On Tue, 28 Aug 2007, Tom C wrote:
> Thanks. Maybe I'll call them and see what it will cost. While I can
> believe my 3 year old *ist D has a problem I can't believe the crap that
> came out of the *ist DS.
>
> http://photo.net/photodb/presentation.tcl?presentation_id=355761
>
> The first is ISO 800 f/1.8 for 6 seconds. The second is a straight up Milky
> Way shot, ISO 800, f/1.8, 20 seconds.
>
> I'm wondering if this might not be an irfanview conversion problem with
> these (PC with Photoshop crashed).
>
> Tom C.
There are two possible reasons that I can think of for what I see
here...
1:
Irfanview is based on dcraw for its RAW conversion. I've had
issues with dcraw in doing starry-night conversions because of the way it
decides on the white point. By default, I think it chooses the white
point at the luminosity of the 99th percentile of the photo. Thus, by
default, 1% of the pixels are blown out.
I've changed that setting on my version of it a few times to make
it 99.9th or 99.99th percentile for star photos. Works great.
2:
The problem with star photos and the DSLRs is that the histogram
cannot be set to logrithmic. When over 99% of the pixels are *SUPPOSED*
to be black, you cannot tell if the 1% that are white are anywhere near
exposed properly because the don't even show up on the histogram.
It looks like you might have a combination of the two. Try the
RAW conversion again, but make sure it doesn't add a bunch of brightness
to it.
-Cory
--
*************************************************************************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
*************************************************************************
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