Thanks. This just strikes me as very interesting -- a good reality check.
Joel W.
On Mon, Jul 13, 2009 at 1:40 PM, Chuck
Norcutt<chucknorcutt@xxxxxxxxxxxxxxxx> wrote:
> What got me on this point to begin with was DPreview's test of the Canon
> 70-200/2.8L which is one of the more revered zooms in Canon's stable.
> Check this page which is the test of that lens on a 5D body.
> <http://www.lenstip.com/115.1-article-Polarizing_filters_test.html>
> Use the aperture slider and watch the resolution graph change. Only at
> f/5.6 to f/11 is the 70-200 able to equal or slightly exceed the 12.7
> megapixels of the 5D sensor (represented by the line labeled "Nyquist
> frequency"). Below f/5.6 some irregular things start happening and
> above f/11 diffraction begins its steady toll against resolution. So,
> if this lens can just barely handle a 5D it certainly can't handle the
> pixel density of a 50D (15 MP on an APS-C size sensor). At f/5.6 to f/8
> the 5D Mk II will pull a bit more out of the lens than the 5D but not a
> great deal. To utilize the resolving power of the 5D Mk II you need
> very good primes. Here you can see that the 50/1.4 can resolve to the
> level of the 1Ds Mk III (21 MP, like the 5D Mk II) at f/5.6 to f/8 (but
> not elsewhere).
>
> Quite apart from noise, one reason to want a camera with larger pixels
> is to be able to find a lens that can resolve to the level of the
> sensor. Little pixels just make the job harder on the lens. That said,
> it's also easier to make a lens that resolves little pixels if the
> sensor is small and the lens doesn't have to cover a large area.
>
> Chuck Norcutt
>
>
> Joel Wilcox wrote:
>> On Fri, Jul 10, 2009 at 8:47 PM, Chuck
>> Norcutt<chucknorcutt@xxxxxxxxxxxxxxxx> wrote:
>>> Not so long ago Olympus was talking about a planned 12 MP maximum for
>>> the 4/3 sensor. If you read the test of the DZ 50/2 you can see exactly
>>> where the 12 MP maximum comes from. At f/4.5 the lens is resolving 1500
>>> line pairs vertically toward the outside and about 1600 dead center.
>>> Come off f/4.5 though and resolution starts to drop. A 4/3 sensor that
>>> can resolve 1500 line pairs vertically has pixel dimensions of 3000 x
>>> 4000 or... 12 MP.
>>>
>>> Since the DZ 50/2 must be one of the better lenses, if it can't go
>>> beyond 12 MP it doesn't make much sense to go to even smaller pixels.
>>> The same is true in the Canyon camp. I suspect that there are precious
>>> few lenses that can resolve the 15 MP of the 50D sensor and the same
>>> holds for the 21 MP sensor of the 5D Mk II (although the 50/1.4 can do
>>> it across the full sensor at f/5.6-f/8 but not above or below that).
>>>
>>> So, the sensors are now outresolving the lenses and even the best
>>> lenses. I guess we don't need any more pixels... but that won't prevent
>>> the manufacturers from giving us more. :-)
>>
>> I will share this with a relative who bought a 5DmkII when they first
>> came out. He shoots at the half resolution setting, mainly because he
>> didn't want to double his file storage instantly and didn't think he
>> needed it for his purposes. It sounds like he really doesn't need it.
>>
>> Joel W.
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