How to compose wide angle scenic on a equatorial mount without horizon angled?

[astroJK (John King)]

Hi folks,

I'm a bit of a beginner at this, so bear with me...

Have been tediously dabbling with astrophotography for little over a year now without much previous practical experiance with a camera, or astronomy. What can I say... I learn best being thrown in the deep end and don't think I've done that badly so far (I'll figure out some way to get the sample under 200kb later sorry)... Albiet, humbally still a long way off being content with my ability

The EF-S 50mm F1.8 has been an excellent lens to begin with, but have gotten a bit bored with producing the same sky-only images as everyone else with better gear and more experiance... I want to start taking shots that showcase my rather privledged dark skies (my parents farm near Yarrawonga).

This has led me to purchase a Tokina 11-16mm F2.8 lens to start doing some scenic wide angle shots that will hopefully alow me to take some more unique views of said dark sky and the lovely unique landscape that I miss so dearly after living in the big smoke for a while.

I use an EOS 550d on a HEQ5 piggybacked off an Orion awesome autoguider package.
The camera is controlled by BackyardEOS (highly recommended) and the goto runs wirelessly off SkySafari on my iphone (yes... only because it's totally RAD and impresses the ladies!)

Anyways... To the point John:

I want a level horizontal horizon, yet can't see in my mind how to orient this on an equatorial mount?
If I aim, lets say east, the resulting horison line will run from the top left of my frame to the bottom right, right??
I don't want to de-align the camera/lens from my autoguider/shortube to compensate for this as I believe (in my noob mind) this will affect the alignment overall and stars will begin to trail? I'm fickle and may be blowing this out of context due to the short exposures resulting from dark sky + fast lens + many exposures stacked. Is 'bending' the camera to the right simply a practical solution to this problem?

Any suggestions welcome

Cheers!

[Octane (Humayun)]

Take an image of your horizon/landscape feature before you begin (handheld or on tripod) and blend it in post with your Milky Way image.

H

[Astroman (Andrew Wall)]

If you can get yourself a good quality Ball mount for your camera that will solve the issue of a crooked horizon. (you can also do it with a normal tripod head) You can align your camera in all sorts of ways with that.. Even if you do have a straight horizon it will eventually rotate a little eventually over time. If you are guiding with the autoguider and have the camera shooting away, don't worry the stars wont trail. You can pretty much shoot 90 degrees from your guidestar and you shouldn't have trailing. The things that may effect this is flexure or a misaligned mount. Depending on what focal length you are shooting on your camera, trailing shouldn't be noticeable anyway.

Look forward to seeing some results.

[astroJK (John King)]

It's great so have such a good Aussie site for such a niche hobby

Thanks kindly for the quick replies! That's set it a bit clearer in my head indeed.

So as long as my guider is tracking something, and assuming mount alignment is good, I should either have at least a little (up to 90deg) room to move the imaging camera to the position I like without it throwing off the effective overall alignment provided by the mount. I assumed they both had to be pointed in the same direction for it to work without the stars moving.

... Or I can cheat and take the foreground and background separately and combine later with software


Anyways, here's my pick of the litter so far:

Acrux 10x60sec (guided) @ ISO400 (stacked in DSS 3.2 with 10 darks/flats/bias and RAW expanded in PS - Didn't play with the color just sharpened it and backed the exposure off a tad)
Focus is off a little intentionally to better show the difference in the colors of the main cross stars... but I WOULD say that even if it was unintentional lol
http://tinypic.com/r/of1t7l/7

Eclipse 16/06/2011
Tamron 100-300mm F5-6.3 (300mm F6.3 ISO1600 1/2sec single frame)
http://tinypic.com/r/sqrq6b/7

Moon and clouds 2010
Canon 50mm F1.8 (50mm F2.8 ISO100 1sec single frame)
Orange was more of a peach, till I fixed it in PS... Whatev looks better this way xD
http://tinypic.com/r/15cms6t/7


Hope you like
J

[Astroman (Andrew Wall)]

As H has said you can "cheat" by doing separate exposures of the Horizon and add the star field in later. It's not cheating as such.

Some good images there, huge halos around the Crux Stars, shows the colours up well. Look forward to seeing some more..

[astroJK (John King)]

Thanks for the encouragment astroman
Does anyone have a good link to some info on blending images?

Cheers!

[astroJK (John King)]

So I've finally completed this, after no end of trouble getting a PC with 8Gb of RAM to let me Photoshop the 188Mb stacked CR2!

Ended up buying portable camera tripod for circa $100 works great for such short exposures and far simpler to transport! This was 4 x 10s F3.2 in my suburban backyard, but plan to travel around a bit now and find more interesting terrestrial landmarks

http://tinypic.com/r/24qskcg/5

[dannat (Daniel)]

John not bad, what focal length was it shot at? The shades are nice but I like stars which are a bit more noticeable

[astroJK (John King)]

Thanks man It was shot at 11mm on a 550D (which makes it roughly 17mm)... Next time ill try opening it up to F2.8 and take more lights and some darks etc at a darker site

[iceman (Mike)]

Hi John

As others have said, a ball mount mounted on top of the scope or mount will allow you to level the horizon, and as Andrew said, take two exposures and merge them in post-processing to avoid the foreground being blurred.

Here's an example I did of this a few years ago:

http://www.mikesalway.com.au/2009/02...the-milky-way/

I took 1 exposure with the tracking off, and 1 with the tracking on.

[dannat (Daniel)]

John I would eave it at f3.2, most lenses don't perform well fully wide open