[LRflex] Re: Thunderstorm last night
- From: "Axel Collier" <axel.collier@xxxxxxxxxx>
- To: <leicareflex@xxxxxxxxxxxxx>
- Date: Sat, 1 Aug 2009 09:50:15 +0200
This is getting way to technical for me, but the picture is in my opninion
breathtaking.
greetings, axel
----- Original Message -----
From: Richard Ward
To: leicareflex@xxxxxxxxxxxxx
Sent: Saturday, August 01, 2009 8:37 AM
Subject: [LRflex] Re: Thunderstorm last night
Hi Aram!
Great and Very Dangerous Photograph! Mega Kudo's. I would like to now
point you toward the topic of "Dark Frame Image Subtraction". This is what is
almost certainly what was slowing your image writes down so much. Canon offers
what they call "Long Exposure Noise Reduction" and it is (in my experience)
easily turned off in your cameras custom function settings. What the 'Noise
Reduction" is trying to do is prevent an occasional issue digital images
sensors have when the shutter speeds increase where pixels get stuck on or give
a repeated false signal and 'muck' up a photographer's image. What happens is,
in your case, for every 5 second of 'image' you shot, the camera took a 5
second image with the shutter closed, and subtracts any pixels that aren't
black from the 'real' 5 second image you shot. This computer processing takes a
bit and add in the 'write' time to record the final image and Voila! your 5
second shot has become a 10-15sec wait before you can shoot again.
I usually turn it Long Exposure Noise Reduction off in the custom functions
area of my 20D. I prefer the extra responsiveness it gives, but it does add to
my post production work. I was experimenting with multi minute star trails
landscapes and I;d be standing there freezing in the dark waiting forever for
the blinking to stop!
You might want to see if your version of Canon Software includes a way to
'automatically' do this during downloads or raw processing. I've heard current
Adobe Lightroom products can do this as well, but haven't ever encountered it
personally and can't comment on it's effectiveness (same for the canon
software).
Richard
________________________________
Life is hard...but I just take it one photograph at a time.
~•~
"You miss 100% of the shots you never take" Wayne Gretzky
~•~
In a world without walls and fences, who needs Windows or Gates?
~•~
It's okay to be stupid. Just don't be gung-ho about it.
________________________________
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From: Aram Langhans <leica_r8@xxxxxxxxxxx>
To: leicareflex@xxxxxxxxxxxxx
Sent: Friday, July 31, 2009 3:31:26 PM
Subject: [LRflex] Thunderstorm last night
We had a small thunderstorm roll through at dusk yesterday. I have never
seen lightning at this time of the day, where there was still some color in the
sky and clouds, so I thought I'd give it a try. I shot 50 frames and only
caught lightning on two of them. Had the camera (Rebel XTi) set on sequential
exposure, and the shutter at 5 or 8 seconds, and the cable release clicked on
so I did not have to stand there. It would fire one shot, then write it to
disk then fire the next shot. Last time I did this was with my R8 and motor
winder and it worked well. Problem with the digital Rebel is that after each 5
second exposure it took about 10 seconds to write the info to the card before
it took the next shot. So, I missed about 66% of the time. And, every time I
saw a great bolt, I looked over to the camera and it was still writing the
previous exposure. Drats. Maybe a 50 D would write faster? I think it has
something to do with the null exposure when using long shutter speeds. Maybe I
could turn that off if I looked at the manual.
did catch this one, however.
http://gallery.leica-users.org/v/Aram/misc/-7.jpg.html
comments and criticism welcome.
Aram
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