Only recently started getting into astro-imaging (infact it's been less than 12 months since I've owned a telescope!), so a lot of what I've written below might sound nonsensical . I've really had fun with the ZWO ASI224MC and wanted to get wider views of the moon and DSOs as well. I bought a 1.25" 0.5x reducer and then I realized that it puts the focus completely out of whack. The backfocus distance of the camera is 12.5mm. The focal reducers information is here:
Focal length (estimated) = 101 - 103mm (3.98 - 4.06")
Total item length (excluding external thread) = 10mm (0.39")
the "working distance" of this specific reducer is estimated to be 51mm, i.e., this reducer will provide a reduction of 0.5x when the center of its lens assembly is placed 51mm from the focal plane of the eyepiece or imaging device.
I still don't completely understand but does the above mean that the distance between the focal reducer and the CCD sensor needs to be ~51mm? I see the number 55mm crop up a lot while Googling, what does that relate to?
Currently the distance between the camera CCD sensor the focal reducer lens is broken down like this: 12.5mm (camera sensor to the top of 2" ring) + length of the 1.25" nosepiece (I've not measured it yet, but I think it's around 30mm) + 10mm (length of the focal reducer). No spacers are involved at all right now and I'm nowhere near achieving focus. When I play around with it, it feels like to get focus I need to make the focusser travel inwards, more than it's physically capable of doing! Is there any solution to this?
Should I have gone for a 2" focal reducer instead?
Sorry for the many questions - but I'm really confused on how to go about troubleshooting this.