Hi everyone,

I was just looking over the camcorderinfo first impression review and in there is a statement that the XL2 is using 3 oversized chips in creating the "native" 16x9 in the camera.

http://www.camcorderinfo.com/content/Canon-XL2-First-Impressions-Camcorder-Review.htm

Then I read a person in another forum who says he slightly tested the camera and commented: "the chips are new and native 16x9 as they used larger chips to start and so the 4x3 mode is the the same size as before"

According to this info it seems the actual CCD chip size is not 1/3" but larger and by cropping down for 4x3 it's 1/3".

From the specs alone a few would assume that the chips are 1/3 but when cropped for "native" 16x9 and 4x3 that the used size is 1/4 or less.

My curiosity is stirred. Does anybody have any info or heard anything about oversized chips in the XL2?

Hi Peter,

Thanks for your interest. What you want to do is look over my XL2 CCD Block Overview (http://www.dvinfo.net/canonxl2/articles/article06.php). Then, if you have any questions about what you read there, just post 'em to this thread, which discusses the article (http://www.dvinfo.net/conf/showthread.php?s=&threadid=28870). Hope that helps,

Hi Peter,

The CCD's of the XL2 are not oversized. Trust me on this one.

The XL2 uses three (3) 1/3" CCD's, each containing 680,000 pixels. The XL2 uses two different "target areas", depending upon whether you set it to 4:3 or 16:9, which are pulled from within the 1/3" CCD. The largest target area used from within the 1/3" CCD is 960x480 (when in 16:9 Aspect Mode), which is not using the entire surface area of the 1/3" CCD.

Rather than going into this all over again in detail for you, let me point you to the facts. Chris has already done a decent job at drawing this all out at http://www.dvinfo.net/canonxl2/articles/article06.php

Please take the time to read the article carefully and thoroughly. All of the information you need to understand how it is done is contained within the article.

Here's something for all to consider: Regardless of the size of the actual surface area used in the CCD, the truth is in the image output. Period. You need to see the footage which has been shot with the XL2 so far and then decide whether it will fill your needs or not. Canon has been very upfront on how they are achieving the aspect ratios and there is no smoke and mirrors being deployed. This is certainly 'new technology' as far as CCD's go, at least it is for Canon. There is a great degree of resolution and detail in the output of the XL2, which is significantly more resolute and more sensitive to light than previous models. It is simply yet another way of creating a high quality digital video image. Some manufacturers prefer to crop & stretch, some prefer to electronically interpolate. Other much higher priced DVCam platforms use true 16:9 chips. Regardless, look at the image output and then decide which you prefer and move on and shoot something. Rent if need be.

- don

Thanks Chris and Don for your quick replies and for this great site.

Yeah those are the only sources I've read that ever commented about "oversized" chips which runs against what info you guys have. That's why I need at least 3 references to have me even consider something as possibly factual.

My curiosity stems from my experience with the PDX10 which happens to get 16x9 the same way the XL2 does. In that camera the 16x9 IMHO outputs better images than its bigger brother the PD150 in certain conditions (especially 16:9). Sony says the PDX10 chips are 1/4.7. Yet, learning from the threads here, I learned that the actual chip area used is reduced, but that doesn't stop the PDX10 from being one of the best buys out there still.

No matter what the chip size, I do look forward to the XL2 reviews and hands on accounts (even though it is out of my price range).

Peace

I think a lot of this "oversized chip" confusion stems from an error on the Canon spec page which says the diagonal in 16:9 mode is .289". Since this is outside the focal plane diameter of the Canon lenses (it's about .240"), this would cause serious vignetting if it were true. Once we know the true measurements, it will all make more sense.
Hopefully Canon will update/fix that page soon.

Dan...

Where did you get the information that the image circle of the Canon lenses is .24 inches? I've never heard this before, and although I've never known canon to publish the image circle dimensions for its xl series lenses, I would assume that that number would be something slightly larger than .33.

Thanks

Barry

Hi Barry

It's on the Canon XL2 Specifications page (http://consumer.usa.canon.com/ir/controller?act=ModelTechSpecsAct&fcategoryid=114&modelid=10350), scroll down to Number of Recording Pixels:

approx. 460,000 pixels (962 x 480) x3 CCD, 0.289" diagonal
approx. 350,000 pixels (720 x 480) x3 CCD, 0.236" diagonal

Gotta be a typo there.

No idea about image size, but don't confuse those chip sizes with actual diagonal measurments. They are nominal sizes that go back to the vacuum tube days - see http://www.dpreview.com/news/0210/02100402sensorsizes.asp

Standard 1/3" 4:3 CCD's are supposed to have a 6mm diagonal measurement. So 6mm x .03937 = .23622 inches. I think that was his point, as reinforced by Chris.

Barry,

Hope you don't mind my jumping in to attempt an answer to this one. I've been emailing Dan on this topic all day, and he's probably tired of hearing about it.
:)


The image area of a 1/3" chip is roughly around .216 inches (or .236 inches depending on who you talk to).

Check out this explanation on Edmund Optics site:

Section 4.3 CCD Sensor Size (http://www.edmundoptics.com/TechSupport/DisplayArticle.cfm?articleid=290#4.3)

Either way, it wouldn't make sense for the image circle of the XL lenses to be any larger than .240 inches, seeing as they are made for 1/3" chip cameras.

Hope that helps.

-Luis


EDITED TO ADD:
Damn you guys all post quickly!

Luis

Damn...you beat me to it...but I'm going to post my post, and add some hyperbole to it as well.


Ok, Dan, Chris, everybody....stop the presses. I just did a little calculation, based on the spec sheets included with my lenses...Dan, you were pretty close....Canon refers to the 1/3" image size as 3.6x4.8mm. I did a rough conversion and that comes out to a diagonal of .236. Ok...now I think that this is not the image circle measurement that dan is referring to, but the otherwise unpublished sensor size of the xl1s.

So if I'm not hallucinatin', then the depth of field worry warts, have nothing to fear about this sensor, as the 4:3 size on the new sensor is the same.... .236.

Regarding the image circle though, my guess is that it is significantly larger than the .236 diagonal (this would be indicated by canon's ability to utilize a .28 16:9 sensor area) typically lenses project a circle much larger than their intended imaging size...to minimize distortions and vignetting near the corners.

What I'm curious about is why anyone who should know this information (at canon) hasn't corrected all of us bemoaning the new sensor size. (where's jan crittenden when you need her--i know wrong company). If this information is correct...then the xl2 is also a "true, or native" 16:9 camera as well.


Barry

Nice link there, Luis. They're simplifying things a bit, but there's a pretty important thing to note: "The nomenclature of these standards dates back to the Vidicon vacuum tubes used for television, so it is important to note that the actual dimensions of the chips differ."

In other words, the size usually assigned to a CCD is not a measurement of its diagonal, but rather it's the diameter of a circle (tube size) that it would fit into. CCD's commonly referred to as 1/3rd-inch, 1/4, etc. are actually quite a bit smaller than that even.

"the 4:3 size on the new sensor is .236"

Barry,

The chip itself has a diagonal of .236 inches.
BUT, the image area used by the XL2 would have a diagonal closer to something like .17 inches in 4:3 mode.
The entire chip is not being used.

In 16:9 mode, it seems that the XL2 has an active image area of .211 inches, slightly less than what you would expect from a 1/3 inch chip (which makes sense).

"this would be indicated by canon's ability to utilize a .28 16:9 sensor area"

I think the point you may be missing Barry is that it seems that the specs on Canon's site are wrong. You cannot draw any conclusions from those specs, as they don't make sense.

If the sensor area were actually larger than .240 inches, then the old XL lenses would show significant vignetting in 16:9 mode.

-Luis

Luis..

see chris's post above...specs from canon. Now why would they have posted the pixel and area measurements together if they weren't referring to effective areas?

Barry

"see chris's post above"

Yes Barry, and right underneath those specs Chris wrote, "Gotta be a typo there"

The XL lenses were made to work with 1/3" chip cameras.
We've already gone through it, and we all agree that the diagonal image area on a 1/3" chip is .236 inches.

So, the image circle of a 1/3" lens is made to cover .236 inches, and maybe a little more for wiggle room.

If the 16:9 area on the XL2 actually measured .289 inches, then you would see vignetting on the sides when using the old XL lenses.

Basically, the specs on the Canon site are wrong.
We know that because the old lenses work on the XL2.

-Luis

PS.
To clarify, it is the DIAGONAL that is wrong on Canon's specs.
The Pixel count seems to be correct.

Somebody call the Product Manager!

Ok..we're writing over the top of each other here. I'm not really willing yet to buy that this is a typo (if it is, then fine) but why do we think it is...because the image circle is .240? where is there a listed spec for that...aren't we only assuming the .240 because we're talking about a .236 chip.

I've been shooting photographs for a long time...and I've never known a lens with an image circle that was nearly an exact match for the sensing area...they are typically 1/3 again or more larger. I don't know this to be true for the xl series...but it makes sense to me that it would be more than .004 larger than the xl1s sensor, that is very small tolerance for an image circle.

on the typo...typo's are usually one number not two... you are suggesting that both numbers are incorrect, yes...that wouldn't be a typo...that would be just wrong.

Again, I just have to ask the question as to why we think that the numbers are wrong...they seem pretty precise to me...not some casual mistake.

And this has always bugged me about the supposed smaller 4:3 sensor area....its the WHY....why would canon not use the whole sensor if it had lens coverage to cover all of it...it just doesn't make sense. (what if they didn't have the coverage...oooh...)

Barry

<<<-- Originally posted by Barry Goyette :.why would canon not use the whole sensor if it had lens coverage to cover all of it. -->>>

There are just too many unknowns here, so everything degenerates into mere conjecture. I would just note that there is a precedent for not using the entire CCD for 4:3 video. The PDX-10 does the same thing: http://www.greenmist.com/dv/16x9/10.JPG. It could have to do with a variety of things, such as not being able to read data from that many pixels 30 times per second. But anyway, from the info we already have, it seems like Canon wanted to optimize this camera for 16:9.

Boyd...

Your example also brings up this...if sony has the ability to process a 667k chip area on the pdx-10 (and an even larger 16:9 pixel count)...I would imagine canon could do the same with the effective area of a 680k chip....but now we are digressing.

I agree that all of this is conjecture. Like Chris said...somebody call the product manager...anyone got his phone #?

Barry

Well since we're having so much fun just wildly speculating... remember that the PDX-10 only shoots interlaced video while the XL-2 is shooting progressive, so one might expect that to require more bandwidth...

Boyd

ok so we're having fun, huh...then teach me how to make those cool italics in my posts....that's fun.

It seems to me that 60 fields of interlaced footage would require about the same bandwidth as 30 frames of progressive footage...but I'm not even close to informed on such matters.

Noticed that the "typo" made it onto the just released XL2 brochure as well. (they fixed a few other things)

If Chris is still stirring...has anyone actually compared (visually) the angle of view between the xl1s, and xl2 in 4:3 mode to see if they are different. (don't quote numbers here...we're all learning not to trust them). Short of taking a micrometer to the sensor, this would be the easiest way to tell if the sensor size has in fact changed. I did a few calculations that seem to indicate that the sensor is the same size based on the 35mm comparison chart you built, and my lens spec sheets. (since excised from a previous post). But they aren't backed up by what I'm seeing in camera.

Barry

Barry, Canon's pretty sure the angle of views are different between the XL1S and XL2... see their focal length w/XL2 (http://consumer.usa.canon.com/ir/controller?act=ModelFeaturesAct&fcategoryid=114&modelid=10350#f11) (scroll down a bit there) and compare that data to their old XL1S lens data... or better yet...

Compare this chart: http://www.dvinfo.net/canonxl2/articles/article04.php

to this chart: http://www.dvinfo.net/canon/articles/article58.php

I took those numbers from Canon's published specs. Also in my CCD article (http://www.dvinfo.net/canonxl2/articles/article06.php), to quote myself, here's what I came up with:

"The multiplication factor for using an XL lens on the XL2 is 1.105 in the widescreen 16:9 aspect ratio and 1.35 in the standard 4:3 aspect ratio."

Use [ i ] and close with [ / i ] to make your text appear in italics. Hope this helps,

<<<-- Originally posted by Chris Hurd : Barry, Canon's pretty sure the angle of views are different between the XL1S and XL2... -->>>

Sorry to rain on people's parade, but yes indeed, in 4:3 mode the Canon XL2 is using the equivalent of a 1/4" CCD.

I just cross-referenced Canon's stated focal-length equivalencies against a chart of equivalent fields of view, and in each case the XL2 4:3 equivalencies matched the 1/4" CCD column.

No need to worry about actual diagonal specs and whether Canon printed 'em wrong, just looking at the focal length equivalencies will show that the camera is looking through a 1/4"-sized window.

Would have been nice to be wrong, but it looks like we're not: in 4:3 mode the XL2 uses a patch of its CCD equivalent to a 1/4"-CCD camera.

A better way to make the same point I did. Thanks, Barry,

"No need to worry about actual diagonal specs and whether Canon printed 'em wrong, just looking at the focal length equivalencies will show that the camera is looking through a 1/4"-sized window."

Well, I think there is a need to worry about it actually, because either the diagonal specs are wrong, or the focal length's are wrong.

But, it seems that everything is pointing at the diagonal specs being wrong.

And I guess now they are wrong both on the website, and on the brochure. That's a shame.


By the way, Barry (Goyette), if you look on the Canon specs website, you'll see the same numbers repeated not only for the chip, but for the LCD. It looks like it was just a bad cut and paste job. Or, like we were saying, a very bad typo.

Either way, it seems to be a mistake.
I won't be surprised if we see a correction in the near future, and the actual diagonals match the numbers I posted earlier.

-Luis

<<<-- Originally posted by Chris Hurd : A better way to make the same point I did. Thanks, Barry, -->>>
I was agreeing with you completely -- that's why I quoted your response in there. You pointed towards the charts, so I went and looked at 'em and yes, sure enough, Canon lists different focal length equivalencies for the two cameras using the same lens. Then I went a step further and compared those equivalencies on an angle-of-view chart and yep, it matches what a 1/4" CCD would deliver.

I know people were getting excited about there being a mistake made, and that maybe the XL2 had a bigger chip than we had all originally thought (hence the title of this thread) but Chris Hurd knows his stuff, and his block diagram article spelled it out in the beginning.

In 4:3 mode, the XL2 is basically a 1/4" CCD camera. Might be a heck of a good performer, that remains to be seen -- but one thing we can say now is that in 4:3 mode the DOF will be equivalent to the GL2, rather than the XL1s.

Regarding the image circle though, my guess is that it is significantly larger than the .236 diagonal (this would be indicated by canon's ability to utilize a .28 16:9 sensor area) typically lenses project a circle much larger than their intended imaging size...to minimize distortions and vignetting near the corners.


Hi Barry (Goyette),
I've measured the image circle on my 1/3" Fujinon, my 1/2" Fujinon and my 35mm SLR lenses and they are all just a tiny bit bigger than the stated format diagonal. This makes sense, because any increase in the image circle size means an increase in glass diameters and therefore cost. So from a manufacturing standpoint, they would always try to minimize the size of the image circle to make it as small as practicable for the format with room for manufacturing tolerance errors.
But .289/.236 is a huge increase (22%). I really don't think the circle would be that big. (But, I've been wrong before!)

Chris, All,

Thanks for clearing this all up. I had tried to make the same comparison's you suggested, but had been unable to find focal length conversions for the xl1s to match up with the xl2's. That left me comparing my xl1s with my canon 35mm ( and the strong impression that I was making an ass of myself).

While I was hoping for all of us that I was right about this, I was, in the background, trying to prove myself wrong. Still, it does seem remarkable that numbers like these could get published.

Sorry for all the hubbub.

Barry

Given that the XL2 active area is 16 units wide and 9 units high the diagonal is sqrt(16^2 + 9^2) = 18.3576 units and the diameter of the exit pupil must be at least that. If one masks off a vertical stripe 2 units wide at each end the active area is now 12 units by 9 units (4:3 ratio) and the diagonal of this area is sqrt(12^2 + 9^2) = 15 units. As the XL lenses are still useful we can assume that whatever the XL1s chip diagonal may have been, the diagonal in 16:9 mode in the XL2 must be about the same and that the active diagonal in 4:3 must, thus, be 15/18.3576 ths of that. If the XL1s chips are 0.3333" then the active diagonal in the XL2 in 4:3 mode must be about 0.28". Is it really any more complicated than that? Am I missing something?

What I'd really like to know is how the extra 33% (4/12) pixels in 16:9 mode get stuffed into the DV stream and, the related question, what is the effective resolution. I've noticed that discussions of TV lines (and SNR) are glaringly absent from any of the material Canon has released. Anyone have any idea about what these most basic specs might be on this machine?

A.J.

"If the XL1s chips are 0.3333" then the active diagonal in the XL2 in 4:3 mode must be about 0.28". Is it really any more complicated than that? Am I missing something?"

Yes, read the entire thread and you'll see a discussion about the actual measurement of CCD diagonals.

A 1/3" chip is not .33 inches in diagonal, but closer to .236 inches, or 6mm.

-Luis

OK so then the XL2 4:3 active area is .236 * 15/18.3576 = 0.193"

I did go through the whole thread and if someone posted actual measurements I missed it. Sorry.

A.J.

<<<-- Originally posted by A. J. deLange :
What I'd really like to know is how the extra 33% (4/12) pixels in 16:9 mode get stuffed into the DV stream-->>>
They don't. DV is 720x480 regardless of whether it's meant to be interpreted as widescreen or as "normal" 4:3.

The CCD pixels do not necessarily bear a 1:1 relationship to the DV frame pixels. Obviously, in the case of a 960x480 CCD and a 720x480 DV frame, they cannot bear a 1:1 relationship. The CCD is an analog device, and in the process of sampling that analog device to convert it to a digital signal, the 960x480 pixels will be sampled down to 720x480.

>> posted by Barry Green : They don't. DV is 720x480 <<

A.J. - Barry is correct. Have a look at this thread (http://www.dvinfo.net/conf/showthread.php?s=&threadid=29087) for more discussion.

I took a vernier caliper to my XL1s this evening and while I can hardly claim a lot of confidence in the measurement (because one has to eyeball from the blades of the caliper to the superposed images of the chips which are quite distant from the caliper) I got 0.221" for the long dimension. This is 5.6 mm which means that the chip is probably a 1/3 incher with long dimension 4.8 mm (according to the Edmund site referenced earlier). But if I stubborly stick to my measurement the chip dimensions would be 0.221 x .166 for a diagonal of .276". This would make the XL2 4:3 active area about 0.225.

Now onto the replies. First, thanks. What I am actually looking for is the details of the algorithms. What I meant by "stuffed" is that DV25 has a fixed bit rate which will support 720x480x3x30 pixels per second whereas the XL2 is gathering 960x480x3x30 which is higher so that either the the number of pixels must be reduced by subsampling or the bits per pixel must be reduced by a more efficient compression algorithm (which is going to have a cost in either spatial or temporal resolution or both). I suspect that the algorithm tries to emulate an anamorphic lens so that programs like FCP can work with the data. This would mean mapping 1 CCD pixel to a tape pixel at the center of the picture and more than 1 CCD pixel (horizontal direction) to an output pixel at the edges. This would mean that the horizontal resolution at the edges of the picture will be worse than at the center. As I imagine the actual algorithms are proprietary I'd settle for some TV lines or MTF data. Obviously this is the most meaningful (or at least most quantitative) way of evaluating the claims of improved picture quality in the XL2. The data I'd like to see are MTF of XL1s and XL2 in 4:3 mode and MTF at center and edge in 16:9 mode for the XL2 as compared to the XL1 with anamorphic lens.


Cheers, A.J.

You sort of lost me in all that tech talk :-) But I think it's just a linear mapping, not one that varies from the center to the edges. Are you suggesting that they would deliberately introduce distortion? Anamorphic DV is just like regular DV except the pixel aspect ratio is different. If you use my photoshop example in the other thread I referenced it will create a proper anamorphic image.

So somehow the camera reads 4 of its 960 horizontal pixels and outputs only 3 to the 720 horizontal pixels on tape. None of this is a new concept, there are other inexpensive camcorders that shoot native 16:9, such as the PDX-10 and GS-400 both of which work with a raw image that's 1152 pixels wide.

Sorry if I didn't understand what you were getting at. Not knowing anything at all about camera design and internal processing, I always assumed that the CCD data was read into some sort of buffer where the transformation is made using simple math. Seems like 1/30 second is quite long in terms of computer processing time.

Boyd,

I was indeed suggesting that the anamorphic distortion was introduced non linearly so that when taken out by the projection lens the center of the picture (the part you'd look at with the fovea) would have higher resolution than the sides which you would look at with the lower resolution part of your retina. But your comments and a little further research have me convinced that in 16:9 video cameras, at least, that's not the case. It apparantly is simply a linear squeeze with an anamorphic lens being composed of two cylindrical lenses with the vertically oriented (axis of the cylinder) one having a focal length shorter than the horizontally oriented one. In a 16:9 CCD the same effect is gotten by sample rate conversion in the horizontal dimension with 4 samples in and 3 out. Sample rate conversion by rational fractions (such as 3/4) can be done with relatively simple math. Whether you'd consider it simple in absolute terms is a different matter. Today's electronic devices do incredibly sophisticated processing in incredibly small devices (and don't forget that the Canon camera use pixel shift technolgy, something else I'd like to understand, to increase the apparent resolution beyond what the CCD pixel count implies). The downside of downsampling in this way is that 25% of the video bandwidh (or horizontal resolution if you prefer) of which the CCD is capable is thrown away. A pity but apparently DV25 just isn't capable of handling it.

Given that that's all there is to anamorphism (from lens or CCD) all FCP (or any other application) has to do is recognize that the pixels from a DV tape should be interpreted as being 1.333 times wider than they are high if the anamorphic bit (I have found that the DV standard defines such a bit) is set. Piece of cake and it all fits. Thanks for pointing me in the right direction.


Cheers, A.J.

Okay, not that this really matters at all, but something occured to
me today about Canon's specs.

Most people assume that a 1/3" CCD is actually .33 inches in
diagonal.

So, it seems that Canon's specs are actually RELATIVE
measurements that assume a .33 inch diagonal on the chip.

I did the calculations the other day, and said that in 4:3 the
diagonal on the XL2 is actually closer to .17 inches, and in 16:9 it
is closer to .211 inches.

BUT, if you do the math, and assume that the chip is .33 inches in
diagonal (which we know that it isn't), then the diagonals for the
image area in 4:3 and 16:9 match Canon's specs.

IF the chip were .33 inches in diagonal, the XL2's image area
WOULD be .236 inches in 4:3 and .289 inches in 16:9

My point is, people assume a 1/3" chip is .33 inches in diagonal.
So maybe Canon figured it would be easier to give 'relative'
measurements of the image area than the actual measurements.

Imagine how confused MOST people would have been if Canon
published the actual measurements, and said that the image
area in 4:3 was roughly .17 inches. People would think that was
the same as a 1/6" chip.

Just a theory.

Ironic that the names for these chips came about to avoid
confusion, and now that tube cameras are long gone, these
names do nothing but confuse people.

-Luis


EDITED TO ADD:

Hey look at that, I'm a trustee

Wait a minute luis...this is where I was coming from the other day...saying there was a lot of assuming going on...and no-one was trusting the listed specs...

Anyway, as it stands now..I think the lens focal length proof...as detailed by Chris...is the most persuasive evidence that the effective areas are smaller than what Canon has posted.

Barry

Barry,

Maybe I wasn't very clear in what I was trying to say.
I am not saying that their specs are correct.
The specs they have listed are impossible, as we have already discussed.

All I was saying was that it is now my theory that Canon's specs are
"relative" measurements, not actual measrements.

The ACTUAL measurements would be much smaller than what Canon listed
because of the fact that 1/3" CCDs are actually .236 inches in diameter.

BUT, if you assume that a 1/3" CCD is .33 inches (as most people do) then
you will get the same specs that Canon posted.
I did the math, and got the same numbers they posted for both 4:3 and 16:9.

My point was that they may have done that to avoid confusion, because
most people assume that 1/3" CCDs are actually 1/3" in diagaonal.

While their specs are still wrong, it is easier for them to list 'relative' measurments
than it is to explain the history behind CCD nomenclature.

I'm not saying this is a good idea, but I think that's what they may have done.
The point is, they may not have posted the wrong specs by mistake.
They may have posted the specs in relation to what they would be on a chip with a .33 inch diagonal, because that is what most people assume a 1/3" chip has.

Does that make sense?

-Luis

Hmm....I dunno about that. The "names" for the formats, e.g., "1/3 inch," "1/2 inch," etc. are always expressed as fractions, and once you know the system, you know what those names represent.
Using a decimal number implies an actual measurement. Thus, the dimensions given on spec sheets for things like focal length, flange focal distance AND imaging areas are always in mm or decimal inch equivalents, never in fractions. I don't think you'll see any spec sheets that call a 1/3" chip a ".333" inch chip, because that has a totally different implication, and suggests that the diagonal image area is .333". But it may be that the person who wrote the spec in the sheet was a non-technical type who made a big (wrong) assumption.

<< But it may be that the person who wrote the spec in the sheet was a non-technical type who made a big (wrong) assumption. >>

My thoughts also. Most likely it was a marketing type who actually thought that a 1/3rd-inch CCD diagonal was 0.333"

"once you know the system, you know what those names represent."

Sure, once you know the system.
The thing is, we're dealing with a prosumer camera, and most
users do not 'know the system.' You'd be surprised by some
of the people I've spoken to in the last week who, no matter
how I tried to explain it, continue to believe that 1/3" means
a chip is .33 inches. Then again, can you blame them?

But, whether or not it was done on purpose or by mistake
is kind of moot. If it was on purpose, it's rather misleading
to use decimals, you're right Dan. So chances are it was just
a mistake.

I guess my main point was that it is not simply a random typo,
(as I originally thought) the numbers would be valid IF the chip
were actually .33 inches in diagonal, which is what most people
think.

I'm assuming most of you have seen the posts, both on this
forum and other sites, where people are pointing to these
same specs to "prove" that in 4:3 mode the XL2 is using the
equivalent area of a 1/4" chip. They see the .236 inch diagonal
and that is what they assume.

Again, all of this is really unimportant.
I just thought it was interesting that the numbers were not
completely random, and made a "relative" amount of sense.


-Luis

Yes, that really is intriguing how those numbers fit the scaling from .33." I wonder if we'll ever know how it really happened, and if so, if it will make sense!
I would think someone who is close to Canon (not mentioning any names...) could call someone in the tech department and get a straight answer and post it.

Yeah, getting into the math is not something I'm too interested in doing, to "prove" something one way or the other. Nobody really knows anything other than what the manufacturer tells us, right?

The proof is in the angle of view of the lenses. An XL1 delivers an angle of view consistent with that which is commonly called a 1/3" camera (regardless of how big the CCD actually proves to be, it's "called" 1/3"). The XL2, in 4:3 mode, delivers an angle of view consistent with that which is called a 1/4" camera. That's really all the proof you need...

The *Angle of View on lenses (obviously excluding zoom lenses) is fixed unless they have a back focus adjustment. Lenses produce a *Circle of Good Definition, this is the area that must cover the imaging device (CCD, CMOS, film etc.). The Circle of Good Definition (on a better quality lens) usually exceeds the radius of the imaging device by a millimeter or two. Poor quality lenses do not exceed the radius and hence Light Falloff or vignetting that occurs. Falloff can be improved by stopping down the lens. The general definition of allowable falloff is 50% (1 stop). Better quality lenses control falloff to 1/3 stop or less.



*Angle of View=The angle formed by the lines from the rear nodal point to the two opposite sides of the imaging device located one focal length from the rear nodal point, lens focused at infinity.


*Circle of Good Definition=The circular are in the image plane within which the lens forms an image having acceptable resolution.

"An XL1 delivers an angle of view consistent with that which is
commonly called a 1/3" camera (regardless of how big the CCD
actually proves to be, it's "called" 1/3"). The XL2, in 4:3 mode,
delivers an angle of view consistent with that which is called a
1/4" camera. That's really all the proof you need..."


Actually, the math is somewhat important Barry.
Looking at the numbers, you'll see that the XL2 will deliver a field
of view which is somewhere between a 1/4" chip and a 1/3" chip
(albeit, it will be closer to a 1/4" chip).

So, it is not exactly right to say it is "consistent with that which
is called a 1/4" camera."

-Luis

I'm not saying the math is unimportant, just not necessary to draw the appropriate conclusion.

By using a field-of-view chart, and Canon's published 35mm equivalency statistics, it appears to me that the XL2 is delivering a 4:3 FOV consistent with 1/4" cameras.

"I'm not saying the math is unimportant

Sorry, I wasn't trying to put words in your mouth there Barry.

You are right, the math is not necessary to draw the appropriate conclusion.
The differences we are discussing are so miniscule at this point,
that I would image they make no 'real world' difference.

-Luis

<<<-- Originally posted by Luis Caffesse : "The differences we are discussing are so miniscule at this point,
that I would image they make no 'real world' difference.

-Luis -->>>


Exactly! Let's remember that the final production models haven't even been released yet.

- don

Without the ability to determine the T/depth of comfusion vs. the M/depth of confusion, the cone of visibility by the field/(chip), (any size), cannot be determined.* T, meaning True. M, meaning Mathemathical.

Or, to put it more bluntly: Put both the XL-1s & the XL-2 together and look at the results.

Every thing else is mere conjecture.



*Chemical Rubber Company: Standard Mathematical Tables, 1959; pp.308