Using TI-83 as camera intervalometer

Found a really cheap solution for hands-free operation. Introducing the handy TI-83 graphing and programmable calculator (emphasis on programmable). Told about this link regarding time lapse photography while surfing for a commercial solution. A good colleague turned me onto this; Geoff is a real jack-of-all-trades sort. Turns out the remote shutter jack on my Rebel XT camera is a 2.5mm audio jack. The data port on the TI-83 is also a 2.5mm audio jack. By programming a routine to time mirror lock up and shutter release, the TI-83 send() command is used to pulse the data line...the same way a remote shutter control pulses the camera. The only difficulty I encountered was locating a male-to-male 2.5mm cable. Only thing I could find was online at BoxWave.

This is so cool! As I type this, the camera is outside working on 200 exposures of M17 tonight. No need for a laptop and cabling, now I'm free to grab the binoculars, star map, a beer, or two. The picture below is a little fuzzy, but you can see my messages printing to the screen as it operates the shutter release.

I programmed the calculator with the following:

[7/13/2008] Thanks to Craig on Andy's Shot Glass site, I've corrected listing. You MUST use the programs menu to enter commands, and remember to use the STO key to assign values to variables (the -> notation):

300->T
Prompt I
Prompt E

T*5->M
T*I->S
S+(T*3)->R
T*5->P

For(N,E,0,-1)
Disp N
Disp “MIRROR”
Send(I)
For(D,M,0,-1)
End

Disp “SHUTTER”
Send(I)
For(D,S,0,-1)
End

Disp “BUSY”
For(D,R,0,-1)
End

Disp “PAUSING”
For(D,P,0,-1)
End

End

Disp "DONE"



Voila!

Monsoons

Monsoon season is here. As spectacular as it is, puts a real damper on
my nighttime activity. Working around the phases of the moon is one
thing, but this just blows. All I can really do is wait, and enjoy the
light and water show.

Using a Barlow Lens

The new T-ring adapter arrived, so once again I can trod out to the backyard and play around in the dark. I decided this night I would spend a little more time with that Barlow lens, maybe I was distracted last time I attempted this when the T-ring failed.

Increasing the magnification, compounds the effects of any errors you might have. I read that on a forum somewhere. It truly is the case. Focusing with a Barlow lens that effectively doubles the magnification, took 10 to 15 minutes! Really had to work to dial it in. This night was particularly challenging. A near full moon was out and monsoon season has officially started, so humidity was up. Any slight fluctuation in the upper atmosphere was readily apparent in the frames I collected.

The following picture of The Ring Nebula (Messier 57) was taken using a 2x Barlow at 1600 ASA, 175 x 15 second frames and automatic dark frame subtraction.

For the next several rounds of nightly shoots, I've decided to try working with JPEG format directly from the camera. I expected that it should dramatically reduce my processing time and have some impact on noise. The frames of this M57 photo were all captured in JPEG format. The optical effects of the Barlow don't help here in getting a fair comparison, but I found that capturing 150+ frames in JPEG format dramatically improved signal to noise ratio as compared to my other runs of 150+ frames in RAW format. It was really no comparison. I'm anxious to try this again in a normal prime focus configuration. For me, I'll use the Barlow approach sparingly where zooming in on a small object seems reasonable.

Rough night...

Well, sometimes things just do not go well. Was late getting set up, didn't start taking pictures until after 11pm. Then about an hour in, I noticed the camera moved...by itself.

Apparently, the T-ring is broken. Camera spins wonderfully around on it, too. Not sure how this happened, I'm not that hard on it. Tried to complete, but I was worried about how much rotation I had to process out. Since the T-ring mount was no longer fixed, it was flexing in the wrong direction as well. Had to wait until all the photo processing was finished only to discover that with all the moving and shifting as the telescope slew, focus was not consistent through all the frames. A new $20 part is on order.

I also tried out a 2x Tele Vue BIG barlow, and through all the other frustration I found that even though the increased view is nice for smaller objects, the visual acuity seems to suffer. Stars are softer, not sharp, and though focused (I think) the digital image seems a little unnatural. It looks magnified. Seems a better approach would be to use a Newt with a longer focal length.

NGC 6960, Veil Nebula

Unguided, 1600 ASA, 200 x 15 second frames, equivalent to 50 minutes of exposure. The Veil Nebula, also known as the Cygnus Loop, is a relatively faint remnant of a supernova in the constellation Cygnus. Interesting to note, the IR cutoff filter in my Canon 350D keeps most of the hydrogen emissions from being recorded, otherwise there would also be a significant red portion to the nebula.

Couldn't decide which portrait orientation I liked better, so I included both.

A Night at Kitt Peak

Last night, my daughter and I drove 90 minutes to the outskirts of Tucson to the famous Kitt Peak National Observatory. From the base of the mountain upon which the observatory resides, we drove 12 miles and climbed to 6800 feet. When we moved to Vail, I was fairly impressed at living at 3300 ft. This was awesome. My daughter was very excited, she had been looking forward to this. She was not disappointed. I've captured a few of our photos below.

We made a reservation a few weeks back as part of their Nightly Observing Program (NOP). Last night they were completely full, at least 3 dozen in attendance. After a light meal, our host rushed us off to begin our nightly viewing. We broke up into groups. Twelve of us volunteered for the open-air roll-off building, and we had a chance to share viewing with a 16" Ritchey-Chretien scope. The Sky6 software was used to drive the system. The scope was hoisted on top of a Paramount robotic mount. Boy, if I had the bucks....

This next picture is of the McMath-Pierce solar facility, the largest solar telescope in the world. The above ground portion of the scope runs over 200 feet above the ground, where the rest runs another 300 feet under ground! The entire assembly (above and below) is refrigerated.

And here as you enter the visitor center, just two of the many domes across the mountain top.

This next photo was taken from our sunset viewing position.

Phone home anyone? Cell phones are not allowed, in addition to the glass and mirror telescopes the observatory maintains a few radio telescopes as well. They don't like cell phones there.

The obligatory big government commissioned observatory sign.

For academic and professional astronomers, this must be a great place to work. Around the site you can find dormitories attached or adjacent to each of the observatory domes. Apparently, to request a dome for research requires submitting a paper. If the paper is accepted, the wait can be 12 to 18 months. Each scope is booked for up to 3 astronomers every day of the year.

This last photo is of the 6-story tall Mayall 4-meter telescope. I'll let you figure out which one it is.

If you ever have the opportunity. Its a great visit. I would love to go back and try the Advanced Observing Programs, where you can spend a few nights using the observatories instruments yourself. You are treated as a visiting astronomer with complete access to their resources. It'll only run you $425/night per person, not including room and board which is an extra $80/night per person. Have to save my pennies...

Messier 13, Great Cluster

OMG, I think I just advanced as a lifeform!

Unbelievable! I guess my premise was correct. Third time's the charm. This most excellent shot of the The Great Globular Cluster M13 in the constellation Hercules was taken on the night of May 26th 2008.

151 x 15 second frames at 1600 ASA, roughly 38 minutes of exposure time.

Look below, I included a before and after shot, just to pinch myself. Incredible. Guess I found the signal, Mr. Universe.

Messier 20, Trifid Nebula

First result from my little experiment. How'd I do? Charles Messier discovered this heavenly object in 1764. The red emission nebula comprises a young star cluster near its center, and is surrounded by a blue reflection nebula. 99 x 15 second frames, or about 25 minutes of exposure. Only tossed out 6 frames from 105, and I was being picky. Thats roughly 5%, a sixfold decrease in defects!

Compare this to the earlier post of M8 and you can see here that the starfield of the Milky Way around M20 lacks the background noise and reddish glow. Stars are more pinpoint. I did pick up some coma in the far upper right; not sure if there was some tube flexure or impact from additional temperature drop.

A little experiment...

I've decided to play with exposure settings. Over the last two months, I've extended unguided exposures from 15-30 seconds to 1 minute frames, and along the way observed how far the impact of tracking error goes. In any given run of 1 minute frames, I will throw out 30% due to noticeable tracking error occurring every 7-8 minutes. After spending 3 hours to take the photos, that seems like a waste of good photons.

"Well, duh!", is probably what some of the hardcore computerized brethren would say. Yes, I could get an autoguider cam, get out laptop, install software, add more cables, adjust guide scope to reasonably bright star, and consume more time in setup and prep.

Or...I could simply take shorter exposures and significantly increase the quantity. Its all about the signal. As Mr. Universe would say, "You can't stop the signal, Mal."

I believe taking a very large quantity of short, high-gain exposures will produce a more desirable signal to noise ratio in the end, reducing much of the 'blowout' in some of the brighter nebula and globular cluster shots, thereby producing richer results, without turning my scope into something from The Matrix. -- So Say I

The emphasis here is on digital astrophotography with the minimum amount of gadgets and expense. Once confidence and happiness is achieved at this level, you certainly can go up ($$$) from here as far as your wallet will take you! IMOP, the most expensive piece should be a quality, motorized German equatorial mount with computerized GoTo handheld. The GoTo saves a significant amount of time and is self-contained. A simple OTA for light gathering should not cost more than $500, and at that cost, driven by your desired aperture. A high-gain DSLR camera body can be found online or at your local fence for $400 or less, providing mirror lockup and automatic noise reduction (dark frame subtraction) built in.

* leveled mount and polar alignment via polar scope (a few minutes)
* 3-star GoTo system alignment (5 minutes)
* laser collimation (less than 30 seconds)
* DSLR focus with LCD review/zoom method (1 minute or less)
* unguided photography using shutter remote for as long as your camera has power and your CF has memory left (3.5 hours)
* beer, coffee, or both (your choice, no time limit)

Folly? I'll let the pictures stand on their own merit. You can all laugh at me later. The next round of astrophotography will be captured this way, without making any changes to post-processing method.

Skol and Compai!

Messier 8, Lagoon Nebula

Couldn't wait any longer, Moon still rising during prime photography time, and the constellations Sagittarius and Scorpius are appearing earlier now in the southeastern sky. With the Moon glow, I decided to drop frame exposure to 30 seconds. This image comprises 94 frames, or roughly 47 minutes. Beautiful.

Zeta Scorpii

In addition to Mu Scorpii, the Scorpion's Tail is comprised of an open cluster NGC 6231 (partially viewed above) and the binary Zeta Scorpii (near the bottom of the photo). This image was simply 2 one-minute frames slapped together. Another part of the Scorpion's Tail includes a diffuse nebula referred to as the Northern Jewel Box. Will save that for another night.

Mu Scorpii

Before heading off to bed, I spotted what appeared to be a comet-like image in the lower southwestern portion of the sky; the southern end of the constellation Scorpius. Having lived in the Northwest and at sea-level for most of my life, I've never had the opportunity to view this portion of the sky. Looking through the telescope it became evident that this image was comprised of an open cluster, and some binary stars.

The photo above is comprised of 5 one-minute frames for Mu1 and Mu2 Scorpii, an eclipsing binary. Mu1 is considered a variable star due to the impact of the eclipsing behavior on its apparent magnitude. May be a little over-exposed.

Messier 83

I have made a list of the most interesting Messier objects left to look at, either due to apparent size or magnitude. M106 and M83 were the goals of this fine dark night. After capturing M106, I had sufficient battery power left to get 25 one-minute frames of M83.

Messier 106

Did not realize there were other galaxies in view until after the photo was processed. 42 one-minute frames, 1600 ASA. Not as many frames as I had planned, as the equatorial mount was extended in that direction as far as it would go. To keep going would require slewing completely around, then the mirror would have to be collimated again, and the camera focused and adjusted to recreate the same orientation as seen in the picture above.

I decided to move on to another object.

Messier 4, The Cat's Eye

26 one-minute frames, 1600 ASA. This looked huge in the scope, never observed this cluster before.

Messier 65 and 66

Two members of the Leo Triplet. 42 one-minute frames, 1600 ASA, automatic dark frame subtraction. Captured 59 frames altogether, but had to toss those with tracking error. Discovered the longest I can go in this fashion with a fresh battery is 3 hours, or a little over 90 one-minute frames using up 70% of my 1GB CF card.

Messier 101, The Pinwheel Galaxy

55 one-minute frames, 1600 ASA, unmodified Canon Digital Rebel XT, automatic dark frame subtraction.

Moon in First Quarter with Mars

Ah, well. Tried to go after some other deep sky objects, but the Moon is back and light reflected from the lunar surface proved to be too much; adding an unwanted to glow to the background. Since she paired herself up with Mars, I thought this would make a nice image.

Messier 81, Bode's Galaxy

38 one-minute frames, 1600 ASA, automatic dark frame subtraction.

NGC 4565, Needle Galaxy

34 one-minute frames, 1600 ASA, automatic dark frame subtraction.