Guide scope issues

[CaptainShiznit]

Hi all,

I purchased a QHY5 guide camera from astrobuysell that came with a seemingly unbranded 9x50 scope. This is my first attempt at setting up auto guiding using sharpcap pro. The first thing I wanted to do was use the polar align feature however I'm struggling to capture anything at all with the camera. If I point it at something bright, the preview turns white so it is working. When I tried the moon to focus, all I could get was a white blur with circular edges. Dialing down the exposure just turned it grey. I was focusing the whole time but it didn't seem to change anything.

I tried pointing it at some stars such as Sirius and at first I thought it was picking up stars as I could see small white points of light on the preview, however, I then noticed that I could see those same 'stars' no matter where I pointed it (see attached video for an example of this).

I've also attached a picture of the scope. Am I right that to adjust focus I just 'unscrew' the lens? As that's all I seem to be able to do. The collar can then be screwed up to meet the lens to lock it into place.

Any thoughts?

[michael8554]

You're going to have to find the focal point of the scope. 

Point it at the sun (fat chance of that in this weather) without the camera attached  and try to burn a hole in a piece of paper.

Where the paper is situated is where the QHY5 sensor has to be. 

You need to visualise that and translate it into spacers you need to add or subtract. 

Fine focus with whatever changes the distance from the objective to the sensor, which might be the knurled ring on the objective. 

Michael 

[CaptainShiznit]

Finally managed to achieve focus with this. The amount of reading I did, I would say the answers seemed to be 50/50 between either the camera needing to be closer or further from the lens depending on the situation. I couldn't really do anything about making the scope any shorter so I took a punt on these extension tubes: https://www.ebay.co.uk/itm/163922212910

With the 30+10mm tubes I was able to achieve perfect focus on the neighbour's TV aerial around 200m away, with the locking ring still attached.

Just posting this on the off chance someone will find it useful.

Cheers.

[CaptainShiznit]

Just managed to have a little play with my guide scope now that I've got the tube extenders. Managed polar alignment in SharpCap which was a breeze, but I'm struggling with guiding in phd. My scope seems to pickup 'fake' stars. There's a bunch of white specks that show up in the same place no matter where I point it and they look exactly like stars. I've cleaned the lens and the sensor as I noticed them showing up before when I was struggling with focus. I've taken darks in phd and it picked up a few hot pixels (I think it said 6) but it's still seeming to pick these not-stars up. Does anyone have any idea what these are and how to deal with them?

I'm also getting an error when trying to start guiding that says the star did not move enough, and I've tried a good few. I have a feeling these problems are related.

I've given up guiding for tonight as I wanted to get imaging before the clouds rolled in but would appreciate any thoughts for next time.

Cheers.

Edit: just to mention I bought this guide scope and QHY5 mono from astrobuysell used.

Edited February 13, 2020 by CaptainShiznit

[Davey-T]

You can select a star manually and avoid those little bright dots, the star not moved is usually because it's on a hot pixel and not a star.

If you're sure it's not trying to calibrate on a hot pixel have a play with the step size to increase how far it moves between calibration images. 

Dave

[CaptainShiznit]

17 minutes ago, Davey-T said:

You can select a star manually and avoid those little bright dots, the star not moved is usually because it's on a hot pixel and not a star.

If you're sure it's not trying to calibrate on a hot pixel have a play with the step size to increase how far it moves between calibration images. 

Dave

Cheers Dave. I had a look for that after googling the problem. Where do I find that setting?

[Davey-T]

16 minutes ago, CaptainShiznit said:

Cheers Dave. I had a look for that after googling the problem. Where do I find that setting?

Click on the brain icon at the bottom of the PHD screen and then the guide tab and you should see step size.

Dave