I recently bought a Paramount MX and have it balanced, polar aligned and an initial supermodel done and now wish to train out any PEC in the MX. When I went to setup the guide chip in my STT-8300M (I had not used the guide chip before) it doesn't seem to show anything (have done the mirror slide adjustment and used the focus nob over varying time intervals (2-15 secs) and incremental changes in focus and nothing visible apart from diagonal dots of lines and noise (main camera shows image ok though). Tried this in CCDOps (8 sec exposure attached) and Sky-X (4 sec attached) and neither shows any stars visible. Tried differing star fields also and nothing (again main CCD shows stars ok). Any suggestions on what I could be doing wrong or contacts to try?
Thx for any help you can offer and hope you all enjoyed your Christmas
I think that you need to do the pick off prism adjustment whilst using a fairly evenly illuminated main chip. So setup like doing flats. Then just wind in the pick off prism until you start to see a shadow on the main CCD. You should now have the POP in the FOV of the scope. Now await darkness, find a nice piece of sky with plenty of stars, anywhere in the milky way or LMC will do fine, focus the main scope. Start taking guider shots, 3 seconds should be heaps to find something, though if your focus is way off then you may need to up this to see the out of focus star (which scope BTW?), then simply focus with the focus knob. I have a piece of duck tape to hold focus rather than use the Allen key screw to lock focus as I find that the focus changes if I use the screw.
I had adjusted the prism 1st and the manual says to just remove the shadow and then taped over the knob. Maybe I have to do it slightly less? Scope is a C11 EdgeHD.
Thx
Peter
Quote:
Originally Posted by rat156
Hi Peter,
I think that you need to do the pick off prism adjustment whilst using a fairly evenly illuminated main chip. So setup like doing flats. Then just wind in the pick off prism until you start to see a shadow on the main CCD. You should now have the POP in the FOV of the scope. Now await darkness, find a nice piece of sky with plenty of stars, anywhere in the milky way or LMC will do fine, focus the main scope. Start taking guider shots, 3 seconds should be heaps to find something, though if your focus is way off then you may need to up this to see the out of focus star (which scope BTW?), then simply focus with the focus knob. I have a piece of duck tape to hold focus rather than use the Allen key screw to lock focus as I find that the focus changes if I use the screw.
Ok, at that FL you might find it harder than you think to find stars on the guide cam. Point to a really bright one, the brightest you can find, even if your off a bit it will show artifacts to help you point.
Your going to find OAG hard without a rotator IMO at that FL
To reduce the focal length I placed in my old f6.3 focal reducer, focused it in on the main chip which is fine but still cannot find any stars on the guider chip. Had adjusted the pick of mirror/prism for the new setup but still nothing visible. Any other suggestions?
Next thing to do is to get a nice bright star on the main CCD, Sirius will do, or Canopus.
Now using focus mode on the main CCD, push the star to the top centre of the CCD, noting the direction you have to move the mount in order to do this. It will be easier if this movement is solely in one axis, either RA or DEC.
Now switch to the guider CCD and put it in focus mode with very short exposures, <1s should be fine for either of the stars mentioned. Now, slowly move the mount to keep pushing the star in the previous direction, i.e. push it off the main CCD, before too long you should see the star in the guider CCD.
Most likely you will see a star that is wildly out of focus on the guider CCD, focus using the focus knob on the FW-8G.
The added advantage of this is that you get a feel for how far from the main CCD image your guider FOV is.
If you do not see a star then the guider CCD may be faulty, mount it in the back of the main scope (like for planetary imaging) and aim at something bright, one of the aforementioned stars would be good. Make sure that you are getting an image.
Be careful with focal reducers, they can distort the stars that are at the edge of field quite a lot.
Thx Stuart - will try that tonight - after the tennis as we are going to see Federer, etc. tonight in Brisbane . I had tried on Sirius, etc. and had not seen any bright edges but will try as you suggest toward the top edge. Thx for your help.
Tried that tonight Stuart (last 2 nights were cloudy) on Sirius and still does not show in the guider. It is an SBIG inbuilt guider chip in front of the filters - STT8300M so cannot put it in separately to check. Thx for your help but seems like it may be faulty?
I have the a similar setup (STT8300 with CFW-8G) with a different scope, so the FOV is different, but you should be able to find a bright star by pushing the bright star off the top centre of the imaging CCD, sometimes there's a fair "gap" between the imaging and guide CCD.
It really looks like the guide CCD may be faulty, did you buy it in Aus? If so then the supplier should be able to take it back and test it for you at least.
You could take the camera off and shine a torch onto the ccd's. This will tell you if it is working or not.
Maybe dim the torch a little, so you don't blast the ccd's to much but they should be able to handle it. Or point the ccd into the direction of the light.
Thx Stuart & Bram; Peter Ward at ATO and the guys at SBIG in the USA have been fantastic and given me some feedback on HDMI cable direction and they also suggested testing the guide chip as you mentioned and it is working. They gave me some fairly specific directions on moving a star into the guider also but it has been cloudy up here ever since so I haven't had a chance to try again with that . If I still can't sort it out, Peter has asked me to send it back and he will check it out. Thank you all for your feedback and ideas.
. I had tried on Sirius, etc. and had not seen any bright edges but will try as you suggest toward the top edge. Thx for your help.
. If I still can't sort it out, Peter has asked me to send it back and he will check it out. Thank you all for your feedback and ideas.
