David, Why high ISOs at all for shots like these? Here's a 36 minute exposure of some star trails I did last year with the K10D:
http://www.primelensphoto.com/star_trails.jpg Notice the tiny bit of sensor bloom in the upper middle left of the frame. This was RAW, ISO 100, f6.3. Can't remember which lens. The white balance was set to AWB but probably should have been set to daylight (that's what stars are after all). Now, I'm at 2,500 feet above sea level with very little ambient light around my place so I have much better natural conditions to shot under for this kind of shot. -Brendan --- David Savage <[EMAIL PROTECTED]> wrote: > Now worries Walt (I've posted these before.): > > <http://farm3.static.flickr.com/2209/2258045616_6bbe97702c_o.jpg> > K10D, DA* 16-50mm f2.8 @ 16mm, 1208 seconds (~20min) > @ f4, ISO 100 > > <http://farm3.static.flickr.com/2119/2481946623_1e672bebcc_o.jpg> > K10D, DA* 16-50mm f2.8 @ 16mm, 969 seconds (~16min) > @ f4, ISO 100 > > Now these have been photoshoped to remove 2 sensor > heat blooms > inherent to the K10D & miscellaneous noise. > > For the heat blooms I use a dark frame that I have > on file (ie 15 min > exposure made with the lens cap on) & I use it > overlayed on the base > exposure & change it's blending mode to Difference > to clean up the > majority of the bloom (sometimes I use 1 or 2 of > these layers). The > rest is done using the clone, heal & patch tools. > > Here is a full sized version of the second shot BP > (Before Photoshop > :-) (~900kb): > > <http://www.arach.net.au/~savage/Misc/Images/K10D/_IGP1494.jpg> > > These were taken in very dark conditions. It's about > 3-4 hours north > of the city & the only illumination that night was > from the stars (and > gelled flashes). > > I'm not surprised about the troubles you are having > at high ISO. These > sensors heat up quick. If you want to try again, use > the inbuilt > multiple exposure feature with EV compensation > turned off. Instead of > taking 1x 3 min exposure take 9x 20 second > exposures. I suspect though > that the heat will still be an issue. > > What I do to guesstimate exposure is take a 30 > second - 2 min exposure > (or more, until the lighting looks good) @ ISO 1600 > and work backwards > from there to determine the exposure for ISO 100. > > Cheers, > > Dave > > > > > 2008/7/1 Walter Hamler <[EMAIL PROTECTED]>: > > David, could you post a sample of a 10 minute > exposure with the K10? > > I have tried some shots around 3 minutes with > mine, NR on, and they > > are almost totally red. This is at iso 1600. 800 > is only marginally > > better. And they were in a reasonably dark site, > mag 6+ skies. > > > > Walt > > > > On 7/1/08, David Savage <[EMAIL PROTECTED]> > wrote: > >> I don't deny that the K20D high ISO is less noisy > than the K10D. I use > >> ISO 3200 & 6400 often. I haven't investigated the > various high ISO NR > >> settings. I just set it to weak & left it when I > first got the camera. > >> > >> However I do shoot a quite a few of long > exposures 10+ minutes, & the > >> inability to turn off long exposure NR, keeps me > carrying the K10D on > >> night shoots. > >> > >> Cheers, > >> > >> Dave > > -- > PDML Pentax-Discuss Mail List > [email protected] > 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 [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
