Summary: I have had this lens for a couple of days now and I like it a lot. Very smooth operation and build quality at a great price. If you use this in low light conditions you will need a tripod. The lens has no auto-focus or image stabilization, of course at this price I can't image anyone would expect it to. On a sunny day with a quick exposer you can ditch the tripod if you are quick at adjusting your focus.
Summary: I purchased this lens mainly for birding. It's built very well and I love the fast 6.3 focal ratio. The color and contrast is excellent. I've also used it for astrophotography with good results; very similar to an APO lens. It can be hand-held but you need a fast ISO and shutter speed. The depth of field is razor thin so it's going to be difficult to snap moving targets that are coming or going away from you while keeping them in focus.
Summary: I recently picked this lens up. It does have some issues as mentioned in other reviews. You pretty much have to shoot in full sun because it is fixed at f/6.3, but if you don't mind manual focus (I kind of like it actually) and you know how to use your gear with a reasonable level of proficiency then this is a VERY affordable alternative to name-brand lenses. You can see a shot I took with the Opteka 500 and compare it to one with the Canon 50mm f/1.8 here [...].
Summary: This is a simple lens. It has no auto-focus, variable zoom, or image stabilizer. You will need a good tripod most likely to accompany this lens. The picture quality is pretty good considering the price. I started taking pictures of birds after installing a bird feeder in my backyard. So most of the time it's predictable where the birds will end up (bird feeder).
Summary: I've used this twice in the month that I've had it, once to get some amazing pictures of the moon and again to get pictures of the space station going by. The space station is a little tricky but this lens will get a good shot if you know what you're doing. For the price, you can't beat it.
Summary: The lens itself is amazing is Ooms out really really really really far and it looks awesome the only thing is you probably want to take your photos into light room or Photoshop and up the contrast and saturation the colors with this Lens are pretty weak so you'd want to turn them up in editing mode
Summary: This lens is awesome! It of course, needs a tripod to function properly, but this is as expected with a mirror 500mm lens. I have taken and continue to take, absolutely awesome photos of the moon and landscape with this lens. It could not be obtained better even at 400 dollars, I'm sure.
Summary: The lens by itself is quit sharp actually, although you need to work hard to get the manual lens to focus right. It's quite frustrating though to focus with the double zoom adapter and it doesn't give great results, so you really need to struggle to have a focus.