Some of you might be thinking I've gone off the deep end.  But it actually makes quite a lot of sense. A telescope is actually a lens itself.  Now obviously a high quality camera lens is going to perform better than the average telescope.  But what if your camera lens doesn't have enough reach to get a close-up of a subject? The great thing about telescopes is that you can get some great magnification for a very low cost.  A lot of you might have one lying around that was given to you as a gift like I did.  I won't go into details about different types of telescopes.  I will tell you mine is not considered very high end.  It is a small 80mm Schmidt-Cassegrain.  In the photos below you can see it's of the Towa brand. Don't ask me who they are, I got this as a present as a child.  So how did my 800mm Monster do?

Well, the first thing to keep in mind is telescopes are fixed aperture.  The lens is 80mm in this case, and the focal length is 800mm. That comes out to f/10.  Keep in mind in this type of telescope design part of the center mirror is blocked, so I'd say it's practically closer to shooting at f/11-f/12.

What you will need to attach your telescope to the camera is called a t-adapter.  These can be found in your local telescope shop, or possibly even some larger better photography stores.  Mine obviously is for a Canon EOS mount but they are available for other mounts such as Nikon and Minolta as well.  This is the same type of mount you would use if you were to attach your camera for astrophotography as well.

Of course like with any large telephoto lens you mount your camera to the telescope, not the other way around.  I find it much easier to attach the adapter to the telescope first, and than mount it on the camera.

I went out on a cold winter day.  This comparison test is between the Canon 75-300 IS USM lens and my 800mm f10 telescope.  Both were mounted on my Manfrotto 190 Pro legs with 486 RC2 ball head .  The test subject, in this case some kind of hawk feasting on a dead wild turkey carcass was probably about 150m away in a farmer’s field.

Now with an 800mm vs. 300mm reach advantage the Canon Lens has to be magnified 2.67 times to get the same crop as the telescope.  Or in other terms you’re losing 2.67x the pixels you have.  That's the only chance my cheap telescope has at getting a better shot of the hawk than the camera lens.

Let’s get to the photos:

Hawk taken at 300mm.

Original photo with 800mm telescope.

Obviously the 800mm focal length of the telescope gets in closer to the subject.  The hawk is hardly visible in the 300mm photo.  But we won't close ups.

This is a 100% crop of the 300mm image blown up to a similar size as the 800mm image.

This is a 100% crop of the hawk with the 800mm telescope

The 800mm photo is a 100% crop of the hawk.  There has been no sharpening applied to any of the photos so far.  The photo shot with the 300mm lens has been blown up roughly 250% to match the photo with the telescope.  The photos show surprisingly similar detail.  I'd say contrast is actually a little better in the telescope as well as detail.

One thing to keep in mind is that the farther the subject is, the better the telescope will outperform the lens.  The reason is simple the lens shot will have to be blown up more and more.  Of course if the subject is within reach go for the camera lens.

The 800mm Telescope produces an image not too bad for web viewing when put through some Photoshopt work.

The result with some Photoshop sharpening, and other work is quite interesting.  The photo taken with the telescope has been turned into quite a decent photo.  At least one respectable enough for me to post on my photoblog.

Yes, if you've understood so far you will know my telescope acts the way a Mirror lens does. I'm sure you've seen these on eBay.  Long telephoto lenses for very cheap.  They are based on the same design, and quite poor quality.  Better than not getting the photo.  

The strange thing about this type of lens design is that it produces a weird donut shaped bokeh.  This can result in some pretty ugly backgrounds.  None were visible in the hawk shots, but this wouldn't be a complete article without showing an example with ugly highlights.

As you can see in the background, there was some extreme side lighting on the bushes which produced very ugly bokeh.

Another thing to keep in mind is you won't get auto focus with this setup.  In fact focusing a telescope is not that easy.  I don't mind shooting with manual focus lenses, but the little tiny focusing knob on my telescope can probably turn 20x in the full focusing range.  That is to say focusing is slow and tedious.  It's also not multi-coated or designed to withstand flare.

I personally wouldn't go out and buy a telescope to use as a lens.  I'd rather save up my money for a sharp lens like the Canon 200mm f1.8, or even a MF prime.  You could use those with a teleconvertor to get you closer and the results would be much better than the consumer zoom I used.  I'm sure the results would beat out my telescope.

But if you have a telescope already to play around with.  Buying a $30 adapter certainly doesn't hurt.  Especially when you can dabble with astrophotography as well.  I'll be taking this combo out more often to see if I can find other wildlife to shoot that I can't get close to.