Home Made Mount - Auto Guiding Help Please

[JamesF]

Got the guide scope, just need the guide camera.......

http://www.astrobuysell.com/uk/propview.php?view=74796

Perhaps?  No interest in the sale.  Just noticed it as I was browsing...

James

[Matt Sz]

Thanks For that James, I have just payed the guy for it! He's posting it to me tomorrow!

Now I have the potential for a great guiding set up, I will let you guys know what improvements it brings.  Really looking forward to trying this out! 

Cheers

Matt

[Matt Sz]

Well!  Got the QHY5 camera and the ST80 and have had a play around with them the other day while the clouds were hiding

Frustratingly I had problems though......., I thought there might be a learning curve using these cameras, but I think I'm missing something fundamental somehow.....?  Apart from not being able to get Guidemaster to recognise the camera, even though I have downloaded the plug in, which is annoying as I prefer this to PHD.....I just couldn't get any stars on the screen

I connected the camera to the ST80 using an old Barlow with the lens removed, pointed it to the sky and opened up PHD to get the camera running.  It connected and the red LED on the camera was flashing in time to the exposure length and I had the black background on the screen with the hot pixels all over the place (these only started showing when the exposure time was set to around 2 or 3 seconds.  I tried slowly adjusting the focus all the way out and then all the way in, then out, then in, then out......... and could not get anything to change on the screen!!  I have read countless other peoples reports on both this forum and other forums with the same issues, but there doesn't seem to be a consistent solution where I could say "oh yes that's what I need to do".  I have just made up an extra long extension tube to try out when the sky comes back, as I have read that some people need the extra back focus, but what's really confusing me is this........When the diagonal is in the scope and I have my 32mm eyepiece in, the focus point is about a couple of mm's from the fully wound in position, which I thought was a bit odd!!  So logic would tell me that if you remove the diagonal and add the Barlow, then add the camera, there should be loads of room to wind out the draw tube to bring the camera to focus!! The diagonal I'm now exchanging for the Barlow has a length of approx 76mm compared to the Barlow of 36mm, leaving a difference of 40mm, requiring the focuser to be wound out 40mm to match where the diagonal originally took the eyepiece to focus (bearing in mind that I have approx 60mm back focus travel left), but then I'm thinking that you would need to wind back in slightly anyway to bring the camera chip to the focal point!, or have I got something wrong??  I have tried different exposure times and moving the slider in the PHD software to the left, but then the screen just fills up with noise and banding!

I have also tried QG Video and get the same result....

I have purchased this camera second hand and I'm now worried that it could be a dud!!  Sorry for the long post, but I thought it best to give as much info as possible to help get a diagnosis   Any help would be really appreciated please!  Thanks

[JamesF]

You could try it during the day to find the correct focusing point using a distant landmark, perhaps.  Also possibly with your old guide scope, since you know where the focal plane is with that?

If the camera appears to respond to dark and light (even just covering it with your hand) then I'd assume for the time being that it works.

The Moon is always a good first target for setting things up in the dark given that it's usually pretty hard to miss.  I've honestly no idea if it's about at the moment.  I've not seen the sky for two months

James

[Chris]

Hi, firstly congrats on building your own mount it looks great and welcome to SGL

Despite imaging for a couple of years myself I haven't done so guided so forgive me if I'm wrong but could some of the problems you are facing with trailing stars be down to your custom gearing not being the same as standard off the shelf mounts? 

There was a thread about belt drive modding EQ6 mounts and I'm sure it mentioned having to alter something in the software due to the change in gearing?

Found it! see below:

http://stargazerslounge.com/topic/119826-eq6-belt-drive-modification/

also good luck with your latest guide cam issue, I'm sure someone will be along to help with this soon

Chris

[Matt Sz]

Thanks for the kind words Chris!  I'm on the case with the trailing issue, as my mate Tim is in the process of modding the stepper motor drivers to enable adjustments in the speed, then I will be able to slow the tracking down to where it needs to be

James, yea I nearly got the old Tasco out that night do do exactly that, but ran out of time in the end, and as you say I'm still waiting for the sky to re appear

Fortunately the camera does respond to light and dark by me putting my hand over it, so as you say, should be ok...

[Matt Sz]

At last the clouds have gone and I've managed to give it another go and it works!!  I'm so pleased...   I could see 3 or 4 stars on the screen.  I knew they were stars because they were moving across the screen due to the fact that I had just mounted the ST80 in an old EQ1 mount and just plonked it on the floor roughly pointing it towards the pole star   I set the gain right up at 95% and the exposure time was set at 0.2 sec. This seemed to do the trick!  Thanks everyone for your pointers, much appreciated.  Watch this space for when I try it out on the proper mount...

Cheers,

Matt

[Matt Sz]

Oh forgot to say, the focus point of this camera has worked out at 109mm from the focuser casting face to the shoulder of the camera where it butts up to the extension tube end.  This explains why I couldn't get it to work last time!!

[Matt Sz]

Hmmm, just realised, the extra extension piece wasn't needed, I must be half asleep!!  I have reverted back to just the single Barlow extension piece.  The 109mm is easily achieved by just winding the focuser out  a bit more.  When I tried this the first time the other day, I must have been moving the focuser too quickly, or perhaps there where no bright enough stars in the field of view at the time??  I don't know....Either way, it's sorted now and I can move onto the next stage.  Hopefully the magic measurement of 109mm will help someone else starting out with this set up