Thank you, Wonderful tips, tested out the live view zoom on my EOS 500D with Jupiter in focus yesterday, and it made it easy to focus very accurately. Seems like I am on the right track, just need to use my other lenses. And buy a new camera. *Petter* *31.7361°N, 6.0422°E / 63.4303°N, 10.4525°E* On Fri, Dec 14, 2012 at 10:47 PM, Marco Langbroek <marco.langbroek@online.nl > wrote: > Op 14-12-2012 21:33, Greg Roberts schreef: > > > > Have no problems with the discussion about "live focus" using modern DSLR > > cameras. Ive just purchased a NIKON D3100 which has this feature - I > focus on a > > bright star - its easy to see and brightness depends on the f/stop of > the lens > > used since you are actually viewing through the lens - then use the zoom > feature > > in "live view" - its actually just a magnified image of the initial > image and > > not a true zoom but there is no problem seeing where the image is > sharpest. > > To be clear: that is true only for the Nikon D3100. With the canon EOS, you > truely zoom in on the sensor pixels. > > About the lens choice: for LEO I use a 2.5/50mm stopped down one stop to > 2.8; > for fast LEO (Keyholes near perigee, objects near decay) I use a 2.0/35mm > at > F2.0 because of the larger FOV, and for faint LEO I use an 1.4/85mm at F1.4 > (this lens, a SamYang 1.4/85mm which is made with fittings for several > camera > brands, I can truely recommend, it is marvelous!). > > For HEO I use a Zeiss 2.8/180mm. I used this for some time for GEO as well > but > now use the 1.4/85mm for that as it has a larger FOV but almost the same > light > gathering power (aperture). I still us the Zeiss for HEO because it better > shows > the tiny satellite trails. > > I work at ISO 800-1000 for LEO and GEO, sometimes 1600 for HEO in the > zenith. > How high an ISO setting is feasible depends on your sky AND the noise > characteristics of your camera (my new EOS 60D is much better with respect > to > noise at high ISO than my 450D was). > > I generally use 10 second exposures (as I initially calibrated my camera > for 10 > second exposures, and it is s fitting exposure for a 50mm lens on LEO > objects). > In strong twilight I sometimes take shorter exposures. > > In my experience aperture actually does make a difference: stopping a 2.5 > lens > down to 3.5 does mean you'll lose in limiting magnitude. > > - Marco > > ----- > Dr Marco Langbroek - SatTrackCam Leiden, the Netherlands. > e-mail: sattrackcam@langbroek.org > > Cospar 4353 (Leiden): 52.15412 N, 4.49081 E (WGS84), +0 m ASL > Cospar 4354 (De Wilck): 52.11685 N, 4.56016 E (WGS84), -2 m ASL > Station (b)log: http://sattrackcam.blogspot.com > Twitter: @Marco_Langbroek > ----- > > _______________________________________________ > Seesat-l mailing list > http://mailman.satobs.org/mailman/listinfo/seesat-l > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://mailman.satobs.org/mailman/private/seesat-l/attachments/20121215/9ff8553d/attachment.html _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-l
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