West of Sadr

[mftoet]

Just west of Sadr (Gamma Cygni) nice H-alpha features can be found. While it isn't ideal to use an H-alpha filter in combination with a CFA sensor (a Nikon D810a DSLR in my case), it makes it possible to pursue deep sky astrophotography under the magnitude 18.5 skies where I live. Without the use of (narrowband) filters I get heavy gradients caused by the light domes of greenhouse complexes (especially those cultivating roses) nearby. I've experience with using a Baader-Planetarium 7 nm H-alpha in combination with a QHY8 colour camera from the past. This time I've chosen for an M48 (2") Baader-Planetarium 3.5 nm H-alpha filter that can be inserted on the telescope side of the Takahashi wide T-ring.

Not an evident choice to use with fast optics like my Epsilon-180ED (f/2.8). With fast optics (< f/3.5) light loss occurs (10 to 15%) due to spectral shift. But then again, it's less light loss than stopping down the aperture of the telescope. Here's an image of the Epsilon on my roof terrace. On the right a FC-76DS on SP mount can be seen that I use for visual observing. Yes, I've become a Tak-Addict...

 

Using a bright star, I can focus on the LCD screen of the DSLR using a Bahtinov mask.

And now for the image. Total integration time of 5 hours and 10 minutes (between nautical dusk and dawn). Subs of 10 minutes @ ISO 1600. Guided and dithered with a Lacerta MGEN. No darks. 40 flats and a masterbiasframe of ~ 130 subs. Data reduction, stacking and DDP in Astro Pixel Processor. Post-processing in Photoshop CC. 

   

Here's an annotated version using the script in PixInsight.

And, for fun, an almost starless, inverted, contrast enhanced version.

 

[Astroscot2]

I always look gforward to opening you're posts Maurice, a beautiful,  delicate crisp image.

 

Mark

[mftoet]

Thank you very much, Mark. 

[pietervdv]

Looks great, well done! Cygnus is such a great constellation.

Pieter

[mftoet]

Thanks, Pieter.