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Forum: Monthly Photo Contests
03-31-2019, 06:17 PM
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In a pasture landscape late at night.
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Forum: Photographic Technique
10-15-2017, 08:53 PM
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I have used the K1 extensively for about a year now. I primarily shoot low light and astrophotography. I use the K1 as a dedicated astro camera coupled with with an 8 inch SCT with a FL of 1280mm, a 7.1 inch maksutov casegrain with an FL of 2700mm and an 5 inch triplet APO refractor with a FL of 952mm. I've also an assortment of lenses some very old and some recent. I've tended to get the best astrophotography using astrotracer with my 35mm F1.4 rokinon and believe it or not a 135mm F2.8 old ass $15 second hand store quantaray film era lens, I think it was made in 1978. My Pentax D FA 28-105mm f/3.5-5.6 ED DC WR is surprisingly not nearly as good with astrotracer as the 135mm. I continue to experiment with astrotracer under varying circumstances with different lenses. What I've found is that indeed a compass calibration is helpfull when changing location, lens or tripod. Things that effect magnetic fields definitely have a negative impact on how long astrotracer can go without showing star trails. I've also noticed the cameras relative aim at the sky has a noticible effect on how well astrotracer does. If you point towards a part of the sky that has greater apparent motion than things don't go as well than if you chose a target closer to the south or northern horizon. I suspect that true lens focal length is critical to making astrotracer function properly. Some lenses are not actually at a stated FL depending on if the lens exibets pronounced focus breathing or lens elements are not in perfect position. I've often wished Pentax would include an option to input precise FL into astrotracer but so far only predesignated focal length are available for selection. I also think it's possible astrotracer could be implemented much better perhaps by someone who can gain access to the software that manages the astrotracer function. It would be totally sweet if you could select a few stars during live view to move the sensor in relation too, effectively autoguiding. I'd be interested to hear others stories of ideal lenses to use with astrotracer after all one of the best lenses I've found turned out to be an ancient $15 film era lens.
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