Im sorry, but quite frankly, sometimes I wonder if this is all worth it,
just to avoid having to develop film and getting an instant image. The
trad off is less than impressive at times, to say the least!





Thomas Womack wrote:

I've been quite impressed by the results of simply pointing my Olympus
E10 at the sky and opening the shutter for eight seconds; it's got a
good f/2.4 lens, and I get images down to about magnitude 8.5 through
dire suburban skies.

On the other hand, it seems to have hot pixels. I thought hot pixels
were essentially a *manufacturing* fault in the CCD, and so a single
dark frame (leave aperture and speed settings fixed, just also leave
the lens-cap on) would characterise them adequately for all time. But
in a set of 100 photos taken last Tuesday, I'm still seeing hot pixels
after subtracting a dark-frame taken two weeks ago.

My temptation is to compute a minimum for each pixel position across
all the photos and use that as a dark frame; the photometry is
dreadful in any case, even after I've summed across 2x2 pixel groups -
not sure if that's a matter of the CCD response and the V filter being
vastly different, I should probably plot brightness-residual against
spectral type and see if there's a correlation. Is this a sensible
way to proceed, given that most of the photos are star fields?

Should I in fact be taking a dark frame for each observing session,
and if so does this indicate there's something wrong with the camera?

Tom