ZWO ASI120MC for Planetary Imaging

[admin]

Hi,

the ZWO 120 should focus with the 130SLT in its normal configuration. If you have modified the telescope to get the DSLR closer in to the tube then you may need an extension tube to put the ZWO camera far enough back to get focus. For instance, something like this : https://www.amazon.co.uk/Svbony-Telesco ... B084VHCTT7

It's a good idea to check the movement range of your focuser before buying the extension tube. If the focuser moves 40mm from fully in to fully out then try to get an extension tube of 40mm or less - otherwise with a 50mm extension there is a possibility that you will still be unable to find focus if the critical position is in the gap that you cannot reach either with or without the extension.

cheers,

Robin

[mixon]

How can I achieve the same process with same camera but using Celestron f/5 FL650mm ? I have beat my brains out trying to capture Saturn. I wind up with a tiny image about the size of a pencil eraser, maybe less!
Could I achieve the same results by apply a Barlow x2 to the camera? That would only make it smaller, correct ? or no ?
I use 25mm to align scope first. Then I switch to ZWO, re-align in the ROI, and re-focus.
I'm stomped, please help to offer suggestions.
Thanks

[admin]

Hi,

the 650mm focal length does give you relatively small images for the planets. A 2x barlow will help (it will make the image 2x bigger in both directions, but fainter at the same time so you will need longer exposure/more gain). Lots of people will capture the planets using a similar camera and an 8" SCT telescope. The SCT has a focal length of 2000mm with no barlow and 4000mm with a 2x barlow, so will produce bigger images again.

Of course, the problem with using a barlow or SCT or anything with a longer focal length is that it makes *finding* the target harder...

cheers,

Robin