I got on Craigslist last night and found a canon 70-200 f4 IS lens that the guy is asking $875 for. It includes the lens collar @ $150 and uv filter at around $50. That comes to around $1400 if purchased at an on-line store such as B&H or Adorama. But this morning I've found the lens on Amazon for $865 and there is an off brand collar that is only around $30. And a filter set for $25.

So I find myself wondering about what to do. First off are the off brand collars any good? $150 seems a bit high to me.
Second is the difference between f4 and f2.8. As I understand it that makes for a 1 stop difference. That's not much for double the money. But what about the difference in back ground blur etc.?

Thanks for you comments.

Andy
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