On 6/20/2023 8:21 AM, coll...@brendemuehl.net wrote:
I have to shoot the stars because I couldn’t hit the broad side of the moon.
Anyway, this Fall when we’re out away from civilization I’d like to try some
astro shooting. If only this once.
The 300/4.5 might do nicely.
But if I were to take a telescope …
I've decided to try to learn this stuff this year, just within the
limitations of the astrotracer. I'm not serious enough about it to go
hardcore and get a star tracker.
A couple of things I've already noticed:
Not every lens is particularly well suited to this, and some otherwise
excellent lenses (I'm looking at you, DFA*50/1.4) are not very good at
night sky photography. The 50 suffers pretty badly from coma, for example.
So look hard at your lenses, the one you are over the moon about during
the day might let you down at night.
Night sky photography is very hard on an optical system.
Don't try to calibrate the GPS anywhere near metal objects (I think
anything iron based is the key here), and do the fine calibration if you
are going to use it. My understanding is that even a few coins in a
pocket or a metal belt buckle can throw off the astrotracer calibration.
I'm carrying my gear at least 50' from the truck to where I'm setting up.
Another, and this is kind of a no brainer, but it's easy to overlook, is
that any tracking method will blur the foreground if there is one, so if
you are including a foreground, shoot one picture with the astrotracer
off and then do your astrotracer image.
You can combine them in post and touch up any wonks in the horizon
caused by this.
If the foreground is complicated, it's probably best to forgo tracking
entirely and go with the 200/ focal length rule for exposure time in
seconds. This can cause you to need to crank up the ISO, so noise and
the resultant reduction of same can cause stars to disappear.
Don't push your ISO to the point where noise reduction becomes necessary.
On the K1, I'm finding exceeding ISO 3200 can be problematic.
And, turn off noise reduction in camera if you are using astrotracer to
extend exposure times or you will be waiting for the dark frame
subtraction to do it's thing, and may be killing stars in the process.
Also, watch your focus carefully. Just cranking the ring to infinity
might take you past infinity, especially with longer lenses, causing
everything to be out of focus.
I purchased a flashlight that can be set from very dim to stupidly
bright that came with a red filter so that I can see what I'm doing
without killing my night vision. This is important if you are all alone
in the wilderness. The last thing you need is to step in a gopher hole
and break a leg.
I went with a Fenix HT18 LED.
On this note also, if you are with a group, be aware that others may not
appreciate you using a flashlight while they are working, so communicate
with them before turning it on.
There is a YouTube channel by a group of guys who call themselves the
Nightaxians who have a lot of great information.
HTH
bill
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