Nikon 18-200 VR focal speed (D40x)

mattslaughter

I took my new 18-200 out to a large cookout this weekend and wanted to get some candid shots of people. I experienced some issues with the speed at which the lens was focusing. I have the lens on a D40x body with a Nikon SB-400 AF Speedlight (new batteries), and was shooting in full auto mode.

Is there is a reason the lens seemed to struggle to to focus on my subject. I would just expect it to focus much quicker, for the price and quality...

Thanks,
Matt

ziggy53

mattslaughter wrote:

I took my new 18-200 out to a large cookout this weekend ... I have the lens on a D40x body with a Nikon SB-400 AF Speedlight (new batteries), and was shooting in full auto mode.

Is there is a reason the lens seemed to struggle to to focus on my subject. I would just expect it to focus much quicker, for the price and quality...

Thanks,
Matt

Matt,

Unfortunately, the Nikkor 18-200mm, f/3.5-5.6G ED-IF AF-S DX VR is not a very fast lens for indoor/low-light use as the effective aperture reduces rapidly as you zoom long. It would also appear that the SB-400 lacks an AF assist light. The Nikon D40x is a fine camera but the AF section is definitely at the entry level end of the Nikon cameras.

Add all of these things together and I'm not surprised that AF suffered.

For best autofocus performance:

You need "fast" lenses, typically this would be f2.8 constant aperture zooms and f1.8 or f2 (or better) prime lenses. The wider aperture allows more light into the camera as well as reduced DOF, which improves AF speed and accuracy. The Nikon D40x does not have an AF screw drive so some of the prime lenses will not AF, somewhat limiting your choices.

You need an external flash with an AF assist light. This is extremely important and makes a tremendous difference in AF speed and accuracy. I believe that both the SB-600 and SB-800 flashes have an assist light, as do the Sigma EF-530 DG Super flashes for Nikon. This alone might give you enough additional help with indoor AF.

Ideally you would also want a camera with a more sensitive AF sensor and more powerful AF processing. This might mean a Nikon D2x or D3/D3x or D700 body, although the D300 AF section is pretty good as is the D200. The difference in the professional bodies is both the best AF module that Nikon has to offer, with improved sensitivity and speed, as well as a better processing engine with more "horsepower" dedicated to AF processing.

My recommendation is to upgrade your flash first to one with an AF assist light and see if that allows the AF speed and accuracy you desire. Next would be a lens upgrade to a lens with a faster aperture. I suspect that those things alone will give you what you desire.

mattslaughter

Thank you. That is just the information that I was looking for.

ziggy53 wrote:

Matt,

Unfortunately, the Nikkor 18-200mm, f/3.5-5.6G ED-IF AF-S DX VR is not a very fast lens for indoor/low-light use as the effective aperture reduces rapidly as you zoom long. It would also appear that the SB-400 lacks an AF assist light. The Nikon D40x is a fine camera but the AF section is definitely at the entry level end of the Nikon cameras.

Add all of these things together and I'm not surprised that AF suffered.

For best autofocus performance:

You need "fast" lenses, typically this would be f2.8 constant aperture zooms and f1.8 or f2 (or better) prime lenses. The wider aperture allows more light into the camera as well as reduced DOF, which improves AF speed and accuracy. The Nikon D40x does not have an AF screw drive so some of the prime lenses will not AF, somewhat limiting your choices.

You need an external flash with an AF assist light. This is extremely important and makes a tremendous difference in AF speed and accuracy. I believe that both the SB-600 and SB-800 flashes have an assist light, as do the Sigma EF-530 DG Super flashes for Nikon. This alone might give you enough additional help with indoor AF.

Ideally you would also want a camera with a more sensitive AF sensor and more powerful AF processing. This might mean a Nikon D2x or D3/D3x or D700 body, although the D300 AF section is pretty good as is the D200. The difference in the professional bodies is both the best AF module that Nikon has to offer, with improved sensitivity and speed, as well as a better processing engine with more "horsepower" dedicated to AF processing.

My recommendation is to upgrade your flash first to one with an AF assist light and see if that allows the AF speed and accuracy you desire. Next would be a lens upgrade to a lens with a faster aperture. I suspect that those things alone will give you what you desire.