soooo...single chip AVCHD vs. 3 chip

DanHD

Well-known member
I see a ton of full raster 1/3rd inch AVCHD cams...but they're only single chips. Then I see the HMC, a 3 chip not-fullraster chip.

What are the advantages of both?

Bayer pattern vs. three chip, ect?
more pixels on a small chip = less low light sensitivity right?
 
Without delving into the whole resolution issue, for me the worst thing about these little high-res consumer palmcorders is the crippling auto only settings, if they could make those little Canon's with a full manual setting they'd make ideal b-cams!
 
We tried three single CMOS AVCHD cams, and two 3-CCD AVCHD cams.

All went back to the store.

We bought a HMC150 to compliment our 170 and it is world's apart from the consumer stuff.
 
but you didnt answer my question,


what MAKES the difference between these consumer AVCHD cams with full raster single CMOS chips and the HMC?

I mean, both have 1/3 inch depth of field
both record 4:2:0
both record 8 bit...
is it the quality of the DSP and the lens, ect?
 
Yes, there are 3 CCDs in the HMC150.

1/3 inch. The others either have 1/6 inch 3 CCDs or a single 1/3 inch CMOS chip.

Huge difference.
 
I'd say the same. Lightyears difference.. Besides this whole full raster vs. pixel stuff gets really old and just seems to be a bit of either blaming or praising the camera. I used to rent the Varicam which did the pixelshifting stuff and that footage was both awesome looking and expensive.


The 150 shoots darn good images. comparable to any of the full raster stuff.. maybe not quiet as sharp, but in the ballpark and for considerable price savings.
 
In general, a 3 chip camera is going to produce better results than a single chip camera. Rather than have a single point one color and the other colors interpolated, the 3 chip camera has all the colors at every point.

If you look at the consumer cameras, you'll find the image sensor is a lot smaller than the 1/3" and larger we find in the Pro line. The smaller image sensor on the consumer cameras means that the image will fall short of the look we get from the better cameras. Also, the lens is never going to be as good as the better Pro Cameras. Overall, the look from a consumer camera is going to be worse that the Pro Line.

In general, a larger image sensor means more surface area to gather light; which means less noise at low light. The problem with consumer cameras is that the size of the image sensor is getting so small, that the low light performance sucks. Now with a consumer camera, they might be willing to up the gain well beyond what a professional would like to use. The end result is a very noisy image with poor color.


Bob Diaz
 
If you look at the consumer cameras, you'll find the image sensor is a lot smaller than the 1/3" and larger we find in the Pro line.

Bob, the 1 chip vs. 3 chip issue is something that I've been wondering about myself. While it is true that consumer camera tends to use smaller chip size then prosumer/professional cams, the newest crop of cameras are starting to have larger single chip solution. For example the HV20/30 uses a single 1/2.7'' class chip compared to the 1/3'' size in 3CCD camera. With a slightly larger chip size like that, does the theory still hold that a 3-chip configuration is superior?
 
Bob, the 1 chip vs. 3 chip issue is something that I've been wondering about myself. While it is true that consumer camera tends to use smaller chip size then prosumer/professional cams, the newest crop of cameras are starting to have larger single chip solution. For example the HV20/30 uses a single 1/2.7'' class chip compared to the 1/3'' size in 3CCD camera. With a slightly larger chip size like that, does the theory still hold that a 3-chip configuration is superior?


Exactly...


But, from what I've learned here, the quality of the DSP, the amount of features and adjustability, and the lens play large factors as well..

So are these single chip AVC cams less sensitive to blue then a three chip cam would be? (less blue photosites) thus making tungsten balance noisy
 
My understanding of how the beam splitter works in a 3 chip camera is that the blue light passes through to the blue CCD (or CMOS) and the red light and green light are reflected onto the other image sensors. (OK, it's not 100% reflection, but most of the red & green light is reflected.)

Let's pretend that the 1/3" image sensor is 1/3" x 1/3"; it's not, but it keeps the math simple. Also, pretend the 1/2.7" image sensor is 1/2.7" x 1/2.7".

On a 3 chip, 1/3" camera, the blue image sensor covers 1/3" x 1/3" = 1/9" = about 0.111"

On a single chip 1/2.7" camera the whole image sensor covers 1/2.7" x 1/2.7" = about 0.1372"; which seems larger....

BUT, with the Bayer pattern, 1/2 the pixels are Green, 1/4 of the pixels are red, and 1/4 of the pixels are blue. Thus, 0.1372" x 1/4 = 0.0343" covers the blue pixels. Yet with the 3 chip, 1/3" camera we have 0.111" coverage for blue.


In general, 3 chips are better than 1 for color. Think of the areas for each chip adding up the total image sensor area.

Also, larger is better; the Red Camera has a much larger image sensor (single chip) and produces a very good image


Bob Diaz
 
Hey DanHD, I recognize you from the "noisy blue channel" discussion.

If you are talking chips of the same size, 1/3" for example, a three chip camera will always outperform a single chip camera. The three chip camera will have better color, and less noise.

Where the single chip bayer pattern cameras can outperform a three chip camera is when they are much larger with a lot more pixels.
 
Back
Top