Saturday, April 18, 2015

Just practicing... practicing... practicing!

Much about astrophotography is about practice.
It takes time to understand all the practices that can make for a good astrophoto.
And that means having sufficient number of clear skies in a row to create a habit.
Such is where I am at after a long "winter" of cloudy skies (but little precipitation.)
So I am "out of practice" and the only way "in" is to take every opportunity to "practice" more.

Summer is rapidly approaching which means less "night" in the night skies and observing (and taking astrophotos) needs to be done much later in the evening or better still in the early am (say, 1 to 3 am).

Last night was nice here after a warmish 70+ degree day. I opened the observatory about 10:15 pm and set things up for astrophotography instead of astrovideoing. Without a goto mount, finding objects, even with a focal reducer, is not easy. After much poking around in the sky I looked at my star chart and decided to point in the region east of the constellation Leo where there are many galaxies close (visually) to one another. Couldn't miss!

Here is a test (only a test, mind you) of 36, 20 second exposures stacked with Deep Sky Stacker of the area near M86. I used my modded Canon XSI body (not the best choice for the subject) on the Celestron C8 telescope (classic version) with the Celestron focal reducer (which makes for a wider field of view but reduces the exposure time by about 40%). This is a cropped (1/4th) view of the full image. It is equivalent to a 12 minute exposure but is quite grainy due to the high ISO setting on the camera. With more exposures stacked it would have reduced the grain considerably.

M86 is the bright blob in the upper right hand corner, a large galaxy indeed.
The other galaxies are (left to right) NGC 4425, NGC 3307, and NGC 4413.

The biggest problem I encountered was the position of the telescope at the time which I was attempting to photograph these galaxies. It revealed itself as slightly streaking stars (instead of the round stars it should have been.) This was due to the telescope's moving from one side of the meridian to the other side. The mass of the scope shifts and the gears don't engage as tightly as the scope approaches its meridian. Only after the scope is sufficiently past the meridian do the gears mess tightly enough to prevent "slop".

What does this mean? Either I need to start the photo session much sooner (more and more unlikely as summer approaches) or I need to get to bed earlier and wake up in the middle of the night when my subject is no where near the meridian or well past it.

Some of this you can learn by reading but experience drives it into your brain!

Practice, practice, practice!

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