I'm not talking about a Barlow. My feeling is that Barlows aren't much good for astrophotography. ________________________________ From: Chuck Hards <chuck.hards@gmail.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Saturday, August 10, 2013 4:28 PM Subject: Re: [Utah-astronomy] Ring Nebula (M57) - Be prepared to squint No, refractors aren't different, but youre not going to get much change of image scale by just moving the Barlow and increasing the extension tube length. Unless you can live with say, two feet of extension tube. Eyepiece projection is a much more compact setup. On Aug 10, 2013 2:52 PM, "Joe Bauman" <josephmbauman@yahoo.com> wrote:
I've used them "extensively" on my SCG without an eyepiece, but refractors may be different.
________________________________ From: Chuck Hards <chuck.hards@gmail.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Saturday, August 10, 2013 2:38 PM Subject: Re: [Utah-astronomy] Ring Nebula (M57) - Be prepared to squint
An extension tube only works with eyepiece projection. It won't work for prime focus imaging. On Aug 10, 2013 2:32 PM, "Joe Bauman" <josephmbauman@yahoo.com> wrote:
Rather than a Barlow, I wonder if an extension tube would work -- I think it would tend to make the image larger, though I suspect a longer exposure would be required. But I haven't used refractors much so I may be blowing smoke. Instead of making exposures that are so long that they show the imperfections in alignment, I prefer to make a pile of shorter exposures and stack them. -- Joe
________________________________ From: Dave Gary <davegary@me.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Saturday, August 10, 2013 12:45 PM Subject: [Utah-astronomy] Ring Nebula (M57) - Be prepared to squint
Ring Nebula, M57. This has no more detail than viewing this feature visually through this scope. I couldn’t get any more detail because I wasn’t willing to invest the increased time on the exposures. These images are 4-minute exposures. You can see the mount was off a little. I kicked the mount by mistake while doing a fine focus. So much for good polar alignment. I don’t have an electric focuser for this little refractor. Wish I did. One question for anyone who knows or has experience with refractors: Does someone make a two-inch Barlow for a refractor that would allow the refractor to reach focus? I have a Zhummel 2-inch ED Barlow, but I do not have near the back-focus with this setup. Not even close. Is the solution, merely, to switch to the Schmidt-Cassegrain to use a Barlow? I don’t have enough experience with these things to know. I really like the little refractor for the tack-sharp focus (well, tack-sharp if you don’t trip over the tripod legs on a regular basis while acquiring an image). However, I’d like to have a slightly magnified image going to the CCD chip. What’s the solution? If this is a really stupid question try to suppress the laughter long enough to e-mail me back and tell me this is a really stupid question. Ask Patrick or Chris, it’s nearly impossible to hurt my feelings.
Thanks,
Dave
http://www.flickr.com/photos/78046474@N06/sets/72157635009053182/with/947806...
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