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Autoguiding


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I never seem to be able to get my scope to track well, even with a successful 3-star align and objects being dead centre. I know I should ensure my mount is level, which I don't :( but thought about getting into autoguiding now I've managed to get going with astrophotography.

Can anyone advise on the cheapest set-up: guide scope, sw etc?

Alexxx

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You are still going to need to make sure your mount is level and correctly polar aligned to get the best out of any type of imaging , guiding will not cure this.

Why not spend some time setting your mount up and see how long your subs increase , you dont say what scope / mount combination you have but i would of thought 60-90 secs are achievable unless you are imaging at a long focal length.

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Hi Alex, I hope that means the handset is working well :(

I would echo Kai's comments, with a good setup I can easily achieve 3 min+ subs unguided. Equally when I've made a mistake or rushed soemthing I can't even get past 30 seconds without the sub lookng terrible.

What mount /scope combination are you using at the moment?

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Yes, the handset's working well now, apart from seizing up at one point, so thank you!

I have a Skywatcher 200P on an HEQ5 mount. I polar align using the reticule and setting circles (from Astrobaby's turorial) and which seems to work (calibrated reticule, set Polaris transit etc, etc). I would have thought that the 3-star align would be out if my polar alighnment was out? So, apart from a non-level scope, what could I be doing wrong??

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Have you calibrated the Polarscope ? , if you have then all i ever did was to use Polarfinder and place Polaris in the small round circle.

Next time you are out forget about the Handset alignment, just have it running , level the scope , set Polaris and point the scope to the East or the West at about 45 degrees and take some images and see how you go from there.

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That's where the auto guiding comes in...the mount may be pretty well aligned but the accuracy of the drives - variations in the gears etc etc can cause the tracking to be less than accurate. The idea of autoguiding is to "lock on" to a star and hold it perfectly in place (within a fraction of a pixel) - this is done by measuring the error (very slight movement of the star image) and issuing a correction signal to the drive electronics to move the star back to position - before the movement even becomes noticable in the image .....white mans majic.

Seriously, if our mounts tracked well, we wouldn't need to go to all this hassle about autoguiding....such is life.

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Im also starting this hobby and asking Q's:

If mount is autoguided, how much different mounts have difference in accuracy? For example EG3..EG6..Losmandy ect..

What kind of focal lenght and quality is needed for guiding scope?

And as the OP asked: Can anyone advise on the cheapest set-up: guide scope, sw etc? I have also skyliner 1200/200mm(f6)

How long subs can one have without guiding, if using shorter focals (85mm..300mm)?

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To ditto Ken, you do not, in fact, have to have a level mount, just a polar aligned one. The very accurate Takahashi mounts don't even have adjustable legs.

Don't confuse pointing accuracy with tracking accuracy. They are not connected.

The difference between mounts in terms of tracking accuracy (lack of periodic error) is enormous and closely related to price. Premium mounts run at a couple of arcseconds of error while budget mounts like the NEQ6 run more like 20 or more arcseconds. But now for the good news; mounts like the NEQ6 autoguide out very well and, unless you are using a long focal length, will allow you to get excellent results. Just get into autoguiding! I can't help on the cheapest option because I see it as the most important part of the setup and don't skimp on it. But an ST80 with QHY5 seems to deliver the goods for lots of SGL members, running in the free PHD software.

Olly

Edited by ollypenrice
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I have a Synguider running on a Skywatcher ST 80. ST80 bought second hand including guiderings and total cost ~300 quid. Not a bad, very portable guiding solution IMHO.

HTH, Ian

Edited by x6gas
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There's some debate over using an 8 x 50 SW finder as a guider with a standard web cam and adapter from Modern Astronomy. I was going down that route the week an HEQ5 / ST80 / QHT5 came up for grabs on the FS section. If money is tight then for £60 - £70 for the adapter and camera it would give you a means of auto guiding without hitting your bank balance too hard :)

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There's some debate over using an 8 x 50 SW finder as a guider with a standard web cam and adapter from Modern Astronomy

The problem with webcams is that unless you're planning to do the long exposure mod, they simply don't expose for long enough to grab only but the brightest of stars. Time you add in the cost/time for the mod, plus either a guideport box or go the EQMOD route buying the necessary lead, then you might as well get a proper guidecam with a ST4 port.

IMO, spend a little more and make it hassle free. Get a specific guide camera like the QHY5, a small cheap refractor and a side by side bar. Install PHD on your imaging computer and off you go. In the 3-odd years I used that setup, it never failed :).

Tony..

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Alex please dont take this the wrong way but names , pictures and links will get you even more confused than you are now.

Why not spend some practical time with somebody at a Star Party for example and see the equipment / process they go through , you will learn faster and actually get a "feel" for what you need and if its the right thing for you.

Im sure one of the seasoned imagers wouldnt mind :)

Edited by Kai
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Hi Alex, QHY5 / PhD autoguiding works fine for me... I just use an 8X50 Celestron finder, eyepiece removed and QHY5 screwed via an adapter I got from Modern Astronomy. In fact, it was Bernard at Modern Astronomy who suggested this setup to me. The whole lot is on my main tube assembly, attached with a TS Optics SuHa50 mount. I get very acceptable results from a relatively inexpensive and simple setup. Nothing fancy, like Merlin66 said... KISS

Jenna

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Alex,

Hope this helps, but I have to agree, if you can find someone local who can help show you the settings etc. Doing it on your own is a steep learning curve, as I'm finding out.

Anyway, if you want to convert your SW finder and connect a web cam or preferably a QHY5 then you'll need a T mount adapter like this

guideadapter.jpg

This replaced the eyepiece and allows the connection of the camera like this

finderguider.jpg

I would have to agree, you will be better off using a QHY5 for guiding than a web cam, but the suggestion was more for information only... it (as pointed out) has drawbacks as it lack the exposures to pick out fainter stars.

The alternative "standard" seems to be the SW ST80 with an QHY5 camera, often piggybacked on top of the main scope, or using brackets and dovetails, along side it. There are lots of examples of this - best place would be to look in the thread of "show us your equipment" that's currently running.

PHD seems to be the defacto freeware program to handle the guiding, and preferred use is with EQMOD to control the scope. The QHY5 also has a ST4 port so if you control the scope via the handset you can plug the camera directly into the handset / mount if you don't use a laptop

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Thanks guys. I do think a demo will be needed. Mind you, I really don't have the money for a guide camera. I was hoping that my Phillips webcam would be suitable but obviously not. I'll just have to get used to sub-standard pics for the time being. Very frustrating!

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Alex, for £29, the cost of an adapter from Modern Astronomy to connect the Phillips webcam, you could always give it a go. If it works out within the limitations of the exposures then all well and good. If you find that you need to point it at a very bright star to make it practical, then look modding the webcam for long exposures. However, it's worth considering purchasing secondhand. Average price for a secondhand QHY5 is £110... that's only a little more than the cost of a pre-modded long exposure webcam (typically £90 off e-bay)

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