Focus with ZWO ASI MC-S

[Bigwings]

My kind friends bought it for my Birthday but getting it to focus on the laptop has been difficult. Perhaps I am getting seduced to imaging. after years of visual. 

I have 3 scopes

1. StellaLyra 6" Classical  Cassegrain  f12

2. Bresser Messier 10" dob (mounted on AZEQ6)  f5

3 SW  Explorer 130 P-DS f5

I have tried with extension tubes  using a tree about 200 meters away which is my most distant object visible from my garden and am fed up of seeing a white screen.

The camera is working with the all sky lens fitted.

Please can somebody give me a ballpark figure about how many extensions I need to get focus. distance from the end of the 2" focusser when fully retracted will help me seatch when I can next see the moon.

Any advice most welcome and thanks for your support.

Kind Regards

Mike

[CraigT82]

White screen might suggest the exposure is way too high? In daytime conditions you’ll need sub- millisecond exposures i think 

[michael8554]

You may not have enough focuser in-travel to focus the two Newtonians.

If you can focus the Cass on an object 200M away with the star diagonal and an eyepiece, just substitute the camera for the eyepiece and adjust the focuser.

Then measure the optical path-length from the OTA to the camera sensor and insert spacers to replace the star diagonal.

Daytime, try SharpCap in video mode and auto exposure.

Michael

[AstroMuni]

23 hours ago, Bigwings said:

My kind friends bought it for my Birthday but getting it to focus on the laptop has been difficult

I am guessing its the ASI120MC-S that you are using. I have the ASI224MC which has a backfocus of around 12.5mm so I would guess that yours would be in similar range. I use mine on my Astromaster 130 which again is quite similar to your SW 130 so you should be able to achieve focus by moving the focuser knob during daytime. BTW, I dont need to add spacers but yours may need them as it uses a shortened tube. Dont add the diagonal, just attach the camera straight on to focuser. Use the ASI provided software or Firecapture/Sharpcap to help get a continuous view.

Edited July 13, 2022 by AstroMuni

[Bigwings]

Thanks guys. Problems solved.