Hi I'm new here so apologies if I'm posting in the wrong place, but I need some lens advice for my Nikon D5500. I'm starting to do weddings and did my last one with 2 D5500, a Nikon 35mm (my favourite lens which I tend to probably over use because it's so sharp and great in low light) and my Sigma 18-200 (which is not so great in low light, soft round the edges and causes really noticeable barrelling in the photos). I'm looking to get a 70-200mm lens to use when I don't need something so wide angle. Which lens is best? I know the d5500 is a cropped sensor, so should I factor that in when looking at lenses and go for a different lens that will offer the equivalent of 70-200? I want something that's going to be sharp, good in low light, fast (I missed some shots because my 18-200 was so slow focusing) and has a decent zoom. Thanks in advance!