GMCPhotographics said:
candc said:
I have been on the fence about this lens for a while. I just ordered one today from BH photo. Here is a review from imaging resource
http://slrgear.com/reviews/showproduct.php/product/1559/cat/all
They claim it is sharper on a crop body which is what I will be using it on. So you are getting similar focal range and performance as you would from the canon 200-400 on full frame. The 1 stop aperature advantage should in theory help counteract the better iso of the full frame setup and you are talking about 1/3rd the price . I will post more when it gets here.
On a crop body, you will loose a stop in iso performance and an effective stop of DOF against full frame. While your camera will state f2.8, the reality is that it is effectively dropping a stop to become a 192-380mm f4..so it doesn't really gain anything. The AF on this lens slower and less accurate than the big white and the focal length drop as the focus pulls into MFD is really quite apparent and dissapointing. I found that I was better off with a native 300mm f2.8 lens or a 70-200 f2.8 LIS with a 1.4x TC.
an f2.8 lens is an f2.8 lens regardless of whether you put it on full frame and crop out a square or on a crop body.
what i am saying is that comparing the 120-300 on a crop to the 200-400 on ff is going to be very similar in practice, standing in the same spot zoomed in they will frame about the same. without doing a shootout you can't say if the iq will be the same but i am thinking it is from what i have seen.
the 120-300 is a 2.8 so its a stop faster and will allow 1 stop lower iso in the same scene framed the same way with the same dof as the f4 lens on the ff camera
it may not be the same its hard to say without a shootout, maybe the 120-300 is better? maybe the 200-400? it would be fun to try i think the results would be closer than you think. and the thing you are gaining is $8400.00