Dark frames on bulb

Hey all,

I was thinking that when you went past 30 seconds (the D100 limit
before needing to use bulb) that the NR (noise reduction) function no
longer worked, but I was wrong. I just made a ~1 minute exposure, and
'job nr' displayed for a full minute after, indicating that it made a
1 minute dark frame. I guess that means that the D100 has some sort of
timer/clock in it so it knows how long exposures are on bulb.

Does anyone know if there's a time limit to the dark frame in this
camera? An hour? 59 minutes? 24 hours?

Another question: if I go out and take a lot of long exposures, do I
need a fresh dark frame for each exposure? In other words, can I just
make a library of dark frames here at home and apply them at will for
images in the future?

Put another way: Let's say I go out and take five 1 minute exposures,
five 5 minute exposures, and five 20 minute exposures. If I turn NR
on, I'll have a lot of waiting to do, because it will take an
additional 15 dark frames for each, and each 20 minute exposure will
actually take 40 minutes.

Can I just go home and create (or use a previously generated) a single
1 minute, a 5 minute, and a 20 minute dark frame, then apply those
dark frames manually in software? If so, how do I do that?

Home vs. location: does the temperature (or some other factor) matter,
requiring that I at least make my manual dark frames at the location
at the end of the shoot? Or can I just go home and do it at my
leisure?

Do they change? Will today's 1 minute dark frame be just like the one
I took last year?

Thanks!
Chris

----
"Better to remain silent and be thought a fool
than to speak out and remove all doubt"
--Abraham Lincoln
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[These opinions are personal views only and only my personal views]

Do they change? Will today's 1 minute dark frame be just like the one
I took last year?

They change with temperature and with aging of the camera. So a dark frame
should always, if possible, be taken right after the picture it will be used
with.

Do they change? Will today's 1 minute dark frame be just like the one
I took last year?

They change with temperature and with aging of the camera. So a dark frame
should always, if possible, be taken right after the picture it will be used
with.