Getting tired of 11 points

[KmH]

As Switch1FX mentioned, on the newer 51-point AF bodies, all the cross-type AF points are in the center of the frame.

Yes, but there are 15 of them to choose from.

 

[Derrel]

YES, there are 15 cross-type AF points, but they are all clustered right in the middle of the frame...that is the problem when one shoots primarily "talls", and wishes to focus off-center, toward the perimeter of the frame, using an AF patch...

The 51-point system has a relatively wide spread on the crop-sensor bodies, and a narrower degree of coverage of the frame on the FF D700 and D700 and D3 series bodies.

Again, it's not the "number" of AF points so much, as the placement of the points, and the capability of the AF module and the in-body AF motor...the D90 has consumer-level autofocus. That's really what it comes down to. It's just not up to the level of the more-capable cameras with stronger AF systems.

 

[Jcampbelll]

I focus with the center point and recompose. :er:

 

[Derrel]

Nikon D90 Review by Thom Hogan
"Autofocus System
Autofocus performance is decent. It's not a big step up from the D80, but it is a very modest step up in the automatic modes, where the camera starts applying its Scene Recognition system. The big issue is that the CAM1000 just doesn't cover much of the frame and has only one crosshatched focus sensor, so the D90 is not going to match a D300, and you shouldn't expect it to. If you need highly off-center autofocus, or excellent low-light focus performance, you really need to step up to the D300.
That said, there was a bit of snap to the D90 focusing that wasn't present in the D80. If your subject has enough contrast and is in the sensor area, the D90 does a credible job, and it does a better job of handling moving subjects than the D80 did (but not in Single Point AF, which doesn't track subjects).
Bottom line is that you're more likely to be confused by the three-part focus setting controls (AF/M, AF-S/AF-C/AF-A, Single/Dynamic/Auto/3D) than you'll be disappointed by the performance once you've figured those controls out. Put another way: if you're not getting the focus performance you expected, I strongly suggest that you spend some time examining the controls--you might not be setting the system optimally for what you're trying to do."

Nikon D300 Review by Thom Hogan
"Autofocus performance is excellent, with one caveat.
On the D300, the new CAM3500 sensor covers a very large portion of the frame, which means that the system is very good at following subject motion and managing off-center autofocus. Coupled with the scene recognition that is being done by the metering CCD in the viewfinder, the new system is sometimes so uncanny in 51 point 3D or Auto Area focus mode that it boggles the mind. This happens most often when there are faces or other skin tone in the area covered by the autofocus sensors. As it turns out, while various skin tones can look fairly different to us humans, to an RGB metering system they all are in the same narrow range and thus easily detectable. However, note that when you're in non-white light--some fluorescent and sodium vapor, for example--this system seems to not work anywhere near as well, probably because the color tint from the lighting is polluting the skin tones the camera is trying to detect.
Low light focusing is also surprisingly good. While only the center 15 autofocus sensors are cross hatched and more sensitive to low light, if there's enough contrast under the outlying 36 sensors the D300 still seems to be able to focus. But in general I find only the inner autofocus sensors confident and reliable in low light with Single Area AF.
The D300 does a very good job with erratically moving objects, such as flying birds and some sports. Indeed, I'd place it much better than the D200 in this respect, and perhaps as good as the D2 series if there's adequate light. Only when the light gets dim and the subject gets decidedly out of the central area did I find any problems with tracking moving subjects."

 

[Dominantly]

I focus with the center point and recompose. :er:

Interesting notion, I should have tried this :meh:

 

[eric-holmes]

I focus with the center point and recompose. :er:

Me too. I don't understand what's wrong with that.

 

[usayit]

Seriously... leave it in the center. Then focus recompose and lean back for the shot. practice.. DOF extends further behind the focused plane than in front. No need to think of solving problems with more tools. Photogs been doing it for years before all this mumbo jumbo...

 

[eric-holmes]

I still don't understand the lean back part.

 

[Dominantly]

Because your near limit of acceptable sharpness is less then your far limit. Meaning if you focus on an object you have less in focus area before that point, then you have after (more after). It's not a 50/50 split.

So if you lean back you pull that far limit towards you giving you a bit more "wiggle room". However, when you start getting some thin DOF, it really doesn't matter as you will miss focus doing this unless you are a calibrated robot with machine hands.

 

[usayit]

This is my understanding...


P1020064a by usayit_2000, on Flickr

THe actual focus plane falls behind the original subject. I ran some numbers and E is less than what most people initial believe (see previous thread I posted a link to)... Since leaning isn't an exact measurement, the fact that there is more DOF behind a subject (as Dominantly mentions in previous post) actually works in your favor.

There are dozens of techniques... This is one that was just taught to me and I adopted.. got used to it. I do this with 50mm @ f/1 quite often.