Orion Skyglow Astrophotography Filter - First Night Out

First off a night with a 66% waxing moon is far from an ideal test night. The purpose of Orion SkyGlow Astrophotography Filter is to remove various bands of artificial outdoor lighting. The moon is broad band reflected sunlight which is not fully filterable. Also making this night non-ideal was high clouds that moved in far sooner than the forecast 2300 EST cutting short the night. 

 That said I was able to image NGC7635, the bubble nebula using 15x2 min and 6x5 min  sub-frames. The Starizona Night Owl 0.4X focal reducer was used for imaging. Images were processed using Paintshop ProX9. To give a direct comparison between the two images the six steps used to process the 6x2min image were saved to a script which was then applied to the 15x2 min case. The process and cropped images appear below. 

On another note I am finding images acquired with the Starizona Night Owl are far more susceptible to the exposure conditions of the flat frames used in stacking. I image using SharpCap 3.2 and acquire flat frames over a range of exposures while keeping the logarithm of the histogram as close to a 20% to 80% range. In any case I would consider either image below to be acceptable considering the phase of the moon.

NGC7635 -- 15x2 min

NGC7635 -- 6x5 min

Some Auto-guiding subtleties - Updated

One of my early postings on the Orion Magnificent Mini Autoguider talked about how well it guided from my second floor patio despite mediocre alignment. Surprisingly it hasn't always been as smooth out in the field even when my Celestron 8 Advanced AVX system was well aligned using the All Star Polar Alignment (ASPA) method. The problem? Balance.

Early on I assumed I could get away with balancing and ASPA aligning the scope using the Celestron RACI visual finder then swapping that finder with the auto-guider which is mounted on the other side of the scope. The guider and finder are about the same weight.  It turns out the balances are not as equivalent as I thought. Often I found the auto-guider would not guide well depending on the direction the scope pointed. Various calibrations and setting changes did not help.

Then it dawned on me to try balancing the scope with the auto-guider mounted then swap the auto-guider for the visual finder to do the ASPA. Then re-swap the finder for the auto-guider. This pretty much eliminated guiding problems. Typically I still re-calibrate if I point to a far different part of the sky; no big deal as calibration takes less than 5 minutes.

The auto-guider is controlled by PHD2 software a sophisticated but easy to use free application originally created by Stark Labs then released as open source. One tip in the comprehensive help I have found useful is to move the scope at 10 to 20 seconds North(or South) before calibration. This generally eliminated a frequent 'not enough movement' error.

On a different note I just procured a 2" Orion SkyGlow Astrophotography Filter to deal with light pollution. Until now I have been using an older Orion Orion SkyGlow Broadband filter which is not really intended for astro-imaging.

Update: The retainer Orion SkyGlow Filter uses a poorly made flimsy plastic retainer ring susceptible to coming loose. This became evident after the filter was out of warranty. Ultimately the ring popped out during tear down after a night of imaging allowing the filter to fall out and break. The filter was replaced with an Optolong light pollution filter. I would recommend avoiding Orion filters.