CCD viable under UK skies?

[perfrej]

I'd say OSC is more difficult to process. Just getting the flats right is a pain in the neck as the pixels are different. I had to do an exact 2x2 average in order to not get pixelated images. Then you end up with something unbalanced that has to be taken care of. Mono is easier.

/per

[perfrej]

Nick,

I have walked up to the peak to the west where there is a stone structure, and there were blood-stains there, so don't be too quick to draw conclusions!

/per

[swag72]

I agree that OSC is more difficult to process. I have mono and OSC and the OSC is something akin to witchcraft to process. Mono is soooo much easier to work with, in my experience.

[Sp@ce_d]

Tom - the great and good have responded but as you pose "is it viable in the UK climate?" It much depends on your expectations. If you're contents with creating half a dozen 'great' shots per annum [and some hereabouts do] - then NO! If you want to grab every opportunity with indifferent skies and brief gap in cloudcover capturing many dozens of DSOs - then YES. The latter has been my tally in the last 12 months - the worst for weather I can recall - but at least I'm not frustrated and still get a buzz with every download

This is very true. Generally speaking I think most of us in the UK go through this. Early on we try to see how many targets we can capture in one night. Like you say, the buzz just seeing them appear in the FOV is an achievement. However, you soon realise that aside from the many skills to learn, if you want to produce good quality shots it takes time on the target. There's no getting away from it, the only way you can speed this up is a faster scope (which brings its own problems & yet more skills to master) and a more sensitive CCD. You have to be prepared to spend multiple nights and in some cases even years to get that data. If you've been using a DSLR and you want to move up the ladder then you should have already realised this anyway. By the mere fact that you are considering investing in what is not a cheap hobby means you have decided to make that commitment. It took a couple of seasons for me to move from DSLR to mono CCD and when I did it was like having a blindfold removed.

Back to the OSC verses mono debate... You already have a OSC in the DSLR anyway. Going to a OSC CCD would only be like painting the walls of your prison cell... it'd be cleaner & might smell nicer but you'll still have the same view!... ...

[Freddie]

DSS is fine with CCD. Just needs slightly different setings that with DSLR.

Oops, sorry answering a question from page 5 there !!!

[George]

Olly, without doubt mono with filters is the way togo.......just not in the cloudy UK at my location and limited horizon.

Most targets for me have a 3-4 hour window and if what's becoming the norm in these parts, if you miss that 6-8 week window before the target is badly place you have had it until next year.......then you start the same cycle

I'm not going to win any prizes for my images, I just grab what I can when I can and make the most of my situation.

[ollypenrice]

I too think OSC is slightly harder to process.

Olly

[Gina]

Olly, without doubt mono with filters is the way togo.......just not in the cloudy UK at my location and limited horizon.

Most targets for me have a 3-4 hour window and if what's becoming the norm in these parts, if you miss that 6-8 week window before the target is badly place you have had it until next year.......then you start the same cycle

I'm not going to win any prizes for my images, I just grab what I can when I can and make the most of my situation.

I find I can get quite a good image in 3-4 hours, no problem. I could get a half decent one with the DSLR. But I can get quite a good image in half that time with the Atik 314L+ mono and filters. The hugely greater sensitivity means much shorter subs for the same result. Not only can I get a good image in half the time, that image is also better - sharper and with a much better dynamic range and none of that coloured background noise that seems inevitable with a DSLR (even cooled to -15C).

[ollypenrice]

If I had four hours to get an image I'd use a Sony chipped mono CCD at a fast F ratio. I'd scroll-capture the RGB-RGB to be sure I got something to play with in the morning and I might get it in Bin 2, depending on sampling rate. Then I'd get as much L as I could. This would give a better result in the time than OSC. I'm sure of it.

When the moon came out and the sky cleared (as it does ) I'd get some Ha for the image, or for another if the original were a reflection nebula or cluster. That would really nail it.

Olly

[RikM]

I generally work with a 4 hour window as well. I use an f/5 Newt (would be an f/4 if I had a permanent obsy for it) then an hour to get set up, cooled, collimated and polar aligned, 90min L at full res then 30min per colour at 2x2 (3.6"/px) all in 5 min subs normally. If it's an Ha target I'll usually give that a night on it's own and shoot it first in 10-15min subs, or if I'm adding Ha to a galaxy then I might tack on a half dozen 10min subs after the LRGB.

I find mono, or at least LRGB much easier to process than DSLR (my only experience of OSC).

[kirkster501]

With mono, and the different filters, do you have to do flats after every filter swap? The dust bunnies will be in a different place on each filter right?

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[Zakalwe]

With mono, and the different filters, do you have to do flats after every filter swap? The dust bunnies will be in a different place on each filter right?

Ideally, yes. Though dust bunnies on the sensor window will be more noticeable as they are closer to the plane of focus.

[perfrej]

You have to do flats for each filter. There simply is no such thing as a clean filter. If you're automated, as I am, you get your flats for free every session wit hdusk and dawn flats. The software (CCD Autopilot in this case) lets the scope track and exposes to the specified ADU. When you stack the flats you just use sigma clipping and all the star residue goes away.

I do not do darks, but I do BIAS frames. Lights, flats and BIAS is my modus operandi. Hot pixels go away with sigma clipping and the BIAS takes care of the botton fuzz.

/per

[Zakalwe]

To be fair, flats are quick and easy if you have a lightbox or panel. You can rattle 50 or so off in a few minutes.

[RikM]

I shoot a set of flats normally the morning after. I have a script in Maxim with the right exposure times for my EL panel and just blast through them before packing the gear away. LRGB flats at 21x each filter takes about 6-7 minutes. The only long ones are Ha flats as these are 26 sec each but even then it is only 10 min or so.

[Zakalwe]

The only long ones are Ha flats as these are 26 sec each but even then it is only 10 min or so.

What light source do you use for H-a? The EL panel?

[RikM]

What light source do you use for H-a? The EL panel?

Yes. I use a 12V 12x8" cold cathode light panel. A Dr. friend used to use it as a desktop x-ray lightbox before going digital.