DIY webcam autoguider setup

[Fulhair]

Hi all!

I want to autoguide on my skywatcher 200p for astrophotography and as price is a major factor, I want to use the 9 x 50 finderscope for the job with PHD. A variation had been done on this before (http://astrocasto.blogspot.co.nz/2012/02/how-to-set-up-guiding-system-for-your.html).  I already had an old logitec 4000 webcam and bought adaptor from Modern astronomy (for the spc900). It al seems to fit together reasonably well with a few caveats.

Wondering if anyone has experience of this can offer guidance.

1. I have to screw in the adaptor and the webcam as far in as they will go but cannot acheieve focus to infinity, only to 20 metres or so. The only option is to remove the locking ring from the from thread carrying the lens. I can then get the focus to infintiy but it seems rather 'heath robbinson'. Any other way I can make this work?

2. The webcam has an IR filter on it. I can remove this but not sure if I should or not. I've read opinions either way on this.

3. I tried the finderscope/webcam set up a night or two ago but could see any stars through it. Could focus on the moon well enough, even in partial eclise, but no stars. Are there a particular settings to use? I have not yet disabled the green led on the webcam but not sure if any light leaking could be the cause.

Any advice is welcome

Cheers

Fulhair

[Shelster1973]

Fulhair,

I had similar issues when I tried to use a webcam for guiding with.  Had the 1st one regarding the locking ring, but I removed it (am taking it you are refering ot the locking ring on the front of the finder scope here).  It should cause you no issues with it having been removed.  If you want to keep it in place thena smally blob of hot melt glue will keep it from rotating.  That can easily be removed without damage to the finderscope too.

With regards to the filter, some say leave it in, some say remove it as you say.  I removed mine, but don't think that was the cause of the issues i had of not being able to use a webcam as a guide cam.

The last one is the biggy and the reason I finally decided to bite the bullet and buy a dedicated guidecam.  I had serious issues of being able to find any stars to guide on.  The big reason for this is that without being modded, webcamsa re very limited in their maximum exposure times.  If you are luck you can get 1/3rd of a second exposure.  With a dedicated guidecam you are looking at exposures of 1 sec at least to be able to get useable guide stars.  It can be used if you are imaging object shttaa have very bright stars nearby, but for ones that don' have it then you are looking at gettign a dedicated guide cam

I had several weeks of frustration and went through 3 different webcams to see if using a different one would work, but finally decided that it was not worth the stress and managed to find a second hand QHYL-II here on the classifieds.  Not sure what classifieds there are down that side of the globe, but you may find something.

On the positive, you have proven that you can focus in on the moon so you now have a cam to image that with