Guiding choice of stars

[SteveBz]

Hi Guys,

I'm using a not very sensitive webcam on a 225mm FL 60 mm diameter scope to do my guiding and I spend much too much time looking for a guide star.

I wondered if I used a .5x focal reducer, I would get more field of vision, a faster guidescope and whether this would help at all, or would the resulting loss in accuracy make it all meaningless.

Regards

Steve. 

[michaelmorris]

I'm afraid I suspect by far the most effective way of increasing the number of available guide stars is to buy a much more sensitive camera.  You should be able to pick up a 1st generation Imaging Source camera such as the DFK21 or DMK21 for around £100 or less secondhand.  These make cracking guide cameras.  The cheapest ZWO cameras can be bought brand new for not much more than £100.

 

 

[carastro]

I agree with Michael, no point in struggling.

Carole 

[Guest]

You could also have a look to this article, https://www.firstlightoptics.com/guide-cameras/qhy-miniguidescope-with-mount.html  MiniGuideScope with the Mount also.. and with the QHY5-II CCD you will have a perfect GUIDE CCD..

Good luck

Martin

[SteveBz]

3 hours ago, michaelmorris said:

I'm afraid I suspect by far the most effective way of increasing the number of available guide stars is to buy a much more sensitive camera.  You should be able to pick up a 1st generation Imaging Source camera such as the DFK21 or DMK21 for around £100 or less secondhand.  These make cracking guide cameras.  The cheapest ZWO cameras can be bought brand new for not much more than £100.

 

 

I do agree with you, but the other problem is that I bought a qhy5 mono (the herritage model) only to find that getting to work on my Linux laptop was nigh on impossible. I should have held out for the zwo asi120mn, but impetuosity won the day.

I'm probably going to have to resell it, buy the zwo and suck up the difference.

But you're all telling me what I pretty much suspected. I'm really being held back by lack of guiding. The few clear nights we get are being messed up by not having a proper guide setup.

Thanks for your support.

Regards

Steve.

[Guest]

Hi Steve,

You should try to google QHY5 LINUX or something simliar.. And you will find the Info, that a driver for LINUX is available.. http://qhyccd.com/bbs/index.php?topic=4026.45

have a look to the Link, maybe you can still use your QHYCCD as a guider..

I am not a LINUX user..

Martin

 

[furrysocks2]

4 hours ago, SteveBz said:

Hi Guys,

I'm using a not very sensitive webcam on a 225mm FL 60 mm diameter scope to do my guiding and I spend much too much time looking for a guide star.

I wondered if I used a .5x focal reducer, I would get more field of vision, a faster guidescope and whether this would help at all, or would the resulting loss in accuracy make it all meaningless.

Regards

Steve. 

I don't guide (but hope to), and was wondering:

• what webcam are you using?
• what is your pixel scale, both for imaging and for the guide webcam?

[Guest]

Steve, hae a look here, maybe also could help you ??

https://sourceforge.net/projects/linguider/

 

Cheers

Martin

[SteveBz]

15 hours ago, artem said:

Hi Steve,

You should try to google QHY5 LINUX or something simliar.. And you will find the Info, that a driver for LINUX is available.. http://qhyccd.com/bbs/index.php?topic=4026.45

have a look to the Link, maybe you can still use your QHYCCD as a guider..

I am not a LINUX user..

Martin

 

Nice that you should post that, I was just signing up to it when your message arrived!

[SteveBz]

15 hours ago, furrysocks2 said:

I don't guide (but hope to), and was wondering:

• what webcam are you using?
• what is your pixel scale, both for imaging and for the guide webcam?

My DSLR is a Nikon D5000, and my scope is an 8" Newtonian with Focal Length = 1000mm.  According to dso-browser, which knows about these things, my pixel scale is 1.120 arcsec / pixel. https://dso-browser.com/picture/view/22695/dumbbell-nebula/M/27/planetary-nebula/by-stevebz

For the guide cam, I'm using this:

https://www.ebay.co.uk/itm/0-91-1-25-Smart-Webcam-2MP-USB-Telescope-Microscope-Electronic-Eyepiece-TRACK/152132740729?hash=item236bd16679:g:9BoAAOSw5ZBWLxZi

With this guidescope:
http://www.rothervalleyoptics.co.uk/antares-versascope-10-x-60-guiding-x-hair-finderscope.html

Regarding the pixel scale, I've just Googled the calculation (pixel size in mm/focal length in mm * 206265), and mine is about 2.6.  Looks a bit larger than it could be.  Thanks for asking the question.  I have a longer FL scope which I could use if necessary, it would be F/7 rather than F/3.5, so I'd need to up the sensitivity of the camera a lot.

But the sensitivity of the cam is not good enough.  If I lock onto a bright star it's fine.

I really need to get my QHY5 working on Linux, which I'm sure would do the job.

Regards

Steve

[furrysocks2]

Hi, Steve.

Glad you got my thinking - I was just working through whether a FR might benefit you or not.

I've got the same webcam and used to use it for lunar, though it's now retired.

 

12 minutes ago, SteveBz said:

1.120 arcsec / pixel

about 2.6

From https://stargazerslounge.com/topic/188777-phd-guiding-basic-use-and-troubleshooting/:

Quote

So a good rule of thumb is your imaging pixel scale should be no more than four times your guiding pixel scale.

If I've got it the right way round, your imaging pixel scale is ~2.3x your guiding pixel scale. A 0.5x FR would take that to ~4.6x, though you could play with spacing of the FR to change the 0.5x ratio. You may also need significant inwards travel on the guide scope to bring to focus. You may benefit I guess, I can't advise though. I don't know if the compressed codec out of the webcam might also affect guiding - I've been playing with webcams on the bench a bit, but not yet on the sky.

QHY5 sounds like the better path to take though. Good luck.

Matt.

 

[SteveBz]

20 hours ago, furrysocks2 said:

QHY5 sounds like the better path to take though.

It's the path I want to take, but I've completely failed to get the Linux driver to install. I'm currently on their support site trying to get it to install, but no luck so far.