Thanks, Chuck. You expressed it in a nutshell, which I appreciate.
Probably the best image I ever made with this camera/lens combination, at
least the one that gathered the most compliments ( and contained no
senoritas) was a shot of a red Canadian Beech Staggerwing cranking up. It
was shot at f/10, so I suspect that f/8-f/9 is about right for the upper
limit. The link to that image is given below:
http://gallery.leica-users.org/v/OldNick/Staggerwing+Cranking+NI.jpg.html
Just to ponder a bit, a macro lens extends quite a bit on closeups,
effectively increasing the f-number. How does your equation account for
that?
Jim Nichols
Tullahoma, TN USA
----- Original Message -----
From: "Chuck Norcutt" <chucknorcutt@xxxxxxxxxxxxxxxx>
To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
Sent: Saturday, June 23, 2012 9:53 PM
Subject: Re: [OM] IMG: More Skippers
> Diffraction is a physical characteristic of the focal ratio and has
> nothing to do with the lens itself. At any given focal ratio the
> minimum size that can be imaged of a point source of light is referred
> to as the "airy disc" and it is determined by the focal ratio. Poor
> optics may make the minimum size larger but never smaller. Therefore
> the maximum theoretical resolution obtainable is determined by the
> aperture. When the minimum size of the airy disc exceeds the size of an
> individual pixel it means the the maximum resolution obtainable at that
> aperture is less then the pixel count on the sensor.
>
> For a 4/3 size sensor of 5MP (E-1) the size of the Airy disc equals the
> pixel size at about f/8 or f/9... and that assumes perfect optics. But
> it's sort of a squishy number since the size of the Airy disc also
> varies with wavelength of light. At f/8 you might be resolving all the
> green and blue pixels but not all the red ones (longer wavelength)
>
> But things that are out of focus are not resolved either. Smaller
> apertures lead to greater depth of field while at the same time reducing
> ultimate resolution. Somewhere there's a happy median.
>
> Chuck Norcutt
>
>
> On 6/23/2012 5:49 PM, Jim Nichols wrote:
>> Thanks, Chuck. I'm not sure about the theoretical point where
>> diffraction
>> becomes noticeable with this lens. I have found that, in the past, f/13
>> results in good images, while f/18 is not as sharp. That is one
>> technical
>> area that I don't care to visit.
>>
>> Jim Nichols
>> Tullahoma, TN USA
>> ----- Original Message -----
>> From: "Chuck Norcutt" <chucknorcutt@xxxxxxxxxxxxxxxx>
>> To: "Olympus Camera Discussion" <olympus@xxxxxxxxxxxxxxxxx>
>> Sent: Saturday, June 23, 2012 4:37 PM
>> Subject: Re: [OM] IMG: More Skippers
>>
>>
>>> I prefer the f/13 shot and would blur the background if needed. f/13 is
>>> a bit into diffraction territory for an E-1. You might get marginally
>>> sharper results by sticking to f/9 or f/8.
>>>
>>> Chuck Norcutt
>>>
>>>
>>> On 6/23/2012 2:49 PM, Jim Nichols wrote:
>>>> I received some valuable tips yesterday from Dean Hansen, on using
>>>> lighting angles to bring out the texture and details of butterfly
>>>> wings. I tried to round up some subjects today to put them into
>>>> practice.
>>>>
>>>> Since the sun provides the only light source for my work, it comes
>>>> down to insect angles and camera position. The first was done with
>>>> the lens at f/13 for details. The light brought out the texture of
>>>> the wings, but the background was not as far OOF as I would have
>>>> liked.
>>>>
>>>> http://gallery.leica-users.org/v/OldNick/Skipper+14.jpg.html
>>>>
>>>> I opened up to f/5.6 for the second shot, and, although the light
>>>> angle did not pick up the texture as well, the bokeh is better.
>>>>
>>>> http://gallery.leica-users.org/v/OldNick/Skipper+26.jpg.html
>>>>
>>>> E-1 and Zuiko Digital 35 Macro
>>>>
>>>> Comments and critiques welcomed.
>>>>
>>>> Jim Nichols Tullahoma, TN USA
>>>>
>>>
>>> --
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>>>
>>
>>
>
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