Technical Questions I have been tossing around in my mind

[rduve]

I am the owner of the FZ20 and I am considering moving up to the FZ30. I think the added features and improved handling alone justify trading up for a couple of hundred bucks more. Now, regarding the whole noiseissue I have been tossing arounda couple ofquestions in my mind on which I need clarification. Can anyone help out?

1. When a lower resolution is chosen (let's say 5 instead of 8 MP on the FZ30), does this mean a smaller space of the 1/1.8 sensor is used or are less (and larger) pixels spanning the full CCD? And, if the latter is true,wouldn't this result in a less noisy image? [/*]
2. How does the "extended optical zoom" feature distinguish itself from a digital zoom, doesn't the digital zoom also just crop the image down to a smaller area with less resolution?[/*]

Your input would be greatly appreciated. Oh, one more question if anyone knows: Has the 3CCD technology used in high end camcorders (and some consumer camcorders by Panasonic) been ever considered for digital still cams? Would it not closely emulate traditional film emulsion, and make a good alternative to the apparently stalled Fovean 3-layer CCD? Has anyone heard anything to that effect? Or is there a reason why that would not work?

[boyzo]

The relathionship betweem lens focal length and sensor size means that 8MP 12x zoom 5MP 15x zoom 3MP 19.1 zoom is real in terms of the relevant resolution and is true optical zoom ... in this instance (FZ30) you have 3 camera's in one ... take your pick ... depends on what IQ you require

The FZ30 maxes at 88.8mm this means for optical zoom at 8MP / 5MP / or 3MP / = 12X 15X or 19.1 X zoom

Focal length and sensor size = optical zoom

3 X CCD yes pana do this in camcorders could they use it in an FZXX yes they could the implemtation of 3X 8MP sensors yes but beam splitting is involved and for a camcorder this is ok but for a still camera not so in terms of image quality .... DSLR is the route

[HarjTT]

Rduve

From what I've read when the FZ30 is set to 5 or 3MP all it is doing is using a smaller area of the sensor. The pixel size is still the same. The smaller the sensor size and higher the pixel count the more noise you have and less DOF.

I just found this article on Digital camera basics - a nice bit on sensors:

http://www.gallerydhaka.com/article/...l_cameras1.htm

More detailed on photo.net:

http://www.photo.net/equipment/digital/sensorsize/


HarjTT

:?

[rduve]

Thanks for your help, guys. Still not quite sure on question 1 though. Does one simply reduce the portion of the sensor that is used by decreasing MP count (for example using only 5MP on an 8 MP camera) or does one spread less (and larger) pixels among the full CCD which would theoretically result in less noisy pictures. My guess is the former since pixels are actually physical elements, correct?

[rduve]

And HarjTT, you are convincing me that I will have to get that big sensor DSLR down the road to complete my camera collection.

[genece]

You do not enlarge the pixels and thereby reduce noise although it does look that way when you view the original size photo because the photo is smaller and that is why when viewed at original size the FZ20 seems to have less noise (the picture is smaller) But in fact the pixel size is almost Identical.. as is the noise.

[rduve]

Thanks. Would the pixel size not be exactly the same since you are using the same physical units, just less of them?

[boyzo]

rduve wrote:

Thanks for your help, guys. Still not quite sure on question 1 though. Does one simply reduce the portion of the sensor that is used by decreasing MP count (for example using only 5MP on an 8 MP camera) or does one spread less (and larger) pixels among the full CCD which would theoretically result in less noisy pictures. My guess is the former since pixels are actually physical elements, correct?

In 5MP mode and at the WA setting the Image uses ALL of the sensor and interpolates the image down from 8MP to 5MP ......as you zoom in ~2x + the Camera uses PART of the sensor area so is able to provide 15X optical zoom VIZ focal length relative the sensor area.

In terms of the image on the sensor the Photo sites are a fixed size, so in 5MP mode you have in reality an image like from an FZ20 ... in terms of noise I cant say one way or the other, as I have only had my FZ30 for a week, I think for web images and small prints 3MP and 5MP are still quality images but I don't think noise is reduced.

[rduve]

Thanks John, that's what I figured. 5 Megapixels basically take up 1/2.5" of the CCD rather than the full 1/1.8". Got it.

[squirl033]

pixel count is determined by the number of photodiodes in the sensor array. this is fixed, and does not change when you select a lower resolution setting. if the sensor is an 8MP array, it will always BE an 8MP array, and the only thing the camera can do is to either use less of that sensor, or digitally crop the image in the DSP chip.

noise is generated by heat, which is a function of pixel density and the efficiency of the sensor array. the FZ30 uses a larger sensor than the '20, but crams more pixels in, so the actual pixel density is virtually identical, resulting in almost identical noise characteristics. using fewer pixels for a lower resolution image doesn't change the number of photodiodes that are powered up, nor does it appreciably alter the amount of heat produced by those photodiodes, so the noise levels should be pretty similar between the 3, 5, and 8MP modes. noise may be less NOTICEABLE in one mode or another, but it will still be there.

the term "optical zoom" applied to the 15.3 or 19.1x zoom functions on the FZ30 is a bit of a misnomer. the actual optical characteristics of the lens do not change - you don't get a more powerful lens by selecting one of the EZ settings - but when those zoom settings are selected, the lens focuses the image on a smaller portion of the sensor, which has the same effect as if the lens actually did have the added zoom capability. since what the '30 does is not "digital zoom" in the sense of cropping the image, they had little choice but to call it optical zoom. and in a way, it is, since the lens focuses the image on a smaller portion of the sensor, which is an optical proces...

hope this makes sense...