Struggling to work out where was best for this topic. I know its been covered numerous times before, but I'm after more reach than 200mm of my 70-200 on my 7D. It would be used primarily for motorsports, airshows and wildlife
Budget is around £1000 which gives me options of:
2x tele converter iii
Anything I've missed?
I have debated the Canon 400mm f5.6, but at that sort of focal length I highly doubt I would get along with a prime.
I have played with the Tamron, but struggled to hold it steady enough about 400 even on a monopod, looking back the shutter speed was just far too low, I've seen on here some excellent images shot with it. To use it above 350/400mm I'd need to use a tripod I think, something I won't always carry as mine is fairly heavy.
I demo'd a 2x converter today and the autofocus felt faster, it was a lighter rig (although the weight felt more than I'm used to with the lens being that bit further from the camera, it was better than the Tamron where the weight moves as you zoom), and is easier to carry than 2 separate, heavy lenses. It's also much cheaper!
Haven't tried the Sigma, I seem to hear good and bad things about it so I'm not sure what to think, the price appeals to me, but its image quality I'm after, then probably weight and thirdly price.
Something I'm uncomfortable with is the focal length and thus the ISO required to get photos, when demoing the tamron lens and Canon converter my camera has gone to ISO 3200 and still captured dark results, it is more noise than is acceptable to me and I'd not want to use whatever I bought. Yes the shop was reasonably well lit, but far from many of the lighting conditions outside in daylight, however better than a wooded area for some wildlife or a tree lined racetrack.
I've thought about the 1.4x tele converter, but having used 300mm previously on another camera I just don't think 280mm would be enough, even though its more than I have now.
I guess I need some advice, reassurance and maybe out of the box thinking. I'm probably a bit averse to spending the money, especially when I won't get to use it more than 10 times per year.
Maybe I should save my money and just crop images until I have the time to use whatever the solution is?