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ISO and actual sensitivity in DSLR's (D70, *istD, 20D, S3...)

 
 
Owamanga
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      03-25-2005
On Fri, 25 Mar 2005 22:42:43 +0900, "David J. Littleboy"
<(E-Mail Removed)> wrote:

>
>"Alan Browne" <(E-Mail Removed)> wrote:
>> Pete D wrote:
>>
>> > And as has been said before, it does not matter one tiny little jot as

>long
>> > as the photos come out right.

>>
>> For those who use an incident meter or seperate spot meters (including
>> myself), such information is useful.

>
>Not really. You have to calibrate your meter against the histograms that
>result in your camera.
>
>And I suspect that the results are simply random, since presumably they used
>matrix/evaluative metering which is, in principle, completely random and
>unpredictable (assuming it does what they say it does<g>).


So, the database of 30,000 images is a big lie, it's just a
pseudo-random number generator.

That actually explains a lot.

I've done some tests with the D70, if my daughter (caucasian), pulls
her face to make her eyes to look more asian, the matrix metering is a
lot more accurate. I guess she suddenly matches some of the faces in
the database.

<g>

--
Owamanga!
http://www.pbase.com/owamanga
 
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Philip Homburg
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      03-25-2005
In article <d214ef$cs3$(E-Mail Removed)>,
David J. Littleboy <(E-Mail Removed)> wrote:
>"Alan Browne" <(E-Mail Removed)> wrote:
>> For those who use an incident meter or seperate spot meters (including
>> myself), such information is useful.

>
>Not really. You have to calibrate your meter against the histograms that
>result in your camera.
>
>And I suspect that the results are simply random, since presumably they used
>matrix/evaluative metering which is, in principle, completely random and
>unpredictable (assuming it does what they say it does<g>).


What does the sensitivity of a sensor have to do with the built-in lightmeter
of a camera?


--
That was it. Done. The faulty Monk was turned out into the desert where it
could believe what it liked, including the idea that it had been hard done
by. It was allowed to keep its horse, since horses were so cheap to make.
-- Douglas Adams in Dirk Gently's Holistic Detective Agency
 
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Owamanga
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      03-25-2005
On Fri, 25 Mar 2005 15:20:24 +0100, http://www.velocityreviews.com/forums/(E-Mail Removed) (Philip
Homburg) wrote:

>In article <d214ef$cs3$(E-Mail Removed)>,
>David J. Littleboy <(E-Mail Removed)> wrote:
>>"Alan Browne" <(E-Mail Removed)> wrote:
>>> For those who use an incident meter or seperate spot meters (including
>>> myself), such information is useful.

>>
>>Not really. You have to calibrate your meter against the histograms that
>>result in your camera.
>>
>>And I suspect that the results are simply random, since presumably they used
>>matrix/evaluative metering which is, in principle, completely random and
>>unpredictable (assuming it does what they say it does<g>).

>
>What does the sensitivity of a sensor have to do with the built-in lightmeter
>of a camera?


Are you talking histograms here? One assumes the manufacturer is
completely aware of the exact sensitivity of the sensor, and so takes
this into account when drawing the histogram.

So, compare external meter reading's suggestion of exposure values for
a given ISO to the resulting histogram at those same exposure values
to see if an adjustment to the meter's ISO setting is required to make
it 'accurate' for that sensor. Personally, I wouldn't trust my
interpretation of the histogram to not introduce yet another error
factor using this method.

--
Owamanga!
http://www.pbase.com/owamanga
 
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Roland Karlsson
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      03-25-2005
Alan Browne <(E-Mail Removed)> wrote in news:d213jh$iuf$2
@inews.gazeta.pl:

> er, this is an equipment group. This *is* one of the things we discuss
> here.


Alan - I just tried to be nice to Pete.

Personally I fully agree with you. I just acknowledged
that not everyone do. And that is OK IMHO.


/Roland
 
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Alan Browne
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      03-25-2005
David J Taylor wrote:

> Alan Browne wrote:
> []
>
>>er, this is an equipment group. This *is* one of the things we
>>discuss here.

>
>
> "This" is cross-posted, so it's not even one group.....


Both groups are equipment related. I apologize for my use of the
singular above and trust that the flogging, while justly deserved, will
be administered mercifully.

--
-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
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-- e-meil: there's no such thing as a FreeLunch.
 
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Alan Browne
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      03-25-2005
Roland Karlsson wrote:

> Alan Browne <(E-Mail Removed)> wrote in news:d213jh$iuf$2
> @inews.gazeta.pl:
>
>
>>er, this is an equipment group. This *is* one of the things we discuss
>>here.

>
>
> Alan - I just tried to be nice to Pete.
>
> Personally I fully agree with you. I just acknowledged
> that not everyone do. And that is OK IMHO.


Appolgies, I thought you were replying to me. My news reader does a bad
job of organizing refreshes.

Cheers,
Alan

--
-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: there's no such thing as a FreeLunch.
 
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McLeod
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      03-25-2005
On Fri, 25 Mar 2005 08:25:09 -0500, Alan Browne
<(E-Mail Removed)> wrote:

>For those who use an incident meter or seperate spot meters (including
>myself), such information is useful.


And if you have time to incident meter, you probably have time to look
at the histogram and adjust accordingly, as well.
 
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Philip Homburg
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      03-25-2005
In article <(E-Mail Removed)>,
Owamanga <owamanga(not-this-bit)@hotmail.com> wrote:
>On Fri, 25 Mar 2005 15:20:24 +0100, (E-Mail Removed) (Philip
>Homburg) wrote:
>>What does the sensitivity of a sensor have to do with the built-in lightmeter
>>of a camera?

>
>Are you talking histograms here? One assumes the manufacturer is
>completely aware of the exact sensitivity of the sensor, and so takes
>this into account when drawing the histogram.


I think you can also show a histogram if you are completely unaware of
the effective sensitivity of the sensor.

The histogram is supposed to reflect the distribution of the RGB values
on an image. How the image was obtained is not revelevant for the histogram
(though the color space might be if you want to show brightness)


--
That was it. Done. The faulty Monk was turned out into the desert where it
could believe what it liked, including the idea that it had been hard done
by. It was allowed to keep its horse, since horses were so cheap to make.
-- Douglas Adams in Dirk Gently's Holistic Detective Agency
 
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Alan Browne
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      03-25-2005
McLeod wrote:
> On Fri, 25 Mar 2005 08:25:09 -0500, Alan Browne
> <(E-Mail Removed)> wrote:
>
>
>>For those who use an incident meter or seperate spot meters (including
>>myself), such information is useful.

>
>
> And if you have time to incident meter, you probably have time to look
> at the histogram and adjust accordingly, as well.


Quicker to set strobes with an incident flash meter. Though I am
developing a worrisome, guilt inducing chimping habit when outdoors with
the D7.

Cheers,
Alan.
--
-- r.p.e.35mm user resource: http://www.aliasimages.com/rpe35mmur.htm
-- r.p.d.slr-systems: http://www.aliasimages.com/rpdslrsysur.htm
-- [SI] gallery & rulz: http://www.pbase.com/shootin
-- e-meil: there's no such thing as a FreeLunch.
 
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Jan Böhme
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      03-25-2005
On Thu, 24 Mar 2005 23:02:51 -0500, Alan Browne
<(E-Mail Removed)> wrote:

>Alan Browne wrote:
>
>> I picked up Casseur D'Images (No. 271, March 2005) and among other

> Chasseur D'Images


No need for correction. It was much more fun as it read first.

Jan Böhme
Korrekta personuppgifter är att betrakta som journalistik.
Felaktigheter utgör naturligtvis skönlitteratur.
 
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