FWIW
I had similar experiences in trying to do astrophotography with a C11 HD Edge
on a Losmandy G11.
I finally concluded that there is too much mirror shift in the C11 HD Edge and
the G11 just is not good enough for serious astrophotography in the sense that
exposures longer than about 2 mins are almost certainly going to be flawed, and
maybe 15% of those under 2 mins might not suffer from uncorrectable (high
frequency) periodic error.
I'll note that there is a website (I forget where but you can Google the topic
here) that has a calculator that estimates atmospheric refraction effects for
different hour angles and declinations. The bottom line is that if you are
significantly off the meridian, unguided exposures - even under a few minutes -
will have a significant fraction of an arc-second refraction which will result
in egg-shaped stars. (On the meridian, stars move parallel to the horizon with
little refraction change.) Almost certainly, the effect will be present if only
guiding in RA and not DEC, so DEC guiding also needs to be decent.
On the other hand, I've had some success with hyperstar since the focal ratio
is f/2 and exposures can be as short as 30-40 seconds - unguided. All of which
tells me long-focal length photography is not feasible/reliable with the G11.
Also, because I need to be portable, I find PoleMaster to be an amazing tool
for polar alignment. I now feel my greatest limitation is using an older DSLR -
a refreshing change from being exasperated by the mount.
Another advantage of using short exposures is that in a series of short
exposures, while refraction might impact the overall series, it produces a
small offset from one exposure to the next that will be removed during
stacking, and the individual photos will be pretty good. So my recommendation
is to try hyperstar.
PH
-----Original Message-----
From: az-observing-bounce@xxxxxxxxxxxxx <az-observing-bounce@xxxxxxxxxxxxx> On
Behalf Of Michael McDonald
Sent: Sunday, March 17, 2019 2:34 PM
To: az-observing@xxxxxxxxxxxxx
Subject: [AZ-Observing] Re: NGC 1973, NGC 1975, and NGC 1977 - The Running Man
Nebula
I think that since your setup is so expensive and I know I can never afford
anything like that (But I lust after it all the same!), it gives me the freedom
to try and see what I can do with my “modest” equipment. I mean in paintings
and sculptures, the tool cost isn’t very high. The only thing keeping me from
producing a beautiful sculpture is a lack of talent. Hard to make up for that!
I do dream of a better mount and a 8-10” F4 Newtonian but I haven’t been bitten
by the bug for anything bigger. I now know my AVX mount has its limitations.
But I also know I’m not to the point yet where I’m getting everything out of it
I should be able to. The old woodworkers’ saying comes to mind: It’s a poor
craftsman who blames his tools!
I wonder if the feeling I get doing astrophotography is what duffers get
playing golf: hook to the left, slice to the right, bunkers, bunkers
everywhere. But every now and then, a tee shot goes straight down the fairway!
And you think “Hmm, maybe I can do this after all!”. At which everyone within
50 yards of the next tee had better be on their toes as my next shot is going
who knows where! :-)
So I haven’t felt depressed. Frustrated? Oh yeah! Big time on a regular basis!
But a little suffering for one’s art is supposed to the good for you, right? :-)
And I’m learning a lot! Mostly patience and how to let go! :-)
Mike McDonald
mikemac@xxxxxxxxxxx
On Mar 17, 2019, at 1:04 PM, Bernard Miller <bgmiller011@xxxxxxx> wrote:
Mike,
Don't get discouraged. If you saw some of my early pictures you would know
how far I have come. Processing skills are at least as important as
acquisition skills. Processing can make good data great, but it can't make
bad data great. It is an unfortunate reality that better equipment (i.e. more
expensive) makes it easier. I don't think you need a $50K setup to get good
pictures, but it is pretty hard to do with a $3K setup. My estimation is 20K
can get you a really good setup for astrophotography. Maybe 15K if you get
used equipment. Spend most of your money on the mount. That is the most
critical part of the setup. A good mount makes all your other equipment
better. Consider taking image processing seminars or getting online tutorial
from Adam Block, Warren, Keller, Mike Crawford, Tony Hallas, to name a few.
Be careful of things you find on Youtube. Some are okay but some are useless.
The main thing is to keep learning and keep experimenting.
Good luck,
Bernard
