Zwo Asi 120mm mini vs 9x50 Finderscope

[Matzi]

Hi all

So I want to use my Zwo Asi 120mm mini as my guidecam, on the original 9x50 Finderscope that came with my SW80ED.

Now first I got a T-adapter with it, but the entire camera would go right through it. I wrote to FLO and then got the right C-adapter that would fit the back thread of the Finderscope, and I could screw the cam into the C-adapter, so it fits perfectly now. But the problem is, I cannot reach focus with it, the only way I was able to reach focus, was to use the T-adapter, with a camera adapter attached. And lots of tape, rolled around the nosepiece for the Zwo cam, and then squeeze it in there. So apparently, the Zwo needs to be closer to the lense of the Finderscope to focus. But this is impossible when using the C-adapter and mount the Zwo cam to it.

Any ideas?

[tooth_dr]

Have you screwed the finderscope lens to adjust focus? I use a 120mm on my SW finderscope with no problems but mine isn’t the mini version 

[Matzi]

Yes I have. No focus obtained even when I remove the small thread under the lens, so I can screw the lens even closer to the guidecam, but even that didn't get me any focus.

[tooth_dr]

Just now, Matzi said:

Yes I have. No focus obtained even when I remove the small thread under the lens, so I can screw the lens even closer to the guidecam, but even that didn't get me any focus.

I see, just checking!  I’ve used 3 different cameras as guidecams - ZWO 120MM, IS DMK21 and a Lumenera LU070 and all eventually came to focus with the finderscope.

Can you screw the finderscope - C Mount adapter further into the finder?

[tooth_dr]

Photos would be very useful too Matzi. 

[Matzi]

No it's screwed in at maximum, still not good enough. I mean I'm literally not seeing anything on the guidecam when turned on, not even objects out of focus.

[Matzi]

Unable to provide any photos right now. But a quick explanation. The Zwo Asi 120mm Mini comes with a threaded nosepiece, and a small threaded ring to attach to the nosepiece. You'll need to use the nosepiece, and the small threaded ring attached to it, to make it fit into the C-adapter. Ditching the nosepiece would allow it to come close to the Finderscope lens, but it won't fit into the C-adapter without using the nosepiece and that small ring. So the Zwo cam is attached roughly 5-8 cm behind the back of the Finderscope.

When I made my own homemade solution with tape, I literally had to push the entire nosepiece of the Zwo cam inside the Finderscope before it was able to get focus.

[alacant]

2 minutes ago, Matzi said:

not even objects out of focus.

What are you trying to focus upon? If in daylight you could use Sharpcap on auto or set the gain to its minimum settings. IIRC, the small round asis like the qhys ( the sensor is about 6mm from the top rim of the camera) all focus by twisting the objective lens; I think you're not able to focus due to overexposure.

HTH 

[Davey-T]

Have you got a Barlow rhat you can stick in front it.

There are some combinations that don't work, I had to saw a bit of my Meade finder to get it to focus using as a guide scope.

Dave

[tooth_dr]

I’ve attached my camera and your camera back focus info. Really need photos of your adapters etc to see how it’s adding so much thickness  

 

 

[fozzybear]

Maybe this might help the camera is a cs fitting is it not with then an adapter to C

 

1. M28.5-CS adapter
2. CS-C adapter
3. 1.25″ extender
4. 1.25″ filter

[Matzi]

1 minute ago, alacant said:

What are you trying to focus upon? If in daylight you could use Sharpcap on auto or set the gain to its minimum settings. IIRC, the small round asis like the qhys ( the sensor is about 6mm from the top rim of the camera) all focus by twisting the objective lens; I think you're not able to focus due to overexposure.

HTH 

I did use Sharpcap when finding focus with the Zwo, it's just black, or turns white if I place my hand infront. I used 10 ms and 1000 ms exposure, I tried with gain 50 and 80-90. But still when pushing in my Zwo cam further into the Finderscope, it works. But not a liable solution

[Matzi]

Alright 'i fixed it now!  - It turned out there was a small thread with a lens on, and if you screwed the ring thread onto that lens thread, you could attach the Zwo directly onto the C-adapter without the nosepiece. Also used Sharpcap, and played a little with the gain, exposure time, and focus on the Finderscope, and I got it working. Thanks for your help all.

[tooth_dr]

5 minutes ago, Matzi said:

Alright 'i fixed it now!  - It turned out there was a small thread with a lens on, and if you screwed the ring thread onto that lens thread, you could attach the Zwo directly onto the C-adapter without the nosepiece. Also used Sharpcap, and played a little with the gain, exposure time, and focus on the Finderscope, and I got it working. Thanks for your help all.

Great news.