With my old D700 whose iso range is (100) 200 - 6400 (25600), I found the upper
limit for well contrasted
low-noised pictures to be 800-1200.
>From 1600 up, the noise becomes more and more visible.
Ary's being more recent (and a Canon), things may be a little different.
I took a series of photos at ISO 200 & 800 without a motorized mount a few
nights ago the same as Arry !).
I used 30 s exposure, with a 20 mm f/2.8.
At iso 200, the stars are almost punctual and one can see meteors, the milky
way and andromeda.
All dimm, but visible.
At 800, the sky is less dark and the pollution due to the lights of the city
begins to be visible.
I am at 41,55° north, and the lens was pointed near the zenith, which explains
that the stars are
punctual.
In the case of Arry, I think he must live nearer and/or souther to the equator
(it's night at the same time
it was still daylight here, and corona borealis is at a place it were 2 or 3
hours after where I live), which
explains that the stars are stretched though the focal is shorter (11 mm) and
though the lens points near
the north pole (located one field right I suppose).
Anyway, all this doesn't solve the dilemma, whether buying a motorized mount or
trying to have the best
from one's hardware with the means at hand.
> Message du 26/08/15 19:49
> De : "Romano Giannetti"
> A : darktable-users@lists.sourceforge.net
> Copie à :
> Objet : Re: [Darktable-users] milky way picture post processing
>
>
>
> On 26/08/15 18:12, Jean-Luc CECCOLI wrote:
> >
> > That said, for astophotography i'd rather (I indeed do) use the camera
> > at its nominal sensitivity.
> >
> > Yours is 100 ISO, that's what you should use. 400 would be still good,
> > but 1600 is far too high.
> >
> > Yes, then you would need to use a motorized mount... but that's
> > another story.
> >
> >
>
> This is not so clear, really --- it will depend a lot on the camera and
> its iso-variance. Look for example at
>
> http://photo.stackexchange.com/questions/12480/is-high-iso-useful-for-photography
>
> http://photo.stackexchange.com/questions/40188/longer-exposure-lower-iso-or-shorter-exposure-higher-iso-what-gives-better
>
> and anyway, without a motorized mount using low iso is practically
> impossible --- unless you want star trails.
>
> Romano
>
>
>
>
>
> --
> Romano Giannetti
> http://www.rgtti.com/
>
>
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