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Old September 18th, 2004, 08:02 PM   #1
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800 lines and DV

I'm hoping to be able to afford a Panasonic DVC200, or the like, next year, but I have a question about resolution. The DVC200 specs speak of 800 lines of res, as do most ENG cams, but it's DV, so only 500 some odd lines are written to tape, isn't that right? So I guess my question has several heads on it's shoulders.

Why 800 lines on a cam that utilizes a 500 line format?

I've heard that more lines than needed is good. How so?

How does one make full use of the 800 lines? (Record to another format? What? Which?)

I feel like this is a common question, at least in some circles, supported by common knowledge, but, what can I say, I'm a left brained shooter! Thanks for indulging me.

Shawn
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Old September 18th, 2004, 10:46 PM   #2
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I believe the 800 lines are horizontal not vertical (which I assume is around 500). That's just a guess though. Note how they carefully neglect to mention which direction they speak of...
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Old September 19th, 2004, 12:10 AM   #3
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Lines of resolution specs generally are fairly useless because of things like this. There are many ways to fudge the spec by measuring differently, and when the manufacturer doesn't tell you how they measured the spec isn't very useful. Sometimes the manufacturer fudges things among their own measurements (i.e. Sony consumer cams), so that makes this spec even more useless.

To answer your question...
More or less Panasonic is fudging their specs probably to get a bigger number. Other cameras in that price range/market also have similar numbers (800 for JVC, ~700-800 for Sonys).

Regardless, I'd expect the camera to be very, very close to the maximum resolution the DV format allows (anywhere from 400-540, depending on how you want to measure). The DVX100 (a lower end camera) also reaches very close to the maximum resolution the DV format allows. You can look at a picture from the DVX100 at the following site:
http://www.bealecorner.com/trv900/cats/cats.html

I'm sure we can all get into a technical long-winded discussion about measuring lines of resolution, but I think the things you need to know are:
A- WIthout knowing how Panasonic measured, the spec is pretty useless (unless comparing to other Panasonic cameras).
B- If you want to know how sharp the camera is, ask people who have shot with the camera and can compare to others. Or, get yourself a demo and/or do your own test.
C- Does resolution really matter that much? Do we really have to be resolution whores?
D- The DVC200 probably only has slightly more than 720X480 per CCD. The CCD itself will limit you to 720X480 pixels. You can't really get more resolution out of the camera by recording to a format other than DV.
*well technically because the camera records in 4:1:1 color space you lose color resolution. There aren't any practical ways of improving on this as far as I know (nothing that makes sense at least).
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Old September 19th, 2004, 01:38 AM   #4
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Alright, yes, I...am a resolution whore. There, my dirty little secret is out. 300 lines more than what the specs I USUALLY read tell me? I say YES. Lay it on me. I want to see every last cat hair on my mother's oriental rug, fully wide, a hundred feet away, in 2 lux of light....And, btw,"Whore" is such a strong word, Glenn. "Resolution person of the night" is somehow more, i don't know, conversational.

:0]

Now that I've got that out of my system...

Yeah, ok, fudgy unscientific number, probably, and a 500 line format anyways. I can dig it. It's the larger chips, the long term options in better quality glass, the refinement in manual control, the long playing tapes, and the shoulder mount that I'm REALLY interested in.

But even after fudging is said and done, there probably is more than 540 lines (800 lines, give or take 260??) happening in a camera whose format resolves no more than 540 lines, period. Right? So, what's that about? BTW, if it seems like there is already more than enough literature in the universe on this subject, please feel free to point me in some direction or other. I'll probably go ahead and do that for myself either way...

Again, thanks for the thoughts.

Shawn
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Old September 19th, 2004, 04:25 AM   #5
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Does it mention TV lines, if so, my understanding is that that is horizontal, not vertical at all.

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Old September 19th, 2004, 10:52 AM   #6
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The DV spec of 500 lines is what goes to tape
The 800 lines is the resolving ability of the combination of lense and ccd system. It is meant as an indicator of the camera not the recording. eg . not all cameras are of the same imaging quality ,however if recorded to dv, the manufacturers would all rate them at 500 lines ( not very meaningful as a representation of THE CAMERA) so they rate the camera only
In the old days there were SVHS cameras rated at 450 lines,however SVHS specs recorded at 400 lines and then there are cameras(which I still use) that are rated at 750 lines.They record to SVHS at 400lines but look much better( and cost 5 x more)
So lines are only a repesentation of 1 factor in a cameras image quality
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Old September 19th, 2004, 12:33 PM   #7
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The short answer is that if you place in series, a group of elements that affect the final resolution: Filter (maybe), Lens, CCD, recording system, you can think of the image as being copied from one element to the next. If they were all 500 line resolution, the final picture would be worse than if the elements would deliver more than what the recording system will place on the recording medium because each element reduces the image resolution.

The reason a 1/2 or 2/3" camera delivers a better picture (that is recorded in DV format) than a PD-170 (that is recorded in DV format) can be laid directly at the feet of the optical elements in the image path. Better lens, Better Better optical block, & Better CCDs

Until newspapers went all-digital, they used to shoot their photos on 4x5" cameras because they could tell the difference on their printed page between a 4x5" source and 35mm. If you start with better quality, you usually end up with better quality, all things being equal.
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Old September 19th, 2004, 07:30 PM   #8
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I think I got it. DV resolves 540 lines, period. CAMERAS (CCDs and lenses) can resolve anywhere between 400 and 800 lines, depending. The more lines the CAMERA can resolve, the better the chances of writing all of the possible 540 lines to tape. Right? That makes sense to me, at least.
But resolution isn't everything that goes into high quality DV imagery...right?
Or is it, if resolution encompasses glass and CCD quality? What else goes into it?
I mean on the internal tech end, not the shooter's-capacity-to-light-and-expose-well end. I ask about this, not to be a whore, but to be the best cameraman I can be, within my personal budget, and to therefore make savvy gear and component choices.

Thanks!

Shawn
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Old September 20th, 2004, 10:25 AM   #9
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Two more major issues that start with CCD size is the image processing that goes on between the CCD and the noise level of the signal chain.

You want a very low noise level (high signal to noise ratio) to prevent the salt and pepper noise you can see when the gain is high. Right now the PD-170/VX2100 and DSR-390 seem to be the best in this area.

Second, you want an outstanding DSP chain that starts with the conversion of CCD voltage to the digital representation (A to D) at as many as 14 bits (I think that is the current max) and the processing of the digital information at a high bit-count.

Then once you have the high bit-count, the efficacy of the image processing comes into play.

There are at least third and fourth issues that come into play:

The quality of the optical block and the type of CCD construction.

The optical block needs to be assembled as perfectly as possible with as perfect as possible components.

CCD's come in many flavors: Whatever they call the base-line CCD, HAD, SuperHAD, IT, and a dozen other flavors. The type of CCD will have a significant effect on the quality of the video . . . for example, high-contrast situations.

Beyond these issues, one can consider the rigidity of the lens mount and it's relationship to the optical block, the long-term stability of the internal circuitry, the frequency of service, the abuse the camera receives, etc.

I'd point out that by the time you get beyond the first two points, HOW you use the camera will have, as you mention, much more effect on the quality of the footage.
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Old September 20th, 2004, 10:27 AM   #10
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<<<-- Originally posted by Mike Rehmus : Two more major issues that start with CCD size is the image processing that goes on between the CCD and the noise level of the signal chain.

You want a very low noise level (high signal to noise ratio) to prevent the salt and pepper noise you can see when the gain is high. Right now the PD-170/VX2100 and DSR-390 seem to be the best in this area.

Second, you want an outstanding DSP chain that starts with the conversion of CCD voltage to the digital representation (A to D) at as many as 14 bits (I think that is the current max) and the processing of the digital information at a high bit-count.

Then once you have the high bit-count, the efficacy of the image processing comes into play.

There are at least third and fourth issues that come into play:

The quality of the optical block and the type of CCD construction.

The optical block needs to be assembled as perfectly as possible with as perfect as possible components.

CCD's come in many flavors: Whatever they call the base-line CCD, HAD, SuperHAD, IT, and a dozen other flavors. The type of CCD will have a significant effect on the quality of the video . . . for example, high-contrast situations.

Beyond these issues, one can consider the rigidity of the lens mount and it's relationship to the optical block, the long-term stability of the internal circuitry, the frequency of service, the abuse the camera receives, etc.

I'd point out that by the time you get beyond the first two points, HOW you use the camera will have, as you mention, much more effect on the quality of the footage. -->>>
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Old October 3rd, 2004, 06:27 PM   #11
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Is there a way to bypass tape yet and record directly to hard drive? That should get a res increase.
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Old October 3rd, 2004, 07:55 PM   #12
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Depends on whether you can get the direct output of the front end or, as Sony labels it, E to E where the signal goes through the recording electronics.

Pro cameras have a direct output that usually produces the highest resolution signal one can obtain. To capture it you have to be able to sample analog video at a high enough sample rate to capture all the information contained in the signal.

One of the practical problems with all of this is that with HD/HDV just around the corner at affordable prices, why bother? No matter what you use in SD video, just about any HD video signal will have a lot more resolution. At $3700, Sony's HDV camera is better (from a recorded resolution point of view) than the best pro SD camera you can find. I'd bet someone is working on a pro HDV camera right now that will take prime lenses and give you the full HD resolution.
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Old October 3rd, 2004, 08:14 PM   #13
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Yeah, I was just reading about the supposed pro HDV scheduled for next year. I'm not sure what additional options it'll pack, but some suggest more picture control and the ability to record to DVCAM. Improved lenses would be great, but the current stock doesn't look bad at all anyway. That cam's definitely at the top of my list.
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