Pixel density revisited

Started Oct 22, 2008 | Discussions thread
natureman Veteran Member • Posts: 3,979
Re: Pixel density revisited

bobn2 wrote:

natureman wrote:

Phil Askey wrote:

I think a 30+ page review correctly qualifies any statement about
pixel density and noise. Where is this reverse evidence?

Snip.

In your previous post you said "It could be any length, but if it
didn't contain any statements relating noise content to final output
size, it wouldn't be qualified, would it?"

Loom at the context, Phil Askey suggested that 30+pages was enough to
qualify any statement about noise (a bit of a bogus claim, since only
3 or 4 pages are anything to do with noise) which raises the
question, what qualifications would you want to make about noise. As
I've said (repeatedly) what matters to most photograhers is final
image quality, so if you don't qualify your statements with respect
to that, they're not really qualified, in the sense of the discussion
to that point. Of course, you can make any irrelevant qualifications
you like, like the results of the tests apply only to rainy Tuesday
mornings, but they're hardly hepful qualifications in the context of
a review to assist purchase decisions.

What's irrelevant is to expect a review site to cater to your every whim and post image sizes that are exactly what you (or anyone else) may arbitrarily choose to print.

What I'm saying is that dpreview does qualify it by showing 100%
comparison images from every camera in their reviews. In other words,
all cameras are compared at equal magnification and the amount of
magnification is specified,

Incorrect, cameras are compared at different magnifications, that is
exactly the problem.

No, they are compared at exactly the same magnification.

and that qualifies their analysis and
comparisons.

But not in a useful way.

It's very useful, and especially if you have the ability to do your own resizing and modifications to see what you'll get with your typical workflow and/or printing choices.

In even more other words, the qualification is the fact
that all cameras are compared at an equal, specified magnification of
their images (100%). The results (noise, etc.) are shown on the basis
of that qualification.

You must have a different definition of 'magnification' from me. What
is it that has been equally magnified?

The maximum factory designated native output size of each camera.

It's not the image frame,
because that gets magnified differently according to the pixel count.
It's not the individual pixel, because that gets magnified
differently according to its size. There is no 'equal magnification'
at all.

They also show some images at other magnifications.

Unspecified onces.

The dimensions of the images are there and so is enough information to determine the magnification.

Regardless of pixel density, dpreview is showing what each camera
produces at its' maximum native output size,

No it doesn't. The native output size of a FF camera is 24x36mm, of
an APS-C camera 23x14 or so, of a P&S less than a fingernail. DPR
shows nothing at native output size, nor would it be useful to do so.

Huh?? 100% magnification is exactly the maximum factory designated native output size, of any camera.

when they show
comparisons at 100%, and that is as objective as anyone can get.

What's not objective is the drawing of conclusions from tests which
don't support them. Any test of anything is objective, it's the
narrative that isn't. Unfortunately, the narrative also encourages
the uninformed to interpret the test results in ways that don't hold
water.

You're going off course.

I
don't know about the rest of you but if I want to see what a camera
will do, noise-wise or anything else, at a particular print size, I
can just resize the 100% images myself.

Not in the way that DPR presents them, other sites provide better
data for that purpose. But surely, the purpose of a review site is to
present results in a suitably digested, easy to use form?

That doesn't make sense. The images on dpreview are easily downloadable and just as easily modifiable to any size anyone likes.

There are other things in the reviews that to me are not
objective/unbiased (like the lenses used) but comparing images at
100% is proper.

And I can't for the life of me see what 'proper' has to do with it.

That's probably why you can't understand the equity in comparing images at 100% (or other equal percentages of magnification of their maximum factory designated output size), or the inequity of comparing them at arbitrary sizes.

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Bob

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