>Or would it assume that it is a solid tripod and you'd get reverse correction?
This. On Mon, Dec 2, 2013 at 10:32 AM, Larry Colen <l...@red4est.com> wrote: > On Mon, Dec 02, 2013 at 08:01:57AM -0600, Darren Addy wrote: >> Larry, >> I'm very impressed by what you got, particularly considering your > Thank you Darren. > >> challenge in finding dark skies. Where were these taken? > > If you look at the photo on flickr, and click on where it says > Rincon california, it should call up a map. It was taken with the > GPS afterall. The short answer is that it is the north west corner > of the UCSC campus, on Empire Grade, abouta mile south of > Smith Grade. > >> The beauty of the O-GPS1 is that you don't have to futz with polar >> alignment. The downside is that you do have to futz with "precise >> calibration", which would often confirm working before I had even >> completed three axis OR fail to confirm when I had done everything >> (carefully) correctly. Then all of the sudden it might work. > > I've only found that to be a minor annoyance. I can't help but wonder > if the OGPS 1 can do real time correction, so that if it were on a > polar mount that wasn't perfectly alligned, would it make it work better? > Or would it assume that it is a solid tripod and you'd get reverse correction? > >> >> Regarding the ballhead, I think that with a decent ballhead you can do >> widefield work, but it helps to have a red dot finder or laser pointer >> in the hotshoe to help you aim. As you know, it is best if your >> subject is in the center of the field since that is were the best lens >> performance will be - corners being where coma and changes in flatness >> of field might show up. > > There is that, but I honestly couldn't see anything to precisely aim by. > I used zoom lenses at the wide end, and hoped to get the galaxy someplace > in the exposure, to dial in on. > >> >> Regarding the lens selection, nothing torture-tests a lens like >> astrophotography. Astrophotography will reveal CA and coma like >> nothing else. Not all lenses will be suited to astrophotography, given >> just those two criteria. You are also NEVER going to get the lenses >> best image wide open, regardless of maximum aperture. You should >> always try (or compare) stopping down 1 stop from maximum. Since that >> is the case, I think that you should give more weight to the aperture >> and less to the focal length, particularly when you are starting out. >> f/6.3 obviously requires a much longer exposure time than f4 for >> example. That longer exposure time is going to make more evident >> problems in your tracking (or influences from other things like >> vibrations in the ground, sagging of your ballhead, etc. The longer >> the exposure time the smaller percentage of your subs will be >> acceptable for stacking. Plus, it is in stacking that you effectively >> build up the integrated exposure. Finally, longer exposures in less >> than dark-sky conditions are going to result in you recording the >> background as less than black. Once that happens you aren't gaining >> anything with a longer exposure because you have reached the contrast >> limit. You don't HAVE to do it with single long exposures. That's for >> the guys with the "real" equatorial set-ups. That being said, I was >> able to get decent exposures of up to 45 seconds with a K135mm f2.5 >> stopped down to f4. > > These were 30 seconds at 200mm, so that is about the same rule of 6,000. > I think we want to keep the multiplier down to about 3,000, maybe 2,000. > >> >> Even in the film days, a 200mm f/4 lens was the one most often used >> for widefield astrophotography. That equates to a 135mm on APS-C. Your >> 200mm shots look very very good. With a DA* 200mm f2.8 you might even >> have the option of using it wide open AND you can get the benefits of >> the lens profile corrections. > > There's at least a thousand and one reasons that I'm using the 80-200 > that I'm borrowing from John F rather than a DA* 200. The one being > able to zoom out to help my aiming. > >> >> Regarding DeepSkyStacker crashing, make sure you are using the latest >> beta. For some reason if you Google DSS the page you get doesn't give >> you access to the latest program. Check to see if you are using this >> version: >> http://deepskystacker.free.fr/download/DeepSkyStacker333beta51.rar > > No, I was using 3.32 stable. 3.33 beta worked fine. Thanks. > > It took some massaging it with lightroom to pull it out: > http://www.flickr.com/photos/ellarsee/11174029125/ > > I also tried a couple of black and white conversions that I > added to the end of the set.. > > I think that I would have had better luck earlier in the evening. > By the time I ended, it was getting close to the horizon. > >> >> -d >> >> On Sun, Dec 1, 2013 at 11:53 PM, Larry Colen <l...@red4est.com> wrote: >> > On Sun, Dec 01, 2013 at 10:36:13PM -0600, Christine Aguila wrote: >> >> Very nice, work, Larry! Excellent. Cheers, Christine >> > >> > Thanks Christine. >> > >> > I spent most of the day trying to get stacking programs to work and >> > get a cleaner version. I finally got an image out of nebulosity, but >> > it looked worse than what I got from a single frame. >> > >> > Meanwhile I loaded Deep Sky Stacker on the Windows laptop I use >> > for work, and it would just choke and crash. >> > >> > At some point, I'll give it another try, and I learned some important >> > things. Like, with astrotracer, it seems like focal length time >> > seconds seems to need to be below 3,000 (200mm * 15 Sec) maybe a bit >> > less. >> > >> > That's five times better than the 600 rule. >> > >> > >> >> >> >> Sent from my iPad >> >> >> >> > On Dec 1, 2013, at 6:06 AM, Larry Colen <l...@red4est.com> wrote: >> >> > >> >> > >> >> > http://www.fluidr.com/photos/ellarsee/sets/72157638239972733/ >> >> > >> >> > Even with the astrotracer 30 seconds at 500mm is too long. >> >> > Now, I need to find stacking software for my mac. >> >> > >> >> > These were photographed on Empire grade at the gate for Grey Whale >> >> > ranch, >> >> > with my Pentax K-5 II, using my O-GPS 1 in astrotracer mode. >> >> > Some were shot with John Francis' 80-200/2.8 and some with my bigma. >> >> > >> >> > I learned that using a ballhead sucks for astrophotography. It is >> >> > impossible to make fine adjustments in just one axis. Hell, it is >> >> > impossible to make accurate fine adjustments period. >> >> > >> >> > -- >> >> > Larry Colen l...@red4est.com >> >> > http://red4est.com/lrc >> >> > >> >> > >> >> > -- >> >> > PDML Pentax-Discuss Mail List >> >> > PDML@pdml.net >> >> > http://pdml.net/mailman/listinfo/pdml_pdml.net >> >> > to UNSUBSCRIBE from the PDML, please visit the link directly above and >> >> > follow the directions. >> >> > >> >> >> >> -- >> >> PDML Pentax-Discuss Mail List >> >> PDML@pdml.net >> >> http://pdml.net/mailman/listinfo/pdml_pdml.net >> >> to UNSUBSCRIBE from the PDML, please visit the link directly above and >> >> follow the directions. >> > >> > -- >> > Larry Colen l...@red4est.com >> > http://red4est.com/lrc >> > >> > >> > -- >> > PDML Pentax-Discuss Mail List >> > PDML@pdml.net >> > http://pdml.net/mailman/listinfo/pdml_pdml.net >> > to UNSUBSCRIBE from the PDML, please visit the link directly above and >> > follow the directions. >> >> >> >> -- >> I don't have a problem with idiots. >> I have a problem with the fact that they have an internet connection. >> >> -- >> PDML Pentax-Discuss Mail List >> PDML@pdml.net >> http://pdml.net/mailman/listinfo/pdml_pdml.net >> to UNSUBSCRIBE from the PDML, please visit the link directly above and >> follow the directions. > > -- > Larry Colen l...@red4est.com http://red4est.com/lrc > > > -- > PDML Pentax-Discuss Mail List > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. -- I don't have a problem with idiots. I have a problem with the fact that they have an internet connection. -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
