01-08-2015, 10:18 PM
@joju
@stoppingdown
Optical CAD is not the enemy. Unless the lens was poorly designed for manufacturability there will be very close agreement between CAD's MTF results and testing of a real lens sample.
The new lens is exceptionally well corrected for spherical aberration and is limited off-axis by either astigmatism or by coma. My money would be on astigmatism. I cannot tell more from the graph. There may be some unexplained loss of contrast due to the fresnel element that does not appear in spot simulations though. I would assume the lens will perform very well.
Quote:The short length of this new lens is extremely impressive - I just mean that the fact that the length is 'exactly' 75mm shorter means nothing - i.e there is no significance to the number 75 here. Bear in mind as well that the length quoted includes some distance in front of the front element for the threads, etc.
And since Japan has also the metric system, I really don't mind about ± 0.1 mm, the difference is 75 mm and I find that pretty impressive. The 70-200/4 has a length of 178.5 mm, so it's longer than the new 300/4.
@stoppingdown
Optical CAD is not the enemy. Unless the lens was poorly designed for manufacturability there will be very close agreement between CAD's MTF results and testing of a real lens sample.
The new lens is exceptionally well corrected for spherical aberration and is limited off-axis by either astigmatism or by coma. My money would be on astigmatism. I cannot tell more from the graph. There may be some unexplained loss of contrast due to the fresnel element that does not appear in spot simulations though. I would assume the lens will perform very well.