Ian

[Spacetrace82]

10 minutes ago, wetwalker said:

Hi, I used the TS-Optics CCD Adapter for Canon EOS lenses to T2 - 26-33 mm it worked well with the ZWO183mm pro tec and my canon lenses with the 5mm spacer with a little adjustment on the ts-optics adapter.

Sorry I cant give you further details I sold them a few months back.

Ian

Hello Ian 

 

Thank you for the reply. I have noticed through various reading about that people have had success but all have been using other adapters  and not the ZWO one. 

If it comes to it, I will seek out an alternative, that is after chatting with ZWO to see if they have even tried it or can help resolve the problem. 

 

Tracey ? 

[geordie85]

Would you not need one of these? 

https://www.firstlightoptics.com/zwo-accessories/zwo_t2-t2.html

 

[Laurin Dave]

Canon lenses have 44mm backfocus and the distance from the front face of the camera to the sensor is 6.5mm so the camera adapter plus spacer should total 44-6.5mm i.e. 37.5mm to obtain focus. Have you measured it? Looks like the zwo diagram for the 183 is incorrect in that you do need to use the 11mm female to female spacer as it shows in the diagram for the 1600.  

For what it worth I have the 1600mono and filter wheel and the appropriate version for Nikon lenses and it focuses fine.

Dave

 

 

 

[michael8554]

Go back to basics.

The 183 has a male M42.5x0.75 thread.

The sensor is buried 6.5mm in from the front face.

A Canon EF lens has 44mm back focus.

So you need 37.5mm of spacers.

The FLO device spec is confusing, maybe the 183 back focus is 17.5mm with the black adater fitted

(Dave beat me to it)

Michael 

Edited January 11, 2019 by michael8554

[Spacetrace82]

49 minutes ago, Laurin Dave said:

Canon lenses have 44mm backfocus and the distance from the front face of the camera to the sensor is 6.5mm so the camera adapter plus spacer should total 44-6.5mm i.e. 37.5mm to obtain focus. Have you measured it? Looks like the zwo diagram for the 183 is incorrect in that you do need to use the 11mm female to female spacer as it shows in the diagram for the 1600.  

For what it worth I have the 1600mono and filter wheel and the appropriate version for Nikon lenses and it focuses fine.

Dave

 

 

 

Hello

Thanks for the info and sanity checks. Certainly not right on the ZWO info! . Now I know that canon needs the 44mm I will go and measure up and come back with measurements. 

 

Thanks 

[michael8554]

37.5mm is an awkward figure, so don't forget you can still  focus through infinity with a distance less than that, say 35mm.

More than 37.5mm won't.

Michael 

[Z3roCool]

How did you get on with this? I am getting the ASI183MM Pro shortly and will use with my Canon lenses (400mm and 70-200mm) I will get the other ZWO adapter that you need with the EFW. It says for 1600 but FLO say it should work fine with the 183MM also. 

Edited February 6, 2019 by Z3roCool

[Gazertom]

Z3roCool (others) did you get a configuration for you Canon lenses and the ASI183?

[PadrePeace]

I had the same BF issue last night with a ASI294 and a Samyang 14mm set at F4. At full whack I was just out of focus. Tried all the combinations as already talked about but fact is you cannot connect two mail T2 threads together and that’s what it seems to need - less BF than I can engineer out of the box. The ASI and ZWO adaptors cannot give the right BF.  My Samyang 14mm works fine on my canon DSLR. 
 

Anyone solved this one?

Edited May 11, 2021 by PadrePeace

[PadrePeace]

8 hours ago, PadrePeace said:

I had the same BF issue last night with a ASI294 and a Samyang 14mm set at F4. At full whack I was just out of focus. Tried all the combinations as already talked about but fact is you cannot connect two mail T2 threads together and that’s what it seems to need - less BF than I can engineer out of the box. The ASI and ZWO adaptors cannot give the right BF.  My Samyang 14mm works fine on my canon DSLR. 
 

Anyone solved this one?

I have now fixed the issue. My ZWO adaptor was only 43.5 mm without the 5mm ring and including the 11mm extension ring that comes with the ASI294MC camera. I still don’t believe it but I added only 0.7 mm spacer shims that came with the adaptor to bring the BF up from the adaptor’s 43.5mm to 44.2mm and that has now placed focus on my Samyang 14mm F2.8 lens in the middle of its travel. Such a small change but that’s how to address this if anyone else asks. 
Clear skies all.

Edited May 11, 2021 by PadrePeace

[Andy_Bird]

On 11/05/2021 at 20:11, PadrePeace said:

I have now fixed the issue. My ZWO adaptor was only 43.5 mm without the 5mm ring and including the 11mm extension ring that comes with the ASI294MC camera. I still don’t believe it but I added only 0.7 mm spacer shims that came with the adaptor to bring the BF up from the adaptor’s 43.5mm to 44.2mm and that has now placed focus on my Samyang 14mm F2.8 lens in the middle of its travel. Such a small change but that’s how to address this if anyone else asks. 
Clear skies all.

 

Hey,

I have just received a  ASI294MC and a ZWO adapter. I am trying to pair with my sigma 150-600.  If i unscrewed the different components a few mm I could get focus at 600mm but no lower (while hoping my new baby did not flop off onto the floor). However, nothing else and 600mm is not all that practical. 

I did not get an 11mm extension ring? Do I need to order one of these to get it all working?

[Andy_Bird]

ok so the 11mm is the thing that the lense cap attaches to.. doh

will drop the 5mm and add a few shims and hope for the best

[PadrePeace]

With such a long zoom I’d suggest you get it to focus as close to the end of the travel as you can so that you get as much zoom capacity as you feel you need. I’d expect it to be sensitive as mine was so be methodical in your adjustments as you don’t what to pass through the focus sweet spot as I did. Given that DSLRs are 55mm BF it, by definition, has to be close to that plus the 1/3 thickness allowance for any filters in the optical path. 

Do let us know how you get on. 

[Andy_Bird]

thanks.. just waiting A star to show.. just realised the aperture issues as well.. I was tying to focus this at f22 apparently

 

[PadrePeace]

Hey, Andy there are those that have and those that will. We are all in there somewhere. F22? Surprised you could see much at all but good spot. Can’t help you with the weather but you may consider using an artificial star. Check it out. I made one from an led torch with the lens covered in about 10 layers of tinfoil lightly pricked with a needle. 

[Andy_Bird]

Hey.. thanks for the info.. dropping the 5mm did the trick.. there were 5 mins of stars tonight but it was enough to prove the point. Many thanks for the help.

 

[PadrePeace]

Happy to help. 
Clear skies.