WO GT81 X WO FLAT6II 0.8X X ASIFILTER XASI83 PRO MM

[WOGT81Reducerx8]

Please help with focusing, my telescope don't seems to come to focus, stars look to big and almost covering all the screen. I think it  is because the back focus is incorrect. Any help with this issues is really appreciated.  Maybe a picture of your setup can be of great help. Thank you. 

[Davey-T]

3 minutes ago, WOGT81Reducerx8 said:

Please help with focusing, my telescope don't seems to come to focus, stars look to big and almost covering all the screen. I think it  is because the back focus is incorrect. Any help with this issues is really appreciated.  Maybe a picture of your setup can be of great help. Thank you. 

Hi and welcome to SGL.

Bit more info on equipment being used would be good.

Is this a camera you're trying to focus, if you move the focuser in and out the star should get bigger and smaller, figure out which way makes it smaller, either focuser right in or right out.

If right in then then the camera sensor is too far away from the focus point if it improves when right out then some sort of extension is needed.

Dave

[WOGT81Reducerx8]

Thank you Davey, 

this is my setup: GT81 Telescope x William Optics Flat6A II 0.8x Adjustable Reducer Flattener x spacers (38.5 mm)x ASI filter wheel (20 mm) x ASI83 pro mm camera. I tried to change the spacers back and forth to cover a wide range of measurements in order to conform with the 71.06 mm recommended by WO. I do try to focus on one star, but she looks so close to screen that I cannot use the Bahtinov mask, to give you a a better idea the star look to magnified on the screen. 

[carastro]

Sorry, deleted as wrong thread. 

[Davey-T]

As  far as I can see,  according to WO based on using a DSLR with 55mm spacing the flattener spacer setting is 7.9mm, depending on how the filter wheel and camera are connected they come to 43.5mm so theoretically if you add 11.5mm to your spacing it should be about right depending if any extra is already added by the camera filter wheel connection.

Good luck, many a hair has been pulled out by astro' imagers trying to get spacing right 

Dave

[david_taurus83]

Hi. I have a similar setup albeit a GT71, Flat6A2 and ASI filterwheel and camera. You should be trying to achieve 55mm from the flattener to the camera sensor. See below my image train. From the back of the flattener I have a 10mm tilt adjuster, 16.5mm M48 to M42 adapter, 20mm filter wheel and 6.5mm from camera face to sensor. Also are approx 0.8mm delrin spacers and approx 1mm back focus added for filter and sensor glass. That gets me very close to the required 55mm back spacing and I achieve focus at approx 34mm on the drawtube markings. Hope this helps.

 

Ps. Where did you get the figure of 71.06mm spacing?

[david_taurus83]

Forgot to ask, what software are you using?

[knobby]

Then it's out of of focus, are you wound fully in or out ...?

[knobby]

Are you all the way out or in on the focuser movement ?

[Davey-T]

This has already been addressed in your other thread on the same subject.

Dave

 

[knobby]

I think he has the flattener spacing ok but cant focus ... Probably needs extension before flattener to bring everything outwards ...

[WOGT81Reducerx8]

Thank you for all your replies. I have very been frustrated with my equipment to the point of quitting altogether and the sell everything. I will try those suggestion in the spring., when the weather gets better. Right now the weather is to cold to be playing with back focus.  I use the SkyX pro to captured.  Any suggestion for a better capture software? I save this thread for future reference. I will post picture of my settings as soon as I put my equipment together, right now everything is boxed. Again, thank you for all your help with my issue. 

[astrosathya]

14 hours ago, WOGT81Reducerx8 said:

Thank you for all your replies. I have very been frustrated with my equipment to the point of quitting altogether and the sell everything. I will try those suggestion in the spring., when the weather gets better. Right now the weather is to cold to be playing with back focus.  I use the SkyX pro to captured.  Any suggestion for a better capture software? I save this thread for future reference. I will post picture of my settings as soon as I put my equipment together, right now everything is boxed. Again, thank you for all your help with my issue. 

Use "Astrophotography Tool" software. Its very straightforward. Plus, you don't require stars to check the focus point of the telescope. It is frustrating to fiddle around trying to get focus on a star. What I do is, I park the scope on my balcony and point the scope towards a far away Electricity Tower (One of those huge ones about 300ft tall). You could use a church steeple or Mobile Phone transmission towers, say 500 meters away. Even a window far enough will help. Try focusing the scope. Anything beyond 500m will be quite close to infinity focus for your scope and that should make it easier to get on to a star. Use a nice bright star, but not one which will be like a  floodlight like Sirius. Use Capella or Aldeberan etc after you've got the hang of focusing on windows ?