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Canon XF Series HD Camcorders
Canon XF305, XF205 and XF105 (with SDI), Canon XF300, XF200 and XF100 (without SDI).


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Old January 28th, 2010, 08:30 PM   #181
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Originally Posted by Steve Phillipps View Post
EX codec doesn't meet EBU broadcast specs, needs to 50 mb/s.
Steve
You are confusing codec with bitrate. That same codec is in the NanoFlash. And I can absolutely guarantee the codec in that implementation exceeds every broadcast standard on the the planet.
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Old January 28th, 2010, 08:44 PM   #182
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Can you imagine how badly H264 encoded 4K footage from a RED camera would bog down even the fastest desktop computer?
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Old January 28th, 2010, 08:49 PM   #183
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Can you imagine how badly H264 encoded 4K footage from a RED camera would bog down even the fastest desktop computer?
Well, depends on the bitrate used. The 5D/7D do a fine job of hammering my 8-core machine! But I have little problem editing RED 4K footage. Wavelet is just SO much better in so many ways...
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Old January 28th, 2010, 08:59 PM   #184
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It's not bitrate that hammers you with H264. It's the number of pixels in the images being encoded or decoded. 4K, even at just 4:2:0, is 4 times as much work for a CPU.
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Old January 28th, 2010, 11:01 PM   #185
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There's h.264 and then there's h.264.

A full implementation will grind most anything to a stand still. It can include sub-pixel motion estimation and a number of other obscure tricks to cram everything into as few bits as possible.

The way codecs are spec'd is by defining the decoder. The decoder has to be able to decode every trick in the spec. No feature can be left out.

The encoder, on the other hand, has no spec at all. As long as the files are decodable by the standard decoder, it's legal.

A simple h.264 encoder isn't much different than a basic MPEG-2 encoder. That's what we get in the 7D/5D2/1D4. It's simple and fast and can run on battery power. And to get a good image, you need lots of bits. Those cameras encode 40-48mpbs. A two-pass, kitchen sink encoder can probably get the same quality in about 6mbps, but you can't spec that in a handheld camera.

So, keep in mind, when you say h.264, you're really talking about the decoder and compatible files. The encoder can vary widely.
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Old January 29th, 2010, 12:14 AM   #186
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[...] the fact is that the market clamoring for that camera simply is not that large. [...] the corporate / event video market that needs AF and long zoom ratios and an MSRP under $5K.
I agree with Chris about the market. The biggest part of the market has a lot of specific needs. Two of the big ones are:
  • Low light and deep DOF at the same time.
  • Motorized lenses with huge zoom ratios, low breathing, etc.

Ironically, low light is precisely the area where large sensors face the biggest problem. Most people think of the 5D2 as pretty good in low light, but that's only because they use very thin DOF. As soon as you start using it at the same DOF as the 3-chip cameras, the low light performance goes out the window. Even my XH-A1 blows the 5D2 away in low light at deep DOF. The large sensor advantage hinges entirely on thinner DOF, but if you don't want thinner DOF, then that is not an advantage. Hoisting a thin DOF camera on videographers that aren't used to it would result in a huge backlash from shots with missed focus, IMHO.

But I think the problem can be solved. Think of it this way. Right now you have the XH-A1 and it gives you deep DOF in low light with a certain level of noise (Say, f/1.6 at +12dB gain.) If you want even less noise, there's no option; nothing you can do. Even if you were willing to accept thinner DOF, there is no choice available to do it.

We can improve on this with a large senosr. Have the software default to f/7, which gives APS-C users (e.g. 7D) the same DOF as f/1.6 on the XH-A1. They'll still have very poor low light performance (likely even worse than the XH-A1), but at least they'll retain the same DOF they had before. But this time, they can take manual control over the camera (and with the right lens) open up to a faster f-number, reducing the noise level.

There are other applications where the advantages would be huge, such as in ample light. Higher contrast, more dynamic range, increased color depth, and more. In ample light we can get the deep DOF needed without the noise penalty. In fact, it means we'll be able to stop using so much ND.

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Sorry, but 1/3" chips are the key to getting a 20x zoom under $4K.
I'm no expert, but I think it's possible to do the same for FF35 and APS-C. From what I've read, it's actually easier to build lenses of similar capability for larger formats. For example, in order to match the capability of the XH-A1 lens on the 7D, we'd need a 20-400mm f/7-15. 20mm f/7 on the 7D has the same angle of view, depth of field, and total amount of light as 4.5mm f/1.6 on the XH-A1. Same with 400mm f/15 on 7D vs 90mm f/3.4 on XH-A1. If you look at lenses on the market, we already have ones like the Tamron 18-270 f/3.5-6.3 for $550. Now of course it is not motorized, has breathing issues, etc., but at the same time it's more than two stops faster than it needs to be to match the capabilities of XH-A1 lens. But it's still only 3.9 inches and 1.2 pounds. Now, they could not make an f/15 still lens because it would not work with phase detect autofocus. But video doesn't use PDAF, so that becomes an option, and that could really reduce cost and weight. I discussed this in more length in a different thread:

http://www.dvinfo.net/forum/canon-eo...eeper-dof.html

Think about back focus. Single chip cameras have a huge advantage in lens design: their back focus can just few millimeters (say, 4mm), even for sensors that are 36mm wide. That's the primary advantage that rangefinders have over SLRs, and the reason why their wide angle lenses have so much better performance. 3-chip systems, on the other hand, require a huge amount of back focus relative to the size of the sensor -- way more than even SLRs. This forces huge compromises on the lens design that greatly increase cost and aberration. On top of that, specific changes have to be made for the prism itself that are not necessary in normal lens design. Both of these work in the favor of single-chip lenses.

Consider parts tolerances. The manufacturing and build quality of 1/3" lenses have to be almost flawless, because even the tiniest movement out of place (0.1mm?) has a large effect on the image. That includes movement of the focus (with lens groups moving only in the most amazingly tiny increments). But in a FF35 system, a component that is off by the same exact amount will be invisble. I think that will greatly reduce the cost of motorizing the lens to the same capability. Then there's MTF (contrast). I think Adam Galt said that lens designers found it more difficult to achieve the same high MTF with 1/3" lenses as they could with larger formats, because it had to occur at correspondingly higher spatial frequencies.

All that is to say that I think it's possible to build a FF or APS-C lens that will match the capabilities of the XH-A1 for the same price class (under $4k -- whatever part of that is the lens cost). It would be a fully motorized 20-400mm f/7-15 on APS-C, and 32.5-650mm f/11-24 on FF with controlled breathing, parfocality, etc. Same weight too. But I'm no expert, and I'm sure there's factors that I don't know about. As for the rest of the camera (body, image processor, etc.), I'd like to think they could do that for about the same price with a line-skipping sensor, the 500D is only $650 after all.

But I don't think they will do it at all until they can do it right -- and that means no line skipping. So I think it will be quite a few years yet.
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Old January 29th, 2010, 12:49 AM   #187
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No line skipping is easy:

1) use bigger pixels,
2) use a lower frequency anti-aliasing filter.

The problem is that it won't have the volume of a DSLR. Dang.

Also, the low light capability of the 5D2 could be much, much bigger. There are artifacts in both the vertical and horizontal dimensions. If it's skipping lines and columns, then it's missing 8 of 9 pixels, the sensitivity could be nine times higher(!) If it's just line skipping, make it three times higher. Start with the 1D4 sensor and you get good performance at 19,200 ISO - or 57,600 ISO(!)

With that kind of sensitivity, one can stop down the lens and get back a lot of that DOF.
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Old January 29th, 2010, 03:53 AM   #188
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Regarding the power requirements if the RED One, it's batteries seem to last a similar time to a HDCAM camera - it's pretty power hungry. That's a lot more than any prosumer camera.

Given that people seem to want the 35mm sensor cameras for a shallow DOF, why would they want a large zoom range lens with a limited max aperture? Besides an aperture ramp of more than a stop is not a good idea on a video camera - personally I find the ramp on the Z1 lens too much
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Old January 29th, 2010, 09:28 AM   #189
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I think Brian touched upon the main reason this cameras has not surfaced or will ever surface. There are really two markets here - Video Video cameras and Film Video cameras.

They each have different styles of shooting. So one design will not help both out.

The film video shooter could get away with a fixed focal length design, the video video shooter could not.

The film video shooter really wants very shallow DOF, video folks want that from time to time, but for a majority of work this would be too thin for reliable focus.

The bigger problem is the film video camera will require all of the R&D and it is the smallest market.

So the manufacturer has to swim upstream on a concept which is a lot to ask.

If technically possible, a dual sensor camera would be great. If one could flip between a smaller and larger sensor depending upon the situation this would make a lot of people happy.
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Old January 29th, 2010, 09:48 AM   #190
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Yes Tim, what you say here looks to be the reality of it all.
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Old January 29th, 2010, 01:01 PM   #191
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Quote:
Originally Posted by Jon Fairhurst View Post
[...]Start with the 1D4 sensor and you get good performance at 19,200 ISO - or 57,600 ISO(!)]

With that kind of sensitivity, one can stop down the lens and get back a lot of that DOF.
Agreed.

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Originally Posted by Brian Drysdale View Post
Given that people seem to want the 35mm sensor cameras for a shallow DOF, why would they want a large zoom range lens with a limited max aperture?
Because that's not the only reason to want a 35mm camera. Is that the only reason why people want 1/2" or 2/3"? There are other reasons too, including improved dynamic range and (sometimes) better contrast.

[EDIT: I should point out that the XH-A1 lens for a FF35 camera could just be one option among many. People who want the regular camcorder experience could buy it, but those who want more control over DOF and/or low light could buy a lens with a smaller zoom ratio, faster f-numbers, like a motorized 24-105mm f/4.]

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Originally Posted by Brian Drysdale View Post
Besides an aperture ramp of more than a stop is not a good idea on a video camera - personally I find the ramp on the Z1 lens too much
Well, if it's only the ramping that you dislike, that can be easily fixed by camming the lens to stay at the slowest f-stop. The 20X XH-A1 would be a constant f/3.4 that way instead of ramping from f/1.6 to f/3.4. But I suspect what you mean is that you want the iris to be constant *and* fast. That is possible, but something else has to give: zoom range, price, or aberrations. Whatever choice you feel is appropriate, my point is that the same thing can be done for larger sensors.

Quote:
Originally Posted by Tim Polster View Post
I think Brian touched upon the main reason this cameras has not surfaced or will ever surface. There are really two markets here - Video Video cameras and Film Video cameras.

They each have different styles of shooting. So one design will not help both out.
Unless there is a single design that can satisfy both requirements, and there is. In fact, many of the side benefits of the cine-style cameras would be a big benefit to vidoegraphers, such as increased dynamic range. (They could have 5 stops of highlight headroom instead of just 2 like they have now -- which means far fewer clipped highlights.)

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Originally Posted by Tim Polster View Post
If technically possible, a dual sensor camera would be great. If one could flip between a smaller and larger sensor depending upon the situation this would make a lot of people happy.
They already invented that -- just use the f-number. On FF35, you get the exact same effect by switching between f/2.8 and f/24. f/24 (and high ISO) gives you the same (poor) low light performance and deep DOF as 1/3", while f/2.8 (and low ISO) gives you the super thin DOF and amazingly good low light performance of super large sensors.

Last edited by Daniel Browning; January 29th, 2010 at 01:46 PM.
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Old January 29th, 2010, 01:20 PM   #192
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I believe aliasing should show up more on 1080 line recordings (which goes beyond the HMC150 imaging block's ability to resolve detail cleanly).
Not so - aliases should be equally visible on 1080 and 720 recordings. (At least in this case.)

Aliasing is a result of not sampling at a high enough rate, either in time or in space. In the case of the HMC150 the sampling is at the horizontal rate of 960 across the frame width, so it could theoretically resolve up to 480 line pairs before aliasing. Any finer than that, and the result will not be true but an alias, and will manifest itself as a *lower* frequency than 480lp, folding back round the Nyquist point. In general terms, no matter how high a frequency you put in, you'll never get a higher output frequency than the sampling rate. Hence, recording 960x540 will capture the lot - "real" detail and aliases.

That's true on a chip by chip basis. Taken as a whole, the H & V pixel shift complicates matters. Without going into vast detail, what it means is that a fine line pattern can be present on the output as both real detail and an alias, the latter most likely being coloured. Either way, recording a 1280x720 raster will capture the lot, going to 1920x1080 won't resolve any more detail (or aliasing).

What I saw was a compression issue, nothing to do with aliasing.
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Old January 29th, 2010, 01:45 PM   #193
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With that kind of sensitivity, one can stop down the lens and get back a lot of that DOF.
Not really, if you stop down too much you'll start getting massive problems with diffraction. Even on a 35mm sensor diffraction starts coming in at around f8 I seem to recall.
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Old January 29th, 2010, 01:48 PM   #194
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Apart from the dual sensor quote being incorrectly applied to me, the main reason that many people seem to be get excited about the 35mm sensors is the shallow depth of field. They don't get seem to excited about other qualities like the dynamic range. However, the video from the DSLR is currently not that impressive in that particular area, apart from the DOF their other strong point is the sensitivity.

The argument can be made for 35mm sensors, the question is more if it's going to be a motion centred design or stills camera with a video capability, but with compromises to keep the price right for the large stills market? For many uses the DSLR video route is fine, but for others the compromises make them unsuitable.

Often the reason for the aperture ramping is to keep the lens size down - a constant aperture zoom can get pretty large even on a 2/3" camera, which is why almost all of them have some ramping. I suspect the 20x on the 1/3" Canon would be somewhat larger than that present.

People will buy the upcoming Scarlets (2/3 & 35mm), but they're a higher price than the video capable DSLRs.
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Old January 29th, 2010, 02:12 PM   #195
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Originally Posted by Steve Phillipps View Post
Not really, if you stop down too much you'll start getting massive problems with diffraction. Even on a 35mm sensor diffraction starts coming in at around f8 I seem to recall.
Steve
Actually, that's a popular misconception. Diffraction is the exact same accross all format sizes because it scales with the optical DOF . f/32 on a 36x24mm sensor has the exact same diffraction and DOF as f/3.2 on 3.4x2.4mm sensors. The only way to get less diffraction is to use less depth of field (either a larger format with the same f-number, or a faster f-number with the same format).

For example, here is 200mm f/32 on a 36x24mm sensor with 6.4 micron pixels:


And here is 70mm f/11.3 on a 12.5x8.5mm sensor with 6.4 micron pixels:


See how similar they are in contrast and sharpness? If anything, the f/32 is a bit sharper thanks to a higher pixel count (even though the pixel size is the same).

If you check a diffraction calculator, you'll see that the math agrees with these examples.

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Originally Posted by Brian Drysdale View Post
Apart from the dual sensor quote being incorrectly applied to me,
Fixed.

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Originally Posted by Brian Drysdale View Post
the main reason that many people seem to be get excited about the 35mm sensors is the shallow depth of field. They don't get seem to excited about other qualities like the dynamic range.
Perhaps I am not in tune with what most people are excited about. In any case, I think everyone would like to have more dynamic range, improved color depth (i.e. SNR over the used dynamic range), and the choice of improving low light performance and/or using a variety of lenses. Even if they are happy with their clipped highlights, poor color depth, and fixed lens, I think they would learn to greatly appreciate the improvement in a true APS-C camcorder once they had it in their hands.

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However, the video from the DSLR is currently not that impressive in that particular area,
I highly disagree. I've compared my 5D2 and XH-A1 and I can get 5 stops of highlight headroom out of my 5D2, with almost as many below middle gray, where as I struggle to get even 2.5 stops of highlight headroom from the XH-A1, and at just 5 stops below clipping at 0db the noise in the XH-A1 becomes very strong. Perhaps the video you've seen from DSLRs was not processed for high dynamic range?

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Originally Posted by Brian Drysdale View Post
The argument can be made for 35mm sensors, the question is more if it's going to be a motion centred design or stills camera with a video capability, but with compromises to keep the price right for the large stills market? For many uses the DSLR video route is fine, but for others the compromises make them unsuitable.
If they can sell the 500D for $650, I'd like to think they can make an XL-series with an APS-C sensor and lens of the XL-capability for only ten times as much ($6,500) -- hopefully even low enough to hit the XH-A1 price point. But I don't know.

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I suspect the 20x on the 1/3" Canon would be somewhat larger than that present.
I'm not sure what you mean. The f-number ramps from f/1.6 to f/3.4 as I mentioned, which is equivalent to f/7-15 on APS-C.
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