There's a lot of misinformation about this lens out there. First, it does NOT sag in the middle. Mine is TIGHT stem to stern and I've had it over a month and it's been used daily. It's is more useful with 2x power at shorter focal lengths. It is VERY useful for the purpose for which it is designed. It is completely manual, which means photographers who only like AF and everything done for them will not care for it. I carbon date to when NOTHING was done for you and each mistake cost $$$$. In the time of post modern Digital photography I don't think I've found a better value for photographing EXTREMELY distant subjects. It's good for Astrophotography if you don't have the budget for a $4K Digiscoping rig. It can get you (only) MOST of the way there on a small fraction of the budget. If you use all the tools at your disposal (including cropping) you can do surprisingly well with it. But experimentation with your camera will be essential. It is the OPPOSITE of PBD. You'll learn a lot though. It will make you grateful for the VR/ED/AF Nikkors you take for granted. But if you like roughing it, and don't mind the work, surprisingly good images can be your reward. I stayed away from it for about 3 years. That was time wasted I wish I could had back. P.S. a First rate tripod isn't a maybe.....

I have had this lens for at least 3 years now however I only recently started using it on an almost daily basis. My thing is bird photography of which appx 95% is done from my sun space on the rear of my house overlooking my bird feeders. I am stunned at the quality of the pictures that it produces. I also have a $900 Tamron 150 - 600 mm and for what I do, I think this lens stacks up very well against the Tamron. If you know your way around the manual settings on your camera, this is a great addition.

I was very pleasantly surprised with this lens. I am an amateur photographer and wanted to take some photos of the moon at night. I took it out the first night I received it, and was impressed with the sturdiness of the build as it is built of all metal. It fits to the camera with a converter and mounts to the tripod on the lens. The lens and camera fit strongly together and I do not have any fears of the camera falling off the lens while mounted. I look forward to using this lens more in the future.

I have being taking some really cool surf pictures with it. Excellent lens for the price. The moon pictures are mind blowing.

This is a pretty slick lens. It is lightweight and pretty powerful. With a little practice, you can easily shoot items that are out of normal range and they look like you are are up close. This is great when you can't make out text on signs, etc. I was able to zoom in on unreadable signs from my distance and make them out perfectly. My first outing yielded some really nice results!

Great lens for what it is intended for. Tripod is a must. I've used both Tripod and monopod at the same time to get some great shots.

At $199.00 it is a lot of fun and worth the $$. You will probably not win a lot of photo contests with it but the pics are not too bad. I also have an 800mm mirror lens which is difficult to focus. This doesn't have the same problem. At 1300mm the focus ring is a long way from the camera body and it needs to be on a tripod. I am happy with it.

This is a real game changer.. You can't ever go wrong with any product from AC Infinity...