Pixel count per square centimeter: 1.6 crop vs. FF sensors

[B Johannsen]

I have nothing better to do right now, so I was wondering:

The 30D sensor has an area of 3.375 cm2 (2.25cm x 1.50cm) and 8.5 million total pixels. This means that it has 2.52 megapixels per square centimeter.

The FF sensor has an area of 8.556 cm2 (3.58cm x 2.39cm) and 13.3 and 17.2 million total pixels (5D and 1Ds Mark II, respectively). Therefore, 1.55 and 2.01 megapixels per square centimeter.

That’s 1 million more pixels per sq cm on 30D sensor than the 5D sensor and 0.5 million more than the 1Ds sensor. Based on this, a FF sensor need to have 21.56 megapixels to have the same pixel per sq cm ratio than our 1.6 crop snsors.

So, is it correct to assume that our modest, price friendly 30D sensors have a considerable higher resolution than those expensive FFs? Is this a logical statement? Or am I missing something here...

 

[karl vollmers]

in some way yes, in other ways no, depends on how you measure it, what assumptions you make and what is imporatant to you. this issue has been beaten to death in many FF vs APSc sensor threads.

What does happen is that if you are focal length limited, (ie, poor and can only buy a 400 mm lens and nothing with more reach) then if you take a pictue of something far away with a 20D/30D and while standing in the same spot take a picture with any other canon camera (with said 400mm lens and far away meaning you will need to crop all the pictures to make them fill the frame) then you will find that the resolution of the 20D/30D will be slightly better. This is why many people who take pictures of small things far away like the APSc sensor. You can get higher resolution pics with a cheaper camera and cheaper lens.

now this is only part of a very well discussed story. There are many areas/reasons where FF sensors offer advantages over APSc sensors. I can not do them justice and suggest you do some searching.

 

[Bakul Vyas]

30D has higher density than 5D and 1Ds II.

So the performance of those cameras is supposed to be better at higer ISOs.

I have read somewhere that 5D is not noticably better than 30D, when it comes to higer ISO performance, but I have no personal experience.

--
Bakul Vyas
http://www.pbase.com/bakul_vyas

 

[MitchAlsup]

I have nothing better to do right now, so I was wondering:
The 30D sensor has an area of 3.375 cm2 (2.25cm x 1.50cm) and 8.5
million total pixels. This means that it has 2.52 megapixels per
square centimeter.

The FF sensor has an area of 8.556 cm2 (3.58cm x 2.39cm) and 13.3
and 17.2 million total pixels (5D and 1Ds Mark II, respectively).
Therefore, 1.55 and 2.01 megapixels per square centimeter.

That’s 1 million more pixels per sq cm on 30D sensor than the 5D
sensor and 0.5 million more than the 1Ds sensor. Based on this, a
FF sensor need to have 21.56 megapixels to have the same pixel per
sq cm ratio than our 1.6 crop snsors.

So, is it correct to assume that our modest, price friendly 30D
sensors have a considerable higher resolution than those expensive
FFs? Is this a logical statement? Or am I missing something here...

(First order) Resolution is the number of pixels to record an image. Since the FF dSLRs have larger pixel counts, these cameras will take images with higher resolution.

But, in order to TAKE an equivalent image, these cameras have to use a lens that is 1.6 times the FL of the cropped camera's lens and shoot at 2/3rds stops slower (DoF).

What we can say about the pixel density of the 20D/30D is that it is harder on the lenses! That is it takes a better lens on a cropped camera than on a FF camera to 'print' the tiniest detail such that that detail falls on one pixel and does not bleed (blur) off onto another {Ignoring all the Nyquist issues}.
--
Mitch

 

[B Johannsen]

Thanks for the reply, Karl

I certainly understand the principles behind the 1.6 crop sensors in relation with the focal lenght. And of course I know about advantages of both type of sensors. It's just that I have seen so many people obsessed with the pixel war, that it made me wonder. 16 mp sensors sounds very impressive, but not really when you really analize it and take in consideration that it's a FF. I was just trying to make a point by pointing out how relative the pixel count actually is and how ridiuculous it is to judge cameras based on that pixel count...

 

[rdspear]

This has been discussed many times.

By this logic, point-and-shoots with 10MP in miniscule sensors would the best out there.

It's not the count it's the quality. Smaller pixels have more noise, more diffraction, etc., to offset the benefits.

I won't hash all the pros and cons - I'm sure others will be more than willing to. If the definition of "resolution" is pxels per are then, by definition, your statement is true. The final output is more important, outside of the lab.

My friend's Sony AV receiver has more watts than my Krell. I don't consider it better.