A few words on Equivalence and comparing systems

Started Apr 2, 2013 | Discussions thread
Great Bustard
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Sorry -- 'tis so.
In reply to klopus, Apr 3, 2013

klopus wrote:

Great Bustard wrote:

klopus wrote:

Great Bustard wrote:

Indeed.  If we took a photo at 100mm f/2.8 on FF, and cropped it to the same framing as a photo taken at 100mm f/2.8 on mFT, the photos would be equivalent (although the mFT photo would be more detailed since the sensor has a higher pixel density and the lens is sharper).\

Is it true that higher pixel density always makes for more detail?

All else equal, yes.

By that logic any tiny sensor point-n-shoot at same ISO will always be more detailed than mFT not speaking of FF. In reality for smaller and noisy pixels any theoretical extra density detail (plus good chunk of base detail) will be destroyed by noise that those small but low "quality" pixels produce.

Different sensor sizes.  For a given sensor size, lens, AA filter, scene, and settings, etc., more pixels will always record more detail.  How much more detail, however, depends on many factors.

Yes, sure, for same sensor size. But in your original quote (see above) you were comparing FF and mFT sensors which are vastly of different size. So you already seem to contradict yourself.

Sorry, what I wrote was correct.  If we have two photos of the same scene taken at the same DOF with lenses that resolve the same lp/mm on the sensor, then the photo with more pixels will resolve more detail.

For example (to go along with what I wrote), a photo taken with a D600 at 100mm f/2.8 cropped to the same framing as a photo taken with an EM5 at 100mm f/2.8 will have 6 MP, so the EM5 photo will resolve more detail with its 16 MP, even though the effects of diffraction softening are the same (but the other sources of blur, specifically lower pixel count, will not).

Assuming same pixel count pixel density of mFT sensor will be higher. It's really questionable if at equivalent ISOs (especially high ones) this will really lead to more detail given how much smaller mFT pixels are vs FF pixels.

Diffraction softening affects all systems equally at the same DOF.  However, diffraction is not the only source of blur, so not all systems will resolve equally at the same DOF.

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