Guiding Options

[ollypenrice]

Finder guiders are fine and the Altair Astro one is good. It locks up nice and tight. However, the longer FL of the 80 means it can guide longer imaging FLs should you ever need to do so. For your present rig either will do the job, I'm sure.

Olly

[Marky1973]

But the ST80 would, perhaps, be a better long term investment if I was going to up the scope collection and include something with a longer FL?

Although if I get the ST80, maybe I'll have to push the budget to an EQ6...you know, just to be sure of the weight! 

But the Altair kit is quite dinky....

Decisions, decisions......

Thanks again everyone, this thread has been a massive help. 

[Zakalwe]

An OAG on a wide-field 80mm scope is overkill. OAGs are finicky to setup, and are a complete pain in the bum if you are using a focal reducer/field flattener. Trying to get the guide and imaging camera parfocal AND maintaining the correct focal reducer spacing can take a fair bit of setting up. Add in a filter-wheel if you want to go mono and you can easily lose an afternoon messing about.

An OAG is necessary in situations where you are using long focal lengths or experience mirror flop. An 80mm wide-field scope doesn't warrant all the hassle.

I've recently changed from an OAG on my 115mm triplet to a ST80 guidescope. Much easier to use.

[Marky1973]

Thanks Zak - which camera are you using to guide with the ST80?

[Zakalwe]

Thanks Zak - which camera are you using to guide with the ST80?

QHY5L-II. At f5 though, you will have no problem finding a guide-star. I'm sure that a cheaper guide-camera would work just as well.

[Marky1973]

Yeah, that's the next decision - although I quite liked the idea of the QHY5L-ii to play around with some (mono) planetary as well.

[ollypenrice]

An OAG on a wide-field 80mm scope is overkill. OAGs are finicky to setup, and are a complete pain in the bum if you are using a focal reducer/field flattener. Trying to get the guide and imaging camera parfocal AND maintaining the correct focal reducer spacing can take a fair bit of setting up. Add in a filter-wheel if you want to go mono and you can easily lose an afternoon messing about.

An OAG is necessary in situations where you are using long focal lengths or experience mirror flop. An 80mm wide-field scope doesn't warrant all the hassle.

I've recently changed from an OAG on my 115mm triplet to a ST80 guidescope. Much easier to use.

I know Zakalwe is a motorcycle enthusiast so he'll see the point in this description of the legendary 1000cc Vincent. 'It's a solution looking for a problem.' Using an OAG on a small refractor is precisely that and is a good way to generate a few problems into the bargain!

Olly

[Zakalwe]

I know Zakalwe is a motorcycle enthusiast so he'll see the point in this description of the legendary 1000cc Vincent. 'It's a solution looking for a problem.' Using an OAG on a small refractor is precisely that and is a good way to generate a few problems into the bargain!

Olly

:grin: :icon_salut:

OAGs also can give pretty horrible star shapes too. PHD seems happy enough to guide with them, but if you are trying to diagnose problems with guiding* then it's one less thing to worry about.

*most times it works fine, but when it starts to go wrong then it can be a PITA to diagnose the problem.

[Marky1973]

And maybe steer clear of the motorcycle analogies - my last experience of motorcyles was being wiped out by a white van while on my Ducati Monster.... I am hoping that getting into guiding will be less painful.... or at least result in fewer cracked ribs....

[Zakalwe]

. I am hoping that getting into guiding will be less painful....

Don't bet the mortgage on it... :grin:

[D4N]

Yeh I've seen oval stars on the OAG, turns out I had knocked the prism out of position.

My main reason for having one on a small frac is weight, my mount would not be happy doing ten min subs if I put two scopes on it

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[Marky1973]

What mount do you use D4N?

[Tinker1947]

I have a ST-80 guide scope it needs a few extension to get it to focus but that's it, bolt it on your scope on your sorted, going a bit further put some tube rings on it and align it so the PHD screen shows the chosen DSO in its centre as well as the center  of you imagine rig and your in the fast lane, slew,  centre on PHD, take a image its as quick as that......

[Marky1973]

Looks easy enough! Maybe I will go back to the original idea then.....just seen a nearly-new ST80 for a decent price on Astro Buy and Sell and I need to keep my costs down.....

[D4N]

What mount do you use D4N?

iOptron SmartEQ Pro.

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