Saturday, July 19, 2008

Pixel density

[I wonder if this is getting too technical for this blog.]

It seems very hard to evaluate the benefits of pixel density and photo site size. ("Photo site": each tiny light-recieving dot inside the camera. The larger it is, the more sensitive it is.)

One thing I noted in a professional review in a British mag, comparing the Nikon D3 with the Canon 1Ds III, was that it gave the overall image quality of the D3 to be at least equal to that of the 1Ds, despite the D3 nigh only half the resolution. (And of course you have smaller files and a more sensitive sensor.) The lenses could have something to do with it though.

My Canon Ixus 960, though, makes much sharper pictures than my old Fuji F10 (which I thought was wonderful), and doesn't have more noise despite having twice the megapixels. Of course, then the Canon is three years newer.

Given that there are so many factors, I wonder if we'll ever have a clear answer.


Bert said...

"I wonder if this is getting too technical for this blog."

What a strange thought... too technical??? ;-D

Ctein said...

Dear Eolake,

When will you have a clear answer?

When the technology has stabilized to the point that all sensors and on-camera data processing streams from all manufacturers are of comparable quality.

Until then, It's like comparing a basket of grapes and a basket of apples and arguing that one will be better than the other because of 'fruit density.'

Pixel density is currently a useless metric for evaluating camera image quality. It smply does not correlate, which is why you see endless arguments and contradictory experimental results.

pax / Ctein

fruitbat said...

I'm not even sure there will be a clear answer once tech stabilizes.... just think if artist's brushes.... which is the best brush? The answer would be "it depends," wouldn't it?

Lloyd said...

I believe in comparing using the same lens, but in processing for the best results (eg DPP for Canon and NX2 for Nikon).

I've done a lot of shooting with the 1DsM3 and D3 now, and there is no question that for large prints (24X16 or larger), the 1DsM3 offers notably better detail. At the same time, the 1DsM3 images fail to impress at times, in spite of their sharpness.

Using both cameras at their lowest ISOs (50 vs 100), the 1DsM3 will make a better large print I think.

But at ISO 200 on up, the D3 produces much cleaner files, with much lower chroma noise. Visual impression on screen is of much higher quality from the D3. But it must be remembered that the D3 image will have be enlarged about 1.3X more, so noise will also be magnified.

Bottom line is that the D3 impresses, per-pixel quality is clearly higher, so if you're doing web or prints up to 24X16 or below, the D3 does the job extremely well. It is also more forgiving of marginal lenses; more megapixels assumes critical focus and a lens that delivers, but also requires more DOF for those pixels to do anything useful.