Hi Guys im new here and after to sort a situation with my D90, i take mainly off road bike shots and for an example if i take a pic of a bike coming towards me say jumping with filled background such as trees, it has a problem autofocus and often its the trees in focus, if however the background is clear such as sky its fine, i also own D200 & D50 and never have a problem with these cameras in this situation, does the D90 have different autofocus, i know in video mode it uses contrast detection, in all other circumstances the autofocus works perfect, i have checked all the settings several times and dont beleive this to be the problem, many thanks in anticipation
I have some experience with taking bike shots; it's not easy.
If that happened to me, I would try: - making a decision on where the riders were coming toward you. - to position yourself to get the shot you want. - to find a fixed object like a tree and focus on that. (if nothing there, you could drop a hat or backback or something) - to then lock the focus on that object. - when the rider is next the tree, take the image. It should work. And, watch out for flying mud
Good luck and let us know how it turns out.
"The Nikon did the work; I just happened to be behind it at the time." TP
The D90 and D200 seem to share large parts of the same AF module, CAM1000. But the D90 adds a 3D-tracking option (custom setting a1). If they are still available to you, it might be worthwhile investigating what the settings you used were that rendered the D200 and D50 (5-point AF) compatible with your mode of shooting. Presumably, the D90 should be capable of that, too but not necessarily using the most advanced mode. The settings you report using do not include any options from a1. If you have a1 set to auto (which the manual claims is the default, p.56), you have virtually no control over which focus points are used. Custom setting a2 only chooses the area considered for the center focus point - it does not lock the AF to the center (or any other) point, that's the job of the lever directly under the multi-selector.
Other settings might get in the way as well. How do you initiate focus - shutter button or AE-L/AF-L button? Do you lock focus?
Try turning off the continuos AF. I tried using the CAF and never could get it to work like I wanted it to. With CAF and a fast moving subject, if you don't hold the focus point long enough for the camera to "lock on" the camera will continue to try and focus even as you take the shot. As has been recommended use a spot focus method. Pre-focus the camera to the area where you expect the best action to be and then take the shot.
not easy to use manual focus when taking kitesurfers for example, what confuses me is the D200 & D50 both cope with this situation, so is the D90 faulty of does it use different autfocus, the manual even says af would be difficult in the scenario im describing
In this case it look like a simple case of a missed focus by the subject moving off the chosen focus point. You were already in AF-C mode. For this kind of shot I would probably go with dynamic-area mode instead of single-point. You might also try out the wide vs narrow center point option.
---------+---------+---------+---------+ Joseph K Seattle, WA, USA