I am finding myself being restricted by the 300mm top end of my 70-300 IS USM (non L) lens. Getting some higher quality glass would be great as well.
I am thinking about the 100-400 of course, but I was wondering if I would be limited by the 400mm top end for birds. Should I also consider the 150-500 BigmOS? I have read all the threads on the bigmOS vs. 100-400 and I would really like to get the L glass but am wondering if 400 is sufficient for birds. I have also read the threads extolling the virtues of primes, but at this stage I would rather retain the flexibility of a zoom lens.
I have also read into adding a 1.4X to the 100-400 and the tape trick, but living in cloudy Oregon, I am a bit wary of both this and the bigmOS due to the reported lack of low light performance.
Thanks for any inputs!





