At 05:45 AM 12/5/2006, Moose wrote:
>I missed commenting on some recent threads about megapixels, resolution
>and prints. But, surprise, surprise, I have some thoughts and opinions
>on the subject.
>---------------
I wondered where you were. :-)
>So why do I now use a 12.7 mp DSLR instead of the 6.1 mp one?
I've also wondered why you bought the 5D when, it seemed to me, that
the 30D would have better suited your shooting style and how you
prefer to view/display your images . I see that you've given an
answer below. (BTW, when I recommended the 5D to you I either didn't
know or had forgotten that you prefer telephotos to wide angles.)
>- Because FF 12.7 mp with a decent lens and low noise allows cropping,
>in effect extending the reach of tele lenses and zooms, which is
>important to me. With my most used lens, the 5D becomes a 28-500
>mm,12.7-5 mp camera. 18x zoom anyone? And still in the rez range for at
>least 16x20 at the long end.
>-----------------------------
>So most of the reasons I have moved up in mps have little to do with the
>need for more mps and lots to do with the other things that come with
>the newer design cameras. Although without the last item under DSLRs,
>I'd probably have a 30D.
At first glance it seems to me that the last reason you gave would
actually favor the 30D, not the 5D. Thinking in terms of
image/sensor widths the 5D is 4368 pixels/35.8mm and so captures 122
pixels per mm. OTOH, the 30D is 3504/22.5 and captures 156 pixels
per mm. That's a 27% denser pitch for the 30D and I would think that
this denser pixel pitch of the 30D would favor it in "crop"
situations like I think you've described. Thinking in terms of MPs
and one particular example - let's say that you're shooting a lens on
the 5D at 300mm (maximum zoom extension) and you plan to crop the
resulting image to the same field of view that would have been
captured by a 30D with the same lens (300mm x 1.6 = 480mm equivalent)
and from the same physical location. In this case the area of the 5D
sensor being used for the final image would be the same as the full
sensor on the 30D or 22.5mm x 15mm and the image size (at 122 pixels
per mm for the 5D) would be 2745 X 1830 or 5mp compared to 8.2mp if
the 30D had been used for the same image capture. That's giving up a
lot of pixels to the 30D.
To see if the 27% denser pixel pitch of the 30D (or 8.2 mp vs. 5mp in
the above example) actually translates into higher resolution
captures compared to the 5D in crop situations we can look at the
resolution tests done by DP Review on the two cameras. They found
that the 5D resolved 2300 lines per image width and since the sensor
is 35.8mm wide it follows that it resolved 64 lines per mm of sensor
width. The resolution of the 30D was found to be 1850 lines per
image width and since the 30D sensor is 22.5mm wide it resolved 82
lines per mm of sensor width. 82 lmm is 28% greater than 64 lmm
and would seem to verify that the 27% denser pixel pitch of the 30D
actually translates directly into higher resolution at the sensor
level compared to the 5D and that the 30D would have the resolution
advantage in crop situations that you would expect given the 8.2mp
vs. 5mp captures in the above example.
I guess another consideration might be that the 5D would have the
advantage under some crop situations that are less than 1.6x but, if
my calculations are correct, that's only from a 0 to 1.25 crop and at
that point the 30D would draw even and start pulling away.
Anyway Moose, I'll admit that I've never even held a 30D much less
tried any comparison shots to a 5D so I'm quite possibly all wet with
the above analysis. What say you?
Later,
Johnny
(OM content - the E-1 is probably as good a crop camera as the 5D
since it has a pixel pitch of 78 pixels per mm in sensor width, 93
pixels per mm in sensor height.)
__________________________
Johnny Johnson
Cleveland, GA
mailto:jjohnso4@xxxxxxxxxx
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