Philips SPC900 Too Zoomed In on Celestron 127 SLT

[ak785]

Had the scope out this week given the crystal clear skies and wanted to pick up AP. I own a Celestron NexStar 127 SLT and I purchased a Philips SPC900NC (already modded for AP with adaptor) on eBay some years ago. Got the moon lined up in my 25mm and thought the image would look something like I was seeing through the Eye Piece. Took the Eye Piece out, slotted the Philips Web Cam In and all I could see was pure black.

Did some Googling/YouTubing and eventually came across SharpCap and also read that the focus for the Eye Piece and the focus for the Web Cam will be totally different. So I set about refocusing the telescope with the camera attached and modified the gain in SharpCap and then slowly I started to see some detail but here comes the problem.

The image I had on my Surface was nowhere near sharp enough, each twist of the focus dial totally lost any sharpness I had. The Moon also looked super zoomed in and there wasn't a way to "zoom out". Having given it some thought this morning, possibly this is where the zoom in SharpCap would come in handy? Or do I need to move the camera back towards to the top of the eye piece "slot" instead of the adapter being all the way in the Eye Piece "slot"?

[Cornelius Varley]

The field of view of the SPC900 is fixed (approximately equivalent to that that of a 6mm eyepiece). There is no way to increase this (zoom out) without adding a focal reducer to effectively reduce the focal length of the telescope. The usual method for imaging the moon is to take a series of overlapping video clips and then stitch the stacked images together using MicroSoft ICE. This way you get a higher resolution image of the moon than would be possible using a 640x480 webcam.  Focusing can be tricky depending upon the atmospheric conditions. The image might go slightly in and out of focus due to the atmosphere but the stacking software (Registax, AutoStakkert!) will deselect any images within the video clip below a certain quality threshold.

[ak785]

15 minutes ago, Cornelius Varley said:

The field of view of the SPC900 is fixed (approximately equivalent to that that of a 6mm eyepiece). There is no way to increase this (zoom out) without adding a focal reducer to effectively reduce the focal length of the telescope. The usual method for imaging the moon is to take a series of overlapping video clips and then stitch the stacked images together using MicroSoft ICE. This way you get a higher resolution image of the moon than would be possible using a 640x480 webcam.  Focusing can be tricky depending upon the atmospheric conditions. The image might go slightly in and out of focus due to the atmosphere but the stacking software (Registax, AutoStakkert!) will deselect any images within the video clip below a certain quality threshold.

Thank you for the explanation, that makes sense. Any advice on the quality of the video?  I'm not sure if that's as good as it gets for the SPC900 but I could barely get any detail in the video.

 

I was wondering whether eye piece projection would help?