Okay, I know many of you are keenly interested in this new gadget. My friend from UPS just handed me a new one purchased from Roberts about 7 days ago, (delayed due to slow ground shipping). So, here are some first impressions after having it for less than an hour. I only tried it on the D2x. First, the great debate over DK-2 vs DK-19. I have seen so many erroneous web postings on the difference, I have to laugh. I have done a critical comparison between the two rubber pieces. I have both. They are the same size, exactly in every way except one... The diameter of the hole in the DK-2 is greater than that of the DK-19. In other words the hole that fits over the rim of the DK-17x eyepiece is larger on the DK-2 than the DK-19. (Think, OJ Simpson and gloves...) The DK-2 fits but is looser. The DK-19 is snug but I can still imagine that it will not be entirely secure because the DK-17m protrudes a small amount away from the body of the camera so the metal rim instead of being seated against the camera body is simply hanging on the edge of the DK-19/17m. I saw a post somewhere, (possibly on the D1scussion Forum ) in which someone used 3 rubber washers to close the gap making it possible to seat the metal ring against something to secure it from falling off. If someone can find that post for me, I would appreciate it, I did not save it. The pamphlet that comes with the DK-17m recommends use of the DK-19 if you want to add a rubber eye cup. I wear glasses for distant vision. My sight is corrected to 20/20 with glasses. I prefer not to wear glasses when looking through the viewfinder only because it is (in my opinion) better to seal out extranneous light from the side which can not be done effectively when wearing glasses. The DK-17m has the same correction ability as the original eyepiece that comes with the camera. I have purchased a -3 diopter piece to give me a corrected image without glasses. The down side of the DK-17 is that it can not accept a corrective diopter. (I believe it could have been designed into this device easily by Nikon by just threading the eyepiece on the out side, but it was not. I believe it will be in the next generation of the DK-17m if we speak out to Nikon) but it was not done in this version, so if you wear glasses and do not like the diopter lense that came with the camera, don't get the DK-17m or be prepared to wear glasses to look through the eyepiece. If you are comfortable wearing glasses with the original diopter lens or your vision is correct with the original diopter, then you will find this device to be helpfull. Now for my observations on the DK-17m. First another correction. I have seen in several posts that this is a 1.5x magnification lens. It is a 1.2x magnification. It says so right in the pamphlet that comes with the DK-17m. I used several lenses including the 85 f1.4, a 60mm micro, and a 70-200mm. I put the camera on a tripod and exchanged the DK-17 with the original eyepiece and the -3 diopter eyepiece. Over and over and over and over and over again. Kind of like when you go to the eye doctor, "this one or this one?" "This one or this one?" With the DK-17m, the scene that you see through the viewfinder is the exact same scene that you see through the viewfinder with the original but magnified 1.2x. The edges fall in the same location on the scene with both diopters, it just looks bigger with the DK-17m. It seems to give you a 100% view of the scene, the same as it did with the original, it just looks bigger (or closer). One difference is that the information on the bottom and side of the viewfinder are pushed out farther to the side and bottom. This is a tiny bit distracting but not a deal breaker. I believe it will take a little bit of getting used to. It does not eliminate any information but it is farther from the scene that is seen in the viewfinder. In other words there is more black space between the scene and information in letters/numbers along the side and bottom when you look through the viewfinder. It is not brighter or dimmer, it looks to me to be the same brightness. I only looked at it in a brightly lit scene. The difference is most spectacular in extreme closeup and long distance. While there was a benefit with middle width lenses, the long and close lenses seemed to benefit the most. The protrusion is not that significant. It brings it out approximately the same width as the ring that goes on the DK-2/19 so I don't think this is a down side. It could catch on clothing or a bag if you are not careful especially with a heavy lens attached, but no more than if you have a rubber eyecup on it without the DK-17m My general impression is that I like it and will continue to use it. I recommend it with the exception of eyeglass wearers with extreme corrections that do not like to wear their eyeglasses when looking through the viewfinder. I think the O ring fix is probably going to be requried to retain the DK-19. As some of you know, I lost one on a trip (along with the diopter) and this was a bit of a problem. I will continue to carry a spare diopter in my bag as a result. I paid about $35 plus shipping from Roberts last week. They had 10 in and did run out right away but said they were going to get some more in. They are highly recommended to buy from. I never had a problem with them on several purchases. If you have any more questions, I will try to answer them for you. Hope this was helpful for you.