Hi everyone,

Just joined FM and wanted to start by whining about the AF on my 40D.
AF is very "nervous" and gets thrown off really quickly compared to my
1D MkIIn. With a 500mm f4L IS attached I found the AF to be fast, but not
noticeably faster than my 30D. If one read the Canon brochures, it would
seem that AF was on a different level with the 40D. It is not; at least not on
my 40D!
Once you attach a 1.4x to the 500mm, it's really hard to get a sharp shot of a bird
in flight; the AF hunts a lot, sometimes racking the lens to infinity and staying
there; and that's with Focus Search ON. When it managed to "find" the subject,
it wouldn't stick with it long, and whether using all focusing points or just the center
AF sensor, it would lose the subject way too easily.
This morning I tried to focus on some purplish leaves on a tree outside
my window, in the shade, about 10' away, using a 70-200mm f2.8L, and the thing would not focus! It kept racking back and forth, then "creeping" just outside the minimum focusing distance, but could not find enough contrast in the leaves to lock focus.
When using all focusing points it would find something to lock on to, but it would pretty much
only focus in One Shot AF. I tried the same shot with the 1D MkIIn and it locked on immediately, in AI Servo and One Shot modes!!
I am very disappointed in the AF on my camera.
I like the 40D and all the new features, but I pretty much bought it to shoot birds using
my 500mm and sometimes with the 1.4x TC, but it cannot match the accuracy of the 1D MkIIn.
I'm not sure if it's only my particular 40D, but given the trouble Canon seem to have with the MkIII's AF, I wouldn't doubt that more people will start complaining soon.

My LCD seems to have a purple cast, too!!!


sorry for the whining. I hope someone will post their experience with a similar set-up
and hopefully their experience is better than mine. For now, I will keep my MkIIn.

Welcome you'll fit right in here!!

Hmmm, you sure it isn't just your 40d? I have a 20d, and the auto focus is horrible! My 40d auto focus is spot on... I was having to do overhead shots at a wedding this past weekend, and was blown away at how few of them I missed. Had I been using my 20d I probably would have lost 70% or more... Also, my auto focus locks on almost instantly, with very little hunting. Just my 2 cents....

I was noticing a similiar behavior with my 40D. I was using a 300 f/2.8 IS and a 1.4X TC. I switched off the CF that allowed hunting, I forget which one off the top of my head, and set the focus limiter switch and it was infinitely better.

It's is also better in one shot mode, which won't help you much with BIF

I don't think it's fair to try to compare the 40D to a 1DMIIn.

Mike

Mike send me that 300 2.8 I'll check it out for ya..

Well to me it sounds like you got a Ferrari, put it's engine into a Golf and complain that it doesn't go like the Ferrari does.
I can only compare the 40D's AF to the 350D(XT)'s and it is a huge step up.
There still must be a reason why the 40D costs only about a third of the mkIIN ;-)

Sorry but I use the 40D with the 500 f/4L IS + 1.4x TC and I'm not having any problems locking focusing on BIF. The same thing your describing will occur with my 1DMKIII if I don't have a subject with good contrast.

I've found the AF on the 40D to be more sensitive than the 30D and therfore it requires the same attention that the 1DMKIII does to the 1DMKIIn. If you let the focus point stray from your primary subject to the BG it will jump to the background thus causing the focus search when you get the point back on your subject.

The 1DMKIII allows you to adjust your sensitivity but the 40D doesn't so your only choice is to be more precise with the placement of your focus point, turn off focus search, or refocus when you lose focus lock (pump the AF-On button).

Jim

I totally understand that a 40D is not a MkIIn; but all the talk about the "greatly improved AF"
was what enticed me to buy this camera. That, along with the higher frame rate, made me think that I could "replace" the MkIIn with the 40D, and save my money to get the new "6D" to finally have a full-frame camera.
Maybe I am a little sloppy in my technique, having had the benefit of AF tracking sensitivity
and focusing point expansion of the 1D series I don't need to be ON the subject all the time.
I just couldn't believe the camera had such a hard time focusing in the shade, even with
an f2.8 lens, while the MkIIn handled it so easily.

And what about the purple cast in the LCD? I read somewhere that a guy had a greenish
cast on his MkIII LCD.

Overall the 40D is a very nice camera, though, and Live View is awesome!

Lucio Gomes wrote:

I totally understand that a 40D is not a MkIIn; but all the talk about the "greatly improved AF"
was what enticed me to buy this camera. That, along with the higher frame rate, made me think that I could "replace" the MkIIn with the 40D, and save my money to get the new "6D" to finally have a full-frame camera.

The other non center cross sensor AF point are a big step from the 30D o in that sense it is a great improvement. The 1 series bodies have a dedicated AF engine so the prosumer bodies are in a different league.

The 1 series bodies have a dedicated AF engine so the prosumer bodies are in a different league.

Can you elaborate on that a little? I never heard anything like that before.
I have heard about a separate imaging engine in the form of digic but never focusing. Is this in Canon literature somewhere maybe? thanks......

Lucio Gomes wrote:

I totally understand that a 40D is not a MkIIn; but all the talk about the "greatly improved AF"
was what enticed me to buy this camera. That, along with the higher frame rate, made me think that I could "replace" the MkIIn with the 40D, and save my money to get the new "6D" to finally have a full-frame camera.
Maybe I am a little sloppy in my technique, having had the benefit of AF tracking sensitivity
and focusing point expansion of the 1D series I don't need to be ON the subject all the time.
I just couldn't believe the camera had such a hard time focusing in the shade, even with
an f2.8 lens, while the MkIIn handled it so easily.

And what about the purple cast in the LCD? I read somewhere that a guy had a greenish
cast on his MkIII LCD.

Overall the 40D is a very nice camera, though, and Live View is awesome!

You may want to read this for a better understanding of how good the 40D AF is. In my experience it has proven to be outstanding. I have not done BIF yet though. Incidently, this is the only practical test I have seens so far besides opinion based ones.

http://www.bobatkins.com/photography/digital/canon_eos_40D_review_4.html#tracking

Lucio Gomes wrote:

I totally understand that a 40D is not a MkIIn; but all the talk about the "greatly improved AF"
was what enticed me to buy this camera. That, along with the higher frame rate, made me think that I could "replace" the MkIIn with the 40D, and save my money to get the new "6D" to finally have a full-frame camera.
Maybe I am a little sloppy in my technique, having had the benefit of AF tracking sensitivity
and focusing point expansion of the 1D series I don't need to be ON the subject all the time.


Not to be rude, but......

You said it yourself in this quote, The 40D IS NOT a MKIIN AF-Wise or any other 1 series camera for that matter. I read this over and over on this forum. 1 series bodies have a superior AF and you have to pony up for it.

If what you are saying is true you have a problem with your camera! My 40D will focus in my office with only the illumination of my 24" LCD monitor and no lights and it does not hunt. I actually tried it focusing on a black file cabinet and centering the focus point on the metal drawer handle. This was with no other lights on in the room. My 20D did nothing but hunt and sorry to say but my 1DMKIIN had just as much trouble as the 20D in the lower lighting. Outdoors in servo mode the 1-series is faster but I have had no trouble keeping birds in flight in focus with the 40D and my 300 f/2.8L IS, my 500 F/4L IS, with and without the 1.4x extender. I really got to try it out a few weeks back at the beach with gulls against a cloudy grey sky and still had no troubles tracking and keeping focus. I myself and very satisfied with the 40D!

bbudman,

What lens were you using? a 50mm f1.4 or a 70-200 f2.8?
My 40D wouldn't even focus on a bunch of leaves outside my window, in the shade,
at 9am. My MkIIn had no problem whatsoever acquiring focus on the same subject.

redman

You're not being "rude;" but you must understand that with each generation
of Canon cameras, they have improved the AF considerably, and since the
AF on the MkIIn is "old" by digital standards, I guess I expected the 40D's
touted "much improved AF" to be on par with the MkIIn, or to perform even better.

I may have to call Canon and ask if I can send the camera in for a look.
Like some MkIII bodies that have AF problems and others don't, maybe
my 40D has the MkIII bug!

geniousc wrote:
The 1 series bodies have a dedicated AF engine so the prosumer bodies are in a different league.

Can you elaborate on that a little? I never heard anything like that before.
I have heard about a separate imaging engine in the form of digic but never focusing. Is this in Canon literature somewhere maybe? thanks......


I think this is what Valerie may be referring to? (It's actually talking about the move to the 1D Mark II.) From the "How to Get the Most From Your EOS-1 Class Digital SLR;" pub date 2004.)

"The EOS-1D and EOS-1Ds had the fastest AF systems available among EOS SLRs when they were introduced, but the EOS-1D Mark II now has the most powerful AF system of any EOS camera released to date (2004). The EOS-1D Mark II was the first Canon camera to feature two dedicated CPUs for AF: one for detection and calculation, and another to control lens drive. EOS-1 class cameras prior to the 1D Mark II used a single dedicated CPU for all AF operations."


Edited by Paul B on Oct 05, 2007 at 09:06 AM GMT (Reason: typo)

I thought my 40D kicks major AF arse. It's better than any EOS body I've owned since 1990 (about a dozen) and certainly much better than I can manually focus. It's not failed me these last 3 weeks even once. Of course I'm not a demigod and lack access to a 1DMKIII. Plus ah dunno if I'm ready to join 24 hour fitness to just hump that brick around.

AF is very "nervous" and gets thrown off really quickly compared to my
1D MkIIn.
--------------------------------
Ok, that statement is so crazy. The 1D bodies all have a seperate processor just for AF.
So I don't care what gimmick they come up with in single, sharing duties, processor, prosumer bodies. There will be no contest reguarding AF.

Paul B wrote:
geniousc wrote:
The 1 series bodies have a dedicated AF engine so the prosumer bodies are in a different league.

Can you elaborate on that a little? I never heard anything like that before.
I have heard about a separate imaging engine in the form of digic but never focusing. Is this in Canon literature somewhere maybe? thanks......


I think this is what Valerie may be referring to? (It's actually talking about the move to the 1D Mark II.) From the "How to Get the Most From Your EOS-1 Calss Digital SLR;" pub date 2004.)

"The EOS-1D and EOS-1Ds had the fastest AF systems available among EOS SLRs when they were introduced, but the EOS-1D Mark II now has the most powerful AF system of any EOS camera released to date (2004). The EOS-1D Mark II was the first Canon camera to feature two dedicated CPUs for AF: one for detection and calculation, and another to control lens drive. EOS-1 class cameras prior to the 1D Mark II used a single dedicated CPU for all AF operations."


That's a reasonable answer and could be true however all servo systems have separate detection and drive even though it could well be integrated. It just depends on how the IC is designed, all in one or separate can achieve the same goal. I have just never seen that stated in any Canon literature.

Here's info on the 40D's AF from Canon USA:

"Sharp, Fast Focus, No Matter the Light
New AF system with 9 cross-type sensors, and world's first diagonal high-precision cross-type AF at center point with f/2.8 and faster lenses."
and then:
"It has a newly designed, high-precision 9-point wide area AF that uses cross-type points with lenses f/5.6 or faster, enabling the camera to focus faster, more accurately, and in ever more complex lighting. Each of the nine AF points has this cross-type coverage, a first in Canon AF SLRs. Adding to this AF performance, the 40D incorporates a diagonally mounted, high-precision cross-type sensor at the center AF point that is sensitive to both vertical and horizontal lines when fast lenses (f/2.8 or faster) are used, for for added accuracy and precision with these wide-aperture lenses. It's the world's first AF SLR where both lines of a cross-type sensor offer high-precision AF coverage. All focus points can be chosen automatically, or accessed using the 40D's intuitive, thumb operated Multi-Controller."

After reading the above, I honestly thought the 40D would have better AF than the "old generation" AF of the MkIIn.
Like I said, maybe it's my particular camera that's not performing the way it should,
and I sure hope that's the case.

Paul B wrote:
I think this is what Valerie may be referring to? (It's actually talking about the move to the 1D Mark II.) From the "How to Get the Most From Your EOS-1 Calss Digital SLR;" pub date 2004.)


Thanks Paul

I have used the 40D with a 70-200f2.8IS, 400f5.6 and 600f4 with and without 1.4x.
I have also used it for BIF. The AF is very good with this setup, it's not of Mark2 calibre, but pretty good and tracks well. I will agree if you move that point off your subject it will refocus pretty quick, but overall I have nothing but high marks for this camera. It is what the 30D should have been

* Shouldn't MkIIN AF be expected to perform better than 40D AF ?
* IMO Auto AF point selection is a treacherous focusing mode on any Canon camera......for the simple reason that the AF systems can not read our focusing intent .
* If the 40D has gained speed and accuracy of AF acquisition over 30D, that's a step in the right direction. The "penalty" may well be in fidgetty focus maintenance as there is no AF point expansion. I.e., you slip off the target and you've lost it. That also happens on MkIIN easy enough on smallish targets with single AF point focusing.

Edited by PetKal on Oct 04, 2007 at 08:23 PM GMT

Lucio Gomes wrote:
bbudman,

What lens were you using? a 50mm f1.4 or a 70-200 f2.8?
My 40D wouldn't even focus on a bunch of leaves outside my window, in the shade,
at 9am. My MkIIn had no problem whatsoever acquiring focus on the same subject.


I was using my 24-70 f/2.8L for the indoor playing around. I tried it on all three cameras and the 40D actually shocked me how quickly it locked focus. Honestly, I was expecting it to just hunt back and forth just like the 20D in such low light but it didn't. For the gulls in flight I was using my 300 and 500 with and without the 1.4x. I was on the Outer Banks on the Sunday that tropical storm Gabrielle blew in so it was windy and cloudy.

Yes, the 40D's AF is CLOSER to the 1 series AF than it's predecessors, but still not on par with it. I think a lot of us hoped for 1 series AF at xxD series prices, but that wasn't going to happen. Well, until Nikon did it. Hopefully next year canon will have to follow suit.

Lucio Gomes wrote:


redman

You're not being "rude;" but you must understand that with each generation
of Canon cameras, they have improved the AF considerably, and since the
AF on the MkIIn is "old" by digital standards, I guess I expected the 40D's
touted "much improved AF" to be on par with the MkIIn, or to perform even better.

I may have to call Canon and ask if I can send the camera in for a look.
Like some MkIII bodies that have AF problems and others don't, maybe
my 40D has the MkIII bug!


The focus of the MKIIN is still preferred by most Professional Canon shooters, especially those that have used it compared to other 1 series bodies.

Having said that, The X0D seies and the 1 series bodies are VERY different. I believe that Canon will continue to improve the X0D series AF, but it will never be on par with a 1 series focus. Canon wouldn't be able to sell a $4000+ body if they made it that good on the X0D series!



Bob