>>3267074I have an Opteka 500mm f/6.3 mirror lens. It is super cheap, but pretty nice for the price and size. I highly recommended using the largest lens hood you can find for mirror lenses. Their contrast isn't very good so the lens hood really helps out a lot. You will want to do some simple post-processing adjustments. The donut bokeh is great, but only if you use it correctly. Focusing can be very difficult, but that is only a steep learning curve and after lots of practice you'll get a good feel for it. If your LCD screen is nice and bright you can pixel peep focus to help with focusing.
I really recommend a camera body with some sort of stabilization built into it. Any lighting that is semi-good for normal lenses will be semi-bad for these. A tripod is a must if you are wanting good photos in low light. The vibrations telegraph really well on these things so setting up the tripod to be as short as possible then sandbagging it will help a great deal. Use a remote to take photos. Otherwise, in low light you'll get nothing usable. If you are going to try handheld video, you'll need a gimbal/steadicam otherwise, you won't get anything usable even with in-camera stabilization.
One of the cooler features of these 3.7-inch diameter lenses is the fact you can "see through" objects directly in front of the camera when you focus beyond them. That helps a great deal when you are in scrub trying to take photos of animals and there's a dozen twigs in the way. Here's a video if that effect with my lens. Most of these things come with a cheap teleconverter, but those just make things worse for the most part. You can use extension tubes with these, but you MUST have a lens support (like the Manfrotto 293.)
Keep in mind that I'm using a super cheap manual focus lens, on a body that doesn't have any stabilization. The higher quality more expensive ones will have auto-focus and a much better image quality all around.
