Saturday, August 15, 2015

Perseid Meteor Shower From NJAA, Nikon D810a First Light

With Wednesday's forecast of clear skies for the Perseid's,  everyone was excited to be at the observatory for the event.  We hosted over 300 visitors that evening and everyone had a great time.  Clouds were mixed all evening until about 1:00AM with a 90 minute break.  I was testing the Nikon D810a AstroPhotography camera for the first time using a CamRanger for control with my iPhone (great combination).  All images were shot using ISO 6400, 15sec exposures and a Nikon 14-24mm at 14mm / F4.0.  The CamRanger is a hotspot that connects to your camera with a USB cable and wifi to your idevice.  The 810a is a 36Mpix image so each raw file is 49MB in size.  This takes about 20 seconds to download to the device when viewing the image with CamRanger.  So I set the image quality to small jpeg for focusing and downing in 2 secs.  Wouldn't you know that just as I focused the camera and took the final small jpeg,  I captured this.  So I didn't have a big raw file to to process.  Well at least I captured one.  Once my focus was set, I changed the image quality to RAW and went on with shooting my sequences.

So this is titled "Milkyway above, Perseid in the middle and light pollution below"...


Since I was taking series of images, I stacked this next image using StarStacker.  I used the Comet Tail feature of the software to make the leading edge of the star look like a Comet.  You can adjust the comet tail length as you wish.  This was a stack of 50 images (50x15sec) giving a 12.5 min in total.  StarStacker lets you if you like, output an individual frame to an external file for each image it stacks.  You can then take those images, import into a video editor, time each frame and make time-lapse of the star trail.  This is how I did the star trail videos on the NJAA's YouTube Channel.


And finally, the same scene with 200 images stacked (43x15sec) 43min.  No comet trail option.  Man , thats lots of stars!  Note in the center bottom just above the trees, there seems to be a meteor.  Its not.  Its a slow moving tumbling booster or other space item, that spanned a number of frames.


As NJAA is celebrating its 50th Anniversary this year, when shooting I often think about the nigh sky view that the founders witnessed in 1965.  Although our Dark Sky meter was showing a NELM (Naked Eye Limiting Magnitude) of 5.9 that evening, the dome of light pollution is evident in all but the shortest of exposures.  So please use "Dark Sky Friendly" exterior lighting when building or renovating.
Clear Skies to all,
Jim Roselli