Over Christmas I purchased the Sigma 24-105mm F4 DG OS HSM / DG HSM | A, for use on my Nikon D610. I must say since the purchase I am more than pleased with it. Although when I came to register it with Sigma I was told that because it has been bought outside of Europe (purchased in Dubai) warranty would not be covered if I was to have problems with it in the future. Not a problem of course unless I have issues with it. I was not aware the Sigma no longer offer a World Wide Warranty program. Rant aside its a great lens fantastic quality, sharp and has not been off the camera since I purchased it. I have mainly used for Landscapes and Night Photography and the occasional casual shot, It's also ideal for casual everyday use and it has a nice focal range. Good for close up's, portraits, weddings and still life. This is one from the Art range of lens, from memory I believe that Sigma categorizing their lens into groups contemporary, art and sports, that's a good idea and helps when purchasing a lens.
It has an aperture of F4 to F22 and weighs in at around 880g
The images that are loaded in my Dubai gallery were taken with this lens, now i just need to purchase new filters as it's quit a large size at 82mm.
All in all I do like the Sigma lens.