Imaging With a Guidescope

Anyone else except me have this genius idea to image using your guidescope ?  Well, I can tell you that if you use narrowband filters, it does work.  The only problem is... that if you want to guide, you need another guidescope, unless you have an off axis guider.  Therefore, I bought a very inexpensive 50mm guide scope from Orion.  Actually, the FOV of the little scope is pretty wide, and its brighter than the original 80mm Awesome Autoguider scope.  I found literally dozens of stars that were in perfect focus and plenty bright enough to guide on.  And the accuracy was just fine for the 400mm focal length imaging scope.  I'll let you know how it works with a longer focal length.

Now I'm using the old guide scope as an imaging scope.  It is not color corrected - its a simple doublet, and very inexpensive.  I think the price of the 80mm is something like $150, which does not buy a whole lot of refractor.  However, I was looking for a way to increase my FOV with the CCD, and it seemed like a logical choice.

Because it is not color corrected, I dont recommend any sort of wideband or one shot color imaging with one of these.  However, narrowband is a whole nother story.  Stars are pretty small in narrowband, because there is no color fringing on specific wavelength lines.

There is one quirk when imaging with this scope.  The FWHM readout during focusing is actually pretty worthless in obtaining focus.  I had to focus the scope for the roundest possible stars.    If I didnt focus that way, the stars sport a tail, all pointing in one direction.  It looks like a guiding error, but is, in fact an aberration in the low cost optics.  This occurred with MY telescope, yours may act differently.  This first image has oblong stars - caused by the way I focused.

Here you can see the stars are oblong.  It does look like a tracking error, however the next image is even farther South, and therefore farther from the NCP which would cause the stars to streak even more, however I made no changes to the polar alignment or guiding parameters.  In fact, I imaged longer frames - 15 minutes over the 10 minutes I imaged the above image.

In this image, the stars are nice and round.  I purposely focused on Alnitak, attempting to get it as round as possible, even if it resulted in a larger, degraded FWHM reading.  The FWHM actually wasnt BAD in this image, averaging around 1.75.  Best of all however, the stars are nice and round without the trails.  Could the focus be better?  I dont know - the nebulosity seems a little soft focus to me, but it is a pleasing image with the round stars.  But the point is...  I'm imaging using a VERY low cost scope.  Are the optics perfect?  Not by a long shot, but it still takes decent pictures.

A Productive Evening

Winters in Ohio are a tradeoff.  You get a lot more telescope time in the evening, but it's not clear out very often.  Tonight was actually mediocre, I guess the correct term would have been 'mostly clear'.  We had a little bit of decently transparent skies, but most of the time, there were thin high clouds overhead.  Fortunately they weren't so thin that it prevented me from imaging.

The first object was something I had imaged before with the Canon T3 a year ago.  The Canon really did a good job with this object, and I dont think this image is really any better, but it served as a warmup to better things to come later in the evening.

NGC891 which has been called 'The Outer Limits Galaxy', due to it being part of the opening credits in the TV show, The Outer Limits.  It is a galaxy that is located about 30 million light years away in the constellation Andromeda.  It is a spiral galaxy viewed edge-on, and is thought to resemble the Milky Way if viewed from this angle.  The size and brightness is about the same, and the Milky Way has a dust lane similar to this galaxy.

This was imaged with the Orion Starshoot G3 monochrome behind red, green and blue filters, 5 of each.  No luminance frames were shot because there were clouds moving in at the time this was finishing up.   I actually thought my night was going to be cut short, but a half an hour later, the sky cleared.

When NGC891 was finished, I slewed the scope towards Jupiter and came inside to process the above image.  I happened to look up at the VPN screen of the laptop, and I could see Jupiter on the edge of the autoguider, saturating the screen.  I centered the object, threw in the barlows and the webcam and shot a couple series of Jupiter.  Trouble is, I shot them too dark, so they were a bit noisy.  I did get some decent stacks, this one being the best:

It didnt turn out too bad actually.  I had wished that I had taken this at the correct exposure, it really would have been exceptional, but its not a BAD image.

When I finished up taking Jupiter, I noticed that Orion was clearing the trees.  I threw in my hydrogen alpha filter in the CCD and skewed over to the Horsehead, IC434.  IC434 is much dimmer than I thought.  I've imaged this a number of times, wide field with the DSLR, but never imaged it in Hα.  What a treat this turned out to be!  I framed it using a 2X drizzle at 60 sec exposure, rotated the camera to get more of the nebula in the frame and went ahead and shot 5 - 10 minute exposures and 1 15 minute exposure.  10 minutes really isn't enough exposure time for this object - it really is pretty dim.  15 minutes is better, and even longer exposures wouldnt be a bad idea either.  I honestly can not figure out how people have been able to see this through an eyepiece!  It really is a dim object.

When I stacked this, I was blown away at the detail.  I think I was a little bit out of focus too (not much tho).  The detail in the ionized hydrogen was more than I expected.

I was so impressed with this image, that I thought I would go with a 2nd processed picture, not quite so bright, and add star spikes to the brighter stars in the field.  I did the spikes in a separate layer and changed the opacity so as to not overdo the spikes.  I think this image is really pretty.  This might be one I may just have printed.  Trouble is, I didnt drizzle this image, but perhaps a bicubic resize will look good.

Well, there you have it, a good night of imaging.  I wish we had more of these, but it might be clear again tonight, and if it is, you might see another post tomorrow.  Until next time....  Clear Skies, all!