[EFS1585]

On looking the comparison charts of various cameras, I found something which I did not really understand the relationship between the pixel density and effective pixels.



EOS 5D MARK II

==============



Effective pixels: 21.0 million

Pixel Density: 2.4 MP/cm^2



EOS 7D

======



Effective pixels: 18.0 million

Pixel Density: 5.4 MP/cm^2



EOS 550D

========



Effective pixels: 18.0 million

Pixel Density: 5.4 MP/cm^2





- When comparing 5D MARK II, either with EOS 7D or with EOS 550D, which one the camera produces nice image with a lens(L or non-L) operated at its sweet spot.



- Also reviews has told that 5D MARK II produces nice pictures when compared to 7D, despite having low pixel density, Is it true?



am I miss-understood something here?

[Guest]

"Low pixel density is good", generally speaking.

Low pixel density = bigger area per pixel = more light per pixel = less amplification needed = less noise

Low pixel density = bigger area per pixel = you're allowed to use bigger aperture numbers before diffraction gets visible.



Don't forget: You may be able to take decent photographs using a compact cam, bridge cam, DSLR, medium format camera. Depends what you need.



Ciao, Walter

[EFS1585]

[quote name='Walter Schulz' timestamp='1282142597' post='1873']

"Low pixel density is good", generally speaking.

Low pixel density = bigger area per pixel = more light per pixel = less amplification needed = less noise

Low pixel density = bigger area per pixel = you're allowed to use bigger aperture numbers before diffraction gets visible.



Don't forget: You may be able to take decent photographs using a compact cam, bridge cam, DSLR, medium format camera. Depends what you need.



Ciao, Walter

[/quote]



Now I understand why the expensive DSLR cameras have lower pixel density.

[Guest]

Don't miss the part "generally speaking".

It doesn't make sense to use this as *the* single criteria for image quality.



And your example doesn't make sense at all, because 7D doesn't have the same pixel density compared to 450D.



Ciao, Walter

[EFS1585]

[quote name='Walter Schulz' timestamp='1282143725' post='1875']

Don't miss the part "generally speaking".

It doesn't make sense to use this as *the* single criteria for image quality.



Ciao, Walter

[/quote]



Yeah, :-) I did not missed that. Indeed, it is not the only criteria and I am aware there are other factors that come into play.



It is nice to know that EOS-1Ds Mark III and EOS 5D Mark II have the same pixel density, eventually the effective pixels. May be the time to save some money from Mark II magic.

[EFS1585]

[quote name='Walter Schulz' timestamp='1282143725' post='1875']

Don't miss the part "generally speaking".

It doesn't make sense to use this as *the* single criteria for image quality.



And your example doesn't make sense at all, because 7D doesn't have the same pixel density compared to 450D.



Ciao, Walter

[/quote]





Now, I understood the arithmetic. May I know what advantage does it bring to have a higher pixel density on a given sensor size?

[edge]

Higher pixel density for a given class of sensors gives you more resolution up to the resolving power of the lens. And generally speaking, this is at the cost of noise at higher ISO.

If your work is mostly stuff like landscapes, a higher pixel density may make sense.

[popo]

Lower density only helps give lower noise *if* you compare like with like, and look at a pixel level. A new generation high density sensor can perform better than older generation bigger and lower pixel density sensor. I have or have had a 1D, 5D, 7D.



1D mk1, APS-H, 4MP

5D mk1, FF, 12MP

7D, APS-C, 18MP.



At ISO3200, which would you pick? Me, it would be the 7D every time. Then again it does have 8 years of technology advantage over 1D, and 4 years over 5D. Looking more recently, the update from 50D 15MP to 7D 18MP was noticeable at high ISO also, with the 7D giving better looking results at high ISO (say 1600+).



Further, if you consider the noise on an equal output area basis as opposed to per pixel level, that changes the results too. Personally, providing you have "enough" pixels, the number or density doesn't matter, the overall whole output does.