> Subject: RE: Awesome ISS photos!!! > Date: Sun, 10 Jun 2001 01:30:54 +0200 > From: "Ulrich Beinert" <analemma@gmx.de> > To: "SeeSat" <SeeSat-L@blackadder.lmsal.com> > > This is very similar to the technique I use to image the ISS with my 90mm > telescopes (see the images on www.analemma.de in "CCD Imaging"). I've even > managed to get a detailed shot of Mir with a HANDHELD scope! The most > important part is that the exposure is short enough to freeze the station Hi Ulrich, Although in photography it is preferable to overexpose rather than underexpose (if one must choose between these alternatives), the converse is true for astrophotography. This is aided by the fact that we can stack images to improve the signal to noise ratio (by the square root of the number of images being stacked ... from what I recall). > rushing through the field of view. Meanwhile, my tracking is good enough to > show the station on 5-10% of all frames of the video! I would bet the reason that your hit rate is higher than Dave's is that you have a much larger field of view with your 90 mm scope. Dave Cash is not only using a 9.25" SCT (ie. around 235 mm) but he further narrows his field of view with the use of a Barlow lens. I am about to go even more extreme with my 14" SCT (355 mm) ... I will probably start out with a focal reducer first so as to get the logistics optimized and then go at it without a reducer and then follow-up with a Barlow soas to increase the magnification appreciably (but I will be cutting down on the field of view tremendously). From what I remember, Dave Cash was getting about 20 frames per 50 mb animation, ie. 20 hits per 1000 frames, or 2%. > Ulrich Anthony. ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www2.satellite.eu.org/seesat/seesatindex.html
This archive was generated by hypermail 2b29 : Sun Jun 10 2001 - 06:27:40 PDT