Canon DSLR CMOS sensor size

[luyouming]

I have checked some DSLR camera, found that the CMOS sensor are different size, if compare the resolution and sensor size, you will see the per pixel size also different, the smaller size CMOS at high resolution, the pixel will be smaller. Does it will effect the low light shooting or more noise compare with large piexl size?

1Ds MKII 16.7M (36x24mm)
5D 12.8M (35.8x23.9mm)
MKIIn 8.2M (28.7x19.1mm)
MKIII 10.1M (28.1x18.7mm)
30D 8.2M (22.5x15mm)
400D 10.1M (22.2x14.8mm)
300D 6.3M (22.7x15.1mm)
if you compare above sensor and resolution, you will find that some old model pixel size quite big compare new model high resolution and small CMOS size. Is it because of cost issue?

[Russ]

In the early days,

A Canon Digital Ixus with a 1600x1200 pixel 1/2.5" sensor (5.8 x 4.2 mm) had a pixel density of about 77kpix/mm2. The Canon D30 had a 2160x1440 sensor 22.7 x 15.1mm had a pixel density of only 9 kpix/mm2. So, nothing to do with technology of squeezing pixels in, but getting the noise levels down was a factor

The problem was more trying to process the files fast enough and writing them to the card fast enough, hence they could have put in 20 mpix into the D30 sensor but the camera engine would have been too slow.

Another problem (this one COST related) is that trying to get 20 mp without too many flaws is much more difficult than 2 mp, even at the same pixel density.

So, yes cost has a part to play.


OH, and whilst megapixels has a part to play in getting more resolution, too many of these introduce noise due to smaller pixels. Hence, the old D30 with 3MP and a decent lens will OUTPERFORM most of the 10MP compacts out there today. Horizontally, the D30 has 2160 pixels, the 10MP cameras have 3500 or so, that is, only about 60% more. But the D30 will have good low noise clean pixels that capture images from a sharper lens.

IMO, adding more and more pixels in compact cameras is a pointless exercise as the lenses cannot resolve to that level. To me, 4-5MP is about as far as small sensor (1/2.5") compacts need to go - beyond that, you get more noise with no better resolution from the lens. Add more MP, more NR needs to applied and even if you can get more resolution from the lens, you lose it through NR processing.

APS sized sensors can perhaps go up to 40 MP, FF perhaps 100MP, medium format 500MP. The larger sensors and better resolving power of the lenses means it makes sense,

[luyouming]

Originally Posted by Russ In the early days, A Canon Digital Ixus with a 1600x1200 pixel 1/2.5" sensor (5.8 x 4.2 mm) had a pixel density of about 77kpix/mm2. The Canon D30 had a 2160x1440 sensor 22.7 x 15.1mm had a pixel density of only 9 kpix/mm2. So, nothing to do with technology of squeezing pixels in, but getting the noise levels down was a factor The problem was more trying to process the files fast enough and writing them to the card fast enough, hence they could have put in 20 mpix into the D30 sensor but the camera engine would have been too slow. Another problem (this one COST related) is that trying to get 20 mp without too many flaws is much more difficult than 2 mp, even at the same pixel density. So, yes cost has a part to play. OH, and whilst megapixels has a part to play in getting more resolution, too many of these introduce noise due to smaller pixels. Hence, the old D30 with 3MP and a decent lens will OUTPERFORM most of the 10MP compacts out there today. Horizontally, the D30 has 2160 pixels, the 10MP cameras have 3500 or so, that is, only about 60% more. But the D30 will have good low noise clean pixels that capture images from a sharper lens. IMO, adding more and more pixels in compact cameras is a pointless exercise as the lenses cannot resolve to that level. To me, 4-5MP is about as far as small sensor (1/2.5") compacts need to go - beyond that, you get more noise with no better resolution from the lens. Add more MP, more NR needs to applied and even if you can get more resolution from the lens, you lose it through NR processing. APS sized sensors can perhaps go up to 40 MP, FF perhaps 100MP, medium format 500MP. The larger sensors and better resolving power of the lenses means it makes sense,

Dear Russ

I am fully agree with you. I have two DSLR body, 300D and MKIIn, I select big CMOS and pixel in reasonable level. I think it works. Ihave also remember my school time, if sensor size small to certain level, it must responds to very good lighting condition, but very poor to lower light condition. The same reason, G7 equipped with DigiIII and 10M pixel, but is small sensor, so that in the lower lighting condition the image is quite noise. Thanks share with me your comments.

[Russ]

Originally Posted by luyouming Dear Russ G7 equipped with DigiIII and 10M pixel, but is small sensor, so that in the lower lighting condition the image is quite noise. Thanks share with me your comments.

Even in bright light, I think you will find the lens cannot resolve to 10MP anyway and a 4MP sensor can give you the same resolution. On my old G1/G2 cameras, with 3-4 MP, when I view on the monitor at 500% magnification (you can see individual pixels), hard edges of objects with high contrast can be easily 2-3 pixels wide and the CA (purple fringing) can be a few pixels wide too. With 10MP, you just spread the blur over more pixels and the pictures are no better.

So it is not just about low light performance.

90% of people are fooled into thinking more "Megapixels is better" just like at one time, in film days, people asked "how many times zoom?" - mine is 10x or 12x. And I tell them, mine no zoom (prime lens on a SLR) - and they think I have an inferior camera - or in audio, people asking "how many watts - my boombox is 1000 W PMPO" and I show them a $100,000 tube amplifier that manages 8 watts but sounds oo la la (no, I don't have one). All pointless....