Over time I have graduated to Canon 5D Mark iii DSLR. It's a great camera but bulky and heavy. As one gets older, bulk and weight of cameras become an issue. After carrying my 5D for several hours, it starts to feel like having a heavy anchor around my neck. It affects my neck, shoulder and back and I don't want it to interfere with my racquetball game. I've tried many camera straps and slings and some are better than others but I still feel the weight and bulk of my DSLR. So I was happy to hear that Sony introduced small and light full frame mirrorless cameras which received very positive reviews. After extensive research, I selected the 36 MP Sony A7R and love it. A7R has a much smaller footprint than my 5D, body only weight and dimensions (WxHxD) 14.4 oz and 5.0x3.7x1.9" (35.2 cubic inches) vs Canon 5D's 30.2 oz and 6.0x4.6x 3.0" (82.8 cubic inches). It's rumored that A7R uses the same sensor as Nikon D800. Number of well known photographers, including Trey Ratcliff, Brian Matiash, and Serge Ramelli, were impressed by A7R and have added it to their gear and use it extensively. I, too, am impressed with A7R's output including image quality, color depth, dynamic range, and low noise at high ISO. I also have gotten used to Sony's EVF (electronic view finder) and actually prefer it to a normal optical viewfinder, although it does affect battery performance. But nothing being perfect in this world, here I some drawbacks of A7R. One being paucity of FE (Sony full frame E mount) lenses. List of the existing and rumored Sony FE lenses can be seen on SonyAlphaRumors website (http://www.sonyalpharumors.com/the-updated-sony-fe-lens-roadmap-and-a-few-thoughts/). There are adaptors (from Metabones and FotodioX) available to allow use of Canon and Nikon lenses on A7R. These adaptors have some reported drawbacks and also somewhat defeat the purpose of having a small and light photo system after attaching large and heavy lenses onto A7R. There are also drawbacks with some of the existing Sony FE lenses. For example, Sony FE 70-200 mm F/4 lens is heavier (30 oz) than the comparable Canon 70-200 mm F/4 lens (27 oz) and also more expensive. I've also read somewhere that it is recommended to carry A7R with FE 70-200 mm lens by the lens and not the camera due to the difference in their respective weights. Now for some minor peeves about A7R. The manual is poorly written and hard to follow and use. The camera comes with a cable for charging the battery in camera and not a separate charger. There doesn't appear to be a single back focus button but requires pressing one button to focus and another to lock the focus, a two button process. It also doesn't appear possible to set a shutter delay and bracketed shot exposure for HDR. Nevertheless, I very much like and use my A7R, but wish that Sony would come out with a greater and more reasonable lens selection. So far I only have a Zeiss 24-70 mm lens for my A7R while hopefully awaiting future Sony FE lens availability. In the meantime, I still carry and use my Canon 5D, mainly because of the lenses that I have and I also can't part with it. Aside from its size and weight, Canon 5D is also a great camera. The above opinions were strictly my own and not influenced or supported by any other(s).