Tuesday, October 11, 2011

Coathanger, NA, Pelican, M106, Lagoon, etc.

A few reprocessed shots.

Coathanger Asterism, small stack of 60 second subs, QHY-8.

NA and Pelican Nebulas, 200 subs x 25 sec x 2 panels, QHY-8, post processed by Sal Grasso
Lagoon and friends, small stack of 60 second subs, QHY-8.

M106 and friends, 30 x 60 sec test subs on first light run with modified Canon T1i, no darks, no flats.

Wednesday, October 5, 2011

Tutorial - How I preserve bright cores when processing images.

I was asked on more than one occasion to demonstrate how I preserve bright cores from becoming blown out during post processing.  So here it is finally.  This example uses the Orion Complex (M42) which has a rediculously bright core thanks to the Trapezium stars, but insanely faint outer details.  Most cameras do not have the dynamic range capabilities and depth to allow you to capture the ultra faint without blowing out the bright core area as it does tend to require rather lengthy exposures to capture enough signal from the faint dust clouds.  Once the data has been stretched out beyond the maximum values in your histogram it cannot be recovered.  You end up with washed out, overexposed looking data. The way to solve this is to actually take exposures of different lengths and meld them together.  There are several approaches to this problem.  I'll outline how I approach the issue. (Raw file stacks are at the bottom of the post if you want to use them to follow along).

In my example I will use a small stack of 20 second, 120 second, and 420 second exposures all shot from my Celestron C8 SCT with a Hyperstar, operating at F/2.0 with a QHY-8 OSC camera.  How many layers you use can vary from two exposures, to several.  It depends on just how long your exposures are and how far you intend to stretch the data.  For this exercise I will stretch the data to what I would consider a moderate degree, so only three layers will be used.

1. Open your stacks in Photoshop.  We will work with the shortest exposure stack (20 second) first.

As you can see, this is such a short exposure that the only thing showing up is the Trapezium core.  However, if you start to stretch the data too much by applying curves or levels, you end up showing more faint detail, at the cost of a blown out core as shown in the next screenshot.

2. Use the Magic Wand tool, or the Polygonal Lasso tool and select the Trapezium core, and the bright nebulosity around it.  Go to the "Select" menu and use "Feather" (CTRL+ALT+D).  A value of 30 to 50 should suffice.  Note - when using the Magic Wand tool, there is a tolerance value that appears in the top tool bar when it is selected.  Sometimes Magic Wand may select more or less of an area than you desire.  You'll need to adjust the value up and down to compensate.

3. Press CTRL+C, then CTRL+V to copy the selected area and paste it as a new layer.  This will be indicated in your "Layers" pane (Bottom Right in the screenshot below)

4. Select the bottom layer which would be labled "Background" in this instance.  Now stretch the data using Curves (CTRL+M).  I recommend a Curve map similar to what I've plotted in the screenshot.

This should draw out more of the nebulosity around the Trapezium core, yet, the core is protected as a seperate layer.

5. Flatten the seperate layer into the bottom layer (CTRL+E) or go through the Layer menu and select "Merge Layers".

6. Now you will repeat the process but expand the selected area beyond the Trapezium core.  Use the Magic Wand tool or Lasso and reselect the original core area, and most of the area brightened up by your recent data stretch.  It should resemble something similar to the following screenshot.  By this point you should include the M43 area as your next few stretches will cause it to blow out otherwise.

7. Feather your selection, again 30 to 50 should do it.
8.  Copy your selection (CTRL+C).  But this time, you're going to bring up your next image stack, in this case my 120 second exposure stack.  Paste the selected layer into the new image.

9. Apply Curves again, using a plot just like before.

10. Flatten the layers again.  As you can see, the bigger picture is beginning to emerge, pulling out the faint detail while the brighter core areas are still under control.

11.  This time we're going to repeat the process on the same layer as this one has much more exposure time and more data to be extracted.  Select most of the bright nebulous area using Lasso or Magic Wand again.  Feather the selection.

12.  Paste on top of the existing image as a new layer.

13. Select the bottom layer again.  Apply curves once more.  There will probably be some variance between the layers.  This will be compensated for in the next step.

14. Open Levels (CTRL+L) and adjust the black point close to the edge of the data spike in the histogram, you should see the two layers blend.  Make sure you're still applying to the bottom layer.

Now if you put the stack you're working on beside the third and final layer (420 second in this instance) you can see where we're going by this point. 

15. Flatten the two layers (CTRL+E) Select the brighter nebulosity again, and feather.

16. Pull up the third image stack, in this case the 420 second exposure stack, and paste the copied data into the image.

17. Apply Curves again, and then adjust the black point in Levels as before.

18. Flatten the layers again.

You should now have a fully stretched Orion Complex.  This process can be expanded to include additional layers with longer and longer exposures.  Below is what I was able to ultimately obtain using larger stacks of the exact same exposure lengths and combining them as above, and finishing up with other post processing techniques:

Hopefully this was of some help.  Just remember, not everyone's data is the same, and your conditions may require a little tweaking on how you select and feather layers, and how aggressive you can apply curves.

Here is a link to the raw stacks, calibrated but unprocessed.  Feel free to download and work with the data and see what you can come up with or if you can replicate the process I've described above.

Q:  "How do I know when to stop layering and stretching with one exposure file and move up to the next?"
 A:  This one is relatively straight forward. Your short exposures (i.e. my 20 second core shot) will only stretch so far before the background areas and even some of the extended object become noise riddled and look terrible. I look at it as if I were stretching that layer like it was the only image I intended to post. So I stretch it until the presentation is optimal in my eyes, and then that's the data I use to copy into the next longer exposure and begin again with that image. If you carry over overstretched and overprocessed data, it will not do your end product any justice.

Q:  "How do I know how much area to select for layering?"

A:  This is where experimentation is advised as there's no magic answer. However, there is a really good way to get a feel for how much you should select and feather.  Put two of the exposures side by side - i.e. the 20 second core shot, and the 120 second shot. Notice how much area is blown out in the longer shot. You need to select that much out of the shorter exposure and then some. When you feather you have to remember that it's a tapered effect on the edge of your selected data and that it will fade out gradually over the number of pixels you've selected. So if your selection is too small, and you feather, then move over to paste in as a new layer you may actually see the overexposed area bleeding through your new top layer causing discoloration, or a "ring" of sorts around your layer, making it very obvious what you did. You should aim to get not just the overexposed area selected in your short exposure layer, but you should try to expand that out an extra 10% or more to make sure you've got it covered. Feathering will take care of the blending for you.

Hope this helps.

Tuesday, October 4, 2011

Rosette Nebula, 3 Hours QHY8 and 2 Hours QHY9 data combined.

Combined my QHY8 (C8 Hyperstar) data from a collaborative effort with Sal last season with my QHY9 (ED80 APO) data and came out with this result.  Not sure if it's better than either, but it's different, and it was good data to reprocess.

Thursday, September 29, 2011

M45 - 9 hours exposure

Data captured almost exactly 1 year ago to the day.  It consists of 3 nights of images, 3 hours each night.  First stack is 3 minute subs, second stack is 5 minute subs, and the last stack is 8 minute subs.  Working a collaborative effort with Sal last year, the 8 minute stack was already processed.  I combined the other two stacks, processed, then layered the new image and the 8 minute data together, making some color balance adjustments manually.  PGC 13696 is just to the right of Electra, at Mag 17.3 which estimates place at 1.4 billion light years distant.  Lots of faint dust around the cluster with so much integration time.  It's not bad flats, that is indeed nebulosity throughout the image.

Tuesday, September 27, 2011

25 hours on Orion, reprocessed from last year

Since I've sold all of my gear again, I have nothing better to do than reprocess old data.  This morning I was out for a jog for the first time in ages due to injuries and surgeries.  The entire sky was overcast except for Orion.  I don't know why, but there was some sublime messaging in there which prompted me to revisit my old data.  I was never quite 100% happy with the earlier renditions.  I guess coming back a year later to take a crack at it from a fresh view helped.  This looks better than my prior efforts in my humble opinion.

Saturday, September 17, 2011

Some manually tracked and manually assembled Lunar Mosaics, Jupiter

As many are aware now, I sold off my deep sky imaging equipment to help out a family in need.  So for the time being, I've been tinkering with an XT6i Dobsonian and a QHY-5 to take a couple of Lunar shots.  Shot an 8 panel mosaic on 09/05/11 an hour before sunset and another this morning, 09/17/11 an hour before sunrise.  Specifics for both images:

Mosaic 1 - 09/05/11
Telescope: Orion XT6i Dob, @ F/8.0 - 1200mm fl
Camera: QHY-5 monochrome, no filters
Acquisition: QGVideo, Gain 15% @ 15fps, 1024x768 ROI, 8 panels
Stacked in AVIStack2, Stitched in Photoshop 7 manually
Marginal seeing conditions, Partly Cloudy skies, 77F
Captured 1 hour prior to sunset
Notes: No post processing other than stitching, no deconvolution

Mosaic 2 - 09/17/11
Telescope: Orion XT6i Dob, @ F/8.0 - 1200mm fl
Camera: QHY-5 monochrome, blue filter
Acquisition: QGVideo, Gain 0% @ 7.5fps, 1280x1024, 8 panels
Stacked in AVIStack2, Stitched in Photoshop 7 manually
Poor seeing conditions, Moderately cloudy skies (thunderstorms in proximity), 55F
Captured 1 hour prior to sunrise
Notes: Mild deconvolution applied, curves adjustment to brighten image slightly.

These will be my last shots with the QHY-5 as I have just sold it as well and shipping it shortly.  These will also be my last astrophography shots for a while.  I won't be replacing any of my imaging gear until I can iron out details shortly about my upcoming relocation to Colorado.  The CFO has already approved the replacement of my gear when I'm ready, but there's no point in rushing it until I know details of "where" I'll be imaging from specifically as it makes a huge impact on what equipment I will go with. 

Links to the high resolution, uncompressed versions:

High Resolution Lunar Image 09/05/11 (click image to enlarge)

High Resolution Lunar Image 09/17/11 (click image to enlarge)

Here are some low-res compressed versions:

Also captured Jupiter, during the Io Transit, and Europa off to the side.  Not real big scale, but I couldn't really push the power up with the terrible seeing conditions.  I caught it between cloud holes and had a whopping 30 seconds of acquisition time.  This is 10 frames stacked @ 1200mm.  = \

Wednesday, August 24, 2011

Sadr Region - Captured by Robert (zerro1)

Robert was gracious enough to send me some raw data to process.  He shot the Sadr Region.  Here's the details on the data:

10 X 15 minutes lights
40 bias
20 darks
15 flats
Stacked/calibrated Images Plus 3.82
camera : QHY9
Scope : AT65EDQ
Mount :Atlas EQ-G
I did the post processing in Photoshop 7. 
I've never shot this area myself so it was fun to actually have some raw data to crunch.  Click to maximize the image.

Friday, July 29, 2011

Cocoon Data from Hyperstar

Last year Sal and I worked on Cocoon data from my Hyperstar rig.  I found some other subs I took and stacked them in as well, and reprocessed the old data to try and bring out more of the dust and increase contrast.  Whether it's better or not I suppose is subject to opinion.

Cocoon - Astrophotogallery.org

30x300sec, no darks
QHY-8 OSC Hyperstar III
Nexstar 8 GPS

Click a second time to maximize to full scale.

Saturday, July 2, 2011

The fires at night

Just finished capturing the fire in the dark from the same vantage point I used earlier.  It's growing, fast.  Here's a few shots.  You can see an observation aircraft trailing in one of the shots.  I animated the three images - taken about a minute apart from one another.  Observe how fast the fire is moving.

Friday, July 1, 2011

Los Alamos Fire from behind my home

The Los Alamos fire is raging out of control still.  We woke up this morning to the familiar smell of smoke and a clouded sky full of smoke and ash.  On my way home I noticed something on the ridge just North of me about 15 miles out.  Seems it's not as far away as originally thought...  After a month of choking on ash and smoke from the Wallow fire in AZ, we had hoped for a break.  The fires in NM are spreading rapidly and I fear for us all this weekend when the fireworks start going off.  No appreciable precipitation since October last year.  Looks like there won't be much AP going on this New Moon cycle either, just like the last one...

In any case, for those of you who wonder what it looks like where I do my AP from, here it is, minus the smoke and clouds usually.  Completely remote and void of light.  Nothing but open country.

Thursday, June 23, 2011

Lagoon and Trifid - Modified T1i

My 2nd attempt at prime imaging with my newly acquired Canon T1i. 

16 x 120 sec, no darks, no flats, no bias
Canon T1i @ ISO 200
W.O. 0.8x Focal Reducer/Flattener
Vixen ED80SF APO
CGEM stock mount
QHY-5 + 50mm Autoguider

Captured in average seeing conditions, and 70 degree temps.  I walked away not realizing I had a slight cable snag creating drag on the mount.  Stars are slightly out of shape as a result..  Bummer..

This camera is exceeding my expectations as I was bracing myself for dealing with high levels of noise with an uncooled camera in warm temps.  It's actually quite mild and can easily be processed out in stacking, evident in the fact I used no darks, and a very small stack of lights.  It's more sensitive than anticipated since I pulled a fair amount of detail with such short exposures.  Not my best Lagoon, but now that I'm a bit more familiar with the nuances of this camera, I will be making a more agressive pass on a target tomorrow night and through the weekend.

Here's a link to the image in my ASTROPHOTOGALLERY

Tuesday, June 21, 2011

Finally a break in the fire conditions - Sagittarius cloud quick pass

I haven't been outside in about 2 months due to regional fires, business travel, etc.  Last night was the first time in a long time that most of the sky was visible through the blanket of smoke and ash that has kept us under siege for weeks from the AZ Wallow fire.  Despite the sky still being degraded, and the Moon blazing away, I decided I needed to shoot something.  So I made a quick pass at Sag and surrounding areas with my newly acquired DSLR - this is only my second attempt using it for AP.

240 sec x 12, no darks, no flats, no bias
Canon T1i modified - Unguided on stock CGEM mount
Canon 18-55mm "nifty-fifty" lense @ F/4.0 ISO 200
Captured in 70 degree temps, and poor seeing
Acquisition - Backyard EOS
Stacking and balance - Nebulosity 2
Post processing in Photoshop 7

Couldn't push any further with the conditions, so I'll make another pass at this with more intensity pretty soon.

Click a second time after loading to maximize the image.

Picasa really compresses these shots something terrible.  Another copy of it is on ASTROPHOTOGALLERY.

I'll write up my own assessment of Backyard EOS shortly as this was my first time using it.  Absolutely wonderful software for this purpose and a little more friendly with DSLRs than Nebulosity as far as connectivity and settings.  A screenshot below.

Tuesday, June 7, 2011

Another Firey Sunset

The AZ fire continues, unchecked, and now burning over 350 square miles of land.  It's now posing a threat to towns in NM.  I tried again to get my dob up before sunset.  I had it up, went to put in an EP and focus.  Saw a sunspot perfectly.  Went to grab a camera and attach it, and the sun moved below my fence line.  Tomorrow I'm going to get this shot I want - an unfiltered shot of sun activity through a telescope, even if I have to drive to a field behind my house to do it.

Monday, June 6, 2011

Arizona Fires

Today is day 5 that New Mexico has been under siege from the Arizona Wildfire.  I just returned home from a day trip to San Diego and found it worse than ever.  It was raining ash the size of giant snow flakes.  Visibility on the west side of Albuquerque is down to maybe 800-1000 ft.  Normally I can view 11,000+ ft Mt. Taylor about 60 miles away with little problem.  I got to my house about 55 miles from the airport and the sun was barely visible as a red glowing orb.  It was perfect density to look at surface features naked eye.  By the time I got in my house and rushed to get the dob out to take high res pics unfiltered, the smoke had thickened too much.  I did snap a few fast ones with the digicam just to give you some perspective of how bad it really is.  I'll note that on my flight in, once we crossed the boarder into NM, the sky was fire orange/red the whole way in to the airport.

Saturday, June 4, 2011

Leo Trio

16x90sec, no darks, no flats, no bias.  Canon T1i modified, Vixen ED80SF, WO .8x FF/FR.

Thursday, May 26, 2011

Cone, Fox Fur, Christmas Tree, etc

Robert loaned me some more data to mess with. I had a lot of fun with this one since I've never had the chance to seriously try to image it myself. It will have to wait until end of this year I suppose. Color balanced in Nebulosity. Post processed in Photoshop.

From this:

To this: