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Wednesday, May 28, 2008

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!

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