Monday, May 07, 2018

tested BDT+AAB (Bradford)

9:01 PM. I was in the backyard with essentially everything ready to go. Barn door tracker with new altitude-azimuth base atop the big photography tripod. Camera tethered to the computer. Dew heater on lens. Everything powered via an extension cord from the deck through my GFCI power bar. Rhonda's little garden table. My astronomy chair. Ready to test. Removed the lens shield and filter. The skies looked good. There was a vulture cat watching me from on high.

Forgot to take a picture of the rig. It was too dark now... The cheapo smartphone camera didn't work.

9:04. Saw a bat flying around. They're back! Nice. I struggled getting the Canon software to work... The EOS Utility application crashed.

9:06. Tried restarting the app. Still dodgy. Gah. Did a full computer shutdown—cold iron.

9:12. Launched EU. OK now. Tried to see Polaris on the Live View. No luck. Turned to the bright star in the south-east. Started working on focusing... Nothing on the Live View on the computer. Shot blind.

Note: All photos captured with a Canon 40D, kit lens 18-55mm at 53, daylight white balance, RAW, ASUS Eee PC, EOS Utility.

bright star out of focus

15 seconds, f/5.6, ISO 1600.

A bright light came on at the top deck. A little annoying even though I was aimed to the south-east. Put on my jacket. Still smelled like camp fire!

improved focus

15 seconds, f/5.6, ISO 1600.

Turned on the tracker controller. Whir-whir-whir.

9:30. Finished focusing using the Live View on the computer.

a mistake but good focus

9 seconds, f/5.6, ISO 1600. Actually a "dud" photo. I cancelled the shooting to readjust settings. Still, good focus.

Set up a very long exposure. Programmed settings using the EOS Utility. Two shots at 300 seconds with a 15 second gap and a 10 second delay.

While the camera gathered data, I took in the whole sky. Ursa Major up high, starting to pour water onto the fields. Leo was over my right shoulder. It was getting quite dark.

first very long exposure

300 seconds, f/10.0, ISO 1000.

9:40. Saw streaking in the 5 minute shot. Turned the BDT speed control one full turn clockwise. Heard the motor speed up.

Compared the first photo to the chart in SkyTools.

9:44. Realised I was not on Spica; rather, I was imaging Arcturus in Boötes. Saw Jupiter rising through the south trees. Spica was down and right...

streaking or drifting reduced

300 seconds, f/16.0, ISO 1000.

Oh hey. Wow, pretty good! Almost dialled out the drift!

9:47. Decided to do one more half-turn. Received the last 5 minute shot.

no drifting - Arcturus in Boötes

300 seconds, f/16.0, ISO 1000.

9:50. Decent shot. Almost centred on Arcturus. ρ (rho), ε (epsilon), and η (eta) included. Frame size in ST3P looked right, comparable.

9:51. Considered another item for the packing list: a camera filter case. This for protection the Sky or UV filter when removed from the lens.

Checked the latest photo. Wow. The stars looked pinpoint (while zoomed out). It looked like the trailing was gone; I only had polar alignment issues to sort.

9:55. I taped down the speed control with a wide strip of painters tape (thanks, rho). Aimed over the house to get on the north celestial pole.

9:59. Out of the corner of my eye, I spotted a medium-bright flare to the north-east. Below Ursa Minor, so in Draco, near the heard of the Dragon. [ed: Was it the Lacross 5 at magnitude 1.5?]

Oh oh. Bumped the lens... I had not taped it...

Encountered a balance issue with the alt-az base if the camera was leaning back. Perhaps the altitude bolt should be attached or retained in a nut as opposed to relying on gravity. A quick fix would be to put a strong elastic on it. It could be robust. In the meantime, I attached a hook-and-loop strap to hold down the BDT to the AAB.

Decided to assume the finder scope was axially aligned. Set up a NCP view in SkyTools.

The new altitude-azimuth base controls worked well! I was able to fine-tune the position. Very happy about that (balance issues aside). Once I realised I was on Yildun and not Polaris, I finished the rough alignment.

Found the focus was off. Damn! Couldn't pick out stars on the Live View. Frustrating. Aimed south-east again and redid the focus. Finished focusing on α (alpha) Boo. Aimed to Ursa Major. Could see a star there. That showed if the lens is even slightly out of focus, nothing is visible in the software! i.e. Need very good focus before going to Polaris...

Was feeling chilled.

10:22. Started a 2 minute exposure, on The Handle. Stars looked quite round. The exposure looked OK. Adjusted settings a bit. Still was programmed for 2 shots... I headed to the house to get a sweater. Rhonda arrived home. Yeh!

Big Dipper handle focused

120 seconds, f/7.1, ISO 1000. Alioth aka ε at the left, then Mizar/Alcor/ζ (zeta), and Alkaid/η...

10:52. Returned from the house with yummy hot chocolate. Didn't need to stay dark adapted... ;-)

Programmed a run with 20 shots. Go! Laid a red flashlight on the ground to show the extension cord. Brought a lawn chair over for rho.

11:07. Rhonda came out. She thought it a really nice night. Indeed.

Chatted about many things as the camera clicked away.

11:12. She spotted a shooting star, heading west, below the Little Dipper. Was it an η Aquarid?

Shared my photography notes. I watched Corvus slide to the west.

The lights run finished.

11:42. I capped and dismounted the camera to shoot darks.

Started the tear-down. Rhonda wanted to head in to watch the election debate recording. She offered to help take stuff in so I gave her the BDT box. Completed packing up and transporting items inside.

11:54. Continued shooting darks. At some point I tripped over the power cord. I think it sent a voltage drop down the line interrupting the camera. Moved the computer and camera to the deck. Finished the darks there.


Lessons learned? Need to deal with the altitude plate flopping open. Need to protect the filter when removed. Need to update the packing list. Did not formally test the axial alignment. It occurs to me now that that does not need to be done on Polaris! Any bright star will work... So, need to adjust my sequence notes. And, focus first or early, so to be able to tag stars in the Live View. And tape (or secure) the lens!

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