Reviewing this lens presents a complex problem because the various aspects of it are compounded by the experience of the user and the conditions of use. Since I can’t cover them all, I’ll make general comments on what I’ve found after several weeks of field use.The best part of this lens is the price. There is nothing that comes close to it at the price range as of this writing. It’s not just the 650mm or so of close reach, but the 1,300mm zoom to and all the zooming in between. Canon just came out with a 1,200mm f/8 lens for the R mount costing $20,000 and it’s selling well. I’m not saying it’s reasonable to compare that lens with one but it’s still a datum point to consider.The executive summary is, that to my surprise, I was able to produce some good images with this lens. Please see the photos posted. The image of a ladder was taken at 650mm. Another image with the camera/lens on a tripod was the setup taken with an iPhone. I’ve circled the area of the 650mm. This is HALF the reach of the lens and quarter the reach if you use the optional 2x extender.Now for some cautions. The lens has no aperture so you’re shooting wide open all the time. The change from f/8 to f/16 is due solely to the focal length of the lens changing as it zooms with a constant objective size of about 81mm (650/81=8). This results in a thin depth of field (DOF). Please see the image of the ladder. This is unsharpened Raw and only minimally processed. You can easily make out the flutes on the ladder steps but the clawed foot is a bit soft. That’s not movement but how thin the DOF is with this lens at 650mm. At higher zooms, it’ll be thinner.If you’re shooting birds, you can get sharp eyes and sharp feathers but only if the bird is oriented laterally to you. Once the bird swings about on its spin axis, you’ll have to choose which ‘slice’ of bird you want to be sharp. This goes for all shooting – not just birds.The other issue is this is one big mama jama lens that’s remarkably unwieldy to use just as all these long ones are. I was unable to get good images without a tripod. The Canon lens mentioned about is IS but even so, is likely a tripod only lens too. I suppose I could crank the ISO and up the shutter speed to use on a monopod but I didn’t have any luck free shooting. Maybe others will. To use, for example, as a sports lens, this will have to be used with a lens cradle that will also double as a bird accessory.Now for two gripes. The close focus is supposed to be 5m but I never got it to focus tightly there. I’d say it’s closer to 10m. The other issue is one of such overweening boneheadedness that it’s breathtaking. The nice case that comes with this will not work with a rear lens cap. Please see the other photos. It will work without the cap 100% guaranteeing a dusty lens.In sum, this lens trades price for convenience. Please look at the ladder which will give you an idea of what to expect using this lens from a tripod. The camera used was a Canon 5D2.