First light

I have been looking/drooling at a telephotolens from Pentax for a long time. I have gone back and forth for ages. And a few weeks ago, I finally jumped in, and bought it. The Pentax DA* 300mm f/4 ED (IF) SDM. I have been waiting anxiously to test it out on heavenly bodies. The initial test on terrestial objects proved very promising. Very sharp. I have wanted it to bring to solar eclipses. I already have the William Optics excellent Star 71 quintiplet APO. But it weigh 2.4 kg. Far from heavy, but still. When setting up the scope on my Star Adventurer on Svalbard for the sun eclipse March 20th 2015, it was obviously far out of balance for the small mount. The 300mm telephoto lens only weighs in at just over 1 kg, and is far better balanced (with the camera body attached), so it would be easier to handle. And easier to carry in my luggage.
This weekend, while attending the monthly astromeet at Harestua Solar observatory, the skies cleared, and I got the chance to really try it out. I had set my mind on a few objects. Unfortunately, one of the objects, the California Nebula, was a dud due to the autoguiding totally freaking out after a few minutes (while I was asleep...). So I came out in the morning only to find all my exposures were just streaks. And just as well. I normally take a few test-exposures using ISO 12800 to frame the object. And ISO 640 for the actual images. But I had forgotten to reset the ISO-settings. So the images where totally burned out. That is, the red channel was. I had used a deep red filter to get he H-alpha out. And thus the red channel was blown, with streaks of stars across it...
But below are the two images I did get.
First the North America nebula in the same field as the Pelican nebula. I used the B+W 091 deep red filter. This isn't quite an H-alpha filter, but it does filter out most of the light, and with the built-in IR-filter in the camera, it creates a wideband deep red quasi-h-alpha filter. It does work quite well. I opted to try really deep exposures, and set my remote shutter controller for 20 minute integrations. I first tried a proportionally shorter exposure at ISO 12800 to get an idea of the histogram. And it looked decent. I had to throw out a couple of exposures due to the autoguider software going nuts and revving the DEC axis constantly. I had to restart the program to make it stop. I did some basic processing like stretching, curves and star shrinking to get the nebula to stand out better.

Tech details : Pentax K5, ISO 640, Pentax 300mm F/4, B+W 091 deep red filter, 14x20 min exposures. 20 flats. Guided with QHY5II and PHD2. Stacked in DSS, processed in FitsWork and PS. Click on the image for larger version.

The rest of the night, I tried and failed on the California nebula. The next night we had about half the night clear, and I pointed at the Andromeda Galaxy. A beloved and easy object for budding astrophotographers. Since the clouds were moving in, some of the images were too bright and where discarded. In the end, I managed to get 16 10-minute exposures that were passable. Also did some basic processing on this one too, since my main objective was to test the lens quality for astro work. Only DDP, star shrinking, and color enhancement.

Tech details : Pentax K5, ISO 640, Pentax 300mm F/4, 16x10 min exposures. Guided with QHY5II and PHD2. Stacked in DSS, processed in FitsWork, Irfanview and PS. Click on the image for larger version.

In conclusion : A very successful test! I am looking forward to using this lens more in the future. And to bring it to the 2017 total solar eclipse in the US! What I intended it for!