[LRflex] Re: Technical question
- From: Richard Ward <ilovaussiesheps@xxxxxxxxx>
- To: leicareflex@xxxxxxxxxxxxx
- Date: Sun, 21 Feb 2010 05:49:08 -0800 (PST)
Hi Walter,
I can offer an excellent educated guess as to the source of your 'Chromatic
Abberation". I am pretty confident -absent using your lens & camera myself- is
what you are seeing is NOT Chromatic Abberation from the lens per se, but is
instead 'Blooming' on the sensor itself. The appearance of it is visually
similar, though. The clue to my answer is the 'visual defect' being quite
limited at iso 400 and pretty dramatic at iso 800. The 'sensors' in digital
cameras achieve their varying ISO's by amplyfing the signals coming out of the
sensor by the striking of light upon it (a simplified description). The lights
in the parking garage were overexposed areas in both the 400 & 800iso shots and
detailess blobs of white, but at 800iso the amplifiers erroneously picked up
color signals blooming off the edges of the overexposed areas and gave them an
inappropriate color fringe around the edges.
This behavior of digital sensors in strongly over exposed areas, especially
at higher iso's, is probably the ONLY complaint I have with sensors versus
film. Friday at a Lighthouse I tried the sun in a shot and ALL I got was a
glowing glob of white much different than the same composition from years ago
on film. It's the nature of the beast. The physics of the technology make the
old habit of exposing for the shadows a risky proposition if one doesn't
monitor where the highlights went on the histogram.
If someone has more or better info to give, please pipe in. I 'could' have
punted the question having never used a G1 or the lens in question - Don't
think I did, but readily acknowledge it's possible. :-)
Richard in Michigan
________________________________
Leica R Lenses.
They R worth it -
They R what I Use -
They R the Answer.
Just Not 4 every ?.
________________________________
--- On Sun, 2/21/10, Walter Kramer <walter.kramer@xxxxxxxxxxxx> wrote:
> From: Walter Kramer <walter.kramer@xxxxxxxxxxxx>
> Subject: [LRflex] Technical question
> To: leicareflex@xxxxxxxxxxxxx
> Date: Sunday, February 21, 2010, 7:48 AM
> I am hoping someone may be able to
> shed light on this.
>
> I thought that chromatic aberration was a phenomena to do
> with the
> lens. The following two shots were taken with a Pana
> G1 with the same
> lens at the same aperture (f1.2) at the same time, give or
> take a second
> or so. One shot displays obvious fringing, the other, no
> fringing. The
> differences are in the shutter speed and ISO levels. Both
> taken at
> aperture priority.
>
> 1/13 sec, ISO 400
> http://www.flickr.com/photos/25126059@N02/4375762022/sizes/l/
>
> 1/40 sec, ISO 800
> http://www.flickr.com/photos/25126059@N02/4375013509/sizes/l/
>
> Both shots taken raw and conv to jpg for upload. The
> difference is
> obvious and I am just wondering how this can be and
> what the in camera
> software is doing.
>
> Comments and opinions appreciated.
>
> Walter
>
> --
> Walter Krämer
> walter.kramer@xxxxxxxxxxxx
> walter.kramer@xxxxxxxxxxxxxxxx
> Bus: 03 9854 2463
> Mob: 0414 884 965
>
> ------
> Unsubscribe or change to/from Digest Mode at:
> http://www.lrflex.furnfeather.net/
> Archives are at:
> //www.freelists.org/archives/leicareflex/
>
------
Unsubscribe or change to/from Digest Mode at:
http://www.lrflex.furnfeather.net/
Archives are at:
//www.freelists.org/archives/leicareflex/
Other related posts:
