Understanding Pixel Counts

Started Nov 22, 2012 | Questions thread
Timskis6
Veteran MemberPosts: 9,562
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Per pixel sharpness
In reply to Great Bustard, Nov 24, 2012

Great Bustard wrote:

Stacey_K wrote:

Great Bustard wrote:

What does "per-pixel sharpness" matter?

It matter a lot IMHO. It's the reason my E1 at 5MP can make a sharp 11X14 print yet a nikon P&S with 16MP can't.

...matters if we are talking about photos made from the same number of pixels. However, the relevant measure is the total resolution and total noise.

Just to chime in, and only because I have a lot of experience with this in optimizing the E-3 output, it is very possible to increase per pixel sharpness from any sensor, making it comparable in sharpness to a higher MP count sensor, by simple image stacking. Of course the reason for this is averaging out noise which increases DR, and what you perceive is increased sharpness due to more detail. I used this technique and wrote about it quite often here, as it allowed me to print much larger than most other E-3 and E-30 users, not to mention the newer tech (at the time) 50D and even D300s.

Of course there's limitations to this method, but it does work, and allows us to improve sharpness and compare per-pixel sharpness (perceived sharpness) across different cameras with different resolutions.

In terms of the E1 vs a 16 MP P&S, well, you'll have to post the photos. However, I can tell you, with confidence, that the 20 MP RX100 will easily outresolve the 5 MP E1, despite having a sensor half the size.

I saw zero difference between my E1 and my E300 for the same reason, normal "logic" would say the E300's 8MP sensor would produce better images with the same lenses that the E1's 5MP, it didn't.

Well, we only have your opinion on that. I've seen photos that others have called "stunning", and let's just say that "stunning" is not the adjective I'd use.

In any case, at best, 8 MP will resolve 26% more linear detail than 5 MP, and that presumes an extremely sharp lens, negligible diffraction, and negligible motion blur.

So if, for example, you were shooting scenes at f/16, where diffraction softening is substantial, no, you wouldn't see much difference at all.

That said, depending on how large you display the photo and how closely you view it, you might not notice a 26% increase in linear resolution at all.

It's also why shopping using MP count is not smart shopping. 5 "good" megapixels can beat 8 or 10 "sorta good" ones every time.

Oh, absolutely. As I've said numerous time, it's not the PPI of a photo, but the lw/ph of a photo. The pixel count is only one element in the imaging chain. That said, put more pixels behind any given lens, and it will resolve more detail (all else equal). How much more detail, and whether or not that increase in detail is "signigicant", depends on many other factors.

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Tim
www.developemotion.com
'I haven't been everywhere, but it's on my list.'
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