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Old 03-07-2014, 08:39 AM
glend (Glen)
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Guidescope Limitations

I am getting frustrated with the lack of capability of my little Orion Mini-guidescope. Trying to image M17 last night I just could not find a star within the field of view of the 50mm guidescope (even with some adjustment) that had the mass needed for PHD2. Is this normal? Does the use of small guidescopes limit people to concentrating on the same objects over and over that provide a good star for guiding? In the end I gave up on guiding the NEQ6 and just went back to the polar alignment routine in V3.35 to get within a few seconds of the SCP and then used PAE to lock onto M17s position. This worked fine and I got the subs I was after.

Is guiding a lazy solution? Would going to a 80mm guidescope eliminate the issue?
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Old 03-07-2014, 09:10 AM
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Chris85 (Chris)
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What guide camera are you using? I have never failed to get a guide star, in any part of the sky, while using a Qhy5 and my 50mm guide scope.. I did use a uv/ir cut off filter attached to the nose piece, though I doubt it would've had that much of an effect on finding stars.
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Old 03-07-2014, 09:13 AM
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Eden (Brett)
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Hi Glen,

It's frustrating not being able to find a suitable star to guide with.

Auto-guiding is not a lazy solution, it's generally considered to be an essential part of the process if you want to take long exposures of DSO's.

With respect to not being able to find a star with sufficient mass -- were you getting errors from PHD2 about the star being lost, or was it flashing up errors about the mass of the star? What exposure time are you using on your auto-guiding camera?
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Old 03-07-2014, 09:19 AM
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Merlin66 (Ken)
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Double check the focus of the guide camera....
The Orion equivalent to the QHY5 should be able to handle down to 8 mag stars...normally plenty of those around....
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Old 03-07-2014, 09:27 AM
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acropolite (Phil)
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I've had no problems with a SSAG and the mini guider. Might be a problem with your PHD settings.
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Old 03-07-2014, 10:03 AM
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I had issues with an Orion SSAG. Went to Lodestar and never had an issue - I can see the DSO in the guidecam image!!! I use a converted Vixen 7x50 finder for the guidescope - I used to use a Tak finder. These are longer FL than most finders, so work well.
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Old 03-07-2014, 10:08 AM
glend (Glen)
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I can see M17 in the 50mm finderscope but it is onaxis obviously and spot targetted. I am pretty sure that the Orion 50mm guidescope is axis aligned but I can never see the DSO in the guidescope camera.

The guide camera is a ZWO ASI130MM, which is a constant streaming high frame rate camera and care does have to be taken with sync of exposure timing with PHD. Being a fast frame video stream it has to be set for a very short exposure cycle with PHD in the low ms range. This is not the problem, as I can see stars, they are the correct shape, and properly focused. Other people are using the ZWO cameras for guiding without any issues.

I am seeing some PHD problems, sudden white screens, lost of star messages, but this is usually due to loss of sync of the framing. Calibration happens and it guides fine on bright stars like Klaus Media.
I just dont seem to have much in the field of view that I can use for guiding, and may try to mount my ASi130 on my AR102S (600mm shortie) and aim at M17 and see if I can guide ok with that.
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Old 03-07-2014, 10:35 AM
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Quote:
Originally Posted by glend View Post
I can see M17 in the 50mm finderscope but it is onaxis obviously and spot targetted. I am pretty sure that the Orion 50mm guidescope is axis aligned but I can never see the DSO in the guidescope camera.

The guide camera is a ZWO ASI130MM, which is a constant streaming high frame rate camera and care does have to be taken with sync of exposure timing with PHD. Being a fast frame video stream it has to be set for a very short exposure cycle with PHD in the low ms range. This is not the problem, as I can see stars, they are the correct shape, and properly focused. Other people are using the ZWO cameras for guiding without any issues.

I am seeing some PHD problems, sudden white screens, lost of star messages, but this is usually due to loss of sync of the framing. Calibration happens and it guides fine on bright stars like Klaus Media.
I just dont seem to have much in the field of view that I can use for guiding, and may try to mount my ASi130 on my AR102S (600mm shortie) and aim at M17 and see if I can guide ok with that.

I dont use the above camera, but I read the other day that these video cameras need to be set at specific exposures for them to work with PHD, this might be your issue.
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Old 03-07-2014, 10:47 AM
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Guide scopes are a little old fashioned. I try to eliminate them from my system as they usually give substandard results. I would be surprised if a 50mm scope had trouble finding a guide star though. Perhaps its out of focus? A 50mm scope would be quite wide field. I don't know where you image though so if you are in badly light polluted areas that could make sense.

These days an off axis guider is a lot cheaper than they used to be and they work extremely well and reliably.

Teleskop services have a few, Starlight Express sell a few. It depends what camera you are using. DSLR?

Atik, Lacerta, Starlight Express, Teleskop Services from my research all seem to make a good off axis guider at low prices and quite thin so they don't take up a lot of room.

I would go that route.

Guide cameras are more expensive. The latest Lodestar X2 from Starlight Express sounds extremely sensitive. I like my SBIG STi guide camera which works well with CCDsoft and takes autodarks and so gets rid of hot pixels (its clean anyway). Lodestar works with PHD and Maxim not so much CCDSoft.

You should consider the guiding part of your system as vital rather than is it really regarded as without a good guiding system you can't get the longer exposures with sharpness you want no matter how good your mount is.

Greg.
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Old 03-07-2014, 11:58 AM
glend (Glen)
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Thanks folks, I have had an email back from ZWO tech support and they recommended I download PHD 2.3 as that has native ZWO ASI support configured. So I have done that and will try again.
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Old 03-07-2014, 11:59 AM
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ZeroID (Brent)
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I've had PHD issues for ages, mainly, as far as I can determine from the low contrast caused by LP in my location. So I am in process of experimenting ( delayed by the Ob roof being blown off ) with a filter on the guide scope. Not your usual LP type filter but a pale blue C80A camera filter. I tested it through my DSLR on widefeild and it has a similar but much less pronounced profile to a CLS LP. Testing gave a much reduced red glow to the images but still holding close to the real colour on the DSLR, always an issue using a full LP filter such as CLS.
Hopefully I'll finish and re-assemble the system this weekend and get back to my testing. Also will try it on the DSLR for imaging as it gave me a blue\black sky on 20 sec exposures whereas before I would see red intrusion easily by then normally.

All I need to do is paint the roof and remount and align the head and scopes.

And wait for the weather to come right.

Try a blue filter on your guidescope if LP is your issue. Our camera shop was selling them at 5 for $10, they are not needed on a Digital SLR of course so the market has disappeared.
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Old 03-07-2014, 12:46 PM
glend (Glen)
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Light pollution is not a problem here, most clear nights are above 20 on my Sky Quality Meter.
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Old 03-07-2014, 04:08 PM
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Lodestar is well supported (along with many others...) by AstroArt V5.
AA5 covers all my cameras, acquisition/ processing needs as well as providing a very good guider system ( Fabio "upgraded" it recently for spectroscopy - majic!!)
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