The Canon 40D/50D have crosstype outer AF sensors. The Nikon D300 has 15 cross type AF sensors grouped in the middle of the frame. The sides of the D300's frame (or bottom and top of the frame in portrait mode) have single axis AF sensors.
So, I am curious: which camera will give more accurate/reliable AF WHEN using the outer AF points in portrait mode to focus on an eye at relative close distances using a medium tele lens? I am talking about selecting one single outer AF point and using One Shot/Single Shot.
In theory the 40D/50D should do better in this particular situation... If you have used both the 40D/50D and D300 can you tell me if this is true in practice as well?
Thanks
FYI I have also posted this thread in the Nikon forum.
Hard to say unless you are experienced at using both bodies under similar circumstances, and not many people will be so experienced.
I did shoot 20/30D and moved to mulitple 40Ds and shoot weddings - low light conditions where the difference matters most.
There is NO comparison - the 20/30D only had the cross at teh center point and in low light the outer points were about useless, and even in good light they'd not focus on a say a person's cheek where there is little contrast. The 40's outer sensors work every bit as well as the center ones on teh 20/30 bodies. I'm constantly amazed at what I can focus on how that I spent years being frustrated by.
BTW, I use the joystick to select my focal points and don't do the focus-recompose game.
prof_fate wrote:
Hard to say unless you are experienced at using both bodies under similar circumstances, and not many people will be so experienced.
I did shoot 20/30D and moved to mulitple 40Ds and shoot weddings - low light conditions where the difference matters most.
There is NO comparison - the 20/30D only had the cross at teh center point and in low light the outer points were about useless, and even in good light they'd not focus on a say a person's cheek where there is little contrast. The 40's outer sensors work every bit as well as the center ones on teh 20/30 bodies. I'm constantly amazed at what I can focus on how that I spent years being frustrated by.
BTW, I use the joystick to select my focal points and don't do the focus-recompose game....Show more →
Yeah, it will be hard... Although there are some switchers around
About the 40D outer AF points... Do you use them in both One Shot and AI Servo? If so, any difference? Also, do you use the 40D in low light with the aid of a flash/AF assist lamp? I think that might improve accuracy.
I have heard some Nikon users saying that the outer AF points of the D300 AF system are not particularly reliable/accurate, especially not in low light. I am just wondering how much it differs from the 40D/50D's AF system...
I once had the opportunity to try a friend's D300 with Nikon 17-55/2.8 AFS and 105/2.8 VR AFS. I used AI servo and tried locking on people walking slowly in a dimly lighted room. Due to the limited time I had I only tried the linear AF points (leftmost and rightmost). I later repeated that with my 40D, 17-55/2.8 IS USM and 100/2.8 USM. Later I went out and tried the macro lenses on a twig moving in the wind.
The results of the Nikon setup were - in a word - embarrassing. It simply struggled to lock focus and constantly had a serious lag. The 40D setup had no problems whatsoever. I simply can't understand why Nikon did not made all AF points cross type.
I recently shot a series of a flying pelican with my new 40D and a 70-300IS using AI servo with all AF points enabled. The pelican moved right accross the screen and was in focus every time, using every AF point (except one frame where the bird wasn't over any points). I was very impressed
Thanks to Chris Dees (another FM member) I had the oppurtunity to test the outer AF points of the D300. We had mounted the 16-85VR and SB-800 flash (AF assist light was on the whole time). Chris was so kind to be the subject.
First we tried the 51 point dummy mode in Single Shot. I had the face of Chris in the upper half of the frame (portrait mode) while he faced the camera. The D300 was quick to grab focus. It had a bit more trouble in low light (slightly darkened room), which resulted in occasional hunting. Outside there was no hunting. The accuracy was so-so... out of the first sequence (inside), 3 out of 8 shots had the focus on the ears (side of the head) while the AF confirmation was on the front of the face. Out of the second sequence (outside), 2 out of 5 shots had the focus on the ears (side of the head) while the AF confirmation was on the front of the face.
Using one selected outer AF point in Single Shot gave similair resuts in acquisition/accuracy.
After that we tried to do the same thing in continuous AF mode with 9 active AF points. I used one of the outer AF points to focus on an eye. Again, acquisition was quick. It had some trouble locking on low contrast targets though (inside and outside). I would rate accuracy the same as when using Single Shot... Again a few shots ended up on the ears (side of the head) instead of on the front of the face (eyes).
We also tried a few shots using only the center AF point (with 9 AF point expansion) to grab focus and to recompose after that... Accuracy results were much better.
So, based on this highly unscientific test I wasn't impressed with the accuracy of the outer AF points. Too much mis-focus going on. Just like I had with my 5D, maybe to a slightly lesser degree. Focus-recompose definetely improves accuracy (when using the center AF points), but this doesn't always work for me. The difference in AF accuracy between the center cross type AF points and the single axis outer AF points was very much noticeble.
Unfortunately, we didn't have a 40D or 50D at hand... so it is not possible to tell if the Canon cams would have done better under the same conditions.
