Sunday, January 30, 2011

Go Long! (in focal length)

Been a bit since I've posted - not for lack of trying.  I've been pounding sand trying to get my head around image processing ultrawide field images.  That would be an essay for another day ... suffice it to say that it has been, ah, challenging.

By ultrawide field I am talking about 24mm or less (lens f.l.).  Unless you are in the Atacama desert there are challenging light pollution gradients to deal with.  That and a whole host of other processing details I've been largely unsuccessful at dealing with - largely related to DSLR imaging.

So I decided to take a break and go "long".  For me that is all the way back to 100mm f.l.  Taking in mere degrees of sky feels like drinking from a teacup.  But oh how much easier it is to process the images!  I imaged Orion's belt and sword for much of the outing and then took just 30min of the M46, M47 region to finish off the night. 

M46 and M47 and a host of Open Clusters.  Click for ginormous* or here for flickr.
* ginormous - a favorite word of mine.  I come to find out that it is now (as of 2007) officially recognized by Merriam Webster dictionary.  For international visitors, it is a neologism - a word made from a combination of two words.  In this case "gigantic" and "enormous".  I will now feel free to use it frequently and without shame.

One of my observing pals, Dan, had M46 centered up in his 10" Meade outfitted with a binoviewer.  A visual treat with the little planetary nebula floating inside the spray of open cluster stars.   Been a while since I've actually done any visual observing and I'm glad I have friends to keep me honest.

So naturally, after he left, my dark imaging nature took over and I decided to try and take a picture of it.  I figured there was little chance of capturing the planetary at the image scale I was working at but if you drill down, sure enough, there it is.

Click image and look for the tiny green-blue dot in the upper cluster (M46).  That's the planetary nebula.  Cool.
This whole area is littered with open clusters.  Other than some admittedly spectacular exceptions I was never fond of looking at open clusters visually.  Taking pictures of them are somewhat more fun - at least they seem easier to pick out from the background stars.  Below is an annotated version.

click for full size or here for flickr
I may have to re-think my strategy for shooting ultra-wide.  I thought I would save time and effort by shooting single frames with a wide angle lens but I think I am now going to pursue doing mosaics.  That will bring it's own set of, ah, challenges, but I don't call this place Cilice for nothing.

Taken at Montebello Open Space Preserve, CA  January 27, 2011
Canon T2i (stock), Canon 100mm f/2.8L Macro IS USM @ f/4
Astrotrac Travel System Mount
15 120sec exposures @ ISO800
32 darks
no flatfielding, vignetting and gradients removed in PixInsight
128 bias frames
calibration, registration and post-processed in PixInsight

No comments:

Post a Comment