At 06:13 PM 7/6/2006, Moose wrote:
Sorry for the late reply. I needed to run get a haircut, pick up
some fertilizer at the farmer's exchange, eat dinner and cut the front lawn.
>Oddly enough, I'm more interested in which result looks sharper to me
>than what numbers turn up, since that's how I will be evaluating actual
>photographs made with them.
I don't find that odd at all. Quite often I use prints from my Epson
1270 to judge IQ since that's really the bottom line for me.
> That was just a quick test, and might have
>been a preliminary to something more formal. Except the difference in
>sharpness was so striking that I haven't bothered to go further so far.
But, you referred to it as "resolution". Aren't resolution and
sharpness two different things? In your test aren't you looking for
resolution first but resolution that can be sharpened to a pleasing degree?
>The 10D and 300D sensors are the same, I believe.
The same size and pixel pitch in any case.
> The pixel pitch isn't
>all that different, 122 px/mm for the 5D and 135 for the 300D, about 11%
>denser. Is that "considerably higher"?
Certainly not as "considerable as 25% or 50% would be. ;-)
>Obviously, our results vary, and I don't have any numbers for mine. All
>I know is that I took the full frame of the 300D and calculated, based
>on the pixel pitch, the size image measured in pixels on the 5D that
>would cover the same physical sensor area as the area of the 300D
>sensor. As expected from the above 11% density difference, the 5D image
>had about 10-11% fewer pixels. I then resized one sample by upsampling
>the 5D image and resized the other by downsampling the 300D image, so
>that any effect of the resampling would show up.
I'm still not sure why you went through all the resampling on each
image. I've got to admit that I skipped over your original message
so there must be something in there that explains what you set out to
test and it must be different than I thought. The question that I
thought you had was: If, for example, I'm using a 300mm lens to take
a picture of a bird and my position is fixed so that I can't zoom
with my feet and the image size is smaller in the 5D viewfinder than
I'd like - would I be better off switching to the 300D body with its
1.6 "crop factor" or would I be better off continuing with the 5D and
cropping the image later in software? If that was/is the question it
would seem to me that all you have to do in the test is to shoot the
same subject from the same distance with the same lens at the same
focal length with each body and process the images using your best
methods for each and then compare the important detail at 100% (sorry
ag - if you're still listening) on the screen.
(BTW, the real answer to the question is "neither of the
above". Actually you should mount the 300mm lens on a body like the
E1 with a 2x crop factor.) ;-)
> > Out of curiosity I just went to the DP Review site and looked at his
> > resolution testing of the 300D and 5D. Those tests give a 10% edge
> > to the 300D in the horizontal direction and a 15% advantage to the
> > 300D in the vertical direction (If my number crunching is
> > correct).
>Hmmm... The 300D test shows H= 1600, V= 1450 LPH. The 5d shows H= 2300,
>V= 2000. I come up with +44% H and +38% from those numbers. Sure you
>were reading the 300D test? Even the 20/30D sensor doesn't give 15%, the
>5D is over 20% above them.
As I think you know, I was referring to lines per mm on the sensor as
you go on to explain below. :-)
>HOWSOMEVER, the dpreview resolution numbers are not absolute numbers,
>but normalized numbers so sensors of different sizes may be fairly
>compared to each other. That's what the "LPH" designation means, Line
>pairs Per Height. So a 1 mm high sensor with an absolute resolution of
>2000 lp/mm and one with a height of 10 mm with an absolute resolution of
>200 lp/mm would both have an LPH of 2000. So those numbers can't be used
>directly for what we are talking about, the resolution of part of one
>sensor compared to all of another.
>
>Using height only, the 300D resolves 1600 lp over 15.1 mm, or 106 lp/mm.
>The 5D resolves 2300 lp across 23.9 mm, or 96 lp/mm. Oops, there's that
>10-11% again. So according to the dpreview resolution testing, the 300D
>should resolve about 10% more detail than an APS-C sized portion of the
>5D sensor.
10% on the horizontal and 15% on the vertical using the DPReview
numbers as I stated earlier. (again <vbg>)
>Theory says one
>should be sharper and the simple test shows the opposite. Maybe I have a
>particularly lame 300D and/or a particularly great 5D, I don't know.
>Maybe the sharpening on the 5D is different than the 300D, but I don't
>see how I could sharpen the 300D image to equal the 5D. I seem to recall
>that I tried that briefly.
In this discussion you haven't talked about such things as Raw vs
JPG, in-camera sharpening settings, sharpening settings in Raw
processing software (if you shot RAW), any USM applied later, noise
reduction settings in camera or other settings or work flow that
might affect the image quality. You did talk about resampling that
could degrade the image quality. I'll assume that you used camera
settings and work flow for each body that have proven to give you the
best results. So, looking at the simple pixel pitch numbers would
lead one to believe that the 300D would have a higher lines per mm
resolution than the 5D, the DPReview tests show that this is true, my
tests with the 10D show that this is true, other tests that I've read
on the web over the last 6 months say that it's true yet you've found
just the opposite. As you mentioned above - there could be a several
reasons for this difference.
a) You have an above average 5D.
b) Your 300D is below average.
c) You've found a superior work flow for the 5D.
d) Your 300D work flow/camera settings didn't show the 300D to its
full potential.
e) I don't have a clue as to what I'm talking about. (This may be
the most likely pick, especially by the "I agree with Moose" t-shirt
wearers.) :-)
>In any case, results are better than I expected, so I'm happy so far.
And in the end that's what counts the most. Based on your work flow
you found what is best for you and you're happy with it. I hope you
realize that I my intent was not to rain on your parade. I probably
should have kept my mouth shut like I did the first time the subject
came up. I'll try to do better next time. ;-)
Later,
Johnny
__________________________
Johnny Johnson
Cleveland, GA
mailto:jjohnso4@xxxxxxxxxx
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