Hi
PHD is a great guiding program but I have noticed on recent and earlier threads that some have problems with its sensitivity in displaying suitable guiding stars.
I was previously guiding with a DSI Colour camera but when I had the above difficulty I was advised to get a Q-Guider mono camera. However, I now find that this camera is no more sensitive than the DSI with regard to obtaining visible guiding stars.
I don't think that this is so much a problem with the camera but lack of gain in the PHD software.
Is there any way I can improve the sensitivity of PHD when using the Q-Guider? Or alternatively, another guiding program that does not have this problem and can use the Q-Guider driver?
I am using a 150mm Mak at f8 as the guide scope so aperture should not be my problem??. Even stars of mag 6 when targetted show up pretty dim on PHD.
Cheers Peter
I use a SW ED80, f/7.5 as a guidescope with an original Q-Guider, never had any problems getting a guide star, perhaps try using a longer exposure, say 2-2.5 seconds and take a Dark, you will get more contrast.
Try guidemaster at http://www.guidemaster.de/index_en.asp
You also need the newer drivers for the Qguide as they seem to have brighter stars.
I use mine through a 127mm APO and can always get a guide star with a 1 sec exposure amd rarely need to go above a 0.5 sec exposure.
I think your problem comes not from the camera not being sensitive enough or the scopes aperture.. But from the rather long focal length you're guiding at.. take into account that the FOV of the scope is fairly narrow, then take into account that the chip is only displaying a tiny portion of that narrow field... and there in lies your problem...
Deano - I think I have the camera gain % right but I will recheck this.
Alex - Yes, good point. I have my 150mm Mak f13 guiding scope focal reduced to about 1200 but I can put in spacers to decrease this to about 820mm before I run out of focuser travel. I will also try the guiding camera on my 80mm f6 refractor, which I usually use for imaging, to see the effect of the wider fov.
Hi All
Just as a postscript to this thread, I tried my QGuider for guiding with reduced focal length on my 150mm Mak, PHD gain set to max, focused carefully and employed a dark frame. With one second images I could now see about 5 guideable stars in my fov whereas before none were showing.
I was pleasantly surprised to see how the dark frame subtraction turned the QGuider screen from grey to black and made the stars more visible.
Thanks to you all for your advice - now to the next problem as there is bound to be one!
Cheers Peter