Pixel density

[oRGie]

Never paid that much attention to all the small details, but recently been choosing so have noticed a bit about this subject. So the 5D eg has a lower pixel density than the 50D eg, now pixel density seems to play a part in final image quality, compacts have a much higher density, hence the lower IQ, FF bodies have the lower densities,

ok all pretty straightforward,

but I had a thought, if you select the medium or low quality raw or jpegs to be captured, you are saving less pixels, so does that mean that the sensor is working with a lower pixel density than it would with high quality settings? 

Could that mean a higher IQ pic with a medium jpeg than a fine jpeg       

[picsfor]

where's a pixel peeper when you want one?

[oRGie]

exactly

by the way, I did look for info, that perhaps its just a more aggresive compression used to make the smaller files, but there is no mention of that anywhere I've looked, so it may be the sensor is being used differently, depending on the file size/quality chosen

[anglefire]

Well, it depends.......

Its a sort of yes and no. Basically what you are suggesting is pixel binning I think and at least from Canon (Dunno about anyone else!) they don't officially say they do this - though I believe the conversion from full frame to video in effect does this as the algorithm takes all the pixels and does some magic and saves the video at 1080p or whatever its set to save as - which is why the noise levels, even at high ISO in video mode is so low.

And pixel density is not as simple as you may think either. CMOS sensors have electronic stuff surrounding each pixel and a lens on top. The depth of the "bucket" with the light sensitive receiver at the bottom also has an effect too (Especially with respect to vignetting.)

The modern sensors have much bigger pixel sites in comparison to the sensor as they are shrinking the electronics so there are less gaps so although the number of pixels has increased, the distance between them hasn't got correspondantly smaller.

For example, the 1DMkIII pixel size is 7.2um and the 1DMkIV 5.7um, despite the IV having 60% more pixels.

Interestingly enough, the 5D has a pixel size of 8.2um, which is the same as the 1DMkII and MkIIN - but has better noise performance at higher ISO than either of them.

Or I could be talking rubbish!

[greypoint]

Pixel peepers? Just go over to dpreview and search pixel density....best set aside a day to read the answers

[ABERS]

Ah well, just another thing to worry about.

[greypoint]

I've only got 12mp....should I upgrade? I'm beginning to feel inadequate

[anglefire]

@ Sue

I've got about 30Mp - but spread over three cameras so I don't think it counts! 

I'm looking at additional storage now as my 1Tb drive is getting to with 10% of being full! A bigger sensor will mean even more storage - that or delete more 

[picsfor]

I've only got 12mp....should I upgrade? I'm beginning to feel inadequate

Nah - we had this discussion yesterday. it's not the size - it's what you do with it!

[Oldboy]

@ Sue

I've got about 30Mp - but spread over three cameras so I don't think it counts! 

I'm looking at additional storage now as my 1Tb drive is getting to with 10% of being full! A bigger sensor will mean even more storage - that or delete more 

No, keep them all. I've see 2tb external drives for about  £160. 

[greypoint]

It's OK keeping them all - it's trying to find them when I want them