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[OM] Re: Some interesting commentary on sensor size, pixel pitch and res

Subject: [OM] Re: Some interesting commentary on sensor size, pixel pitch and resolution
From: "C.H.Ling" <ch_photo@xxxxxxxxxxxxx>
Date: Sun, 20 Apr 2008 09:09:36 +0800

----- Original Message ----- 
From: "Chuck Norcutt"


>
>
> C.H.Ling wrote:
>> To me, I will only treat this as a subjective personal opinion.
>>
>> - His assumption about the poorer resolving power of the EF70-200 F4 than
>> his N85/2 is not proofed, many zooms perform very well at center when
>> stopped down.
>
> I don't think he made any assumption about the resolving power of the
> zoom other than it was likely less than his 85mm Nikon prime.  He simply
> took two pictures... one with an old zoom on a 5D and the other with a
> top notch Nikon 85mm prime on a D200.  Then he shows a 1:1 pixel crop
> and shows that the 5D image is superior.  And, by the way, it is very
> much superior... not just a bit.

May be I misunderstood, but he mentioned the 20 years old EF70-200 and
his best 85/2, I assume he expected his 85/2 will perform much better in
lp/mm.

>
>>
>> - He mixed up a very simple thing - screen resolution and print
>> resolution,
>> if he is right then I can get a good 13" (the width of my 17" monitor)
>> wide
>> print with a 1280x1024 pixel image.
>
> I can't find anything in his article that would support your statement
> above.  The only statement he makes about prints is that a print made at
> the same low resolution as the screen shots shown here would be 1.1
> meter wide.  He makes no comment whatsoever about the quality of such a
> print nor does he imply that one should make such a print.
>

I could be wrong again but then there is no point to tell people how big the
image would have been on prints at 72dpi.

>>
>> - Using JPEG is a poor approach. Anyway, compare a 10MP image with 12.5MP
>> is
>> not fair. One can download the converted RAW of D300 and 5D in dpreview
>> to
>> make a comparison. I just did that and see no big difference between the
>> two.
>
> Regardless, I do see a big difference in his paired images.  Are they
> fake?
>

Nikon JPEG is not that strong and less sharpen by default (according to
dpreview), RAW is a better approach if you just want to compare image
quality of different sensor size. The 2.5MP difference also make up the
difference in image quality.

BTW, dpreview's image will not be fake too and they will make more than one
shots to find out the best to compare. I expected it will be more reliable.

>>
>> - The new 4/3 lenses generally has better resolution than the old lenses,
>> their MTF is specified at 60lp/mm rather than the general 30lp/mm for
>> 35mm
>> system.
>
> How did the lens slip in here or don't I understand?  I thought we're
> talking about the diffraction limitations of the sensor itself.  A good
> lens doesn't help beyond a certain point and given aperture.
>

But you don't need to stop down too much for 4/3 lenses.

> Chuck Norcutt
>


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