Archived posting to the Leica Users Group, 2019/06/17
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]This was really useful fo rme, Howard. Thank you! With Jupiter so bright in our sky right now I?m thinking it?s time to give this a shot. Adam > On 2019 Jun 17, at 8:20 AM, Howard L Ritter Jr via LUG <lug at > leica-users.org> wrote: > > That?s a pretty good image for the lens, Peter, and some optimization > would make it even more impressive. > > In your shot, the relatively small image size of the moons, which are > effectively point sources at this FL, suggests that you could capture > Jupiter's atmospheric cloud bands if you avoid the overexposure of this > image. In photographing the rich but low-contrast detail in the > atmosphere, overexposure is your enemy. Underexposure, with enhancement in > post-exposure processing, can record nice detail, while overexposure that > saturates anything more than a few of the brightest pixels irretrievably > obliterates detail. You might try it again at 1/30 and shorter, and play > with the result in PS Camera Raw, especially the exposure, contrast, > clarity, and dehaze sliders. You might lose the moons at optimal exposure > for the atmosphere, but you could do a composite image. > > And of course the sweet spot for resolution is somewhere between wide > open, where diffraction-limited resolution is best but aberrations can > occur, and fully stopped down, where aberrations are negligible but > diffraction-limited resolution is worst. If you can find > resolution-vs-aperture data for this lens, that might guide you. At f/11, > the effective aperture of a 300-mm lens is just over 1 inch, which by the > Rayleigh criterion has a resolving power of about 4.5 seconds of arc. (The > angular diameter of the Galilean moons is about 1 arcsec, and of Jupiter, > currently at opposition, about 45 arcsec.) You might experiment with > larger apertures once you?ve found the optimal exposure time at f/11. If > your lens goes to f/5.6, you could double your resolution ? even if that?s > wide open, the aberrations might affect mostly the off-axis portions of > the image. > > Sorry if I?ve turned a trip to the playground into a regimented chore! If > you try any of this, please post. If I ever get clear weather, I?ll put my > M240 on my 155-mm f/7 apo refractor and see what I can get. > > ?howard > > >> On Jun 17, 2019, at 5:06 AM, Peter Klein via LUG <lug at leica-users.org> >> wrote: >> >> <https://www.flickr.com/photos/24844563 at >> N04/48078173256/in/dateposted-public/> >> >> Jupiter and its four largest moons. E-M5 on tripod, my $30 bargain-bin >> 300mm Soligor lens, 1/8 sec at f/11, 100% pixels. One could do better >> with a telescope, but I thought it would be fun to see what I could get >> with what I had on hand. Enjoy! >> >> --Peter >> >> >> >> _______________________________________________ >> Leica Users Group. >> See http://leica-users.org/mailman/listinfo/lug for more information > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information