Supernova remnant RCW 103, a SINGLE 1 hour exposure!
Howdy
Just as a test I always wanted to try this. A single 1 hour exposure with a DSLR.
I used the Baader 7 Nm Hydrogen Alpha filter to stop any chance of over exposing the sky background as the moon is full.
1 hour ISO 400, modded 350D, 10 inch f5.6 newtonian, I took a single 1 hour dark after that, didnt bother with flats or offsets. On the full size image theres some field rotation as the mount needs polar alingment as the ground has dried out and moved a bit. However I did the exercise to see how much noise would be present. Iris did a good job removing the dark current noise, especially as it was a warmish night.
Scott
I have to laugh when we all think hand guiding for an hour is so difficult..well?.. it is! However, this was what we all did before autoguiding became wide spread in the early 90's. Bofore the 90's it was not uncommon to hand guide a 2 hr exposure actually. Using a trusty drive corrector and hand dec ajustment knob, I personally guided seveal 1hr and even a 90min exposure with my 8" F7 newtonian back in the good'ol days of film with my eye glued to the guide eyepiece Argggg! In fact when I got back into this hobby again in late 2002, after an almost 14 yr break, trying to become the world's strongest man (got close ), I did a couple of 45min - 1 hr manually guided exposures with the 12"LX200GPS and the (excellent) off axis Lumicon giant easy guider. Well yep, it was the turning point for me, I decided I was locked in the 80's and I had to modernise! I had to learn about sub exposures, quantum efficiency, autoguidng blah blah blah...So from then on a CCD camera was in my sights... and the rest is history as they say
Hand guiding can never be as acurate as autoguiding and with the small pixel and high resolution available in CCD imaging, sub arc sec autoguiding is essential in my opinion. Having said that, those who do still hand guide and produce even reasonably round stars (even with a relatively low resolution DSLR) deserve a bloody medal
Thanks
In the old film days I remember reading an article in Astronomy Magazine re deep sky astrophotography using hypersensitized high res. 2415 technical pan film. The writer said "Exposures should run 60 to 120 minutes under a dark sky" And thats without the benefit of immediately seeing the result, they would consider stacking of electronic images a luxury had it existed back then. I guess in those "old days" mounts would have to be extremely well polar aligned as even a slight error would see field rotation in a 120 minute exposure. Flexure must have been a difficult problem too.
RCW103 is faint but not impossibly faint, I was able to record it on my unmodded 300D without any filter. Eric, your rig will easily record it with the UHCS filter.
Scott
), I did a couple of 45min - 1 hr manually guided exposures with the 12"LX200GPS and the (excellent) off axis Lumicon giant easy guider. Well yep, it was the turning point for me, I decided I was locked in the 80's and I had to modernise! I had to learn about sub exposures, quantum efficiency, autoguidng blah blah blah...So from then on a CCD camera was in my sights... and the rest is history as they say 
