SynGuider calibration

[cjdawson]

Hi all.

I had first light with my SynGuider through my ST80 at the weekend.  I had problems finding a guide star, and think that most of the issue was down to me not having spent time calibrating the SynGuider (wanted to make the most of the fantastic weather)

I was using Vega as a guide star, which was extremely bright - it served my purpose, but wasn't ideal really.

What I noticed what as I changed the exposure time, there was only one settings (500) that showed the star, all the rest simply showed noise.

Whilst that was good enough to get me up and running for an M57 shot, it's obviously not going to be productive over time.

So, what I'm wondering is....

Are there any instructions websites that show's how to setup the SynGuider to make it easier to get myself up and running?

I'm looking to be able to use alot dimmer guide stars and also to not have to keep messing with the settings once it's all setup and working well.

This is a project that I can happily do under cloudly skys as I have an artifical star

Can anyone point me in the right direction so that I can get the Guider calibrated for the image capturing part?

[Steve Ward]

http://www.astronomyshed.co.uk/forum/viewtopic.php?f=34&t=3949

[cjdawson]

Thanks Steve.

This is the bit I was having problems with...

5) Go to your chosen object, once your main scope is centered, look on the synguider screen and check that you have stars, follow the instructions in the manual re turning up/down the EXPOSURE setting and the NOISE setting, this is covered fairly well in the manual so doesn't need repeating, BEAR IN MIND that synguider seems to remember noise/exposure settings, so if you change exposure, also check noise levels, I tend to find that noise settings of around 4, 5 or 6 work well for me or at least as a starting point. You're aiming to get a BRI reading of between say 12 to 18, a little either side of this is fine but the nearer to the lower end the better.

Looking at the Synguider instructions it appears to read as if each exposure setting has it's own noise setting as well.  When I get some scope time next (possibly tomorrow evening) I'm going to run though the SynGuider and check to see if this is indeed the case.

Tomorrow would be good as I'm also getting a SkyWatcher Flip Mirror that I'll dedicate to the SynGuider.  Whilst I've parafocalised an eyepiece, it would be much nicer to be able to flip between the Guider and an eyepiece.

The main reason that I ordered the Flip Mirror is that the SynGuider was binding up on the locking knobs of my ST80's diagonal.  So, removing that part from the equation will also mean that I can happy remove the binding issue - which may also effect the focus as I couldn't place the guider snug against the scope.

[Mered]

Funnily enough I had my first go with the Synguider and ST80 combo this weekend. Your experience pretty much mirrors mine!

Next chance I get I will make the parafocal eyepiece and spend a bit more time getting it set up properly.

Other advice I've seen is to mount the ST80 in guidescope rings, rather than bolted rigidly to the main scope. This allows you to tweak the orientation slightly if there are no bright enough guide stars in view (as mentioned in that link).

[cjdawson]

hi Mered.

Yep. as you can see from my profile picture, my ST80 is already on guidescope rings.  That was the only reason that I was able to get the Guider working on Vega whilst imaging M57.   Making the Parafocal eyepiece isn't hard, just don't rush the process.  What I did was take a few minutes to point the synguider to a bright star (I used vega, but that's probably not the best candidate) then slowly turn the focus knob until you achieve focus with the SynGuider.  At that point, remove the guider and replace with an eyepiece, but with the parafocal ring in place (but loose),  now slowly lift the eyepiece until the star is in focus.  Then tighten up the ring.  When you get go of the eyepiece everything should remain in focus.  Replace with the SynGuider and your star should be in the field of view and in focus.  You can double check by knocking the focus out, and refocussing using the eyepiece.  Then switch to the SynGuider and see if it worked.

The process is exactly the same with a Flip Mirror, only you do have the fun of collimating the mirror as well

[Mered]

Thanks

Do you bolt your guide rings directly to the dovetail or do you use clamps?

[cjdawson]

My ring system is the Astro Engineering Parrellel ring system.

Basically, it's two hex bars that go through mounts that screw to the top of my scope.

The bars are tight on the mount and also held in place with lug nuts.

I have both the 5" and 7" rings which I can swap out. They're held in place on the bar with two lug nuts. Onces set, the whole setup is very tightly held in place.

The scope is then held in place in each ring by three threaded bars with knobs on the end. The end that touches the scope have plastic caps so there's no damage.