Finding Jupiter

[+Ibbo]

found this

 

http://www.ebay.co.uk/itm/vixen-flip-mirror-for-astronomical-telescope-/221209392867?pt=UK_Photography_Telescopes&hash=item33811b76e3

[dawson]

It's 2"; how would i fit it in my 1.25" focus hole?

James

[The Bagman]

Try using the webcam without the powermate for a larger field of view, it will give you an idea of the centering of the webcam and a chance to find focus. If using Sharpcap, centre using the reticule and then try the powermate. Regularly failed to find Jupiter with a 3x barlow

 

Chris

[+Graham]

James might I suggest you set this up in the day time. Focus it on some distant chimney tv ariel or the like.

You can then swap over to the web cam,

As it is day light you will be able to see from the image how far off target you become, you will also find out which way you have to move the focuser to gain focus when going from ep to web cam.

Everything becomes much much easier if you do it in day light and will save you an enormous amout of frustration trying to sort it in the dark.

Obviously standard precautions to prevent looking into any sunlight goes without saying.

[dawson]

Chris, thanks. I've tried that several times, though previously my mount has been so easy to move that changing from eye piece to webcam may have also introduced some error. I've since tightened it up so that may helped.

Graham, that is a spiffing idea! I will do that today. I don't have many really far objects to focus on in the back garden, but i often use my ariel to line up the finder scope. Good thinking bat man!

Thanks both.

James

[Orion]

James might I suggest you set this up in the day time. Focus it on some distant chimney tv ariel or the like.

You can then swap over to the web cam,

As it is day light you will be able to see from the image how far off target you become, you will also find out which way you have to move the focuser to gain focus when going from ep to web cam.

Everything becomes much much easier if you do it in day light and will save you an enormous amout of frustration trying to sort it in the dark.

Obviously standard precautions to prevent looking into any sunlight goes without saying.

James. Did you get a chance to try Graham's idea? I was reading thro the thread and thought of this too If you know the field of view diameter in arc seconds, or arc minutes, you could take a photo (video) of the object with and without eyepiece and webcam (both in focus). You could print thouse off and calculate the error in terms of arc seconds. If you then train back to Jupiter with the eyepiece, centre, then swap for the webcam and apply the offset - either positive or negative, Jupiter should be in the web cam view I would think, or close.  This assumes the error lies in one plane - it may be a vector of X and Y.  How you move the scope by the offset, I'm not sure. But if you have motor controls and you know the slewing rate (say y arc seconds/second), you could apply a certain speed slewing rate for a burst of x seconds, where the scope will have moved a distance d equal to the offset = x.y.  E.g. The error was 120 arc seconds. I'm going from memory, but if we assume Jupiter diameter is 40 arc seconds, the error is 3 Jupiter diameters out (left or right in one axis).  Speed up or slow down (or stop) the slewing rate such that the distance moved is equal to 120 arc seconds. I don't know if this makes any sense of what I'm trying to say.  It's a daylight linear calibration and application of slewing the scope to recenter the object.