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Understanding CCD - The Basics


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#1 Marcus Phipps

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Posted 16 October 2009 - 09:25 PM

Greetings. I have a multitude of 'newbie' questions. However, I am going to hopefully ask something that maybe has been answered in ten previous posts but not quite what i've found so far. In summary, hopefully it will help other newbies to understand the basics of CCD video technology and how it might apply to their needs.

First, I am a newbie. Please understand that I do not have but limited CCD video technology information. I pose these questions as a newbie and you may have to steer my questions to something more specific. I hope this thread might serve as a ping-pong-ball for newbies to ask all their CCD questions. I had difficulty finding results online for these answers. Not saying things aren't available. I'm saying as a newbie sometimes the discussions become saturated with jargon and can be quickly confusing to the newbie masses. I simply hope to get my questions answered below from you that have a hands-on experience with technology in the last (assuming) ten years.

In advance,... thank you VERY much for your gentle criticism. I searched online for video forums. There are many. I chose Cinematography.com merely because from the various posts I observed, they were well written and offered fewer arguments and 'angry' profiles in which no one likes those folks anyways. So,... here I am. I look forward to learning from you all. In turn I hope to also post back and help in my stronger points as I learn hands-on. ;)

Remember, this is trying to serve for us newbies. Some questions may seem trivial to you. However, they likely have reason for the newbie. Myself included.

1) Approximately when did CCD technology begin?
2) Did CCD technology replace what is termed 'old tube' technology?
3) I see chip sizes in CCD as (1/4" - 1/3" - 1/2" - 2/3"). If a camera boasts 2/3" chips,... does that mean it results in better color than a camera with (let's say) 1/2" chips? I'll further give an example. Looking at the Canon XL1s which states it has three 1/3" CCD chips. Comparing to the Sony DXC-537 which states it has three 2/3" CCD chips. I am trying to gain clarification on what really matters in the end. There is allot to gather in CCD technology. Merely looking for "3" CCD cameras is no longer enough. There are sizes to consider. I want to understand what a newbie needs to know when considering a 3CCD purchase for $1,000 or less. I know this may start a thread war on which cameras. Let's ignore what they are or the budget i'm suggesting. I'm merely trying to understand (in this case) why I would or would not want to buy the Sony 537 which has the 2/3" chips instead of the Canon XL1s that has only 1/3" chips.
4) How does light have implications to CCD? Please try and keep this semi-basic. I know there is likely a long scientific explanation. However, I am thinking along the lines of a fixed lighting shoot. Camera on a person sitting. Like a news camera man shooting a home owner in their kitchen. Do they take extra lights with them to 'fill' the kitchen? Or does the flourescent lights in kitchen ceiling cast that dreaded yellow effect? That's how i'm thinking at least. Something basic like that. If you want to elaborate further that's great. However, please at least help me out with the basics. This question is haunting me! LOL

Anything more you wish to elaborate on for a newbie's sake related to CCD video technology is great appreciated. I am certain this post will get allot of newbie views. I hope I am asking the right CCD questions. If there are more newbie questions relative to the CCD technology specifically, it probably would best serve for those questions to fall into this particular post.

However, I may be (then) violating board rules here. I do NOT want to do that. I have several other posts as a newbie that i'd like to understand. I'd be very appreciative if you could browse them as well and hopefully lend me some pro / semi-pro direction.


Most Respectfully
Acastle

Edited by A Castle, 16 October 2009 - 09:30 PM.

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#2 Chris Millar

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Posted 17 October 2009 - 12:15 AM

Got an assignment deadline looming ? :rolleyes:
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#3 Marcus Phipps

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Posted 17 October 2009 - 01:15 AM

No assignments looming as of yet. I am being pro-active. In hopes that in the Winter months I can be locked indoors like the rest of us and learning a new trade.


Respectfully,
Acastle
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#4 Chris Bowman

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Posted 17 October 2009 - 01:25 AM

While I wouldn't claim to be an expert on CCD technology, I think I can answer a few of your questions.

1) CCD technology in broadcast video cameras showed up sometime in the early 80's, you can probably find a more exact answer on wikipedia.

2)CCDs replaced cathode ray tubes for image capture because of their much lighter weight, lower power consumption, sharper image that didn't soften over time, and a number of other reasons.

3) The size of the CCD chip has a number of affects on the image. First, a camera's sensitivity to light is directly proportional to the size of the chip's photosites (pixels). Small chips with high resolutions have tiny photosites which require more light or more gain (which causes "noise." Larger photosites gather more light, and therefore tend to require less gain, and are therefore less noisy.

The size of the CCD also affects the "depth of field" for focus. Larger image sensors produce a shallower area that can be held in focus. Since we have all grown accustomed to the fairly shallow depth of field that 35mm film's relatively large image size produces, many people find larger sensors produce a more pleasing depth of field. There are even cameras now that have image sensors the same size as a frame of 35mm film so that they will have exactly the same depth of field (and can mount the same lenses).

The size of the CCD also affects the length of the lens that is required to achieve a certain magnification (zoom). The smaller the image sensor, the shorter (also lighter and more compact) the lens must be to achieve a desired level of magnification.

Three chip CCD arrays split the light passing through the lens into the three primary colors with a prism, and expose each of the three chips with the entire picture in only one primary color. This allows the camera to capture each primary color at the full resolution of the chips.

Single CCD designs must place a color filter over the CCD in a Bayer pattern. This means that the camera gathers each of the primary colors at only part of the resolution of the chip.

4) Cameras, unlike the human brain, record exactly what is there. Unfortunately that means that where there are fluorescent lights there is a huge amount more green than any of the other colors, unless the light was designed very carefully not to (These tend to be expensive). Our brains usually filter out this green spike, but cameras don't. Many of them have a "florescent" white balance setting which is designed to compensate for this, but that's simply the way these lights are.

There is a control on video cameras called the white balance, which allows you to control the camera responds to different light sources. Incandescent household lights typically output light in the 2800 Kelvin range which is actually very red, while studio incandescent are typically 3200 kelvin. Natural sunlight at noon is probably somewhere close to 5600 Kelvin. The camera can be adjusted to display white as white under all of these varying lighting conditions. Once white is white, all of the other colors tend to follow.

As far as how to light for a specific purpose . . . this really depends on what you are trying to accomplish. A news crew on site will probably just use whatever lighting is available, since it is inconvenient to carry, set up, and power light kits on the run. Just about everyone else doing professional film and video will adjust lighting as much as they can to make everything "just right." Lighting is really what makes photography of any kind an art. For a kitchen in a movie, it wouldn't be at all uncommon for there to be 20 or more very, very carefully positioned light sources. Making the lighting perfect is probably the biggest part of a Director of Photography's job.
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#5 Matthew W. Phillips

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Posted 17 October 2009 - 01:31 AM

First, I am a newbie...


Ask Keith or Phil because they know everything...or so it is thought. Compared to them, we are all considered newbies. They even told ole JJ his crew didn't know what they were doing when JJ's main man has a Ph.D. in quantum physics :lol: Just be careful of the questions you ask around here that are electronically related.
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#6 Marcus Phipps

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Posted 17 October 2009 - 01:33 AM

Chris,... And again, most most most thankful, sir! I and others will greatly appreciate this information. This is what makes a forum great. When those that have the knowledge, share the knowledge in a courteous manner.

Matthew,... you snuck your post in before I posted this. Thus, I edited. I will be careful on my electronic questions. I am keeping things very basic. Thank you, sir.



Most Respectfully,
Acastle

Edited by A Castle, 17 October 2009 - 01:36 AM.

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