Oag prism orientation/setup

[Bottletopburly]

maybe @Bob Dobber can answer this ,does the oag prism need to be square to the sensor as on my zwo533 /zwo mini filter wheel  i can only get the prism at an angle to the sensor ?  does this matter ,how do you know if you have the prism clipping the light path enough.

[+Ibbo]

Yes if you need to put the prism in that far you will need to to align it.

I have used a bit of insulation tape as a spacer before now.

 

You can confirm if it impinges by inspecting the flats.

Edited May 1, 2023 by Ibbo

[Bottletopburly]

6 hours ago, Ibbo said:

Yes if you need to put the prism in that far you will need to to align it.

I have used a bit of insulation tape as a spacer before now.

 

You can confirm if it impinges by inspecting the flats.

Thanks Steve I do have some thin spacers which may work within the tolerance for the backspacing for the cc 

[Bob Dobber]

I think as Ibbo has ably addressed the matter, however as he has intimated - does the prism _need_ to be in that far? Not sure mine is (I have 533 also and it's not perfectly aligned and doesn't seem to upset me) - just as long as you can see some stars in your guiding application (presume PHD2) so doesn't need to be right the way in. I have never had the patience nor motivation to attempt to space it out but if I found I had no choice maybe I would!

[Bottletopburly]

30 minutes ago, Bob Dobber said:

I think as Ibbo has ably addressed the matter, however as he has intimated - does the prism _need_ to be in that far? Not sure mine is (I have 533 also and it's not perfectly aligned and doesn't seem to upset me) - just as long as you can see some stars in your guiding application (presume PHD2) so doesn't need to be right the way in. I have never had the patience nor motivation to attempt to space it out but if I found I had no choice maybe I would!

 Wasn’t sure how far prism needs to stick out 🤷🏻‍♂️ I will try to focus on a chimney during daytime if I can 

[+Graham]

So long as the prism is in the light cone it will be fine.

That looks way too far in as it should not cover any part of the chip.

It will need to be square to the light path otherwise your guide stars will look like seagulls.

This will become blatantly obvious when you focus the OAG. 

[Bottletopburly]

30 minutes ago, Graham said:

So long as the prism is in the light cone it will be fine.

That looks way too far in as it should not cover any part of the chip.

It will need to be square to the light path otherwise your guide stars will look like seagulls.

This will become blatantly obvious when you focus the OAG. 

Cheers graham I just assumed you had to have it covering part of the chip , I will shim the camera hopefully that will square things up , why zwo didn’t design the OAG better so orientation  to the camera chip was easier.

[+Ibbo]

You might find it helpful to arm yourself with a pencil and a tape measure or calipers for setting up.

Focus main cam and mark positon and/or measure then do same for guider and then you will have an idea of where and how much spacer you need (though you could be lucky and they are par focal)

[Bottletopburly]

The thinnest spacer I had was enough to get  square orientation to sensor 👍

[Bob Dobber]

1 hour ago, Bottletopburly said:

The thinnest spacer I had was enough to get  square orientation to sensor 👍

 

Maybe I need to do this. I'm too lazy and it currently is fine though... The way the OAG attaches is a bit of a mystery to me all round to be honest, like it forbids certain orientations for no good reason. (No need to explain to me, I'm at peace with it 😂)