Asi120mm with orion st80@400fl

Using SharpCap's Polar Alignment feature
Post Reply
Aldures
Posts: 4
Joined: Sat Aug 25, 2018 6:10 pm

Asi120mm with orion st80@400fl

#1

Post by Aldures »

Hi,
I wanted to know if using my asi120mm with my orion st80 400mm focal length scope will work for doing polar alignment. I have read many messages here which have mixed results.

Fyi - No I don’t want to to put a .5 reducer on the camera since I use this setup with phd to track as well and don’t want blurry edges.

Has anyone had success using similar setups or have any advice?

Thanks,
Tim
Last edited by Aldures on Sat Aug 25, 2018 9:29 pm, edited 1 time in total.
User avatar
oopfan
Posts: 1321
Joined: Sat Jul 08, 2017 2:37 pm
Location: New York
Contact:

Re: Asi120mm with orion st80@400fl

#2

Post by oopfan »

Tim,

I had to use a 0.5x reducer with a 400mm scope and ASI120 for PA. I now use a dedicated 200mm Orion guider/finder scope using the ASI120. Imaging is done with a 416mm scope and Altair 290M. I don't think you will have success doing PA with 400mm.

Brian
Aldures
Posts: 4
Joined: Sat Aug 25, 2018 6:10 pm

Re: Asi120mm with orion st80@400fl

#3

Post by Aldures »

oopfan wrote: Sat Aug 25, 2018 9:07 pm Tim,

I had to use a 0.5x reducer with a 400mm scope and ASI120 for PA. I now use a dedicated 200mm Orion guider/finder scope using the ASI120. Imaging is done with a 416mm scope and Altair 290M. I don't think you will have success doing PA with 400mm.

Brian
Thanks for the reply Brian. Dang it, I didn’t want to get another tube and change my trusty setup. I really like my 400mm guide scope. I have always polar aligned with the polar scope and fine tuned everything with phd with great results however Sharpcaps polar align method seems much more elegant and easier. I wanted to avoid getting another camera/finder combo.

Cheers,
Tim
User avatar
oopfan
Posts: 1321
Joined: Sat Jul 08, 2017 2:37 pm
Location: New York
Contact:

Re: Asi120mm with orion st80@400fl

#4

Post by oopfan »

Tim,

An alternative is to just purchase a new camera with a larger sensor, and sell the ASI120 to defer cost.

Brian
Aldures
Posts: 4
Joined: Sat Aug 25, 2018 6:10 pm

Re: Asi120mm with orion st80@400fl

#5

Post by Aldures »

Hi Brian,
Just out of curiosity on the asi120 with reducer, did you simply get a screw on reducer for the 1.25 eyepiece? I currently screw-on my asi120 via an M42 extension directly to the finder scope for less moving parts. I am pondering the reducer however I don’t know of any M42 thead .5 reducer. Would you mind sharing your setup info?

Thanks,
Tim
User avatar
oopfan
Posts: 1321
Joined: Sat Jul 08, 2017 2:37 pm
Location: New York
Contact:

Re: Asi120mm with orion st80@400fl

#6

Post by oopfan »

Hi Tim,

I purchased the screw-on type here.

That then slipped into the tube/receiver on the back-end of the scope and tightened with thumb screws. Easy on/off to switch between PA and imaging.

Brian
User avatar
oopfan
Posts: 1321
Joined: Sat Jul 08, 2017 2:37 pm
Location: New York
Contact:

Re: Asi120mm with orion st80@400fl

#7

Post by oopfan »

Tim,

That's good thinking to have a solid connection between the camera and scope but the thumbscrew-type, if properly engineered, can be highly effective.

Avoid those that have the thumbscrew come into direct contact with the camera extension -- there is the potential for wiggle if the thumbscrew backs off during the course of the night.

The best in my opinion have a strip of metal in a channel on the inside of the tube. The thumbscrew presses on the strip which then makes positive contact with the camera over a much larger surface area. Inspect yours to ensure that the thumbscrew applies pressure to the metal strip. Sometimes the strip can slide in the channel so that the thumbscrew bypasses it. That could happen during shipping.

Brian
User avatar
oopfan
Posts: 1321
Joined: Sat Jul 08, 2017 2:37 pm
Location: New York
Contact:

Re: Asi120mm with orion st80@400fl

#8

Post by oopfan »

Tim,

My ASI120 came with a 1.25-inch nosepiece. I purchased a 1.25-inch IR-cut filter and kept it permanently attached to the end of the nosepiece and then screwed the focal reducer onto it. I did this to keep dust off of the sensor window since I wasn't taking flat frames at the time. If you are taking flats then I wouldn't worry -- just screw in the reducer directly to the end of the nosepiece without an IR-cut since there is one built into the sensor window.

Brian
Aldures
Posts: 4
Joined: Sat Aug 25, 2018 6:10 pm

Re: Asi120mm with orion st80@400fl

#9

Post by Aldures »

Hi Brian,
I just purchased a M42 to 1.25 adapter along with a .5 reducer and will try that combo out. I prefer screwing my camera’s to the scope for stability however I will share my results when I actually get a chance to try the setup out in a week or two.

Thanks again,
Tim
Post Reply