Originally posted by wa2kqy Hi,
CCD does just fine as long as you have good light. The CMOS will work better in low light. The CCD just can't boost ISO in the same way. And so, the CCD will have more noise than CMOS when you do boost ISO.
The CCD also has to move the analog signals to the A to D in the dark. CMOS does not. So, CMOS gives you Live View and Video.
The 645D sells for quite a bit less than the 645Z on the used market. And you can still get the Z new. For as low as $3k usd from Ricoh USA for a refurb last I looked.
I went for a 645D as I knew I'd be using it in daylight and so opted for the lower cost and accepted the limitations.
Stan
The above explanation is correct. Three addenda may be in order. Firstly, it is my understanding that CCD had better low ISO performance at the time that it was abandoned in favour of CMOS. Secondly, stronger colour filters were in use at the time, and so colours are thought to possibly have been more clearly defined because of that. Since then, colour filters have tended to become weaker, straying away from a narrow-band RGB model and a little closer to YCM, improving light yield but losing colour definition. Thirdly, picking white balance correctly is easier with more light being available, and has a major impact on the perceived quality of an image. So a collection of images from a camera that restricts shooting to low ISOs may tend to look better.
However, on my first point I should add the counter-point that as attention shifted from CCD to CMOS, CMOS sensors have continuously improved and benchmarks suggest that the 645Z was already better across the board in various metrics,
as you may see on the DxOMark website, particularly if you click through the various graphs under "measurements".