Jump to content

sgl_imaging_challenge_6_banner_jupiter_2021.jpg.eacb9f0c2f90fdaafda890646b3fc199.jpg

 

 

The baseline for camera orientation angle?


Recommended Posts

Hello all,

I am a trifle confused about the baseline for camera orientation angle on a refractor imaging scope. 

This is having read the following from page 78 of the excellent Making Every Photon Count, 3rd edition: "in astro-photography, the baseline is the plane of the RA axis."

My confusion is that this definition doesn't tell me what plane is the baseline because the orientation of a plane is not known from knowing only one straight line (the RA axis here) that it passes through. Think of a paddle wheel on a paddle steamer. The plane of each paddle passes through a common straight line; the centre line of the driving axle. Hopefully this conveys my confusion with regard to the authors description above.

If anyone can clarify what the baseline/plane actually is for camera orientation used on a refractor, I would be grateful.

Thanks.

Link to comment
Share on other sites

I'll try and describe the plane referred to in words... might be tricky, but I have a feeling it will be better than my drawings!

Imagine the mount in the home position. You are standing behind it, looking up the RA axis as it points towards Polaris. Now imagine a plane that runs horizontally, cutting through the mount head from left to right. The plane is tilted up towards Polaris. That is the baseline plane.

When I'm setting up my camera on my scope, I find the best way to get things level, thereby helping with orientation from session to session, is to rest the scope on its dove tail plate on a table. I then attach the camera ensuring it is level with that, helped by the surface of the table.

When framing a target, I use two positions to make things easier if I come back to the object at a later date. First position as described above and the second position is at 90º to that. I then make a note with each target which orientation I have used.

Good luck and I hope you are enjoying some clear dark skies in Somerset!

Link to comment
Share on other sites

I'll try and describe the plane referred to in words... might be tricky, but I have a feeling it will be better than my drawings!

Imagine the mount in the home position. You are standing behind it, looking up the RA axis as it points towards Polaris. Now imagine a plane that runs horizontally, cutting through the mount head from left to right. The plane is tilted up towards Polaris. That is the baseline plane.

When I'm setting up my camera on my scope, I find the best way to get things level, thereby helping with orientation from session to session, is to rest the scope on its dove tail plate on a table. I then attach the camera ensuring it is level with that, helped by the surface of the table.

When framing a target, I use two positions to make things easier if I come back to the object at a later date. First position as described above and the second position is at 90º to that. I then make a note with each target which orientation I have used.

Good luck and I hope you are enjoying some clear dark skies in Somerset!

Very helpful thank you Gav.

So would I be correct in saying that the baseline plane is the plane where the female dovetail shoe of the mount (that screws onto the male dovetail bar of the scope) meets the the section housing the DEC axis. Would this be the same plane as the one you described? I have drawn a quick paint style sketch of what I'm describing. Is the top red plane the one you've referred to?

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.