Why using expensive guidescopes?

[jeffwjz]

Hello! I think I have a rather stupid question! While I was browsing articles and astro images online, I couldn't help notice that the professionals are using very high quality scopes for guiding. For example there are people using 80mm ED scopes for guiding, let alone the even higher end specialised guide scopes.

As for myself, I'm currently using a second hand skywatcher ST80 bought for £40, and I have been quite satisfied with it (so far). So I'm wondering, what are the differences that high end guide scopes can make? 

I think the same question also applies to guide cameras, as I see a lot of very expensive dedicated guide camera in the market. I guess better cameras are able to increase the sensitivity of guiding, and good at suppressing dark currents.

Thanks very much!

[vlaiv]

I don't think they all purchased high end scope with sole purpose of using it as guide scope.

Many people with high end gear started their imaging with simple scopes like ED80. After upgrading to more expensive imaging scope in that class (by class I mean focal length primarily), ED80 remained (they could not part with it or be bothered to sell it) and it was relegated to guide scope role.

There are people that can afford better guide scopes. While scope itself might not bring anything in terms of guiding precision - they justify expense by build quality of such item. Nicer focuser, better stability due to CNC tube rings and so on.

After some time spent in imaging hobby, you start appreciating good guiding (and here I don't mean round stars, I'm referring to guiding your mount as good as it can be guided) as it has direct impact on image quality (sharpness), so you start upgrading your components in order to get best guiding you can have - and this is why people use good guide cameras (and also for similar reasons as above - good guide camera can double as good planetary cam, good EAA/EVAA camera and such).

[paul mc c]

I suppose its like having an old banger of a car,it will get you from A to B,but so will a nice Mercedes,they will do the same job,but if you can afford the high end one thats nice.

[Skipper Billy]

I have used a converted SW finderscope, an ST80, an Evoguide 50 and currently a SW Evostar 72 with various cameras inc Lodestar, Atik GP and currently a ZWO 290MM mono cam.

I have used all the above with short focal length scopes <560mm and to be honest there was nothing to choose between them all. At >1000mm that might be a different story!

The biggest improvement came from making everything screw together and using good quality rings to eliminate flexure.

My current mount would probably guide at <0.5 arc secs total RMS with a toilet roll tube and a webcam. 

The benefits (to me) of my current setup are - its all screwed together, the focuser is lovely to use and stays put, there is no 'droop', the camera is seriously sensitive.  

Would I change it if a nice Borg came up for sale ?? Probably - I like nicely made things!!  Would it work any better - probably not!

 

[Jkulin]

I think the point is being missed here, if you look at Astrobin, it lists the Telescope and the guide scope often as the same, giving the impression of high end guide scopes, that is not the case, they are using Off Axis Guiders (OAG) and when you use one you are using the same telescope as the one to capture the image, thus giving the impression that you have a high end guide scope.

For my 10" RC I use an OAG as it has a focal length of 2000mm, whereas with my Esprit 80 and Esprit 100 I use an ST80 and when using my DSLR I use an Altair Guide Scope

I'm shortly moving the Esprits over to OAG as it makes things so much easier when swapping stuff over and will improve the guiding.

[pete_l]

14 hours ago, jeffwjz said:

I couldn't help notice that the professionals are using very high quality scopes for guiding.

Many retailers terms like "serious" or "experienced" astronomer when trying to sell expensive kit. The notion being that cost equates to commitment or skill or some other factor. That promotes the idea that higher prices equals better - there is a whole new thread waiting for that topic!

But if you are paying, say, £20,000 for a telescope system then a grand or two on a guide scope and guider-cam doesn't make much difference. While you may wonder who would pay that? It's only £100 a week over 4 years. You could spend that watching Chelsea. (And probably end up just as disappointed )