Andrew Chase wrote:
Can you explain to me why different BG's matter and why not having the first frame in focus makes his test "flawed"?
Andrew, the background may affect the test if it provides a dominant contrast upon which the camera can focus better than it can on the subject, and if it is close enough to the intended target for the selected AF sensor to see it. If the subject is larger than the AF sensor and if only one sensor is active, as in that test, then the background has minimal effect.
AI Servo mode applies predictive focus calculations to predict where the focus will be when the next image is captured, and it sends the lens to that focus distance. It does this prediction based on two or more recent focus measurements and calculates the subject's speed of approach or departure. It should be doing this much faster than it is taking photographs (up to 6.5 fps for a 40D, 10 fps for a 1D3). If the original photo is out of focus then the predictive focus does not have a reasonable starting point for its calculations and the predictions may be wrong but even so it should be able to recover very quickly. i.e. that initial focus error does not write off the entire test sequence or even much of it. A few frames at most - and only that many because the subject is accelerating from a standing start.
To prevent the first few frames being OOF it is preferable in AI Servo mode to let the AF system track the subject for a while before you start shooting. Just don't release the AF button even for a moment or the predictive AF info will be instantly discarded and predictions will have to start from scratch when you restart AF.
I'm not sure about the 40D but when you activate all of the AF sensors on a 1-series body in AI Servo mode, the camera begins tracking only with the centre AF sensor and once it has acquired a contrast pattern (a.k.a. subject) it will continue to track it even if it moves to another sensor. This approach is another reason to be tracking the subject before you begin shooting - so that you know what subject or part of the subject is being tracked. The 9-point AF sensors of the xxD or xxxD cameras are so far apart that a pattern being tracked on one sensor can fall into a gap between sensors before being picked up by another, and focus may be lost. It is therefore more critical to maintain good aim when tracking with a xxD camera.
You're welcome. I still don't have my 1Ds2 back. Three weeks so far. I doubt the 40D will be any faster. My 1D2 took almost ten weeks (but at least they fixed it so that it works nicely).
Alan321 wrote:
My 1D2 works well too, so maybe it's just the lesser AF systems that are affected so noticeably.
Our 1-series experience suggests that using AI Servo on a stationary subject need not necessarily be impossible or result in a high failure rate. Given that, then surely it is reasonable to expect new and enhanced xxD AF systems to improve on previous generations in this regard.
The 40D is supposed to be an enhancement with its better AF hardware and faster AF computing, and I reckon it should be closing the performance gap on the three-year-old 1D2 AF technology more than it has. Naturally, I don't expect it to do as well as the 1D3 AF is supposed to do because that system should also be improving on the previous generation.
The 40D is not, nor will it ever be a pro camera. It does not, nor will it ever have pro AF. Canon is giving you the disease to sell you the cure: to have the AI servo work the way you want you have to buy a 1. It doesn't matter how much you don't like it, that is the way it is. I want the 40D to have pro level AF, too. It doesn't. Maybe some day when Nikon is kicking Canon's ass all over the place with the d300/d400/d500 they will make a crop cam with pro series AF and weathersealing for under $2000. But that day is not today.
timbop wrote:
The 40D is not, nor will it ever be a pro camera. It does not, nor will it ever have pro AF. Canon is giving you the disease to sell you the cure: to have the AI servo work the way you want you have to buy a 1. It doesn't matter how much you don't like it, that is the way it is. I want the 40D to have pro level AF, too. It doesn't. Maybe some day when Nikon is kicking Canon's ass all over the place with the d300/d400/d500 they will make a crop cam with pro series AF and weathersealing for under $2000. But that day is not today....Show more →
, that 'someday' is a long way away-given Canon''s market share. Nikon's been playing catchup for years, and although they just (finally) came up with some competitive products, they're a long way behind in the pro/prosumer field.
Exactly my point - it will be a very long time. For now, Alan, just return the 40D and get another 1dm2. I don't think you are going to be happy with the 40D, and it isn't worth frustrating yourself.
timbop correct of course; as much as we hate it we have to pay the dollars for a 1 series if AF is paramount. Ever since I bought my EOS 3, I've realized how crap Canon's consumer AF is. Ok 40D is a huge improvement, but the coverage is too small and the gaps between AF points too large. They should have put 2 extra points on the main row making it 5 and added the invisible helper points around the centre point. This would have been trivial and cost effective and not in any way stepped on 1 series toes.
Gosh I'm tempted by the idea of a D300 and 200-400 f/4 VR, but that's a big commitment. I will get a 40D as it's so much better than the 20D in so many other areas it's still a great upgrade, but I just wish they'd resolve the 1D III AF issues. I'm happy to pay for a 1 series as they are just beautiful tools to work with, but damn they realy do need to offer an EOS 3 class DSLR with pro AF and maybe with the D300 doing so and probably catching Canon right off guard they will have little option but to respond. people have been demanding better AF for years in an affordable camera, but the 40D only partially douses the fire. 15 x-type points and even better tracking would have been a great leap forward.
Pixel Perfect wrote:
timbop correct of course; as much as we hate it we have to pay the dollars for a 1 series if AF is paramount. Ever since I bought my EOS 3, I've realized how crap Canon's consumer AF is. Ok 40D is a huge improvement, but the coverage is too small and the gaps between AF points too large. They should have put 2 extra points on the main row making it 5 and added the invisible helper points around the centre point. This would have been trivial and cost effective and not in any way stepped on 1 series toes.
Gosh I'm tempted by the idea of a D300 and 200-400 f/4 VR, but that's a big commitment. I will get a 40D as it's so much better than the 20D in so many other areas it's still a great upgrade, but I just wish they'd resolve the 1D III AF issues. I'm happy to pay for a 1 series as they are just beautiful tools to work with, but damn they realy do need to offer an EOS 3 class DSLR with pro AF and maybe with the D300 doing so and probably catching Canon right off guard they will have little option but to respond. people have been demanding better AF for years in an affordable camera, but the 40D only partially douses the fire. 15 x-type points and even better tracking would have been a great leap forward....Show more →
It does help (talking about the Nikon D300) having "51-point 3D Tracking" at your disposal. Covering a large area left to right and vertically. With the sensors closely grouped together. IBut I wonder how it will do in the real world.
I too think Nikon will be bring to market another winner in the D300. And as for Canon responding...we'll see 18 months down the road.
Pixel Perfect wrote:
Ever since I bought my EOS 3, I've realized how crap Canon's consumer AF is. Ok 40D is a huge improvement, but the coverage is too small and the gaps between AF points too large. They should have put 2 extra points on the main row making it 5 and added the invisible helper points around the centre point. This would have been trivial and cost effective and not in any way stepped on 1 series toes.
I agree: the coverage is rather small but does anyone know or has anyone seen the actual AF pattern for a 40D yet? We've seen Alan's screen cap of the metering spots but they are not the actual AF pattern. The diagram I've seen for the Nikon D300 shows a honeycomb-like pattern with no gaps in between. I can't believe Canon would actually leave gaps there. Sure, there are points where the AF is less than optimum but would it not default to the nearest point of high contrast?
timbop, I've had far more frustration from my defective pro cameras than I have had from my 40D
If I buy another one any time soon it will be a Nikon with a useful and versatile lens that'll live on it full time. That way I won't have to replace a whole collection of Canon cameras and lenses but it will be worth having. I won't be buying any more Canon lenses for a while either, because there is now a chance that I will buy Nikon instead. I reckon I can run Nikon and Canon systems together as easily as I can use different Canon models.
Canon now have two of the last three cameras that I bought, and the return of my 1Ds2 has been delayed until the middle of next week. That's almost a month without my top of the range camera just because Canon hasn't got a quality control system that weeds out the crappy units. Suitable testing would add less than 1% to the cost of a 1Ds2 and prevent such failures reaching the customers. Unfortunately I can't join CPS and get better service because I'm not actually a pro photographer. I also can't get mine serviced quickly because someone else is in CPS.
I read recently that Nikon is outselling Canon in Japan. My guess is that will continue and maybe they deserve to win for a while.
Sometimes I think I should have taken up woodworking instead of photography, but with my luck I'd probably just cut my fingers off
Alan321 wrote:
...the return of my 1Ds2 has been delayed until the middle of next week. That's almost a month without my top of the range camera just because Canon hasn't got a quality control system that weeds out the crappy units. Suitable testing would add less than 1% to the cost of a 1Ds2 and prevent such failures reaching the customers.
Alan, I know your pain.
You should try getting a movement replaced in an Omega Seamaster Co-Axial GMT. My watch was away for 3 months. Since the beginning of November last year it has been in the workshop 4 times and the first three times were five weeks each. When it went in the fourth time they bit the bullet and replaced the movement but that took 3 months. That's nearly 7 of the last 10 months in the workshop. Omega make fantastic watches but after 2 years of flawless service, this one turned into a hangar queen.
J.D. wrote:
I agree: the coverage is rather small but does anyone know or has anyone seen the actual AF pattern for a 40D yet? We've seen Alan's screen cap of the metering spots but they are not the actual AF pattern. The diagram I've seen for the Nikon D300 shows a honeycomb-like pattern with no gaps in between. I can't believe Canon would actually leave gaps there. Sure, there are points where the AF is less than optimum but would it not default to the nearest point of high contrast?
J.D., I'm not sure what diagram you are referring to but AF sensors are either linear or cross-type. Individually they don't cover any significant area and are certainly not honeycomb shaped. I suspect you are thinking of the metering zones rather than the AF sensors.
The metering sensor is up near the pentaprism while the AF sensors are below the main mirror. However, many of the metering zones coincide with an equivalent location (relative to the main image) of an AF sensor.
For the AF there is the effective shape of each sensor as laid out on the image, and then there is the actual shape as laid out on the AF sensor chip. This is quite different but that doesn't matter because of the way parts of the image are redirected via AF mirrors and AF lenses onto the chip. Get hold of the Canon 40D White Paper and you will find a diagram but in isolation it is a bit confusing.
In practice there are big gaps between the AF sensors on the 9-point AF systems. If there wasn't then they would be far too big to be selective enough when you want to focus on a small subject. The only way to resolve both limitations is to have many AF sensors - 45 on the canon 1D series or 51 on the new Nikons.
No, you aren't confusing it. They do show a diagram with all the af markers in the VF, as does canon for their cameras. The diagrams aren't the actual shape, but you can see how tightly packed they are compared to the meager 9 of the 40D. If you search for "40d whitepaper" you can find the canon doc, and on pages 10 and 11 they illustrate how large the AF sensors overlaid on the VF screen.
That diagram indicates a whole mess of T sensors rather than + sensors.
For instance the outer sensors are ineffective "outside" the pattern of viewfinder AF sensor position indicators but are effective within it. Most of us are used to the idea that the indicator shows us where the sensor is centred. The gap between the middle column of sensors and the others is quite obvious too.
If you compare the diagrams on pages 10 and 11 you'll see that they represent the shapes of the sensors differently, so it is rather confusing.
The 1D2 manual very clearly shows the metering patterns with both the honeycomb-shaped metering zones and the AF focus sensor locations overlaid onto the image area (page 80, if you want to download it from the Canon site). My 20D manual does not show that sort of diagram and nor does the 40D white paper. I don't presently have the 40D manual to compare it to. This diagram is what leads me to think that you (J.D.) have confused the shapes of the metering zones and focus sensors. Nikon may have published a similar diagram for their new system.
Alan321 wrote:
This diagram is what leads me to think that you (J.D.) have confused the shapes of the metering zones and focus sensors. Nikon may have published a similar diagram for their new system.
Well, in the end, you may be right. I just can't remember what I saw.
Ai is designed for moving subjects it is noy uncommon for the camera to hunt to try and detect movement. It is constantly trying to detect movement. You swaying 1cm whilst shooting will cause it to hunt.
I get the picture now (no pun intended). 
, that 'someday' is a long way away-given Canon''s market share. Nikon's been playing catchup for years, and although they just (finally) came up with some competitive products, they're a long way behind in the pro/prosumer field. 
