We're talking relatively short exposure times. Frequently and often under 10 minutes. Depending on the subject and the setup, maybe not open for even a minute. The art is such that multiple exposures are digitally stacked and aligned so that luminance builds up, for example, 20 3-minutes exposures = a single 1 hour exposure.
The other answer is, apparently not that often... :-) I don't have a dedicated DSLR for astrophotography, but if I do it will be a Canon (if I was buying one today). Tom C. >From: "Amita Guha" <[EMAIL PROTECTED]> >Reply-To: Pentax-Discuss Mail List <pdml@pdml.net> >To: "Pentax-Discuss Mail List" <pdml@pdml.net> >Subject: Re: OT: DPR Nikon D3, Full-Frame, previewed >Date: Thu, 23 Aug 2007 15:30:38 -0400 > >Thanks! How long can you keep the shutter open on these cameras? Don't >the electronic shutters burn out eventually if you keep them open for >too long? > >Amita > >On 8/23/07, Tom C <[EMAIL PROTECTED]> wrote: > > I should have said "the best for this application at a reasonable >price". > > > > Tom C. > > > > > > > > >From: "Tom C" <[EMAIL PROTECTED]> > > >Reply-To: Pentax-Discuss Mail List <pdml@pdml.net> > > >To: pdml@pdml.net > > >Subject: Re: OT: DPR Nikon D3, Full-Frame, previewed > > >Date: Thu, 23 Aug 2007 13:02:26 -0600 > > > > > >The main thing is their extremely low noise characteristics. Noise >will > > >build up in any sensor of course, but of all the DSLR's out there, the > > >Digital Rebels and the 5D are recognized as the best. There's also > > >hardware > > >(filter mods) and control software that's been written for them > > > > > >Surpassing them are the dedicated, cooled, CCD cameras specifically > > >designed > > >for astrophotography, that both record the image and send guiding >signals > > >to > > >the scope's computer, off of one chip. > > > > > >Tom C. > > > > > > >From: "Amita Guha" <[EMAIL PROTECTED]> > > > >Reply-To: Pentax-Discuss Mail List <pdml@pdml.net> > > > >To: "Pentax-Discuss Mail List" <pdml@pdml.net> > > > >Subject: Re: OT: DPR Nikon D3, Full-Frame, previewed > > > >Date: Thu, 23 Aug 2007 14:27:52 -0400 > > > > > > > >On 8/23/07, Tom C <[EMAIL PROTECTED]> wrote: > > > > > > > > > Viewfinder > > > > > aside, they are a standout in astrophotography circles, with the >most > > > >bang > > > > > for the buck of any DSLR. > > > > > > > >Tom, why are the Digital Rebels good for astrophotography? I thought > > > >mechanical shutters were still the best thing for astrophotography. > > > > > > > >Thx, > > > >Amita > > > > > > > >-- > > > >PDML Pentax-Discuss Mail List > > > >PDML@pdml.net > > > >http://pdml.net/mailman/listinfo/pdml_pdml.net > > > > > > > > > > > >-- > > >PDML Pentax-Discuss Mail List > > >PDML@pdml.net > > >http://pdml.net/mailman/listinfo/pdml_pdml.net > > > > > > > > -- > > PDML Pentax-Discuss Mail List > > PDML@pdml.net > > http://pdml.net/mailman/listinfo/pdml_pdml.net > > > >-- >PDML Pentax-Discuss Mail List >PDML@pdml.net >http://pdml.net/mailman/listinfo/pdml_pdml.net -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net
