I (not a pro, affordable) have had this for 3 years and this is a great deal… Most Excellent Bazooka lens, It is sharp and clear!!! AF works the entire range even in APS-C mode on a full frame camera (Sony A7 series). No need for the 1.4 teleconverter for the Sony is 1.5 in APS-C and if you really need the 2X you can reach out to 1800mm (in APS-C, MF), the moon will fill your frame. Now the not so bad, first Canon/Nikon have problems with AF f/8 with converters (so have read) and above, with Sony no problems the entire range to f/22 150-600 or 900mm in APS-C. But when using either teleconverter AF works to the 400mm mark when hitting f/13 but Manual focus after (easy at your fingertip). Sigma says teleconverters do not work with MC-11 but they do but lens info is not correct (for some reason). I have used with A7S/RM2/M3 with outstanding results. You get lens update with the USB Dock as well as adjust the lens focus sharpness points to your shooting method at home and not have to send back to the factory like a Tamron. You can also adjust AF/IS in both C1/C2. Hint: to carry around for awhile get a heavy duty binocular harness strap and connect to D ring on tripod mount, easy to disconnect and place on a tripod – this also makes it easy to walkabout and capture birds flying by. Hint 2: Wear desert camo (digital if you can) it does not spook wildlife (deer/squire/birds) like wearing your own shelter! For flying birds the A7M3 with 10 frames a second is best, capture longer with buffer size or A9 (do not have). The AF will track when a bird flies behind a tree very sharp also, most times I see no bird in EVF but will have 8 to ten frames perfect focus. The lens comes with it’s own carry case (MC-11 fits in while mounted to it), I put in a fishing tackle bag with binocular strap also away from prying eyes with 2x (just incase) also comes with protective filter. If you need more reach than the SEL24240 (360mm). Do not be afraid to use APS-C mode even just a cropped 600mm you get better focus even out to 150 yards with a American White Pelican (filling a frame). Works great hand held. Also captured lunar eclipse with it in 20 degree weather only needed a heater below tripod to keep frost away from lens, superb large images!!! If you are a pro get the 60-600 it also has to be great!!!