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General HD (720 / 1080) Acquisition
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Old May 13th, 2005, 01:55 PM   #1
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HD lens optics

I don't know much about lens optics but some people have said that it is very hard to get decent HD off of a 1/3" CCD with a biult in lens.

My question I guess is then how can a 6 megapixel digital still camera give full resolution with a cheap tiny lens? I'm not talking about the nice digital SLR cameras but the tiny handheld cameras. Based on what can be done with a tiny chip and very tiny lens it doesn't seem like it would be all that hard to make a cheap HD lens built into the new HD cameras.

Again I do not know anything about lens optics. This was just a thought I had after reading some of the posts about HD lens concerns and then looking at images from my Kodak 6.3 megapixel camera.

At first I thought perhaps because a still camera only has to take a still image. In terms of the kind of detail a piece of glass shows shouldn't really matter though.

But then why is it that film primes were not as good with HD cameras?
Would a film lens also not be very good on a digital SLR then?

Hopefully Graeme or somebody else can point out why this doesn't work in this case.
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Old May 13th, 2005, 02:17 PM   #2
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Your logic is undeniable! Bravo.
If the lenses of the tiniest 6M pix cameras would not match the resolution of the sensor, they would defeat the whole purpose, wouldn’t they? So, they must be very good then, right? I bet they are!
HD usually have three chips. Film lenses work well on one chip (Drake, Arriflex, Dalsa, etc). 3CCD/CMOS need different lenses corrected for the longer path through the prism for red, green and blue.
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Old May 27th, 2005, 02:27 AM   #3
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Actually overall optical quality is less critical on video camera because image is generally moving. On still camera you look at image from frame for long time so for instance color fringing becomes more distracting.

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Old May 27th, 2005, 06:43 PM   #4
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Quote:
how can a 6 megapixel digital still camera give full resolution with a cheap tiny lens?
Those lenses may be tiny but they are not cheap. Perhaps you could call them inexpensive, but definitely not "cheap," that is, as long as we're talking about Panasonic (Leica lenses), Sony (Carl Zeiss lenses), Canon (Canon lenses) or Fuji (Fujinon lenses).
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Old May 27th, 2005, 08:51 PM   #5
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Lenses for video cameras are generally more complex than those for stills cameras, and they need more bits to account for the prism I think.

Even cheap digital stills cameras have a larger imaging area than a 1/3" video camera. Looking at stills on digital cameras, especially the more affordable ones, they have a lot of colour fringing / chromatic aberations.

What I have learned is that lenses and their resolution are an incredibly complex issue with no easy answers.

Graeme
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Old May 27th, 2005, 10:53 PM   #6
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You can say that again Graeme. Another consideration to bear in mind is that the majority of digicams have a rather limited zoom range, usually only 2x to 4x or so, primarily due to chromatic abberation at longer lengths. The long-lens digicams such as the Canon PowerShot S2 IS, which has a 12x optical zoom, is one of only a few exceptions to that general rule. Video camcorders on the other hand are usually 10x or more across the board. So yes it's a complex issue with no easy explanations.
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Old May 28th, 2005, 08:49 AM   #7
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I think you've clarified what I was getting at quite nicely there Chris, with the zoom ration etc. That coupled with larger pixels (although usually a lot more of them) and lack of beam splitting prism probably accounts for the vast amount of the difference. This is one subject where I'd like to know an awful lot more than I do now.

Graeme
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Old May 28th, 2005, 09:02 AM   #8
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Quote:
Originally Posted by Thomas Smet
I don't know much about lens optics but some people have said that it is very hard to get decent HD off of a 1/3" CCD with a biult in lens.
Some people have said a lot of things, but for a little over $3000 the Sony FX1 captures HD video which looks pretty darn good on my HDTV display. If you're worried about lens quality on prosumer-priced HD cameras, you may want to take a look at the upcoming JVC "ProHDV" model with interchangeable lenses. It's supposed to start shipping in July of this year according to a local JVC rep.
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Old May 28th, 2005, 04:07 PM   #9
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Hopefully in a couple years they will have single chip HD cameras that will surpass even the $100k HD cameras today. I think the world of 3 CCD's now, but think of the cost savings in cameras when technology can put out a single chipper rather than three... sony is already on the way with it. If you gave me a choice between a 4000x2000 pixel 30p video on one chip compared to 1440x1080 60i on three chips, I would take the 4000 pixels for the same price (although this is years off in terms of computer power and cost). What I am getting at is that I hope the next revolution in cameras is better color single chips, it simplifies everything, including the cost.
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Old May 28th, 2005, 05:28 PM   #10
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Could anyone doubting/complaining about HDV lenses (Z1) post a clip depicting the "low quality" of these lenses please? (or forever hold your peace?)

I have found that the same "cheap consumer" GS200 has provided very good images AND... color fringe! On the same scene, same focal length same all, by a mare contrast ratio change in light levels. CCD can not handle the life's light extremes. Is not the lens, is the CCD's and the "sharpness enhancing circuit" that are accountable for lower quality images. Knowing this, one must carefully adjust the lights (framing)/camera settings (when possible and available)/grad ND filters, so the light levels in the frame are within the CCD's ability to respond (without blooming and color fringing) (...I think...)

Doubting years of expertise on the manufacturers behalf raises a question about the doubter's knowledge....don't blame the "damn car" for being a bad driver (kind-a-thing!) I know they are not perfect (for nothing is), but I doubt it I could "suggest" improvements.... On the other hand, that does not mean in any way to "swallow" whatever you are feed without raising the right eyebrow! (or the left one when appropriate...;-)<
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Old May 28th, 2005, 08:32 PM   #11
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Lenses do indeed have chromatic aberations which cause colour fringing, but colour fringing on cheaper 1-chip cameras is more often due to sharpness algorithms and the such like interfering with the bayer pattern and stuff like that if it's contrast based, rather than chromatic aberation, which usually appears stronger towards the edges of the image.

There are plently of examples floating around that show such artifacts on the FX1 / Z1, especially from the person who chopped off the stock lens and put a better one on it. You can also see from resolution charts that the stock lens is a bit soft.

That said the FX1 / Z1 produces great images for the money, but by spending more money, you can make better images, but as the law of diminishing returns sets in, it costs more and more to get those last few percents of quality.

Graeme
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Old May 28th, 2005, 08:47 PM   #12
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true, true.
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Old May 29th, 2005, 12:54 PM   #13
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Quote:
Originally Posted by Jared Carey
If you gave me a choice between a 4000x2000 pixel 30p video on one chip compared to 1440x1080 60i on three chips, I would take the 4000 pixels for the same price ...
The problem with increasing resolution is that this makes it even harder to store the video on any sort of affordable medium, plus it looks like we're petty much settling in now on HDTV formats with resolutions of either 720p or 1080i. I'd be happy if I could get a reasonably priced camera which records 720p at 60 frames per second to an inexpensive laptop hard drive, and we're getting close to having something like that with the upcoming Panasonic and Ikegami cameras. Just build a mount for a standard laptop drive right into the camera instead of making it an expensive external option, and we'd be all set...

By the way, we're starting to see digital still cameras which can record several frames per second at high image quality until they fill up the available storage. Extrapolate that another few years and it's not hard to imagine a still camera which can capture several-MP images at video frame rates, and the only question is whether that would translate well to displaying as an actual video. But you still have to have some way to store, retrieve and edit the result, which brings us back to current practical limitations for making videos.
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