Hi John
Just upgraded to 4.15.9 and I needed to reinitialise my system. This version of CCDAP is now warning me that because my position angle is near a cardinal point that it could impact on predictive guiding. I know this was a feature of early versions of CCDAP, but have you now reintroduced this? Thing is, my camera is screwed to the telescope, no rotation possible. I did not get this warning in 4.15.7?

cheers
Martin

Hi Martin,

I haven't run into that warning myself, but I would think that is all it is, just a warning to make you aware of the camera position and the cardinal points. You can probably proceed and initialize just fine. John is away for a few days, and he can verify this when he returns.

Hi Frank
I initialised in Maxim and the warning did not appear - as the helpfile suggests, this version now adds this warning for CCDSOFT only. Fact is, I then took images with CCDSOFT despite the warning, and guiding was off somewhat.

Had to revert to 4.15.7.

As I said, I recall in earlier versions that you had to be +10degrees away from a cardinal point, but I do remember John 'fixing' that in a later version so it did not matter what angle your camera was at.

cheers
Martin

Hi Martin,

I was not happy with the reliability of initializing near a cardinal point due to some users having difficulty, Therefore, I no longer allow initializing near the cardinal points.

It should be a simple enough matter to initialize off the cardinal points. Even if you have threaded connections between the telescope and mount, you can loosen it 10 degrees or so, initialize and then tighten. The initialization will still be good.

As mentioned above, this is only an issue with CCDSoft and not with Maxim.

Hi John
Actually, here is my situation.
I am using an ST402 on a guide scope, which of course is not fixed! It is my imaging camera that is fixed.

Therefore, do you advise that I rotate my guide camera to a position 15 degrees or more beyond the cardinal point and intitialise there but return it to the cardinal point? I ask this because if my guider is off at an angle, lets say 240degs, I do not understand how guiding can work well when my imager is fixed at 270degrees. So, do I move the camera to 240degs, initialise and return it to 270, or can I actually leave it where it is?

sorry if this sounds obvious.

cheers
Martin

Hi Martin,

By your description, it sounds like your ST-402 is attached to an OAG. In that case, you can rotate the 402 just enough to move off the cardinal points, but not enough to cause the 402 to hit anything as it rotates around. Then leave it at that orientation. When using separate cameras for guiding and imaging, one has no relationship to the other. The initialization takes care of guiding angles and the PA of the imaging camera. HTH .....

Hi Frank
no, the ST402 is attached to a BORG 76 mounted atop of my FSQ106. My imaging camera is a FLI Proline. I really wish I understood what you say about having no relationship. I have always thought that in order to get round stars in my imaging camera, my guide camera has to be at the same angle as the imaging camera i.e when using a guide scope, not an OAG.

But this the problem. At the start of initialisation, CCDAP warns you of the fact that your imaging camera is near a cardinal point. Then you have to confirm you want to go ahead (twice) even before it stars the calibration on the guider.

I certainly do not understand it.

cheers
Martin

Hi Martin,

That makes it much easier

Just rotate the 402 about 10 degrees off the cardinal points and leave it there.

Think of your setup this way. The guide cameras job is simple to make corrections to the mount based on the position of the guide star. Once the guider is calibrated, it knows which direction and how far to send the mount based on the stars position. The PA of the guider is used to set the vectors for the X/Y corrections. The guider will send the correct X/Y movement to the mount, regardless of the PA after the vectors have been determined by the calibration. The corrections sent to the mount have nothing to do with the photons falling on the imaging camera. Since it is rigidly attached to the scope, it just follows along passively. So if the mount corrections are being delivered accurately, then the photons from the stars will basically fall on the same pixel(s) as the mount tracks. Then with all other things being tuned, round stars can be the result. HTH ....

Martin,

Let's talk about this at AIC. I have some ideas...

The issue here is that the monitor for the "forbidden region" is not properly configured for a guide scope. That will be resolved in an upcoming release. In the meantime, rotate your guide camera on the guide scope a little off the cardinal points and ignore any cardinal point warning messages you get during initialization.

Hi Martin,

The only thing I can think of is to make sure your focal length is properly entered in the file defaults section of CCDSoft.