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Re: [APML] Lybia 2006 total solar eclipse : remote control offilm camera
Hi Claudio,
No CCD or DSLR camera is going to be able to handle the dynamic range of a
total solar eclipse in a single exposure, the bit-depth does not matter.
To record the entire dynamic range, you are going to need to bracket your
exposures.
You almost certainly will not be able to get any kind of CCD camera that's
worth anything for your budget. I am not denigrating your budget, its just
that those kinds of inexpensive CCD cameras aren't going to be very good.
I think your best bet would be to get some kind of DSLR, such as a Canon
Digital Rebel (300D), or Digital Rebel XT (350D) and the Canon TC-80N3
remote release timer:
http://tinyurl.com/985nv
If you want to totally automate it, you could get something like DSLRFocus
(http://www.dslrfocus.com), and a serial cable from Hap Griffin
(http://www.hapg.org/astrocables.htm). Of course then you would need a
laptop also... If you already have a laptop (which I guess you would need
if you were going to shoot CCD...) then DSLR focus is an inexpensive way to
do this.
If you just want to automate the camera on the cheap and don't have a
laptop, use the TC-80N3 and then use the Camera's built in exposure
bracketing which is + or - 2 stops. You can cheat this to make it 4 stops
in one direction, which you will want to be in the direction of plus
exposure. Ideally, you would want to go from about 1/500th second at ISO
100 at f/8 down to about 5 seconds at ISO 100 at f/8, or possibly longer
depending on atmospheric conditions etc. That's 10 stops, but if you want
to totally automate with the TC-80N3, then 4 stops is probably the best you
are going to be able to do. Maybe someone else can think of some trick to use.
Here's how you trick it to get the 4 stops in one direction... you set up
the camera to shoot so that the autoexposure give you 1/500th second at f/8
when totality starts... you do this by cheating and changing the ISO until
it gives you that exposure at MINUS 2 stops. Then the camera's auto
exposure bracketing will go, in one half stop increments, down to -1, then
0, then +1 then +2 stops.
Also think about the size of the field you will need if you want to record
the maximum corona up to 3, 4, or 5 solar radii, and the digital camera's
crop factor (1.6x on the Canon Digital Rebels) and the focal length of the
lens you plan to use.
You'll also need a safe solar filter (I recommend the Baader solar filter,
they are great and they are very inexpensive) for the partial phases and
for framing before totality starts.
Having never really seen the only total solar eclipse that I went to in
Baja in 1991, I think you are absolutely doing the right thing in planning
on devoting your entire time to watching it, instead of playing with
cameras, and automating the camera to take the pictures.
Jerry
>what imaging device would be best suited for the task , considering a
>limited budget of max 1500 $ ?
>
>I made a list of requirements
>
>1) Remote control of exposure time
>2) Remote control of exposure trigger
>3) wide dynamic range of recorded light intensity to catch both corona
>subtle details and solar prominences
>
>This seems to lead to two devices :
>
>4) CCD camera with 16 bits digitization and megapixel sensor
>5) Advanced 35mm Camera with remote control
>
>Curren Digital SRL cameras like Canon Digital Rebel or Nikon D70 have only
>12 bit quantization and I fear this is not enough to meet requirement 3)
>
>I'm far to be up to date with current CCD camera prices but it seem to me
>that they are overbudget.
>For remotely controllable film cameras I'm stuck to Nikon F100
>
>Can you guys give me some hints ?
>
> Ciao to all , Claudio Lanciotti
>
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