Imaging on a Cheap Telescope

Imaged through a Celestron 70mm refractor.

Back a couple of months ago, I wrote about rebuilding a cheap telescope we had lying around collecting dust and taking up space in our small home. I had rebuilt it using old parts from another cheap, useless telescope we threw away as well as a few new parts to increase the quality of this cheap telescope. Overall, I spent about $350 upgrading this telescope which could have bought me a decent telescope but then I would have thrown this telescope in the trash bin as well. I felt it was worth trying to rebuilt it and upgrade it so the grandkids could use it occasionally.

For some quick, easy views of the night sky, this rebuilt telescope has proven to be a decent scope... not a great scope... but it is decent. This telescope and mount is relatively lightweight and small which makes it easy to just grab and go out to the yard and that is a definite plus. As mentioned before, since I rebuilt it and upgraded it, this telescope now provides some acceptable viewing for the price point. 

Last night, I decided to really put it to the test by attempting to mount a camera on the end of the scope... which, for those of you who have already attempted an endeavor such as this, really is absurd silliness but I figured I would give it a try anyway. I could get lucky, right?

The resulting image of the moon, above, isn't terrible but I see some optical problems. There is unevenness in sharpness across the frame... it lacks clarity and crispness... and, most importantly, the whole experience in getting just this one decent photo was frustrating and difficult.

The first problem was that the mount, a Celestron CG-2, is not sturdy enough for astro-imaging. This mount made the simple act of focusing with a camera mounted incredibly frustrating and difficult. But, this particular mount is lightweight, I already owned it (meaning I didn't need to buy a new one), and it is far better than the mount that came with this telescope.

The second problem is that my lightweight, small Sony a6000 body threw the balance off so much that I could no longer balance this lightweight scope on the mount. I slid the scope all the way forward on the mount yet it was still too heavy on the rear end where the camera was mounted. There are some advantages to lightweight scopes but this is a disadvantage. In short, this telescope and mount simply is not meant for imaging. I already knew that but I was hoping to get lucky with some lunar imaging.

The third problem is that even though I upgraded most of the parts of this telescope, the main optics are still only "okay" or mediocre by imaging standards. A discerning eye can tell that the view through this telescope, although not overtly noticeable by most people while viewing, lacks some contrast, is a bit hazy, and it simply is not as crisp as most telescopes. This point is very obvious when imaging but only experienced photographers and astronomers would notice these shortcomings when simply viewing the night sky. 

So, attempting to do some imaging with this lightweight, cheap telescope wasn't a great experience and it made me long to use my better telescope. Of course, the disadvantage of my better telescope is that it is big... it is heavy... and it takes some time to assemble in a few small but manageable pieces. 

At this point, after only 30 minutes of viewing, the moon was already behind trees and the atmospheric conditions for viewing Jupiter or any planets wasn't all that good... and, honestly, I was frustrated by the whole experience of trying to capture decent images with this combination.

This little experiment showed that this lightweight, cheap, rebuilt telescope is pretty good for viewing and may be a nice scope to have around for quick grab-and-go viewing sessions but it is in no way a tool for imaging the night sky... although, I'll probably run a few more experiments anyway (see below) because that is just the way I am... this is a challenge I'd like to overcome at least once when all the conditions are just right so we'll see how it goes in the future.

In the end, I'm not too enamored with Celestron and will probably never again buy another Celestron telescope as a result. I've thrown away one Celestron telescope and I had to rebuild the other (this one) just to make is usable.  



POST EDIT:  It is now the following night and the moon was bright in the twilight sky so I attempted to do some imaging with this small rebuilt telescope again...

Celestron 70mm refractor on an equatorial mount with a Sony a6000 and barlow using prime focus imaging.

Clearly, this newest image, directly above, is far better than the previous attempt in the top photo. I did some things a little bit differently this time around which is worth mentioning. Of course, this photo looks a little different than we see in the night sky because I rotated the image a little more than 90 degrees counter-clockwise to provide a different composition.

In the top image, I was attempting to do imaging through an eyepiece which is called 'eyepiece projection' imaging. Unfortunately, the combination of the eyepiece and the camera was too heavy for this small telescope so, tonight, I resorted to imaging directly to my camera without using an eyepiece or lens which is called 'prime focus' imaging. The other problem with imaging through an eyepiece is you can get some distortion which may account for the uneven crispness/focus in the top area of the top image. 

Switching to prime focus helped me keep the telescope balanced which improved the image quality considerably not to mention made the whole process significantly easier. In this image, directly above, I also added a small barlow into the mix to get a little bit of a closer view without adding too much weight. This 2.5x barlow allowed the moon to fill the frame.

Another thing I did this time around is I used a wireless remote to release the shutter. I had dead batteries in my usual remote yesterday so I was stuck using the timer on the camera which turned out to be less than ideal. I remembered I had an intervalometer so I pulled it out to use as a remote tonight and that worked great (I wish I thought of this yesterday). This allowed me to keep my hands off the telescope altogether while shooting images.

Since I was again using a remote of some sort to release the shutter, I was able to shoot about ten images in about twenty seconds. This allowed me to stack the images for a super-resolution image of around 82 megapixels. 

In the end, I managed to capture a detailed image of the moon by using my little rebuilt Celestron 70mm refractor telescope and my small Sony a6000 camera. This means that some astrophotography in the form of lunar astrophotography is not absolutely impossible with this telescope. It is difficult and you need the right equipment but it is not impossible.

This bottom photo was shot using prime focus with no barlow and is a single exposure. I'm pretty pleased with these two shots of the moon!