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Which guide scope and OTA location for my 60mm f/5 wide FOV refractor?

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#1 PhotonHunter1

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Posted 23 February 2024 - 02:16 PM

I just purchased a Gear 60 refractor manufactured by Starfield Optics. This is a 60mm quadruplet f/5 Petzvel APO and my first foray into wide FOV astrophotography. I am considering pairing the AT 32mm f/4 mini guide scope with the Gear 60, and using the OTA shoe to mount the guide scope. My questions:

  • Does this pairing make sense?
  • Any concerns mounting the guide scope using the OTA's off-center (~11:00 location) shoe?

All previous refractors I've owned, I've mounted the guide scope directly above/in-line with the refractor (12:00 location). My concern mounting the guide scope off-center is potential field rotation issues when guiding on an object throughout the night. This may be a non-issue given the wide FOV of both the Gear 60 and AT mini-guide scope. As a note, I will be using ASI220 mini guide camera.

 

Appreciate any guidance.



#2 Tapio

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Posted 23 February 2024 - 03:32 PM

It's a suitable solution for such a short fl scope.

The position of the guide scope is not an issue.


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#3 gnowellsct

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Posted 23 February 2024 - 03:37 PM

It's a suitable solution for such a short fl scope.

The position of the guide scope is not an issue.

Are we talking equatorial mount or alt-az?  Seems to me:

 

1. Equatorial mount not an issue.

2. Alt-az mount could be an issue, if the secondary scope is trying to track an off center star.

3. Likely trivial for short exposures.

 

Greg N


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#4 PhotonHunter1

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Posted 23 February 2024 - 06:01 PM

Are we talking equatorial mount or alt-az?  Seems to me:

 

1. Equatorial mount not an issue.

2. Alt-az mount could be an issue, if the secondary scope is trying to track an off center star.

3. Likely trivial for short exposures.

 

Greg N

I would be using an equatorial mount. Longest exposure would be 5 minutes for narrowband imaging. 



#5 gnowellsct

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Posted 23 February 2024 - 07:01 PM

I would be using an equatorial mount. Longest exposure would be 5 minutes for narrowband imaging.


Should be fine.
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#6 Spaceman 56

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Posted 26 February 2024 - 03:02 AM

This is a 60mm quadruplet f/5 Petzvel APO and my first foray into wide FOV astrophotography.

 

I am considering pairing the AT 32mm f/4 mini guide scope with the Gear 60, and using the OTA shoe to mount the guide scope. My questions:

  • Does this pairing make sense?
  • Any concerns mounting the guide scope using the OTA's off-center (~11:00 location) shoe?

All previous refractors I've owned, I've mounted the guide scope directly above/in-line with the refractor (12:00 location).

 

 

I had a ZWO 30F4 guidescope for my 80mm Stellarvue.  I never liked it.

most of those budget guide scopes are difficult to focus. I even bought a bahtnov mask and still couldn't focus it.

 

I upgraded the guide-scope to a Skywatcher ED50 doublet. its much better for focus and has a wider FOV. 

 

people say you don't need good focus for the guidescope, but I think thats rubbish. 

 

as for the off centre part, it should not matter, but your idea about mounting on top with solid rails is better.

if you guide off the finder shoe you can get flexure if the guide scopes heavy. those real cheap light guide scopes can go on the finder shoe if your happy to deal with the focus issues discussed earlier.

 

Spaceman.


Edited by Spaceman 56, 26 February 2024 - 03:04 AM.

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