I dont usually write reviews - I am not particularly good at them. But about once a year I buy something that I am can get quite excited about. So no rigorous and careful testing or a review littered with beautiful images like Ming Thein. Just a couple of loose comparisons and some snap shots. However I definitely think it is worth taking a look. First this lens - the Minolta 500 F8 reflex (it was later rebranded Sony). Its a mirror lens which means it small and cheap but typically comes with costs such as sharpness, contrast, bokeh and slow aperture. One thing rather 'unique' about this mirror lens is that it does have autofocus (in fact, from that perspective, I believe it is unique.) The small size of the lens was a great attraction to me. I dont use a long telephoto a lot but I did want something longer than the 70-200 f4 even though it can be cropped quite a bit on my A7r2. I am perhaps more happy than most to give up a bit of image quality for size especially (rather than in spite of having) a no compromise A7r2. To me the underlying specs of this lens - small lens but 500mm, f8 - make it ideal for an A7x2 body. You have image stabilisation and very good low light performance up to at least iso3200, so the cost in terms of aperture isnt terribly bad. Of course there is a 500mm f4 from Sony but that will set you back US$13,000. One thing for sure the lens is not expensive. I paid US$420 but there were cheaper available (I chose one in near perfect condition). I was also keen to get the extras which include a back filter and an ND4 back filter. Without the back filter your lens will have a gaping hole and it will cost you US$100 to buy one off Sony. I have absolutely no idea what the ND4 filter is supposed to be useful for on an f8 lens. As it is an A mount lens you also need a LAEA4 adapter (which I already had) which adds something to the size and quite a bit of cost. But the big question is how does it perform? I mean it wouldnt be of any use to me if my 70-200 f4 performed better cropped down to 500mm, than the 500mm f8 performed. But, as we shall see, it actually performs pretty well. First off the autofocus. It only has a single centre focus point - all the other focus areas are disabled with this lens. But focus is surprisingly fast at least in af-s. It doesnt quite matchmy 70-200 but it is similar (or faster) than the A mount 135 f1.8. Very occasionally it hunts but when it does lock on it seems pretty accurate. Really the focus is a godsend for me as the thought of manually focusing a 500mm f8 lens is a bit of a nightmare for me. I imagine if you dont mind manual focusing there are other lens you could buy in preference to this.Af-c isnt so good - the lens tends to hunt and af-continuous quite often turns into no af at all. Not ideal for birds in flight or fast moving antelope although from what I have read it is quite popular at air shows. I microadjusted the AF (-1) with an object about 20m away. The minimum focus distance is an unimpressive 3.5m and as an aside I think the lens is a bit soft in distances less than 7m. So it certainly isnt a lens for macro. The other thing that struck me when I first put this lens on my camera is that it is 'slow' in light terms. I dont mean f8 slow - I mean it is a slow f8. I measured it against my 70-200 f4 @ f8 and it is a minimum of 1/2 a stop slower, probably nearer a stop. So it is probably a T11 or possibly higher in light terms. Of course the LAEA4 adapter doesnt help - taking away about 1/3 of a stop of light but one imagines the whole mirror thing entails quite a bit of loss light too. So here is my brick wall test but in this case the brick wall is about 100m away in the form of a neighbouring condo... In Lightroom I made some quick adjustments - white point, black point, +25 sharpening and a boost to vibrance. What you can see is... 1) Noticeable vignetting. I dont know how much it is but it is certainly noticeable. You can pretty much correct this manually in Lightroom. 2) There is no chromatic aberrations at all. While this particular shot isnt perhaps the sort that generates C/A, I couldnt find any in any of my shots. I imagine this has something to do with the simple lens design. 3) There is very little distortion that I can see. When I brought this image into Lightroom I was struck by how low the contrast was looking at the histogram. This is supposed to be a characteristic of 'mirror lenses'. Maybe, maybe not. When I took roughly the same shot with my 70-200 f4 (which has been cropped to 500m equivalent), it also showed a lack of contrast. Perhaps the reason for this is the atmosphere over 100m - this will tend to reduce contrast quite a bit - especially in Thailand. Anyways bringing up contrast in post isnt really a big deal. Looking at the 70-200 f4 crop compared to the 500mm f8 image (downsized to 2000 pixels on the long end) there really doesnt seem a whole of difference. But when you start cropping the 500mm f8 image the difference really starts to show. Below we have a 2000 pixel (long end) 100% crop from the same shot. That is the equivalent of 2000mm!! And it looks pretty good to me. Notice the brand of the towel is easily visible. From where I took the photo you cannot even see that there 'is a towel'. Trying to achieve the same FOV with 70-200 shot (where I had to upres the crop) all you get is a very soft (unusable) photo whereby the towel branding is just a blur. First the 500 f8 100% crop... ...then the 70-200 f4 equivalent... There isnt much good you can say about the bokeh. Mirror lenses produce this donut shaped bokeh. Very occasionally one can say it adds 'character' to a shot but, in general, it is just distracting. The good news is that it isnt always apparent (and often not that noticeable). Essentially, the donut bokeh will appear when the background is not far back and includes specular highlights. If the background is in the distance the bokeh looks pretty good. Anyway, you can judge for yourself in the shots below. The lens does have a focus hold button so you can easily focus and recompose. Generally speaking though I focused in the centre of the fame and then cropped in post. The shots below were taken in a short visit to the zoo. They have all been cropped and edited in post. So there you have it. This lens is definitely a keeper for me. It punches well above its weight and size and even further above its price point. It is possible that I might eventually get a longish prime native to the FE mount when one is introduced but the chances are I will be put off by the size (and likely the cost). (A teleconverter would be a good start.) I think this lens has potential to be either a standin until something better comes along, a cheap long telephoto or a light weight alternative for A7xxx users. The biggest drawback for me was that the light transmission is not particularly close to what you might expect from f8. Finally, it just seems a shame that Sony stopped producing this lens in 2010 and will almost certainly never make one native for the FE mount. Its a shame because I think its specs are remarkably suited to the A7 cameras where small size is viewed at a premium (by most).