Guide scope suggestion for SW 130PDS and other Qs

[Astroguy99]

Hi guys,

I'm looking to buy a guide scope pretty soon, up to maybe £70-80 at the top end.

I have a Skywatcher 130PDS OTA on the Celestron LCM goto mount from my first scope, with the ZWO autofocuser, and there's two camera options, the Altair GPCAM BASIC Colour one here, or my mono GPCAM2 (which I plan to use on the guidescope until I can get a filter wheel).

I'm guessing you can just whack one in on the finder scope dovetail? What size do you guys think would work best for me? On a bit of research, 50mm looks good enough, but my concern is with getting focus onto the sensor. Would appreciate any input on that.

Also, I have a SERIOUS problem with backlash. In the software and CPWI, the maximum is 99, but the actual backlash appears to be substantially higher than that, and has been since I bought it a year and a half ago, and things almost always drift, but actually not that much for say 4-8 second subs.

I am looking at getting the SW AZ-GTI and a rotator at some point. Is this as good an option as just going for an EQ mount?

I don't actually have a garden, so I'm lugging it to my sister's place once a week or so to get images (which I haven't actually managed yet due to still learning - and probably picking the wrong kind of things - and alignment can be tricky). I'm hoping with the guide camera at a larger FOV that it will pick up much more and be able to plate solve and sync better (as well as acting as the tracking).

I'm very happy at the moment to get 100s of subs at sub-minute exposures, so that part isn't an issue for me for quite some time. I'm just thinking fund-wise and doing it in upgradeable parts rather than spending out like £500-£1000 on a really complicated and expensive mount.

Will this extreme backlash be an issue, or will PHD2 compensate for that? If not, is there any other guiding software that might?

Apologies for the 500 questions guys, but felt the need to explain as much as possible.

 

Thank you

 

 

 

[Kev M]

The standard 8x50mm seems to be popular, there are adapters available that allow you to reach focus with a guide cam ( gpcam or similar ).

There are also purpose built guide scopes of around 50mm, which are basically the same but have reduced focal length and come complete with adapters.

I assume the dovetail for the 50mm is the same size base as the smaller guide scope you already have ( plenty of owners on this site to confirm )

[malc-c]

OK I'm going to state the obvious here... you are using an ALT/AZ mount which will suffer the same issue of all ALT/AZ mounts and that is field rotation.  Now if you guide on a star for long periods, I would have thought that may also be a problem due to the field rotation??

As for guidescope, I've used ST80 and now the  stock  Skywatcher 9 x 50 finder  and found that both worked well.  Given the weight saving the 9x 50 would be the cheapest option.  You will need an adapter to suit the camera so you can connect the two (best speak with RVO or FLO).  The 9 x 50 SW finder is £54, and should slot right in the shoe where the current 6 x 30 finder is.

However, I would seriously suggest you consider looking at upgrading the mount to an EQ (ideally an Skywatcher so you can use EQMOD with an EQDIR cable) to really get the benefit of guiging for longer exposures.  An EQ mount will also help with stacking and post processing the results as you won't have to deal with the field rotation issue.

[Tan Zhi Qi]

I'm also thinking of getting a guide scope for my SW 130pds. I'm looking into the Svbony 50mm (or will the 60mm be better?) guide scope and a T7c (clone of ASI 120mm mini) . Not sure if anyone use it? I hope someone can give me some advice here XD

[Jamgood]

I use the Orion 55mm Guide scope and Orion Astro Shoot Guide Cam with my 130PDS. I got it used from someone here on SGL but it works great for me.

[ollypenrice]

Almost anything will do as a guidescope so a quick scout around second hand might be in order. Old camera lenses will do as well. What's vital is that it have no flexure but even poor quality scopes can be screwed, and even glued, up solid to avoid this.

Like malc-c, though, I wonder about the value of guiding an alt-az mount. I'm not even sure it will accept guide inputs but perhaps it will.

Olly

Edited April 2, 2021 by ollypenrice
typo

[malc-c]

2 hours ago, ollypenrice said:

 

Like malc-c, though, I wonder about the value of guiding an alt-az mount. I'm not even sure it will accept guide inputs but perhaps it will.

Olly

Olly, I was going to add that to the equation, but thought it may complicate things.  Most of us use EQMOD to handle the mount control, with guiding handled by PHD2.  However the OP has a celestron mount which is not supported by EQMOD, and even if it did, wouldn't function as the clue is in the name, EQmod... for EQ telescopes.   

Personally, given that guiding is an aid to taking  long exposures, the field rotation (15 degrees an hour) will be in issue, especially when trying to stack three or more hours worth as the software will most likely complain

[malc-c]

There's a listing in the classifieds Here