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Hi folks! I know most planetary imagers have serious purpose-built setups, but my daughter has a Celestron Powerseeker 114, and I just upgraded my astrophotography mount and can accommodate the weight of her telescope. It's a spherical mirror, but it has pretty decent views of the planets with a 6-15mm eyepiece and 900mm focal length. I image with a small refractor and have been doing deep sky imaging for a few years now. I don't think there's any point in me doing deep sky imaging with the 114, but I was wondering if it might be possible to use my ASI120MM guide camera to do planetary imaging with it. I checked the FOV in Stellarium and Jupiter and the Galilean moons would fit nicely even without a barlow. I guess my main questions are: - Would this venture be advisable or am I just heading for disappointment/frustration? I'm not looking for incredible results here. - Should I purchase a barlow, and if so, how much magnification should I consider going up to before I max out the resolving ability of the telescope? - Should I use my ASI120MM with some filters (and if so, which ones?) or should I consider purchasing an inexpensive colour camera? Thanks in advance for any guidance here! CS, Mark |
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Short answer - give it a go! I have a small 4” refractor and whilst it doesn’t produce the incredible images you get from large scopes, it nonetheless gives pretty satisfying pictures. It’s a good opportunity to learn about stacking, lucky imaging, sharpening etc. To answer your specific questions: - A 2x Barlow would be helpful. The usual rule of thumb is to image at a focal ratio about 5x your camera pixel size in microns (3.75 um for the ASI120MM). Currently you’re at about F/7.8 and want to be targeting 5 x 3.75 = F/18.75. A 2x Barlow will get you to F/15.6 which is close enough. - To produce colour images with your camera you’d need a set of RGB filters (31 mm diameter would be fine) and a filter wheel. You then collect 1-2 min videos using each filter in turn, stack and sharpen and combine to make a colour image. There’s a bit of a learning curve here and you’d also need to use Winjupos to manage the derogation and combination. You’d probably be up for a similar cost to buying a cheap colour camera and the learning curve would be less - might be the easier way to go. The Cloudy Nights site has a couple of long-running threads on ‘small bore’ planetary imaging using scopes of 6” or less that will give you a good idea of what you might expect to achieve. The Jupiter thread is https://www.cloudynights.com/topic/398608-small-bore-challenge-jupiter-w-6-or-less |
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Brilliant - thanks @James! Given the focuser is plastic and pretty weak, I'd probably skip the filter wheel and screw the filters in one by one, but maybe an OSC is a better approach after I factor in the cost and effort of LRGB. I'll check out that thread! CS, Mark |
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Hi, It for sure is possible. within the limitations of the aperture though.. I have a 6 inch which in the end is not that much bigger. The asi 120 is a great camera for lunar/planetary imaging. I'm asolutely positive that especially for lunar you could do some very nice things. give it a go. You have all the gear. |
