Polansky said:
Canon used to have contrast AF detection only on the 1D series. Which measures in 'black and white' so to say.
While Nikon uses a RGB chip to measure differences in objects and distances. This is why their AF performance is more or less equal.
That seems a bit confusing/misleading. Phase detect AF is just that - it detects differences in phase, which are best detected at contrast transitions, but detected much faster. Nikon's AF points are still phase detect AF points. What I think you're trying to say is that previous Nikon cameras used data from the autoexposure sensor to supplement the phase detect AF system, and now the 1D X is doing that, too.
Angryoak said:
I love canon, and have much invested in glass, but let's hit reality. Nikon has it all over canon with respect to AF, particularly in the prosumer models.
I don't buy this argument. Nikon does not 'have it all over Canon' nor vice versa. Yes, Nikon cameras have more AF points than corresponding Canon cameras, especially in the prosumer segment. But if you believe that the number of points is what determines the effectiveness of an AF system, then do you also believe that the number of MP determines sensor performance, and thus Canon 'has it all over Nikon' in the sensor department? Cross type points are superior to single-orientation points. Nikon's current pro bodies have 51 points with 15 cross-type points. Canon's have 45 points, but 39 of them are cross type, and the Canon cross-type points are distributed across the frame whereas Nikon's are clustered in the center. Furthermore, Canon has f/2.8-sensitive AF points, and the wider triangulation baseline makes those more accurate than f/5.6-sensitive sensors (when used with f/2.8 or fasterlenses, of course) - Nikon has all f/5.6-sensitive points.
At the prosumer level, i.e. D7000 vs. 7D, again Nikon has more points - 39 vs. 19, but fewer cross-type points (9 vs. 19), and again, no f/2.8-sensitive points. IMO, not even better, let alone 'having it all over Canon.'
Viggo said:
How is it that the Nikon's have only 9 "normal" crosstype, and the Canon has 45 and 5 dual crosstype, and yet they seem to have VERY similar performance, AF-wise.
The tests done with the D3s and the 1d mkIV they said they were pretty much equal, shouldn't the Canon be WAY better with that much more Cross-type sensors?
I think you're mixing up your models here. The D3s (and D3x, D3) have 51 total points with 15 cross-type points. The 1D IV has 45 points with 39 cross-type points and no dual cross points. The 1D X has 61 points, of which 41 are cross-type and 5 are dual cross. The D4 spec rumor (and it's still a
rumor, today at least) is that it will have improved 51 AF points (whatever 'improved' means), and '9 cross-type sensors that are operational up to f/8.' There could be more cross-type sensors at f/5.6, we don't know that yet. An f/8 sensor is going to be less accurate than an f/5.6 sensor, but of course if you have an f/8 lens+TC combo you'll probably take less accurate AF over no AF at all...
Regarding the tests done with the D3s and the 1D IV that said they were pretty much equal, what tests? I've seen comparisons showing the D3s is better, comparisons showing the 1D IV is better, and comparisons showing it's a wash. It all depends on what's being compared, and how. For example, the 1D IV has 39 cross-type points only with an f/2.8 or faster lens. Throw on an f/4 lens and how many cross-type points does the 1D IV have? One. How about with an f/5.6 lens? In that case, the 1D IV has zero cross-type points. None. Zip. Nada. Meanwhile, with any lens down to f/5.6, the D3s still has all 15 of it's cross-type points. Also, even though f/2.8-sensitive points are more accurate, they are slower - for AI Servo tracking of moving subjects, the AF system uses primarily the faster-locking f/5.6 lines. So Nikon, with all it's lines at f/5.6, is going to be able to lock onto moving subjects and track better, especially with the 15 cross-type f/5.6 points clustered in the center, than Canon's single-line points at f/5.6. From that standpoint, even the 7D is better since all 19 of it's AF points are f/5.6-sensitive crosses. But they're more widely spaced and the 1-series has better algorithms, so the 1-series still beats out the 7D.
The 1D X will be a different story. Unlike previous Canon bodies, the 1D X will have 21 cross-type points with most f/5.6 lenses, 41 cross-type points with most f/4 or f/2.8 lenses, plus 5 dual cross-type points with most f/2.8 lenses (but only one with a few, including the 24-70L). So, at the minimum it will have 21 f/5.6 cross-type points in the center (more than the D3s' 15 central f/5.6 crosses). Plus it will use the 100,000 pixel RGB sensor to assist the AF system.
But in terms of comparing the 1D X to the D4 specs, we'll need to wait until the D4 is officially announced. We'll have to wait even longer for real-world copmparisons, but keep in mind that the lens used will affect the comparison.
, though after a while you learn to work around it and avoid the pitfalls but it shouldnt be like this, the AF system is critical and i took it for granted that all of canons range would have an acceptable AF system like nikon have. Canon need to pick up their game here and I hope that the new 61 point system is awesome and works perfectly so that the old 45 point system will make it into lower models like the 5d3 its also not about the number of points its about the performance of the points you have.
