QHYCFW2-M-US + Canon lens + CS mount camera not reaching focus

[Jannis]

Just received my QHYCFW2-M Ultra slim wheel yesterday plus a set of Baader 2" LRGB filters and the Canon EF lens kit for the wheel. 

I put everything together and tested it OK, but i quickly run into a major problem... I can't focus beyond around 2 meters...
To connect the CS mount camera i received two quite low profile adapters. One from M54 to T2, and then one from T2 to C mount. All in all this does not build up very much, but it appears it was still just not close enough to reach inf. focus. I don't know exactly how many mm closer i need, but it's not much.

I tested by manually holding the camera closer without an adapter and it appears i can then  reach focus and well beyond that without touching the filters. So in theory, this means i should be able to get it all working with an ultra low profile M54 to C mount adapter - but does anyone know where i could be able to find such an adapter? Bernard at modern astronomy unfortunately did not have any lower profile adapters then the ones he had already sendt be. 

Alternatively, if there exists a lower profile M54 to EF mount adapter that would work too, but I've been unable to find it.

[John78]

What camera are you trying to fit on this?

[Jannis]

The QHY5L-II-M. It appears i can grind it down a few millimeters, but i'm hoping to avoid that.

[John78]

8 minutes ago, Jannis said:

The QHY5L-II-M. It appears i can grind it down a few millimeters, but i'm hoping to avoid that.

I take it the plan is to upgrade sometime to a better camera 2" filters on that is super overkill

 

The body of the camera is 1.25" correct?  You can just screw in an eye piece adapter into the FW and push the camera all the way down to virtually touching the filters - that should solve your problem?

edit : dont look like they make one, you need an m54-m42 step down and an m42-1.25" compression ring and then you should be golden.

[John78]

https://www.modernastronomy.com/shop/accessories/adapters/low-profile-t-thread-to-1-25-eyepiece-holder-with-additional-t-thread/

https://www.firstlightoptics.com/adapters/atik-m54-to-m42-t-adapter.html

 

Should fix your backfocus problems, you've probably already got something like the first link anyway.

[Jannis]

Thank you!

Yes, it is indeed planned to upgrade the camera at a later point, but that will not be before earliest next season, and so i was hoping i could use the QHY5L-II for now.  

I already have the M54 to M42 T M-F adapter, it actually looks like it's identical to the one Bernard sent me. I just gave him a call now, and he have both the T2 to 1.25" that you linked to, and the standard length in stock. I will check which ones is best suited and make an order for it. The only risk i see by using this solution is the risk of the camera slipping and falling onto the filter, should i be un-careful in the middle of the night - but the 5L have a protection ring i can use if i go for the low-profile type so that shouldn't really be an issue. 

[LightBucket]

1 hour ago, Jannis said:

The QHY5L-II-M. It appears i can grind it down a few millimeters, but i'm hoping to avoid that.

You need the newer QHY5LII with the CS mount and not the older one with the C mount as shown here 

 

[John78]

 @Jannis

 

BTW I have tried what you're doing using an ASI120MM - my struggle was focus using a lens - but I've fixed that issue now - so I guess I could have another go...  This was 200mm lens @ F5.6 and 15 second subs about 20 minutes of total data.

[Jannis]

Thanks guys! 

 

I didn't even know there was a C and CS option available for that camera, i assumed it was CS. I will double check. However, i did try with the Polemaster as well which i know is CS, and that didn't focus either - and a different solution then my current adapter will for sure be needed. 

[Jannis]

Well, i found out i unfortunately have the C mount 5L, not the CS - however i found a solution thanks to you guys!

First of all, this worked fine with the C mount front in place even though this or 5mm longer then the CS mount front.

I didn't find a T2 to 1.25" adapter, but i found an adapter from T2 to slightly smaller (yet larger then 1.25") thread that came with the lens lit from QHY that just happens to fit perfectly with a 1.25" adapter i had laying around when installed backwards!

This is what was needed to connect the 5L to the wheel and reach inf focus (and way beyond).