SW 9x50 guidescope focus + USB queries

[Aramcheck]

I recently bought a ZWO ASI 120MM Mini and a C adapter so that I could convert a spare SW 9x50 finderscope, to have a go at guiding, but  I think I'm having trouble getting it to focus.

I've looked at @eikie's earlier thread: https://stargazerslounge.com/topic/347996-focussing-guidescope but I can't get it to focus on a distant object & when I try to view a star I'm not sure if the result is good enough or not. (See attached image from ASICAP with Capella enlarged & at original resolution. The star looked ok through the main scope & I couldn't see any high cloud).

Also, at present, I'm running a 5m USB lead from my DLSR to laptop & similarly using a 5m EQDIR cable to control the mount. The USB lead that came with the camera is 2m, so am I better off getting a hub or a USB extension cable? (I usually leave the laptop in a storage area under our house & just bring it near to the mount during initial set-up)

I think longer term I'll be opting for a different guidescope, which I can mount on the OTA rings, but was hoping the finderscope would be a way to get started...

Any advice would be much appreciated!

Cheers
Ivor

[knobby]

If you need more travel you can take the lock ring off the objective cell, allows about an extra 2 or 3 mm travel.

[fozzybear]

you did take the nosepiece off the ASI120MM mini as per the picture below?

[Aramcheck]

32 minutes ago, fozzybear said:

you did take the nosepiece off the ASI120MM mini as per the picture below?

Yes - it looks exactly as per the picture.
Going to have another try tonight...

Cheers
Ivor

[fozzybear]

17 minutes ago, Aramcheck said:

Yes - it looks exactly as per the picture.
Going to have another try tonight...

Cheers
Ivor

maybe as per @knobby If you need more travel you can take the lock ring off the objective cell, allows about an extra 2 or 3 mm travel

[Aramcheck]

As @knobby and @fozzybear suggested, removing the locking ring did allow me to get focus. Without the ring however the star position is very sensitive to any movement in the objective. I'll have to look to see if the locking ring depth can be reduced.

Had hoped to do an imaging run tonight, as skies here are nice and clear.... but nearby neighbour has a garden fire going & I don't think it'd be sensible to proceed with the wood-ash fallout.

I've ordered a USB hub and active extension lead too.

Cheers
Ivor

[fozzybear]

Ivor

try turning the locking ring the other way round if you know what I mean on the finder scope then attach the lens cell ...

Andy

[Aramcheck]

2 hours ago, fozzybear said:

try turning the locking ring the other way round...

I've tried that as per @eikie's thread but it didn't work, i.e. the objective lens couldn't be screwed in as far, but thanks for the suggestion. Maybe there's a large tolerance variation in the length of these finder-scopes?

I'll know I'll need to use a guidescope that can be attached to the OTA rings at some point, as I can't get balance with the 130dps and DLSR+9x50, though the 200dps is fine.

Cheers
Ivor

[knobby]

I've got a strip of white tape on my thread, stops the Wiggles !

[Aramcheck]

I filed down the ring lock a little bit (on the thread side), so that it's now about 10.6mm in depth. That seems to have worked ok, as I can now get focus.

Thanks for your help!

Ivor