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stu7 04-25-2012 03:34 PM

pixels / pixel size / sensor size
 
Ive been looking at pixels / pixel size / sensor size

pixels are something every inexpensive digital camera
seems to have a lot of.

Next I see sensor size... so, question #1 is - how do
these two relate ? Does sensor size necessarilly equate
to larger pixels... couldnt the manufacturer just fill
a larger sensor with cheap old small pixels ? : -)

After reading some more, I decided the whole problem can
be fixed with a simple trick... get one of the el-cheapo
10 megapixel or greater P&S cameras... pump up the dpi to
600 or 1200 dpi, and, youve got an image with four times
the pixel size, yes ?

I havent had time to test this yet... hopefully somebody
will know if it could work.


thanks for reading

David Dyer-Bennet 04-25-2012 03:56 PM

Re: pixels / pixel size / sensor size
 
stu7 <stu7seven@gmail.com> writes:

> Ive been looking at pixels / pixel size / sensor size
>
> pixels are something every inexpensive digital camera
> seems to have a lot of.
>
> Next I see sensor size... so, question #1 is - how do
> these two relate ? Does sensor size necessarilly equate
> to larger pixels... couldnt the manufacturer just fill
> a larger sensor with cheap old small pixels ? : -)


Well, they're not cheaper or more expensive particularly, but yes, you
can put a wide range of pixel counts on a given sensor size; the Nikon
D700 puts 12 megapixels on a full-frame sensor, the D800 puts 36
megapixels there.

The sizes used on cell-phone cameras are, in practice, not used in
full-frame DSLRs, though.

> After reading some more, I decided the whole problem can
> be fixed with a simple trick... get one of the el-cheapo
> 10 megapixel or greater P&S cameras... pump up the dpi to
> 600 or 1200 dpi, and, youve got an image with four times
> the pixel size, yes ?


No. DPI is a meaningless attribue of a digital image (it will influence
default size for image placement in page layout programs, but that's
about it).

There ain't no such thing as a free lunch!
--
David Dyer-Bennet, dd-b@dd-b.net; http://dd-b.net/
Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/
Photos: http://dd-b.net/photography/gallery/
Dragaera: http://dragaera.info

David Dyer-Bennet 04-26-2012 02:42 PM

Re: pixels / pixel size / sensor size
 
bugbear <bugbear@trim_papermule.co.uk_trim> writes:

> David Dyer-Bennet wrote:
>
>>
>> No. DPI is a meaningless attribue of a digital image (it will influence
>> default size for image placement in page layout programs, but that's
>> about it).

>
> It should reflect the size of the sensor, so I wouldn't say it's meaningless.


Of the sensor? No. Nothing I know uses it that way.

> It's not of much practical use though.


I certainly agree there.
--
David Dyer-Bennet, dd-b@dd-b.net; http://dd-b.net/
Snapshots: http://dd-b.net/dd-b/SnapshotAlbum/data/
Photos: http://dd-b.net/photography/gallery/
Dragaera: http://dragaera.info

stu7 04-26-2012 03:17 PM

Re: pixels / pixel size / sensor size
 
> David Dyer-Bennet wrote:
>
> No. DPI is a meaningless attribue of a digital image (it
> will influence default size for image placement in page
> layout programs, but that's about it).


*** to which BugBear responded ***

> It should reflect the size of the sensor, so I wouldn't say it's


> meaningless. It's not of much practical use though.


> BugBear


First, let me thank David for the info about different
pixel arrangements on full size sensors... thats so
interesting.
Now, rather than disagree about my second inquiry,
regarding PPI... this is a bit funny really... David
answered this correctly in my view... as did BugBear
in his response, though there seems to be disagreement
between them(!)... so perhaps I should clarify, that
I had not imagined any quality of pixels-per-inch
/but that/ it provided a means to visually condense
more pixels into a smaller space, thus [approximating
the effect] of larger pixels on larger sensors... or...
squeezing more small pixels into the same space as
fewer larger pixels occupy, is the best I can say it.

Really, what I was looking for, and didnt ask about
specifically, was for some kind of technical / qualitative
definition of this effect... again... how many smaller
weaker pixels grouped together might equal how many
larger stronger pixels ?
There are other qualities associable with pixel power...
Ive seen the matter mentioned here a few times... basically,
as regards how luminosity is recorded... pixel sensitivity
maybe ?

+ +


Wolfgang Weisselberg 04-29-2012 11:03 PM

Re: pixels / pixel size / sensor size
 
stu7 <stu7seven@gmail.com> wrote:

> Really, what I was looking for, and didnt ask about
> specifically, was for some kind of technical / qualitative
> definition of this effect... again... how many smaller
> weaker pixels grouped together might equal how many
> larger stronger pixels ?


That depends on the pixel size of each and what you define as
"equal".

> There are other qualities associable with pixel power...
> Ive seen the matter mentioned here a few times... basically,
> as regards how luminosity is recorded... pixel sensitivity
> maybe ?


Full well size?

-Wolfgang


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