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Gimboid

First guide scope advice

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Hey all.. If I may I would like to pick some brains....

What would be folks thoughts on this as a future guide scope?

https://www.ebay.co.uk/itm/HELIOS-ST80-Helios-Sky-Watcher-Telescope-D-80mm-F-400mm-Coated-Optics/113726201256?hash=item1a7a9c1da8:g:pjwAAOSwV9RcnOUG 

I have had a quick look online and at a glance it seems very similar to the Sky Watcher Startravel 80 which I have seen recommended as a being used as a guide scope.. The cheapest ST80 I can find is £98 + post. Now the seller doesn't want to offer postage due to total weight but I was thinking that maybe he would consider posting everything but the mount and maybe to sweeten the deal offer him the same price without the mount.. actually I got a 5% discount with ebay at the mo so if the seller was up for it then i'd have a new guide scope for £60.80p plus postage..  Obviously being very new to all this I wouldn't have a clue as to the difference in quality between the Helios and SW scopes so was wondering would this be a good buy?

Edited by Gimboid

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Hi,

looks interesting. One thing to consider is that this telescope will have fixed clamps, ideally for a guide scope you want to have clamps which allow you to centre the scope and align it to the main tube. An 80mm diameter will help in picking up faint stars, but it will also depend on your guide camera and the focal length of your main scope (for short refractors a small guide scope is usually enough). Then you should consider the weight, ideally you want to have it as light as possible not to affect to much your imaging train. At the moment I use a cheap (about £50) 50mm guide scope but I will soon move to a SW EvoGuide 50ED (https://www.firstlightoptics.com/guide-cameras/sky-watcher-evoguide-50ed-guidescope.html). It is a more expensive scope but after looking at it in person I noticed the huge difference with a cheap one and the ED glass surely stands out! Personally, I prefer good optics for guiding rather than large diameter, as the star shape in the guiding camera is important for good performance.

Hope this helps!

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Reason I came across this scope... I'm currently reading the book 'Making every proton count' as this size telescope used as a guide scope comes recommended in the book so I had popped on Ebay simply out of curiosity to look at prices and ofc found this one... The book also covers the subject of the tube rings, to save money and weight I would make an adjustable set of my own out of aluminium. As for my telescope..  I currently have SW 150pl on a eq3-2 which I bought before considering AP so the plan is to sell the current set up and purchase either a 150 or 200 pds and ofc a much better mount.

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1 hour ago, Gimboid said:

tube rings, to save money and weight I would make an adjustable set of my own out

Hi. No need to make adjustments for a guide telescope. In fact it's recommended not to do so; anything to make the connection between it and the main telescope more rigid, rather than less.

Bolt the guide telescope using its regular tube rings to a rigid plate bolted itself along the top of the rings of the main telescope. A a second dovetail plate is good for this.

HTH

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16 hours ago, alacant said:

Hi. No need to make adjustments for a guide telescope. In fact it's recommended not to do so; anything to make the connection between it and the main telescope more rigid, rather than less.

Bolt the guide telescope using its regular tube rings to a rigid plate bolted itself along the top of the rings of the main telescope. A a second dovetail plate is good for this.

HTH

I can see the reasoning about this and I agree, however if for some reason your scopes end up misaligned wouldn't this affect your guiding? I am thinking in terms of cone error between the two scopes. Of course an adjustable dovetail plate solves this issue.

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On 14/11/2019 at 03:59, Gimboid said:

Hey all.. If I may I would like to pick some brains....

What would be folks thoughts on this as a future guide scope?

https://www.ebay.co.uk/itm/HELIOS-ST80-Helios-Sky-Watcher-Telescope-D-80mm-F-400mm-Coated-Optics/113726201256?hash=item1a7a9c1da8:g:pjwAAOSwV9RcnOUG 

I have had a quick look online and at a glance it seems very similar to the Sky Watcher Startravel 80 which I have seen recommended as a being used as a guide scope.. The cheapest ST80 I can find is £98 + post. Now the seller doesn't want to offer postage due to total weight but I was thinking that maybe he would consider posting everything but the mount and maybe to sweeten the deal offer him the same price without the mount.. actually I got a 5% discount with ebay at the mo so if the seller was up for it then i'd have a new guide scope for £60.80p plus postage..  Obviously being very new to all this I wouldn't have a clue as to the difference in quality between the Helios and SW scopes so was wondering would this be a good buy?

You dont need a guide scope over 50mm aperture  / 200mm focal length unless you are guiding a imaging scope of more than 1000mm focal length. 

Anything bigger is a waist of money and more importantly weight. 

The Skywatcher EVOGUIDE 50mm is a great permium option, but I have used this for the last 5 years with perfect guiding results:

https://www.amazon.co.uk/Orion-Deluxe-Guide-Helical-Focuser/dp/B00B1N7576/ref=sr_1_23?keywords=50mm+guide+scope&qid=1573820385&sr=8-23 

So what mount do you have and what imaging scope / camera are you using?

Adam

 

Edited by Adam J
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Alignment isn't necessary and 50mm is sufficient to guide within the limits of the atmosphere in the UK. I personally question the value of the Skywatcher ED guide scope, I've never had any issues using cheap achromatic scopes.

The issue you'll have with the ST80 is the focal plane is too far back, so you wont achieve focus with a guide camera without an extension which adds additional cost.

You can pick up 50mm guide scopes on ebay for £45.

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Have you considered an off-axis guider?  You could go down that route for similar money and you'll never have to worry about differential flexure.

 

 

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OAG certainly the better way to go if you're using mirrors, as they have a tendency to move within the scope.

Disadvantage is reduced field of view to pick stars from, and adding extra weight to the focuser can result is more focuser sag/tilt.

Advantage of using a guide scope is it can be used for polar alignment using Sharpcap.

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I have always used second hand st80's for guiding. I find that a cheap plastic barlow can be used to give you enough back focus, although I now use a couple of metal extensions that screw directly into the focus tube to stop any movement. 

I used a metal bar and elongated bolt holes so I could adjust the scope left and right and washers under the scope to adjust the angle. Then made sure it was all bolted down tight.

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4 hours ago, SamAndrew said:

Alignment isn't necessary and 50mm is sufficient to guide within the limits of the atmosphere in the UK. I personally question the value of the Skywatcher ED guide scope, I've never had any issues using cheap achromatic scopes.

The issue you'll have with the ST80 is the focal plane is too far back, so you wont achieve focus with a guide camera without an extension which adds additional cost.

You can pick up 50mm guide scopes on ebay for £45.

More over the focuser on the ST80 is likely to result in flexture.

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On 15/11/2019 at 12:17, Adam J said:

You dont need a guide scope over 50mm aperture  / 200mm focal length unless you are guiding a imaging scope of more than 1000mm focal length. 

Anything bigger is a waist of money and more importantly weight. 

The Skywatcher EVOGUIDE 50mm is a great permium option, but I have used this for the last 5 years with perfect guiding results:

https://www.amazon.co.uk/Orion-Deluxe-Guide-Helical-Focuser/dp/B00B1N7576/ref=sr_1_23?keywords=50mm+guide+scope&qid=1573820385&sr=8-23 

So what mount do you have and what imaging scope / camera are you using?

Adam

 

I haven't got anything yet....  well, that's not exactly true.. I have a SW150pl on a EQ3-2 mount however that's going up for sale shortly and then I will start to look around for the best bargains I can find to put a suitable kit together for AP..  I bought the current equipment a year or so ago, haven't hardly used it and still a complete beginner but after only a couple evenings playing around, reading up online and looking through these ere forums I quickly decided that it's AP I want to get in to and ofc realised I don't really have the best gear to start with.  So basically starting from scratch besides a cheap canon 1100d I picked up recently.  Only reason I picked this scope was because I came here and was told just like pretty much everyone starting off.. buy this book.. so, bought book and was simply going on the advice within... It recommended the 80/400 scope and as this seemed very similar to the SW version I wondered if good value as a starter....  at the mo I haven't got my eye on anything in particular, I just browse around to see what is about.. money not great at the mo so figured I would buy various pieces as I go until I have what I need...  however, I was thinking along the lines of a sw 150pds and the best mount I can afford but again, that will depend on what comes up at the right price at the time. 

On 15/11/2019 at 13:50, x6gas said:

Have you considered an off-axis guider?  You could go down that route for similar money and you'll never have to worry about differential flexure.

 

 

off-axis guider..  no because I haven't a clue what it is lol    Im reading a book and it has touched on the subject but that's as far as I have got... I have been reading up as much as possible of late trying to learn but I'm simply not a reader..  Watching videos, shown or told.. no problem but all my life when it comes to reading I just hate it and don't seem to absorb the information quite the same but if it's worth considering then I will do my homework. 

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I got this guidescope.  Really pleased with it and the locking focuser works like a dream.  Decent price a superb build with good solid mounting rings.

https://www.rothervalleyoptics.co.uk/altair-60mm-guide-scope-kit-straight-thru-precision-locking-focuser-no-eyepiece.html

I then got this as my guide cam and again.  Really good package and once all set up is pretty simple to get working:

https://www.rothervalleyoptics.co.uk/altair-astro-gpcam-v2-mono-ar0130-mono-guide-imaging-camera.html

I went for the full package as the small amount extra is worth it for what you get in the box.  

Overall very pleased with it. Appreciate it is quite a lot more money but it will be your first and last guide scope unless you move into the realms of very high end and very large scopes :)

 

Edited by dannybgoode

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