At f/11 on a full frame sensor you are diffraction limited to about 13
megapixels. You'll have to drop to about f/8 or even f/5.6 to resolve
to the level of the sensor if your lens can do it.
Chuck Norcutt
C.H.Ling wrote:
> I expected this could be your answer :-) I just too lazy to shot another F11
> or F16 shot. In that case you will not detect the 28mm shot's backgroud is
> out of focus and the 300mm shot will just look the same (serious out of
> focus).
>
> Even I took another F11 shot you may say my 21MP sensor is too low in
> resolution. I need a 400MP sensor since the COC used in the calculation
> should be 0.003mm not 0.03mm. A higher pixel sensor is required :-)
>
> BTW, I just put 0.003mm as COC to the calculation, the DOF of 28mm lens is
> still much bigger than a 280mm lens with 0.03mm COC. Or the calculator
> itself is wrong?
>
> I used the following data:
>
> F11, object distance 10ft, COC 0.003mm, the DOF of 28mm lens is 2.66ft
>
> F11, object distance 10ft, COC 0.03mm, the DOF of 280mm lens is 0.24ft
>
> http://www.dofmaster.com/dofjs.html
>
> C.H.Ling
>
>
> ----- Original Message -----
> From: "Ken Norton"
>
>> We must not confuse "bokeh" with DoF. The 300mm image is exhibiting the
>> bokeh characteristics of a specific lens design (I'm assuming Zuiko
>> 300/4.5
>> as it has this distinct look), but the cropped image shows the bokeh
>> characteristics of a modern wide-zoom. The backgrounds in each shot are
>> out-of-focus, so there is no comparing DoF, just bokeh.
>>
>> Ctein alludes to something in one of his last posts in that topic when he
>> states:
>>
>> "Something I hadn't mentioned, and possibly should have sooner, is that
>> trying to nuance this too far is pointless, because real-world lenses
>> NEVER
>> have the same DoF that the equations predict. The precise shape of the
>> light
>> 'cone' near the point of focus has a big effect on where the diameter of
>> the
>> envelope hits the CoC limit, and the shape of that envelope is very
>> sensitive to lens designs and residual aberrations. There have even been
>> lenses with a floating element that tweaked the mix of aberrations so as
>> to
>> let the photographer alter the balance between near and far DoFs!"
>>
>> This is something that I've been harping about in the diffraction-limits
>> and
>> DoF discussions for years. Many modern telecentric lens designs with
>> multiple asperical-shaped lenses have the ability to direct the "cone" in
>> such a way that you get very little spread and in fact will actually
>> invert
>> the cone for out-of-focus light paths forming ring-shaped bokeh artifacts.
>> I have noticed over and over again how some modern lenses do not have a
>> "plane of in-focus" but more of a "zone of in-focus"
>>
>> AG
>> --
>> _________________________________________________________________
>> Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
>> Archives: http://lists.thomasclausen.net/mailman/private/olympus/
>> Themed Olympus Photo Exhibition: http://www.tope.nl/
>>
>>
>
--
_________________________________________________________________
Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
Archives: http://lists.thomasclausen.net/mailman/private/olympus/
Themed Olympus Photo Exhibition: http://www.tope.nl/
|