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Monday, June 30, 2008

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):

Prompt I
Prompt E


Disp N


Disp “BUSY”



Disp "DONE"


Thursday, June 26, 2008


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.

Tuesday, June 17, 2008

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.

Monday, June 9, 2008

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 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.

Sunday, June 1, 2008

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...