There is another phenomenon known by the archaic term "dodging," now
known as brightening with masks. I must confess to doing it. I was
trying to preserve some texture in the moon, and when I did, Jupiter
became so dim that it could hardly be seen in the photo. When you have
teeny objects of such diverse brighness, defined by only a few pixels
each, it is difficult to get them all looking like they looked to the
eye in a single exposure. Sorry if I overdid it. Jupiter actually
appeared a little smaller and quite a bit dimmer than Venus.
In this view:
<https://www.flickr.com/photos/24844563@N04/18425870393/in/dateposted-public/lightbox/>
I got the relationship between the two planets better, at the expense of
grossly overexposing the moon. We won't even talk about the trees, but
I kinda like the way this turned out, like a charcoal drawing. Even if
it's Banding City. :-)
This one, taken the next night, shows the relationship better, but
Jupiter is still a bit brighter than in reality. The planets are
resolving to one, two or three pixels
<https://www.flickr.com/photos/24844563@N04/19040978812/in/dateposted-public/lightbox/>
Here's the above image with the "dodging" removed, and no sharpening.
The moon is still burnt in a bit. Even here, the difference between
Venus and Jupiter is less than on the screen in the raw
converter--Jupiter is too bright. And the planets look a little
mishapen, because there aren't enough pixels in the reduced web JPGs to
define the shape accurately. The sharpening evidently rounded their
rendition.
<http://gallery.leica-users.org/v/pklein/temp/P6210544+_2_+.jpg.html>
I dunno how the big-time astrophotographers do it. My object was to
make a purty picture, rather than scientific accuracy, and I did the
best I could.
--Peter
----------------
On 6/22/2015 4:41 PM, Chuck Norcutt wrote:
I understand clipped is clipped but I had expected Venus to be
clipped over a larger diameter. But after your comment I decided to go
lookup the angular diameters of each. Jupiter ranges from (rounded)
30-49' and Venus from 10-63'. While Jupiter never gets as large in the
sky as Venus at maximum it's quite possible for them to appear as nearly
the same size. I have no idea what sizes are appearing right now but
suspect that they can't be too far apart in apparent size.
Is there such a thing as digital halation?
To which Moose replied:
There used to be. When the 'bucket' of a single sensor filled up,
extra electrons 'spilled' over and affected neighbors. (My physics is
probably wrong, but the effect was real.)
As I recall, Canon first found an on chip solution, which led some
folks to accuse them of pre Raw processing. All rather hazy now. I
suspect that all contemporary better camera sensors have a way to avoid
the problem.
Overflowingly Electric Moose
--
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