Guide scope image quality

[69boss302]

I got in my guide scope and camera today, and started messing with it tonight....until the clouds rolled in

For a scope, I got Orion 60mm Guide Scope with Helical Focuser, and for the camera, I got the ZWO  ASI290mm.   If it matters, its sitting on a Zenithstar 73. 

I entered the camera info in PHD2, but when I went to cycle through pictures for focusing every second or so, the image quality was horrible.  Yes, it was a full moon, light clouds and bortle 5 so hardly good conditions at all.  One of the issues I saw was when focusing it, I had to focus all the way out, and it was still blurry. I then loosened the thumb screws on the camera and took it out f the tube as far as it would go without falling out. It got better but feel it could still go more. Maybe the two arent compatible? Image below of what I got, and some settings.  On top of it all, I could never get PHD2 to pick a star and start tracking.

Bob

[CCD-Freak]

They typically have lots of chromatic aberration so the focus is quite soft.  I use a UV-IR filter to help improve the image.   PHD will normally guide well even though the stars look bad.

 

[ONIKKINEN]

I have the TS 60m f/4 guidescope, which looks like it might be the same as yours but in a different package. Stars are awful, even with a UV/IR cut filter.

 

But it doesnt seem to matter at all. Focus can be quite a lot out before i notice anything. I typically dont refocus after setup. 

 

If the Orion 60mm is like the TS, you want to buy an extender (20mm probably fine) for the camera because the focal point is pretty far behind the scope.

[69boss302]

Thanks guys, Ill give it another shot tonight. Hopefully itll be a little darker. Ill also see if I can get an extension tube.

 

[michael8554]

PHD2 isn't an imaging prog, so the display was designed just good enough to display stars.

I would use something like SharpCap to give a true indication of the guidescope quality.

Your exposure is only 0.5 seconds, up it to 1.5 or 2 seconds and the stars may be good enough for PHD2 to select one when you hit the Loop button.

Michael

[69boss302]

@michael8554 I think if I have it any longer, it gets too bright and is washed out, but Ill try again.  Fair point on PHD2, Ill try sharpcap and see what it looks like through that.

[ollypenrice]

Although fine focus isn't critical for guiding, you do want to get it reasonably close. It sounds as if you need an extender, and you don't want the camera inserted by the skin of its teeth because that risks making it move a bit in the guide scope. One common 'extender' which people sometimes have lying about is an old or low grade Barlow. If you have one, simply discard the lens and use the body as an extender.

Olly

[newbie alert]

Your guide loop is far too short at .5 secs, try 2 secs plus.. if its too bright then alter the exposure and gain.. it won't just guide as it's not calibrated 

With your guide scope if you need more hanging out the back make sure the lens at the front is screwed in 

[malc-c]

It would seem that the focal point of the scope is still slightly beyond the CCD when the focuser is fully out.  If there is a way to shim the camera out slightly more that may work.  Also googling the camera shows it with a lens fitted.  This may be an issue, as in my experience the image from the scope is focused direct onto the CCD without anything in between.

Also in PHD the slider next to the exposure setting adjust the contrast on the image which can also help reduce the stars to points rather then over exposed blobs.

Sharpcap would be a better application for image gathering, but then you are using a guide scope which has the most basic of optics so don't expect too much

[69boss302]

Thanks @malc-c.  I did order an extension tube for the camera, so that should be in tomorrow hopefully to try. The slider youre talking about is already maxed out. If I move it in the other direction the image is just bright white   

I also notice I had the focal length wrong in the camera settings, so I just now changed that, but wont be able to try it for quite some time, as weather here is not looking promising at all

[Budgie1]

8 hours ago, 69boss302 said:

The slider youre talking about is already maxed out. If I move it in the other direction the image is just bright white  

I see your camera gain is set to 95 in the PHD2 screenshot. You could try lowing this setting, I've read elsewhere that somewhere between 35 & 50 is a good area to try for the ASI290 to stop the stars from being over exposed. It will also give you more control with the slider and allow you to increase the exposures to 1.5 - 2s.

[michael8554]

On 21/10/2021 at 14:51, 69boss302 said:

@michael8554 I think if I have it any longer, it gets too bright and is washed out, but Ill try again.

You could try the Camera Gain "Reset" button in the Camera window, my ASI120MM defaults to 48.

Whatever the exposure setting in seconds, when you hit the autoselect  button, PHD2 will select a suitably exposed guide star for guiding.

Don't manually select a guidestar, leave it to PHD2.

Michael

[Paul M]

I'm with @michael8554, try 2 or more seconds, camera gain at default and adjust the screen gamma slider (bottom left) for a nicer display. I don't think the gamma setting affects the internal algorithm just how it's viewed on screen.

With my 50mm guidescope and ASI120MM I use 2 secs and the gamma slider is usually in the l/h 3rd of its travel to give a reasonably sharp display.

Having said all that, your focus does look soft  

[69boss302]

I wanted to give an update on this. Thank you for your recommendations... I got an extension tube, dialed back my camera gain to 50 and upped the camera cycle in PHD2 to 2 seconds and I was able to get pin point stars for guiding!   PHD2  now guides and locks quickly and easily. Thank you!

bob

[malc-c]

Glad to hear you've sorted the issue... thanks for the closure