Friday, December 31, 2010

Brain Virus

Hey it's the end of the year and time for some reflection 6 months into this crazy pusuit.

I have some wonderful observing friends to blame thank for all of this hair-shirting.  You see,  I was going to miss an observing trip because it coincided with our annual family vacation to New Mexico.  Hmmmm,  new moon ... dark skies ... I thought I could at least vicariously participate with them by doing some astrophotography.

Only one issue.  I didn't do astrophotography.

"Yeah,  I'll get a camera and some kind of lightweight mount I can ship out to New Mexico and do some killer astrophotography".  From such naive beginnings began this storyline arc.

I remember the exact moment this pernicious virus infected my brain.  April 4, 2010 at about 10:15am.

You see I was in the waiting room at the doctors office trying not to think about my appointment when it came to me.  In the 15minutes before I was called in I imagined myself peacefully taking pictures of the heavens under wonderful skies churning out stunning mosaics.  My observing pals floored with admiration.

Distraction accomplished.  Didn't matter that it was a far cry from reality.

The blog started as a way to share images with those guys while on vacation.  By then I already knew enough about astrophotography to give it this rather odd name - Cilice.  Hair-shirt ....

Here is my very first astrophoto.  June 20, 2010

Lyra.  Vega dead center.  One pixel in there is M57.
A stack of 5x30sec images, f/5.6, ISO1600, taken with the 18-55mm kit lens that came with the then 12hr old Canon T2i.  New camera smell still pungent in the warm summer air.  No flats, no darks.  I was thrilled, if not a little concerned at how hard it was to focus.  Ahhhhh, the first hint at the pain challenges to come.  But hey ... there were stars there ... and a recognizable constellation. 

Next came the real lens ... the "big gun" I was going to take to New Mexico.  The venerable 200mm EF-L.  First light on July 3, 2010.

M13.  200ml EF-L lens.  Center crop from the full T2i frame. 
Hey, this time I even used dark frames!  But ... this processing stuff sure takes a long time.  And Photoshop?  WTF?   Sigh ... this may be harder than I was expecting.  But look Ma!  There's a lot of stars there!

A couple days later I met one of my dear friends (and partner in imaging pain) at a Bay Area "dark" site.  Here was my very first big boy picture.  Darks, flats, flat-darks,  the training run for New Mexico. 

I *still* don't know where all the blue-green in the Lagoon is coming from.
This one is 40x60sec, ISO800 at f4.  Hmmmm ... once you are done fratzing with your equipment in the field you get to pound your head against the wall for hours with processing.  Then it still doesn't look like you expect or think it should.  And color?  Enough to make converting everything to grayscale the first step in processing.  But my, what fun it is.

The blog starts up later in July with a 2 week trip to legendary New Mexico dark skies.  And this is what it looked like most of the time.

Beautiful but hardly astronomy friendly.
If you care you can pick up the story from the earliest posts in the blog.  Might give you some comfort and cheer while you are calibrating your light frames or contemplating what to throw when you realize you forgot to shoot flat frames.

I have suffered the good hair-shirt fight and it has all been worthwhile.  I've improved my skill and my images are getting better.  I've had something new to throw myself into at a time when I needed distraction.  I've enjoyed writing about the journey and have shared parts of it it with nearly 1000 people from 50 countries.  That's pretty neat.

I've met a few new friends and grown closer to the four who just had to go out observing when I was on vacation.  Thanks gents.  Securis in corde meo est.

Now for next year I have some really amazing ideas ....

Saturday, December 25, 2010

Timelapse Eclipse

I wasn't sure what to do with all of the pictures of the eclipse so I decided to assemble a timelapse.

Only captured the first half of the event due to clouds.  Crickets just for fun.

What a colossal pain!  There has to be a better way to do this.  Has to.  If someone knows what it is please leave some advice in the comments.  I'll describe what I did just to share the pain.

Going into any imaging session with some clear plans and goals ahead of time will save yourself a world of hurt later.  This is something I almost never do.  I hurt a lot.

If I knew ahead of time I was going to shoot a time lapse sequence I would have set up on a accurate polar aligned mount to save the painful image alignment process later on.  Also I would shoot 2 or 3 exposure times for each segment to dial in the constantly changing light as the moon is eclipsed.  Obviously this doubles or triples the number of exposures but that would have come in handy later on.

I decided to downsample all the images so I would have smaller files to deal with to assemble the movie.  The plan was to go back and do this with the full resolution pictures but it took me so long to do this with the smaller images I just can't bear to do it now ... or ever.  

Now remember my images are drifting all over the frame do to inaccurate polar alignment, re-framing, bumping the mount while checking focus and changing camera conditions.  How to align all these images?  I figured using Photoshop content aware alignment would work ... but alas it only worked on the images from the beginning of the sequence - as the moon went deeper into the eclipse photoshop got confused.  Maybe Registax?  I downloaded and fussed for a while be it was too much to learn without being absolutely sure it would give me what I wanted.

What I wanted was aligned and cropped individual images.  Maybe Registax could do that but I didn't see how. OK.  Back to photoshop.  Time to put on the hair shirt.

Load up all the images (downsized) into separate layers.  Make top layer (full moon) visible - turn off all other layers.  Blend mode difference, opacity 80%.  Make the layer immediately underneath visible and highlight it.  Manually move to align.  Turn off visibility of this just aligned layer. Select visibility of next layer down and highlight.  Align.

Repeat 150 more times.  Yeah.

As you go through toss away the bad ones.  Wrong exposure, clouds, out of focus, whatever. Oh yeah, don't forget to go back and return your blend mode and opacity of the top image to normal.

Then crop the whole mess and then save each layer as a file (at least there is a script in the file menu for that!).   Then load up all of these into iMovie (we don't do Windows in Cilice-land - I am grateful to the axemen for my conversion).  Fiddle, export, be satisfied.  It's not perfect.  Far from it.  Don't think about repeating with higher resolution.  Just *don't* do it.  Not worth it.  Really.  Don't look back.

Now go enjoy your Christmas!

Wednesday, December 22, 2010

Red Moon over Orion

After I clicked the shutter on the last image (see previous post) I had a few moments to enjoy the eclipse by eye before clouds rolled overhead.  I just don't seem to be able to watch anything for long before I want to grab the camera.  In this case I had only a couple minutes.  Like two.

I quickly removed the refractor from the travel mount and replaced it with the camera body and 10-22 EF-S lens.  Frame. Click.  Oh ... great picture of my chain link fence in the bottom half of the frame.  I've got to get to an area behind our yard with a clear view.  I grab the whole mount (it is light) and before I walk away I remember I am attached to a dew heaters and a battery.  Nice.

OK.  Calmly make sure I am not tethered and walk away again.  Up and out of the backyard trying not to stumble in the eerie not-moon light.

I plop the mount down (tick tock the clouds are coming),  point in, well, that direction, guess an exposure time and take the picture.  Oh yeah! Focusing would be helpful ... (tick tock) ...there is Sirius at least.  Focused.  Take the picture.  Whew.  I spend the next 5 minutes taking pictures with random exposure times but it was that first (focused non-chain link fenced) picture that was the best.

click image for super-size-me or here for flickr
I spent a couple hours minding the camera on the telescope taking picture after picture and occasionally looking up.  But watching Orion reach in vain for the red moon before drowning in the clouds is what I will remember from the lunar eclipse of 2010. 

Happy Winter Solstice!

Red Moon over Orion

San Jose, CA  December 21, 2010
Canon T2i (stock), Canon EF-S 10-22mm @ 13mm  f4
Astrotrac Travel System Mount
15sec exposure @ ISO800
in-camera dark subtraction

Rain on Full Moons (except on occasion of lunar eclipse)

One of the best lunar eclipses in quite some time and it is rainy and cloudy all day.  The one time I actually want to look at the moon, to watch it's blinding light get swallowed by earths shadow, and winter weather comes to spoil the party.

But come dusk, a break in the clouds.  I quickly set up shop:  Little 80mm refractor on travel mount.  Attach camera.  Focus on full moon.  Cover set up with large garbage bag so the rain gods cannot see a telescope in the open.  Go inside.  Wait.

The garbage bag must of worked as the clouds went north, south, and only occasionally by the moon.  Come showtime it was mostly cloud free until near totality.  Here is one of the last shots I took before a massive cloud bank spotted me and rushed to cover.

click a couple times for XL version

I was so very lucky to see so much of the eclipse and had forgotten how spectacular it is to watch the stars come out.

Since we are apparently stuck with a bright moon, and pretty obvious that we need rain I am of the belief that the two should go together.  Let's get our rain durning the full moons only and not waste perfectly good dark skies with clouds.  Except on lunar eclipses.  Then it needs to be clear.  I don't think that is too much to ask do you?

Lunar Eclipse
San Jose, CA  December 21, 2010
Canon T2i (stock), Astrotech AT80LE, 480mm  f5

Astrotrac Travel System Mount
1.6sec @ ISO800

Thursday, December 16, 2010

North and Up ... Now with Roadmap!

Here is an annotated version of the wide field below showing constellations and some of the brighter and most obvious objects.  If you pixel peep you can find much more especially since we are in open cluster central.  But I think the image is best appreciated when taken in all at once.

click for larger version

Tuesday, December 14, 2010

North and Up

I like widefields.  This probably stems from my enjoyment of gigapanning which I dabbled in before falling into this astro imaging black hole.  I like the perspective and the framing possibilities of a nice wide vista.

I already have a 100mm EF-L lens but found myself wanting even more reach.  I got it in my head that it would be cool to frame M31 and M33 in the same field.  I thought the 100mm would be able to do it but after a valiant attempt (laying in the dirt making adjustments while looking at the camera back) to squeeze them both into the opposite corners of the frame ....  Oh, so close but no-go.  And about a week later after Rogelio Andreo put up this image of just the conceptual frame I imagined.  He did it with a 3x4 mosaic'd panel (and considerably more skill and artistry than I would have!).  Incredible and inspiring but my skills are not up to trying a mosaic panel just yet.

So a few days before CalStar last October I ordered a 10-22mm EF-S lens.  Yeah, a bit overboard but I wanted the lens for terrestrial imaging as well.  I wanted wide ... lets go wide!

But Robert Burns knew how this would turn out.

The best-laid schemes o' mice an' men
Gang aft agley,
An' lea'e us nought but grief an' pain,
For promis'd joy !

I like the lens for terrestrial photos.  It is ... fun.  It's a good lens, not a great lens, but actually fun to use.  But as we know, a good lens, even a fun lens does not a good lens for astro imaging make.  I knew there would be aberrations at the edges of the field but there was more than I expected.  Oh, focusing.  Don't even get me started.  What a pain.  No camera back focusing here.  I had to connect to a computer and do a live view focus on jupiter just to see anything.

And then the vignetting.  Lots of it.  Flat fields that look like driving through a tunnel.  OK, a bit of an exaggeration but still.  And no sky flats possible with a field as wide as that.  I took much more time trying to get a decent flat frame than I did getting the actual images.  Much more.  In the end I took my flats off my laptop screen.

After all that ... calibrating with my flats made the images worse.  I'm still trying to puzzle that one out.  The flats severely over corrected the vignetting.  I dunno ... only thing I can think of is that my flats were not representative some how.  Something to figure out.

So after wrestling with flatfielding I decided to only calibrate with darks and bias frames and deal with the gradients in PixInsight which has some powerful tools to throw against it.  I tried a bunch of background models and finally stumbled into one that was "good enough".

Cassiopeia nearly centered.  That's Deneb and the North American nebula at left.  Andromeda upper center. And a zillion stars from the Milky Way. Click image for larger version or here for flickr.

Of course the tree was out of the field when I started but slowly crept in during the hour I was taking the images (in the end I only used 10 of the 30 2min exposures I took).  During star alignment that tree area becomes a blurry mess so I just pasted the tree from the last frame in place.

There is a lot in there.  Double cluster right of center.  M31 mid top and if you look on a larger version you will find M33 just near the top of the frame to the right of M31  (yes, by design ... I got my wish).  I should work on an annotated version some cloudy, rainy night.

So, more lessons learned.  Maybe I should have spent the time learning to put mosaics together after all.  But there is something kind of neat about this field of view.  When I was taking the images I noticed that the field was an approximation of what you see with the unaided eye.  Plus or minus.  Look North and Up and that is what you would see ... if your eye could integrate photons.

North and Up

Taken at Lake San Antonio, CA  October 9, 2010
Canon T2i (stock), Canon EF-S 10-22mm @ 14mm  f5
Astrotrac Travel System Mount
10 120sec exposures @ ISO1600
10 darks
no flatfielding, vignetting and gradients removed in PixInsight
32 bias frames
calibration, registration and post-processed in PixInsight