Summary: I purchased this as a gift for my wife. For a manually operated zoom lens, this one is very good. You'd pay $5000 for one of these that are fully automated, so it's a good compromise. We took some very good photos of the lunar eclipse last spring with it. One problem out of the box: The threads on the mounting plate - the one that mounts to a tripod - were somehow damaged.
Summary: This thing is huge and the picture does not do it justice. My wife wanted this to take pictures of storm and the moon. The Good: Moon and Star Pics look great. Quality is superb. Images are crisp and clean. Zoom is great. The Cons: Need really sturdy tripod to hold this thing. Cannot use for storm, the wind causes it to be blurry. Need Calm conditions because of size. Impossible to use without Tripod.
Summary: Great lens for still shots. Photographed some amazing moon shots at night. Not good for any action shots as it is manual focus and once you focus it works great for those Lon distance shots. Very affordable price for a long distance lens but don't buy if you plan on shooting action shots.
Well worth the cost, but lots of practice is required
31 December 2013
Summary: A lens of this size through the Canon line would be around $13,000.00. Realizing that this lens is under $300, one must also expect less. Surprisingly, this is a well built lens. I got to try this lens for the first time Christmas afternoon. Two bald eagles had landed on an ospreys' nest at the end of our family dock. Not wanting to get to close and scare them away, I attached the lens to my Canon 5D Mark III. WOW!
Summary: Closest analogy: It's like holding a big magnifying glass in front of a 12" TV, trying to make it look like 42". Astronomy: I got plenty of moon photos at 650mm and 1200mm. Two tripods and "pillow" under the lens, because even with the camera timer, the lens/camera kept shaking for several seconds. I managed to keep it completely still and used the remote. Then I compared it with a moon picture I took with my 200mm Canon lens a week ago.