Re: The 2000 ppi test


"Chris Loffredo" <me@xxxxxxxxxxx> wrote in message
news:3u603dFv09i7U1@xxxxxxxxxxxxxxxxx
> William Graham wrote:
>> "Chris Loffredo" <me@xxxxxxxxxxx> wrote in message
>> news:3u5i3iFvnnucU1@xxxxxxxxxxxxxxxxx
>>
>>>William Graham wrote:
>>>
>>>>"Father Kodak" <dont_bother@xxxxxxxxxxxxx> wrote in message
>>>>news:fkhqn1h1g59qfnce0scr8d28u3qu0rl7i1@xxxxxxxxxx
>>>>
>>>>
>>>>>On Thu, 17 Nov 2005 15:29:41 +0200, DD <roxy@xxxxxxxxxxxxxx> wrote:
>>>>>
>>>>>
>>>>>
>>>>>>In article <KhRdf.316$q93.179358@xxxxxxxxxxxxxxxxxxxxxxxx>,
>>>>>>no_name@xxxxxxxxxxxxxxxx says...
>>>>>>
>>>>>>
>>>>>>>>A lot of digital proponents argue that, once they have a 20 mpix
>>>>>>>>sensor,
>>>>>>>>diigtal will beat film, EVEN IF A COKE BOTTLE IS USED AS A LENS!
>>>>>>>>
>>>>>>>>Both media are dependent on the lens forming the image (sorry -
>>>>>>>>digital
>>>>>>>>isn't magic; the laws of physics still apply), and if you use zoom
>>>>>>>>or
>>>>>>>>non top-range lenses, then maybe you really can't see a difference
>>>>>>>>between 6mp digital and film.
>>>>>>>
>>>>>>>And it don't matter how good the glass you're shooting through if
>>>>>>>you've
>>>>>>>got a glass eye to the viewfinder ... 20 mpix of drek is still drek.
>>>>>>
>>>>>>That's the best comment I have read about digital photography in 4
>>>>>>years.
>>>>>
>>>>>Completely agree, ,and the correct spelling is, "dreck."
>>>>
>>>>
>>>>But I understood that it would be possible, with a digitized photograph,
>>>>to compensate for lens distortion in software. (provided you knew the
>>>>formula for the distortion, of course.) You wouldn't be able to
>>>>compensate for lost information, such as out-of focus photographs, or
>>>>photographs that were severely over or under exposed. But if your coke
>>>>bottle bottom was made of good enough glass, and you knew the formula
>>>>for its curvature, you would be able to "undistort" the image in
>>>>software, and produce a good photograph.
>>>
>>>William, William...
>>>
>>>Was optics (along with history and political theory) one of your "beauty
>>>rest" courses at school?
>>
>>
>> BS in math....1974......U. of Santa Clara........
>
> My point being that - yes you can cure distortion digitally, but not all
> the other aberrations (coma, astigmatism, curvature of field, spherical
> aberration, flare, chromatic aberration and so on) - which many brilliant
> minds have been working on reducing for about a century now.
>
> No matter what glass and digital processing you use, you won't get a good
> image out of a coke bottle (or a 12 to 400mm zoom for that matter).

Hummmm......It seems to me that astigmatism, curvature of field, and
spherical aberration are the kinds of things that would be repairable in
software. Aren't these all distortions in the glass of the lens? Perhaps not
spherical aberration, especially if it resulted in the separation of the
colors due to prismatic effects......Essentially you are correct. I know
very little about optics. It was never a field I had to work with, although
I did work with magnetic, charged beam optics to a small
degree........Bending and focusing charged particle beams using magnetic
dipoles, quadrupoles and sextapoles.


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