AF speed D700 slower than D3? how come ?

Started Aug 7, 2009 | Discussions thread
Marianne Oelund Veteran Member • Posts: 7,121
It is not the batteries

Joseph S Wisniewski wrote:

James Kei wrote:

I am not alone,

No, you're not. Having the same AF sensor is only part of the solution. The AF sensor tells the camera if the lens is focused too near or too far, and how much to move the lens. The motor (camera motor or lens motor) then has to move the lens, and the motor runs on the camera's batteries. Increase the battery power, and the motors move faster.

I think MDH was the only one to get this right.

Joseph, I'm very respectful of your expertise, and greatly appreciate the wealth of information you have contributed to this forum. However, I must correct you on this issue: The batteries have nothing to do with AF speed .

AF motor drive is tightly regulated by the inner servo loop in the lens electronics, which completely compensates for variations in battery voltage. Regardless of whether one uses a freshly charged EN-EL4 in the battery grip, or an almost-dead EN-EL3 in the body, AF motor speed will be exactly the same .

The price evens out a lot if you get the battery grip, D3 battery, charger, and the stupid end-cap you need to put on the battery to use it on the D700 grip. That all eats up some $800 to bring the AF speed of the D700 up to D3 levels...

As explained above, if the D700 is slower with its internal battery, it's still slower when using the battery grip. You can't "turbocharge" the D700 AF speed with better power supplies.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

But, is the D700 really slower? We see a confusing jumble of contradictory anecdotes and test results. As it turns out, the truth is: It depends on which lens, and even what focal length setting is being used! No wonder there is a plethora of divergent opinions on the subject.

AF system control parameters are table-based, with different sets for the various lens focal length ranges. The D300 and D3/D3x have different tables, and there are cases for which the D300 actually drives AF motors faster .

I haven't tested a D700 yet, but I'm becoming very curious to see whether it behaves as a D300, D3 or something completely different.
More later (after I get my hands on a D700) . . .

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