I think the proof is in the results. The sensor of the 5D is
diffraction limited at f/11 and his f/8, 11 and 16 results would seem to
show that. The lens improves up to f/11 but diffraction starts to take
over from there.
Chuck Norcutt
Jez Cunningham wrote:
> Clever - the more detail, the less the jpeg compression can work -
> brilliant! But is there a reference paper that 'proves' it?
> br
> jez
>
> On 22/03/2010, iwert bernakiewicz <zuikooh@xxxxxxxxx> wrote:
>> Preparing for a study trip with students to Switzerland and Italy next
>> week I did a very unscientific test today.
>> I was thinking of traveling really compact and taking just the 5D, 35
>> shift and 90 macro.
>> But I was a bit unsure about the 35 shift lately, and about adapter
>> thickness influencing image quality.
>>
>> So I did three series with the three adapters I have, a silver AF
>> confirm adapter, a plain silver one and a cameraquest black/silver
>> one.
>>
>> Just looking at converted jpeg sizes I can see the quality of the
>> files! The plain silver ones were the best @ 8,2 and 8,1 MB file size
>> @ f8 and f11 (the best aperture for this lens is f11 when checking the
>> files. Even fully shifted the corners are sharp, just a bit CA)
>>
>> F2.8 - 5.6 is sharp center but soft in the corner (6,3 to 7,1 MB file size)
>> F16 is 7,8 - 8,1 MB, due to either camera shake/diffraction (speed was
>> 1/60 I did not use a tripod because I won't have time nor space on the
>> bus trip. Other speeds ranged from 1/2000 @ f2 to 1/125 f11)
>>
>> The best combination is either silver adapter @ f11, the worst overall
>> is the black adapter (that is when looking at the files @ 100% :).
>>
>> So the silver one will come with me. Just in doubt if I'll take the 28
>> f2 as well for interiors... (or the 21f3.5) So I'll have some more
>> testing to do tomorrow...
>>
>> All the best,
>>
>> Iwert
>> --
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>>
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