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.