Phils CCD research and some answers
I'd had these datasheets lying around for some time, brushed the dust of them and took a look at the specifications. So here's the answer (and it's pretty much what most people had concluded) to Sony's F505V 2.6 megapixel resolution. It's all in the effective pixels...
- The Sony DSC-F505 uses the Sony ICX224AQ CCD (or one of its derivatives).
- The Sony DSC-F505V uses the Sony ICX252AQ CCD (or one of its derivatives).
(as used in the F505)
(as used in the F505V)
|Known as||2.11 mp 1/2"||3.34 mp 1/1.8"|
|Size||Diagonal 8mm (Type 1/2")||Diagonal 8.933mm (Type 1/1.8")|
|Package dimensions||13.8mm x 12.0mm||13.8mm x 12.0mm|
|Pixel cell size||3.9�m x 3.9�m||3.45�m x 3.45�m|
|Total pixels||1688 x 1248||2140 x 1560|
|Effective pixels||1636 x 1236||2088 x 1550|
(diagonal 8.00 mm)
(diagonal 8.933 mm)
|Recommended||1600 x 1200||2048 x 1536|
|Used||1600 x 1200||1856 x 1392|
We've assumed what Sony have done is simply take the ICX224 out of the existing F505 body and inserted the newer ICX252 (package size is identical), if we simply used the previous "Used pixels" the calculation doesn't seem to work, however if we use active pixels instead, we get the following results:
- ICX224: 1636 x 1236 = 6.38 mm x 4.82 mm
- ICX252: 1856 x 1392 = 6.40 mm x 4.80 mm
We're assuming here that the Zeiss lens has been setup to produce an image across the effective pixel area of the CCD not just the recommended area, on the F505 only using 1600 x 1200 of this, and on the F505V using the full available area (at this pixel cell size that could easily be 1856 x 1392).
The diagrams below (top down view) show the relative sizes of each component of the CCD sensor, the final image shows the amount unused by the F505V (the red portion). Diagrams below appear about 3 times larger on your monitor than in real life.
|ICX224 1636 x 1236 effective pixel area (green)
6.38mm x 4.82mm
|ICX252 2088 x 1550 effective pixel area (green)
7.20mm x 5.35mm
|Masked ICX252 1856 x 1392 effective pixel area (green)
6.40mm x 4.80mm
|Plastic package (13.8mm x 12.0mm)|
|Glass cover (12.7mm x 10.9mm)|
|Effective pixel area|
|Unused pixels on F505V|
There we have it (hopefully), we don't know what else has changed within the F505V (other than the obvious improvements to firmware), but I would expect some other electronics improvements too. If the F505V is priced alongside the F505 then it could still be a sensible choice.
Putting things into perspective
- With it's 2.6mp the F505V has 34% more pixel area than the F505
- With a full 3.34mp it would have 64% more pixel area than the F505
- With a full 3.34mp you'd only gain 192 pixels horizontally and 144 vertically
3.7 MP Interpolation
The F505V also features an interpolated resolution of 2240 x 1680, created from the native 1856 x 1392 resolution. This means every native pixel is responsible for 1.45 pixels of the interpolated image. The two images below are examples generated by cropping a Nikon Coolpix 990 image down to 1856 x 1392. This is designed to show the interpolation MAY mean.. it's not using Sony's algorithm.
|1:1 from 1856 x 1392 image||1:1 from 2240 x 1680 interpolated image|
Obviously these images are just simulations, though we (guess) the CCD in the F505V and Coolpix 990 are the same the electronics and algorithms won't be nor will the interpolation algorithm Sony use in the F505V (the "SRC" algorithm) plus the fact that Sony will be interpolating the CCD RAW data rather than the JPEG we've used here.