add a clarification on the product after use. I'm very happy with the Nikon 35 1.8DX on this adapter.. which I thought was a bit thick.. I expected some loss of brightness. Since there is nothing in the product details, I tried to ask K&F about it: no answer... :( Well, I did the measurements myself... with the same aperture on a sensor with the same resolution, we go with the adapter from 1 /800 to 1/500.. so 3/4 of an additional f-stop my 1.8 Nikon becomes a 2.2... a 2.8 becomes a 3.5 the product is excellent but good to know this loss of brightness ( would have liked to see it noted). As with the extended rings, the lens attached does not lose any sharpness I was waiting to receive it, at least not expecting the best... Surprise; the product is heavy, well finished (I have already extended All plastic rings) I grab my XM1, I pull out my fixed AFD focal lengths... the 24... that becomes a 36... and the 35/2 a 53mm my first attempts at shooting don't work: he you have to Select "shoot without lens" in the xm1 settings, I continue to shoot, excellent the system of" ; "Rand" on the screen when the MAP is ready, (I tested at 1.8-2 to verify this map, on the computer the map is actually correct). The contrast system is only really apparent at a wide aperture... As with some old cameras, open the aperture card wide and stop before shooting with other cameras in range that also have viewfinders. It might be easier to focus manually: the ring also allows you to do glare, you do that "at your discretion", but it's great to have. The 35 1.8Dx is very good at 1.8 for anything that doesn't need an ultra-fast card (j) I've tried portraits of my dogs... that move... well, manual focus on the XM1 screen remains quick and accurate ), for anyone who has a quality focal length stash that doesn't want to buy new ones that aren't necessarily better in terms of sharpness (no choice on Xmount Mount). I recommend this ring in addition, very affordable I am very happy with this surprise purchase, all my Nikon lenses are reworked with this camera