OK. Here is what I am saying. On a 30D you have a sensor that is 22.5mm x 15mm with 8.2 million effective pixels. The total area of that sensor is 337.5 square mm.
On a 5D you have a sensor that is 35.8mm x 23.9mm with 12.7 effective pixels. The area of that sensor is larger at 855.62 square mm. However, the 5D has an area that is 2.5 times greater than the 30D yet has only 55% more pixels. So the density is less. If you look at the newer Rebel XTi with 10.2 effective pixels in a sensor that is slightly smaller at 22.2mm x 14.8mm you have an area of coverage for an image of 328.5 square mm. This means again the 5D will have an area that is 2.6 times larger but has only 25% more pixels than the XTi. Again, the density of pixels for a given area is greater in the XTi. So if I have a small object in the image I would have more pixels covering that area of the image with a 30D or XTi than I would with a 5D. Now I am not talking Dynamic Range, Noise reduction, or anything else other than pixel density. That is all I am saying. The main benefit is that the pixels are physically larger on the 5D enabling it to offer improvements at higher ISOs, hence cleaner images. There is something called pixel pitch which is the size of the pixels on an image sensor. The 5D is terrific with an 8.1 micron pixel pitch, while the 30D has a 6.4 and the XTi smaller at 5.7. The result is a cleaner image overall with the 5D v. the others when using higher ISOs. According to Canon about a year or so ago the pixel pitch should be no smaller than 6.4 microns. But since then they seem to have found a way to do this since the XTi has a pitch of 5.7 microns, smaller than what Canon claims, and I quote, “would result in lower image quality at high ISO speed settings compared to our current design.” Peter K ----- Original Message ---- From: Tom Pfeiffer <[EMAIL PROTECTED]> To: [email protected] Sent: Thursday, June 21, 2007 2:19:25 PM Subject: RE: EOS A slightly silly query > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Austin > Franklin > Sent: Wednesday, June 20, 2007 5:31 PM > To: [email protected] > Subject: RE: EOS A slightly silly query > > Hi Peter, > > > No Austin. If you and I take an image and I use a 10MP sensor on > > say a Rebel XTi and that is half frame camera. And you use one > > with 12.7 that is full frame, and let us say we take the same > > exact image of a group of people. I will have more pixels > > covering a small face in the crowd than you will. > > That's not right, and I would really like you to explain the math behind > that, because if you do, you'll find out it's wrong. > > > Austin > Here's the math as I see it, using the specs of a 400D and a 5D as the 10 & 12mp cameras. Hopefully, we can all agree that if we use an identical 50mm lens on each camera (mounted side by side and facing the same subject), that we'll get two identical image circles, except that the lens with the smaller sensor will capture only a cropped part of the image. Now, our 12 mp sensor is 36x24mm with a resolution of 4368x2912, which works out to a nice even 121.333 sensors/mm in each direction. Using THAT density of pixels, if we were to "chop off" the sensor to make it the same size as our APS sensor (22.4x14.8mm), it would have a resolution of 2693x1795. At that size, both sensors would have the same image coverage, but the 12mp camera would have a 2693x1795 image versus a 3888x2592 image from the 400D. And it seems to me that 10,077,833,935 pixels in an image is more dense than one with 4.833.935 pixels. tomp ____________________________________________________________________________________ Boardwalk for $500? In 2007? Ha! Play Monopoly Here and Now (it's updated for today's economy) at Yahoo! Games. http://get.games.yahoo.com/proddesc?gamekey=monopolyherenow * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
