root cause of 1dm3 AF issues found?

I posted this on FM's 7d thread as well, but thought I'd repost here in its own thread. The original doc on canon europe: http://www.canon-europe.com/cpn_eos7d/

Something very interesting on that "technical" section caught my eye. Notice how on page 8 they start to mention how larger AF sensors were thought to be better, but that resulted in problems at high temp. Hmm, sounds a lot like the 1dm3......

Here's the excerpt (emphasis added):
"When designing the sensor, a larger size was considered however _research_ has shown that when _all_ factors are considered, a larger AF sensor is not necessarily better. Larger sensors are more susceptible to changes in temperature rises and falls. This in turn has an impact on the accuracy of the AF system overall. In order to maintain consistency and accuracy the size of the sensor has been optimized to ensure that changes in temperature have little or no affect on AF performance"

---- smoking gun, perhaps?

They also state that having all cross-type sensors is a unique feature in a camera with an APS-C sensor. They seem to have forgotten that the first camera with that was Canon's own 40D. Not 19 AF points, but all nine of them are cross type.

Very interesting! I'm guessing we'll see smaller AF sensors in the 1D MKIV then...

Would that means it's cheaper too ?

timnosenzo wrote in post #8654766
Very interesting! I'm guessing we'll see smaller AF sensors in the 1D MKIV then...

maverick678 wrote in post #8654778
Would that means it's cheaper too ?

Oh. That would really be rubbing salt in the wound.

apersson850 wrote in post #8654685
They also state that having all cross-type sensors is a unique feature in a camera with an APS-C sensor. They seem to have forgotten that the first camera with that was Canon's own 40D. Not 19 AF points, but all nine of them are cross type.

The meaning of 'unique' has become more loose and is no longer restricted to an 'absolute' meaning. 'Unique' is generally accepted and defined as also meaning 'uncommon' or 'not typical' now.

i wonder if we will get a recall to have smaller AF sensors fitted to the mk3
Rob.

Intuitively, it seems that smaller AF sensors are great all the way around. For instance, I imagine that it will make it easier to focus on an eye, and not have to worry so much about the camera accidentally focusing on the nose or cheek.

Is there any real downside to smaller AF sensors?

XterraJohn wrote in post #8657159
Intuitively, it seems that smaller AF sensors are great all the way around. For instance, I imagine that it will make it easier to focus on an eye, and not have to worry so much about the camera accidentally focusing on the nose or cheek.

Is there any real downside to smaller AF sensors?

They gather less light, so need a brighter scene to do the same job.

I doubt that's what they mean. I assume they talk about the whole AF sensor, not a single AF element. Making smaller AF sensors then means that you can't equip them with, say, 52 Af points (just to have one more than Nikon), since that will not fit in. But you can have less points with higher accuracy (at least in theory).

Thanks for the insight in the modern English language. I was still under the impression that unique was just that.

huh.

apersson850 wrote in post #8654685
They also state that having all cross-type sensors is a unique feature in a camera with an APS-C sensor. They seem to have forgotten that the first camera with that was Canon's own 40D. Not 19 AF points, but all nine of them are cross type.

Maybe they mean the most cross type in an APS-C camera...

LotsToLearn wrote in post #8654912
The meaning of 'unique' has become more loose and is no longer restricted to an 'absolute' meaning. 'Unique' is generally accepted and defined as also meaning 'uncommon' or 'not typical' now.

That's just another bastardization of the language. I cringe every time I hear "very unique" or "more unique" or "most unique".

I think I first noticed this trend when I saw "irregardless" listed in the dictionary. Its definition is "regardless". So, the definition of an incorrect word is...the correct word.

Now, back to our regularly scheduled program.

I don't think we will see the sensor change on the 1D Mark IV. There are too many sport photographers that are tied into the 1.3 sensor. If Canon changes the sensor size they might just see a mass exodus. That is why they won't change.

JBF wrote in post #8658071
I don't think we will see the sensor change on the 1D Mark IV. There are too many sport photographers that are tied into the 1.3 sensor. If Canon changes the sensor size they might just see a mass exodus. That is why they won't change.

They are referring Auto focus sensors... not the actual sensor itself.