rscheffler Offline Upload & Sell: Off
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Deborah Kolt wrote:
Interestingly, I gave the new 400 f2.8 II a workout on a brilliant sunny day on field turf where the heat waves were visible - everyone's nightmare. Shot from five yards behind the goal posts, sitting directly on the turf. My original 400 and 600 would have given me frame after frame of oof shots; in these conditions, I usually go with a 300 and chase the action along the sidelines until later in the afternoon when the sun is at a lower angle. The new lens had some heat haze issues at 100-80 yards away, but only intermitently and then it rapidly cleared up as the subject got closer, a benefit I never expected. ...Show more →
This is interesting. My experience with the 1DIII and the original IS series 400 & 600 on Field Turf is identical to yours. I'm not sure , even after a couple years, that I can say the IV is much better, though it does seem to be a more resistant to massive AF misfocus fluctuations in these conditions. Purely speculation but there could be something to the revised AF drive algorithm of the version II lenses, such as faster communication to better allow the camera to find the most optimum sharpness. Shooting across heat waves on Field Turf I've often found that I can manually focus on a stationary subject with better sharpness than the AF usually provides, but once the subject starts moving, I just don't have the skills anymore to manually get consistent focus.
gdanmitchell wrote:
I'm convinced that among the reasons people will report that some long lens "isn't sharp" is that they haven't yet come to understand all of the tricky aspects of using such lenses.
Dan
I agree. Even though RG denied it was a factor in his infamous 1DIII and 1DIV follow up AF tests, I strongly suspect that it had an influence on the ability of the AF system to find a consistent lock in hot conditions. If you consider how outright jumpy and sensitive the 1DIII was at first release, it's conceivable that any slight shift in apparent focus could cause the AF system to try to compensate, and in the meantime the focus has shifted again. Throw in a moving subject...
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