Go Back   Steve's Digicams Forums > Digicam Help > General Discussion

Reply
 
Thread Tools Search this Thread
Old Nov 24, 2004, 11:52 AM   #1
Junior Member
 
Join Date: Nov 2004
Posts: 7
Default

I am new to digital photography and wondering about the CCD sensors on digital cameras, I noticed many have 1/1.8 and some have 1/2.5 and do on. Is the bigger 1/2.5 better and why?:O Is it because it is bigger and able to sense more light? Thanks for the input and does it make that big of a differenc? Maggie M.
MaggieM is offline   Reply With Quote
Sponsored Links
Old Nov 24, 2004, 12:01 PM   #2
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

Maggie, you're looking at a type designation, designed to give you an idea of how their sizes compare (it's actually an old system having to do with the diameter of the video tube, and the actual sensor sizes are smaller).

If you do the math for a sensor, you'll get the size (not the actual size though). For example, the 1/1.8" CCD is larger than a 1/2.5" CCD (1 divided by 1.8 = .556"; 1 divided by 2.5 = .4").

As far as sensitivity to light, the size of the photosites make the bigggest difference.So, if you have a 1/2.5" (.4") CCD with 4 Million Pixels, it will have larger photosites for each pixel compared to a 1/2.5" CCD with 5 Million Pixels.

So, in theory, less amplification of the signal will be needed from the CCD with larger photosites, and this should result in lower noise (if everything else is equal with the CCD design between two sensors).

But, advances in CCD design and image processing are being made. So, you really need to examine each model on an individual basis to see how it compares.

Now, the DSLR models are a bit different. Their sensors are MUCH larger than any of the sensors used in the non-DSLR models. So, they can shoot at higher ISO speeds with lower noise. Again, you really need to compare these on a case by case basis, too (but their much larger sensorsare in a different class, compared to the non-DSLR models)
JimC is offline   Reply With Quote
Old Nov 24, 2004, 1:51 PM   #3
Senior Member
 
Join Date: Oct 2004
Posts: 838
Default

Let me just to reiterate JimC's points...

Sensor size makes a huge difference. It is a key determinant of image quality in digicams. Given everything else is the same, a bigger sensor is better. Most sensor sizes are specified using fractions so it is best to convert them to decimals and then compare. For example, 1/1.8 (0.56) is better than 1/2.5 (0.4). And 2/3 (0.66) is better than 1/1.8 (0.56). And so forth.

One thing that will confuse the matter is that megapixels impact the quality: given the same size sensor, the more megapixels, the worse. But it's hard to say which camera is better. For example, is a 5 megapixel camera with a given sensor worse than a 3 megapixel camera with a sensor? An example of this issue is the Panasonic FZ20 (5MP) vs FZ3 (3mp). The FZ20 supposedly has more noise but is "better" than the FZ3...
Sivaram Velauthapillai is offline   Reply With Quote
Old Nov 26, 2004, 11:27 AM   #4
Senior Member
 
Join Date: Jul 2004
Posts: 1,724
Default

Ah, another digicam topic to become acquainted with... I have been told by a seemingly knowledgeable sales person that no matter what the cameras ccd size, and make, there are only a couple of ccd manufacturers. Sony, for one, and I think maybe Kodak for another. I was curious to dig a little into this because the Panasonic FZ20is one I was veryinterested in, but their CCd size for a 5 MP camera is small. I assumed they had some special CCD of their own and was informed no, it's a Sony, (or Kodak, can't remember which) and the technology is nothing out of the ordinary. When I saw this topic I thought I'd mention that point. I'm now assuming that because a 5MP camera is using a 1/1.8 CCD, rather than 2/3, the liklihood is there will be more noise. Anyone? Best regards,

KennethD
KENNETHD is offline   Reply With Quote
Old Nov 26, 2004, 11:54 AM   #5
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

If you see a camera using a 3, 4 or 5 Megapixel 1/2.5" CCD, chances are, it's a Panasonic (Matsushita Electric). Here are some of the popular CCD's they offer for Digicams:

http://www.semicon.panasonic.co.jp/c...A00006IE04.pdf

Here is the datasheet on their 5MP 1/2.5" CCD:

http://www.panasonic.co.jp/semicon/p...F/M00656AE.pdf

Now, Sony does make a lot ofCCD's (for example, most of the 3, 4, and 5MP 1/1.8" CCD are made by Sony, the 2/3" 5MP and 8MP CCD's you see in many cameras are made by Sony, etc.

But, Panasonic is one of the larger CCD manufacturers.


JimC is offline   Reply With Quote
Old Nov 26, 2004, 6:30 PM   #6
Junior Member
 
Join Date: Nov 2004
Posts: 7
Default

Let me see if I understand this. The 1/1.8 ccd is bigger, but when you use the same size ccd with more pixels, 4MP vs. 5MP, then you begin to lose quality (more noise) with the 5 MPwhen compared to the larger photosites on the 4 MP. So, is a 5 MP camera with 1/1.8 ccd better than 4MP with 1/2.5 ccd. And has technology improved so greatly that an older Sony V-1 with 5 MP, 1/1.8 ccd is outdated as compared to newer models with smaller ccd, i.e. panasonics newer cameras with 4-5 MP's with ccd that are 1/2.5. Honestly, I had no idea that there were so many choices and technology advances. It seems that the Sony V-1's price is so reduced now that is an incredible buy, but then when you think about the technology, is it outdated now when trying to compete with newer models and makes. Thanks all for your input, Maggie M.
MaggieM is offline   Reply With Quote
Old Nov 26, 2004, 6:53 PM   #7
Administrator
 
Join Date: Jun 2003
Location: Savannah, GA (USA)
Posts: 22,378
Default

MaggieM wrote:
Quote:
Let me see if I understand this. The 1/1.8 ccd is bigger, but when you use the same size ccd with more pixels, 4MP vs. 5MP, then you begin to lose quality (more noise) with the 5 MPwhen compared to the larger photosites on the 4 MP.
Only ifeverything else about the CCD design is equal. You really need to take them on a case by case basis. In the case of the Sony 4MP 1/1.8" CCD versus the Sony 5MP 1/1.8" CCD, I think the 4MP CCD is a better choice from a noise perspective.

Of course, you also have to take the image processing being done by the camera into consideration. Two models using the identical CCD can have different noise characterics due to the way the image data is being processed.

For example, from what I've seen so far, images from cameras using the new Sony 7MP 1/1.8" CCD appear to have less noise compared to images from cameras using the 5MP 1/1.8" CCD (even though the photosites on the 7MP 1/1.8" CCD are smaller).

Quote:
And has technology improved so greatly that an older Sony V-1 with 5 MP, 1/1.8 ccd is outdated as compared to newer models with smaller ccd, i.e. panasonics newer cameras with 4-5 MP's with ccd that are 1/2.5.
IMO, no it's not outdated (I think it's got a lot of bang for the buck at current prices, and I'd personally go with it versus most current 5MP models with similar characteristics). However, some people don't like the ergonomics, so I'd "test drive" one to see how well it fits you.

The 1/2.5" CCD's you're looking at are made by Panasonic. Panasonic incorporated a relatively advanced microlens design into their newer CCD's to help amplify the light hitting the photosites. As a result, the noise isn't as bad as you'd expect from a CCD using photosites this small (but it can still be objectionable to many users, as it is not "low" noise at higher ISO speeds). The supporting chip set and image processing also play a factor in noise.

In order to make an "ultra zoom" model in a reasonably sized package, the sensor needs to be smaller (so that the lens can be smaller, too).

In the case of the Sony you're looking at, it's got very good noise characteristics for a camera using the 5MP 1/1.8" CCD when compared to other models in it's class. If I were shopping for a similar model, it would be on my "short list".
JimC is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 11:01 AM.