I was just re-reading this post of yesterday when it occurred to me that
I could easily calculate what I might consider the maximum *usable*
resolution of a full-frame sensor. By usable I mean the 80 lines/mm
practical resolution limit that Williams attributes to the very
experienced photographer working on a good tripod. Turning that into
pixels with a simplistic calculation gives 22MP. Allowing for Bayer
interpolation it's probably a bit bigger than that, say 25MP or maybe
even 30MP. In any case, current sensor technology is already there or
very nearly so. Even assuming my lenses can resolve that much or more
(not likely) waiting for even more pixels would be futile. My working
technique will never be able to utilize that much resolution.
Chuck Norcutt
On 9/10/2011 7:39 AM, Chuck Norcutt wrote:
> I recently bought an old book entitled "Image Clarity" with a sub-title
> of "High Resolution Photography" by John B. Williams, Focal Press 1990.
> I just got it a couple days ago so certainly haven't read it much
> beyond skimming the contents. But I did take note of the last couple
> pages which are a section titled "Diminishing Returns".
>
> In that section he supposes a hypothetical camera/lens/film system
> capable of resolving 100 lines/mm or what he calls "a system of superb
> quality". But in the hands of a rank amateur with no photographic
> training the likely result will be no better than 5-10 lines/mm. In the
> hands of an experienced photographer (working hand held) typical results
> will be about 20 lines/mm and with very careful technique (such as Ken's
> "between heartbeats") hand held results may reach 40 lines/mm. The same
> experienced photographer working on a tripod may routinely reach 80
> lines/mm but many photographs will not. Camera motion (even on the
> tripod) will be one but not the only reason for failing to get above 80
> lines/mm. Lens faults, diffraction, focusing errors, micro vibrations
> within the camera, ground vibrations on long exposures will all play a
> part. With extraordinary care and massive camera support, careful lens
> and aperture selection, extreme care in focusing, etc. it may be
> possible to achieve 95 lines/mm in field work. In the studio with even
> greater control it may be possible to reach 98 lines/mm... but not
> necessarily consistently.
>
> Ignoring the problems of Bayer array interpolation, a 12.7 MP Canon 5D
> sensor can resolve about 60 lines/mm. Allowing for the Bayer array it's
> something less than that. Proportional to the 5D sensor, 40 lines/mm
> for the very careful hand held photographer equates to about 6 MP... a
> number I quoted the other day from another source.
>
> Chuck Norcutt
>
>
> On 9/9/2011 11:46 PM, C.H.Ling wrote:
>>
>> ----- Original Message -----
>> From: "Ken Norton"<ken@xxxxxxxxxxx>
>>
>>
>>>> The live view magnifier on the 60D is starting to convince me that a lot
>>>> of softness that I've put down to other factors
>>>> over the years has been less than perfect focus.
>>>
>>> Exactimundo! The two killers for me is camera/subject motion and focus
>>> imperfections.
>>
>> Same here, I have been knowning myself a non stable shooter for a long time
>> and found out AF can be inaccurate since using the E-1.
>>
>>> The problem for me is that focus imperfections are
>>> addressable by closing the lens down. camera/subject motion is
>>> addressably by opening the lens up.
>>>
>>
>> To me the solution for camera motions is a camera that shoot high ISO with
>> beautiful image quality, 5D II do help some.
>>
>> Aperture is mainly for DOF control, it is so poor if it fall to use as focus
>> error compensation. The OM viewfinder with Minolta Acute Mate focusing
>> screen is close to perfect but not available to any DSLR :-)
>>
>>> I don't believe that emperical evidence supports the claim that
>>> "...any handheld camera used at an exposure of longer than 1/1000 s
>>> isn't going to resolve mroe than about 6 Mpix in any case, reagardless
>>> of the lens or sensor used."
>>
>> My expression will be shutter speed of 1/focal length is far not enough for
>> maximum image quality. It also vary with camera body and lens, the worse
>> combination for me is 5D II with OM 200/4. Last time I shot 5 images to get
>> a perfect one at 1/640s handheld.
>>
>> C.H.Ling
>>
--
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