Friday, April 22, 2016

The Magic of 3D Printing

I remember seeing a show on the Science Channel some years ago about 3D printing. It did indeed seem like magic to me at the time. They appeared very similar to the CNC machines that I was familiar with, but instead of removing material from a block of aluminum or steel, these things actually build things from a spool of material. Fast forward a few years and now I'm seeing the near limitless capabilities from this wonderful invention.

Charles (Chuck) Hull, co-founder, executive vice president, and chief technology officer of 3D Systems created the first 3D printer in 1983, and he has been refining his invention ever since. This solid imaging process known as stereolithography (3D Printing) is the first commercial rapid prototyping technology that is now available to the masses.

This process has really blossomed over the last few years. There are a few companies now offering personal 3D printers, and I have looked into getting one for myself. Some are very reasonably priced, and you are limited only by your imagination in what you can create. Well, and maybe by the size of your machine, but thats just a minor detail.

I'm lucky enough to know a few guys through my astrophotography hobby that happen to own a 3D printer. In a very short time I have seen just how useful these machines can be. I was reacquainted with the technology about a year or so ago, when some of us were seeing what we described as an "iron cross" artifact on bright stars when imaging with our William Optics Star71 telescopes. Some examples of the scope are worse than others, and the problem seemed to be worse in cold weather. A couple of the guys made a simple aperture mask that slipped over the dew shield and it seemed to fix the problem.

My friend Josh Smith sent me one of these to try out on my scope, and the results were clearly better with the aperture mask in place. My scope as delivered was much better than some I had seen, but I still did not like the artifact. You can see the difference it made with these test shots on the star Vega.

5 second luminance, without aperture mask

5 second luminance, with aperture mask
Josh later took this a step further. The dew shield of the Star71 is very short, so he incorporated a removable mask inside of an extended dew shield. The aperture mask snaps in and out for those wishing to only use the aperture mask on cold nights, when the artifact is much worse, but take advantage of the extended dew shield year round.


Another nice touch is the bahtinov focus mask. I prefer to just leave the aperture mask/extended dew shield on the scope all the time, so he even made a dust cover for me.




mask/shield w/bahtinov focus mask
Dust cover
If you've been following along, you know that Little Piney Observatory was lucky enough to get a new equatorial mount a couple months ago. I now like to keep the Star71 piggybacked on the TS 107mm triplet, but this presented a slight problem when it came time to take a set of flats for the little scope.

I have found the longer I can expose the flats, the better results I see. I also like to place at least one sheet of plain white paper on the scope, and lay the light directly on the scope with it pointed at zenith. To do this on the Star71 using my Spike-A flat fielder, this meant removing the dew shield of the 107mm and sliding the Star71 forward so the light could lay across both telescopes. This was a bit more hassle than I wanted to fool with, so I contacted my friend Josh again to see if he might have a remedy for this situation.

What he later sent me was the perfect solution. Using his 3D printer, he fabricated a frame around the light panel that slides directly over the dew shield. When in use it easily clears the dew shield of the 107mm, and the light came with a dimmer switch. Problem solved! I was also told that he's currently working on a USB controller for the light panel. You know that I'll be calling him to see when that will be ready!





Needless to say, he has one happy customer here at Little Piney Observatory. If you have some similar needs, or just a idea in your mind, get in touch with Josh. He's an engineer by trade, and shares my love of the night sky and astrophotography. You can get in touch with him through his website at www.catchingthecosmos.com. Be sure and check out some of his amazing images while you're there.

Some other neat things to come from 3D printing are these ringed standoffs from my friend Tony Akens. These simple rings work great for keeping wires out of places they dont belong, and also make a convenient place to tie off other wires when not in use.


Tony is another great guy that just did some upgrading to his 3D printer. He says he's looking into other cable routing ideas, and I'm wondering what he will dream up next! Tony is a regular on the Cloudy Nights forum, and anyone wishing to contact him can do so here. You need to be a member of Cloudy Nights to contact him there, so if you aren't already a member, be sure and sign up today. Its free to join and there's a wealth of information there. Another plus from being a member is 5% off any purchase from the forum sponsor, Astronomics!

Enjoy the warmer Spring nights while you're out under the stars, and be sure to let me know about the 3D printing ideas you've dreamed up. If its top secret, I'll understand, you can trust me. ;)

Clear skies, and happy imaging!

Thursday, March 31, 2016

Growing Pains

The new mount outlined in my last post has turned into a love-hate affair. It can certainly carry more weight than my Atlas Pro, and when it works, it works very well. I've seen the guiding perform just as well with the new mount carrying 60+ pounds, compared to the Atlas Pro carrying about 25 pounds. After having two months to work with the new mount, I think I've had it long enough to write an unbiased review, and discuss what I believe to be a design flaw in the EQ8/HDX110 mount.

The main problems that I'm seeing stem from, in my opinion, both the RA and Dec motors hanging off the west side of the mount (as seen in northern hemisphere with mount pointing toward Polaris).

First of all, I need to say I did not buy the polar scope that hangs off the opposite side of the mount. From what I can tell, the brackets look to be fairly thick and heavy, and these brackets combined with the polar scope itself, could balance the mount. As it is now, I can balance RA to be quite a bit east heavy, and when I release the counterweight shaft, it will fall down to about a 30 degree angle before the weight off the motors cancel things out. When I say "quite a bit east heavy", I mean very east heavy compared to what I've always done with the Atlas Pro and CGEM DX mounts. I'm afraid to go any further with it. This graph sums up what I've been seeing at times. It seems to always occur in this "dead zone" pointing east where the weight of the motors cancels out the weight of the counterweight(s). It also happens right after flipping meridian. I can move the counterweight down the bar after the meridian flip and it stops happening, but guiding is not nearly as good.


I first tried to go about things by offsetting the scopes to the east a little. I bought an ADM side-by-side saddle and loaded up the mount with my 10" Meade SCT, TS 107mm, and WO Star71.




It worked reasonably well most of the time, and then I'd see RA taking off on its own. First one direction, and then the other. When this starts happening it usually takes me an hour to get in a single 10 minute exposure. It gets very frustrating as you might imagine.

Apparently this is nothing new to EQ8/HDX110 owners, because I ran across these images in Stargazer's Lounge showing what others have done.



Since these dont show the polar scope attached, it really makes me think the weight of the polar scope and brackets hanging off the side balances things out. I really dont see any other reason a polar scope would be mounted in this fashion. I question its accuracy mounted in this configuration as well. I will try something as pictured above and report back. Again, when it works, it works great, and should allow me to buy and use a larger carbon truss RC that I have been wanting.

Guiding with 0.29" rms total error
 At least its warmer now with Spring in full swing here. I'm hoping to get this nailed down soon and purchase a new large aperture scope for imaging. Hopefully it happens soon, because I otherwise really do like the mount. Wish me luck, and happy imaging everyone!

Sunday, January 31, 2016

New Year Upgrades

It's been a little while since I've posted here. Part of it has been the normal cloudy winter weather here, another part has been some downtime for some upgrades. What better time for upgrades than while it's cloudy though, right?

The first thing we did here was finally getting that ethernet cable cable ran out to the observatory. I have to say, it has been really nice using Remote Desktop from the warmth of my room here in the house. Being able to keep a check on things, or making adjustments to the guiding, without walking out into the cold weather has already made the digging worthwhile. Not to mention the numerous other good things that come with having internet in the observatory.

It was about 180 feet or so out to the observatory from the corner of the house. Thankfully it didnt need to be buried that deep, and we ran the CAT5e cable in some 1/2" pvc conduit.

Merry Christmas to me! :)







Internet is nice, but we want to see to see some new astronomy gear, right? Well, it was supposed to be a new camera, but the Starlight Xpress Trius 694 I bought just didnt work out for me. Soon after buying the camera, I ended up selling my 8" RC to a friend in the Houston area. I have always wanted to go to a larger RC.

Well, it isnt a new larger RC....yet. I feared my Atlas Pro couldnt handle a 10" RC, so with the camera refund, along with the money from the sell of my 8" RC, I decided to go ahead and get the mount I wanted to buy months ago, the EQ8. Or more specifically, the Orion branded HDX110.

Before I could install the mount on my pier, I needed a new pier adapter. I ended up contacting Dave Yates at TPI (Telescope Performance Improvements) in Canada. Dave specializes in custom machining and makes everything from custom pier adapters, to tripod spreaders, battery trays, tripod leg levelers, and several upgrades for CGE, EQ6, and CGEM mounts.

His website is www.tpiastro.com and I'd highly recommend Dave to anyone. He's a super nice guy and his work is top notch.

I had the Starizona pier adapter that I used for both my CGEM DX and Atlas Pro mounts. Dave knew exactly what I had and machined a new top for my Starizona pier adapter. I could not be happier with how it turned out.





Once the new pier topper was in place, it was time to get the beast mounted. I bought the mount only, minus tripod and counterweights. I ended up buying the 21 lb and the 11 lb Losmandy counterweights from Astronomics. These are made for the Losmandy G8, G11, and Titan mounts, and have a 1.25" bore. A perfect fit for the HDX110 mount.







With the new mount back on the pier, I put the Teleskop Service 107mm triplet and the trusty SBIG STF-8300 on the mount and it was time for a test drive!

As I'm typing this, the first night of testing is wrapping up. It has gone well after a few bumps in the road getting started. Guiding has been running between 0.50" and 0.65" with terrible seeing conditions. This isnt too bad for a first night out, all things considered.

I'll continue to work with this combination a while and try to get things fine tuned before galaxy season kicks off this spring. With a little luck, I'll have a new long focal length scope sitting on top of the new mount in a few months. I still havent decided for sure just yet what that scope will be, but with a mount that is capable of carrying 110 lbs, my choices have just expanded greatly!

Wednesday, November 4, 2015

Why stack multiple images, and how many is enough?

During one of my recent projects, the Heart Nebula, I decided I would stack some images at different intervals and report here on my results. I used my SII filter for this test. SII usually will not have anywhere near the signal you'd get from the hydrogen alpha filter. As a matter of fact, I did not use any noise reduction at all on my hydrogen alpha data of this region. I thought SII would be a good filter to use for this test, because we can better see the awful noise and artifacts.

So first of all, why stack multiple images? Stacking images can actually be used in any setting that isnt changing to increase resolution and decrease noise. Or in other words, it will increase your signal-to-noise ratio (SNR) and increases the dynamic range. Astrophotography happens to be perfectly suited in this manner. Deep space objects (DSO) are virtually permanent and remain static for long periods of time.

You also want to stack multiple images because each exposure will inherently have cosmic rays, satellite trails, airplanes, and noise in both hot and cold pixels that stacking algorithms like sigma clipping will correct.

Lets see how stacking more and more images improves the final data we have to work with. Each of these are a stack that has had a Screen Transfer Function (STF) applied in PixInsight so that we can actually see what we have. Without the STF applied, the images are very dark and we would not be able to tell anything. You can see how the images gradually increase in SNR and ultimately become much easier to work with.

Each of these stacks are from images that have been binned 2X2 and 2X drizzle has been applied in the stacking to gain back most of the resolution. Please take note of the black specks (cold pixels) in each image and how they are gradually reduced and ultimately eliminated. These are center crops at 100% and each image stacked is a 900 second exposure.

5 subs
9 subs
12 subs
15 subs
23 subs
28 subs
40 subs
So, how many would be considered good enough to you? Some would say 15-20 subs would be enough and would not want to spend 10 hours on one filter. This is perfectly fine. As a matter of fact, I'm working on one right now that I will likely call good enough after 20 subs with the SII and OIII filters. But you can clearly see, if you look close enough, that adding more and more can only help the final image. There is, however, a point of diminished returns. I feel that 40 works well for me when binning and drizzling the SII and OIII data. I shoot my H-alpha at full resolution (1X1) using 20 minute subs and find 8-12 hrs works very well. When shooting this long I sometimes do not even need to use noise reduction.

The above center crops have had no processing at all. Here is a crop of the final SII after processing.

Final crop of the SII
Here is a center crop of the final image using the hubble palette to assign the color channels. SII for red, Ha for green, and OIII for blue.

Final SHO, center crop

And finally, here is the final full image. The full screen image can be seen here, and by clicking on the icon at top right it can be expanded out to full resolution.



I hope this has shown some beginner and intermediate astrophotogaphers why it is important to get enough subs to make a nice image. It is ultimately left to the astro imager to decide for themselves how many is enough, and there is no right or wrong way to do this.

Happy imaging everyone, and happy Thanksgiving!



Tuesday, September 22, 2015

Creating Hubble Palette Images

I usually try to post here at the end of every month, but neglected to do so in August. I think the TS 107mm got more than just a little attention, it got a thorough workout: eleven hubble palette images and one HaOIIILRGB image since mid July, not to mention a few more that I yet to process. I have a few on the back burner that I'm saving for a rainy day.

The recent images from the 107mm scope can be seen here, starting with the Wizard nebula and ending with the Cave nebula. I have switched back to the Star71 for some wide field imaging.

I also got quite the workout with the stretch of clear weather. I had a severe case of astrophotographer fatigue, so I let August slip by without a new post. I did, however, get in a lot of practice on creating hubble palette images, and thought I would share a little bit of what I do to create these images here at Little Piney Observatory this month.

Hubble palette images are basically created by using data from three narrowband filters, SII (sulfur) is assigned to the red channel, Ha (hydrogen alpha) to the green, and OIII (oxygen) to the blue. Some people also call this SHO, substituting the SII (S), Ha (H), and OIII (O) in the channels represented as RGB, or red, green, and blue. Just simply putting the image together in this fashion will usually result in an image that is very green, since Ha is almost always very dominant in every image. The process I use to create the image is sometimes referred to as modified hubble palette, because it uses some selective color adjustments to manipulate the colors. However, this "modified" hubble palette is what creates what most are so used to seeing in the hubble images with the classic golds and blues.

To demonstrate, I'll use some data from an image I'm working on right now. I'm back to using the Star71 again to try to do some hubble palette images of some widefield targets. Right now I'm working on IC 1848, the Soul nebula.

I process each image before combining into a color image, being careful to try to keep star sizes as equal as possible in each image. Here are the three channels I will be working with.

SII - for the red channel

Ha - for the green channel

OIII - for the blue channel

As I mentioned earlier, a straight combine using no selective color adjustments tends to usually come out very green because of the dominant Ha channel. I put one together here to show the effect.


I don't particularly care for the green look myself. There are a lot of steps that go into creating the traditional look of the hubble palette images, but it's worth it in my opinion. I will go through the steps here and then show you a much easier and quicker way in the end.

Start out by taking this image with the straight combine of SII for red, Ha for green, and OIII for blue, and using Photoshop, make these Selective Color adjustments to bring out the classic gold colors seen in many hubble palette images.

First, align your color channels by using Levels and looking at your histogram to align the three channels.

After aligning your three channels, stay in Levels and select your red channel and set your black point to 4 and leave your white point at 255. (You will leave the white point at 255 on all channels)

Select your green channel and move the black point to 9 and set gamma (center slider) to 1.27

Select your blue channel and move black point to 8 and set gamma to 1.38

Now go to Selective Color, and with Method set to Relative, choose green from the dropdown menu and set Cyan to -100% and Magenta to -25%

Choose Yellow, Relative mode, and set Cyan to -100% and Magenta to 25%

Choose Cyan, Relative mode, and set Cyan to -1% and Yellow to -100%

Again with Cyan in Relative mode, set Magenta to -25% and Yellow to -100%

The final adjustment in Selective Color uses Absolute as the mode. Select the color Yellow and adjust Magenta to 15%, then select Blue and adjust Magenta to -20%.

Quite a few adjustments there huh? The easy way here is to buy Annie's Astro Actions from Anna Morris. This is a great action set for Photoshop for only $15, and it includes the Hubble Creation action as outlined above, plus a bunch of other very useful actions for processing your images.

Once I run this action, I get an image exactly like the one above, and then am prompted to adjust levels to even out my colors as necessary. Once doing that and clicking "OK" I have an image like this.


Now we have an image with the classic golds we usually see in this type of image, but there are a few more steps. If you do a search of hubble palette you will likely see a lot of these images that have pink/magenta colored stars. This is where I go back to PixInsight and use Pixel Math and type in this expression.

R/K: $T
    G:  m = min($T[0], $T[2]); iif(m>$T[1], m, $T)
    B: $T

symbols: m

Then just drag the triangle over to the image and the pink/magenta is magically gone from all the stars. The pink stars always gave me fits, and I'd like to thank David Ault for giving me this pixel math expression. It has been a tremendous help. Thanks David!! :)

After cleaning up the stars, I go back into Photoshop to work on the colors a little more. I also have Carboni's Photoshop actions and like to use his "Increase Star Color" action to get a little bit of star color here. Its tough to get good star color in narrowband images without taking some RGB data and overlaying that for star color, but this action does help. Be careful though not to over-do it.

Another action of his that I use a lot is his "Deep Space Noise Reduction." This noise reduction action masks off the brighter parts of the image so as to not lose any details, and focuses mainly on the background. It basically only affects the darker regions.

I also prefer more blue from my OIII compared to the greenish-blue hue seen here. To fix this, I use Selective Color and work with Cyan. Adjust the Cyan to -30%, Magenta to 30%, and Yellow to -100%. These adjustments vary from image to image so adjust these to taste. From this point I usually make some Vibrance and Saturation adjustments.

With this image I have only completed capturing my OIII data. I still want to double my SII data, and I need a lot more Ha. At this point I only have 6 Ha subs, but the Ha signal is strong, and I managed to produce this with the data I have. This is very close to what my final image of this will look like. It looks fine right now in this small image, but when seen full size right now the "warts" are easily seen. More data will get this cleared up.


One other thing that helps a lot on some images that are weak in SII and/or OIII, is a very mildly stretched hydrogen alpha image. I integrate that into the color image, then come back and use a fully processed Ha image as a luminance layer. Just saturate the color image to taste and then add the Ha/luminance for the detail and blend as usual. Images strong in SII and OIII do not need this done. They blend very well into the Ha. This area of the sky has strong SII and OIII components and did not need this.

I have really enjoyed shooting narrowband lately and putting together these hubble palette images. I always thought that I enjoyed shooting and processing LRGB more, but lately about all I have been doing is working with narrowband and hubble palette. Its very enjoyable to me and I hope that a few people find some of the information in this post useful for their own imaging endeavours.

So on this day of the Autumn Equinox, happy imaging everyone!


Friday, July 31, 2015

The Cool Observatory

This is a follow up on the last couple of posts here at LPO about the observatory upgrades and motorized focusers.

The new insulated roof has helped a lot at keeping down temps inside the observatory. However, it just wasnt quite enough once we felt the full brunt of Summer here. We have started insulating the walls with the same 1" foam we put on the new roof, and have installed an a/c unit in the wall. I just came in from checking on things in the observatory and it is a dry 86 degrees inside the observatory. Much better than the humid 100+ degree temps we saw before the upgrades. I feel much better about keeping my equipment out there now.


As soon as I finish up the insulation I will put some blandex (waferboard) on the walls and paint it a flat black. Should be really nice in there for all seasons when that is done. I dont want things cold inside, just cooler. If it were very cold, everything would fog up this time of year when I rolled the roof off. As long as it stays below 90 degrees inside all the equipment should be fine.

Now for the fun stuff. When I wrote about motorized focusers, I had yet to motorize my widefield scope, the Star71. The large single speed knob of the Star71 is not removable. This forced Leon Palmer at Rigel Systems to add an extension to the motor shaft and run the gears off of the fine focus knob. It might not be ideal, or as clean an install as the one on my TS107, but it seems to do the job just fine. It is nice to have the focusers on all three of my imaging scopes motorized now.



I enjoyed using the Star71 for a while, taking several widefield images, but it was time to start using the TS Photoline 107mm triplet again. I had been using my RC telescope for most of the Spring shooting galaxies, then the Star71 for several of the large Summer nebulae. So it was time to give the 107 some attention.

I have now completed two hubble palette images with the 107mm and started on a couple more. The first one was NGC 7380, the Wizard nebula. For this image I used 12 subs of 900 seconds each of Hydrogen Alpha, 14 subs of 1200 seconds each of OIII, and 12 subs of 1200 seconds of SII, just shy of 12 hours total.


I spent considerably more time on the next image, Sh2-86, or Sharpless 86. It was much tough than I expected and with the low OIII sensitivity of my 8300 camera I probably should have tried binning, or shot even longer than the 30 minute subs I used. Binning would have been easier I think than shooting 45 minute to 1 hour long subs. Since I used the H-alpha as my luminance layer after using a weakly stretched H-alpha to combine for the color, I think binning would have been fine. I'm hoping to buy a new camera soon with the Sony ICX814 sensor. Until then I think I will stick with targets with good OIII signal when shooting color narrowband images.

Sharpless 86 is a very interesting area in the constellation Vulpecula, near M27, the Dumbbell nebula.  The most striking feature is the trunk-like pillar of dust and gas protruding from the east side of the nebula towards the open cluster, NGC 6823 in the west. Remarkable dark globules of gas and dust are also visible in the nebula, much as is seen in the better known Eagle Nebula in Serpens or the Lagoon Nebula in Sagittarius. The stars in the center of NGC 6823 are about 2 million years old and are predominantly "young" bright blue stars.


I have over 20 hours in Sharpless 86 and threw away a few hours as well because of focus problems. I used 23 Hydrogen Alpha subs of 1200 seconds each, 12 OIII subs of 1800 seconds each, and 13 SII subs of 1800 seconds. I would like to come back to this one and shoot some RGB for star color. If I dont have RGB for star color I prefer to just make my stars white instead of the typical magenta color you get in hubble palette versions.

The two works in progress are the Bubble Nebula, aka NGC 7635, Caldwell 11, and Sharpless 162, in Cassiopeia, and the Eastern Veil Nebula in Cygnus. The SII and OIII signal in the Veil is super strong, probably the strongest signal I have ever seen since I began narrowband imaging. Here's an example of the three channels.

Hydrogen Alpha, 20X900 seconds
SII, 15X600 seconds, binned 2X2 
OIII, 18X600 seconds, binned 2X2
The SII and OIII were shot binned 2X2 and then stacked using 2X Drizzle to match the resolution of the Hydrogen Alpha shot at 1X1. I have put together a couple preliminary images using this data. I would also like to add some RGB to this one for star color.

Bi-Color image using the Hydrogen Alpha and OIII from the above data
Hubble Palette version of above data
So far I have only the hydrogen alpha data shot on the Bubble Nebula. I'm hoping to get started on some SII and OIII for it as soon as the Moon become less of a factor. These images will be posted soon to my Astrobin gallery.

Happy imaging everyone and stay cool this Summer!!