CCD viable under UK skies?

[Macavity]

I see VIDEO astronomy as a mid-budget bridge to (classical) imaging... Albeit a bridge I may never cross! I rather feel I wasted time (money) on low-sensitivity CMOS "lunar and planetary imagers". VIDEO (many, short, subs) is rather the antithesis of "proper" imaging, but delivers nice real-time images and reasonable (stacked) "snapshots" of DSOs etc.

I am getting to grips with LRGB - Darks & Flats. These latter, useful, even for VIDEO work. One day maybe Peltier cooling? (Not much needed at the moment! LOL) After a quick bash at spectroscopy - Seeing M57 split into H-Alpha & O-III... Next up, a few narrow band filters to play with? Widefield with standard (vintage!) SLR lenses?

Aside: I see my beloved "Watec" is now being superseded by... something new? Maybe these various technologies will converge? Even (classical) Imagers and Video Astronomers will converge. [teasing] Large format, fine pixel, ultra-sensitive, CCDs will become... as cheap as chips?

[dmahon]

APT works with CCDs. Other options include Nebulosity* and Sequence Generator Pro.

* I have no issues with the stretch, maybe because my Sony chip has less noise

[swag72]

Artemis software that comes with the Atik is the perfect capture programme in my opinion. APT is now compliant with CCD's, but I don't think I'd get any benefit from using it. All you need is to be able to state the set point cooling and take exposures to then use as focus and framing (which you can do on a loop) and then take the images themselves.

For stacking I have gone over to Pixinsight. I feel this gives much better results than any of the other stcaking programmes.

[dmahon]

APT does integrate with Astrotortilla (plate solving). SGP with Elbrus and Maxim with PinPoint.

I find plate solving very useful, both for mount alignment and centring targets - clicking on an image and saying "centre here", or loading a prior image and saying you want to take the exact same shots again is great.

[Komet]

SGP stores the plate solved coordinates in any sequence so you can have a list of targets you may want to add to, just load one of them and it will put you on the money with all the settings you originally had for that particular target (exposure, no of subs per filter etc) all loaded and ready to go. Basically you carry on where you left off the previous session. Nice!

[kirkster501]

A small amount of dither or even just slight polar misalignment and a sigma routine will nail hot pixels. Or just use a hot pixel filter. Or a bad pixel map. Lots of solutions. WIth our Kodak chips I use darks.

I don't yet use the EFW in Artemis capture but you can certainly sequence if you want to. I don't know if you can name the filters. Edit, see post above. You can!

What I detest about Nebulosity is the awful screen stretch on which I can see precious little in framing subs. I feel this wastes bucketloads of time compared to Artemis.

Olly

Ok that's interesting. I shall read into it. it appears from what you are saying Olly that a bit of polar misalignment is almost deliberate to "disguise" the hotspots?

Somehow, I just HATE doing darks. Always seems precious "outside" time being wasted to me...... So I have started a new habit. I get the camera/scope assembly in the garage after I have packed up and fire the darks off then in a sequence and then go to bed. Following morning - 30 darks and a flat DSLR battery Indeed, I am going to make a darks library. Heck, my pictures will not be gracing Astronomy magazine cover from a DSLR so why not simply things for myself. A CCD and no darks is a interesting proposition.

A 314L/wheel/filter setup is looking likely for me later this year - I am my final year study fees to have to sort out first.

[earth titan]

Taking darks is a major pain and the ability to take images without darks would be brilliant. As a result, i can see why CCD is popular.

[dmahon]

Some CCDs require darks (only the Sony ones are OK without) however set point cooling means you can take them once and reuse them again and again. You can even "stretch" them and take one duration only if you really want to.

My camera (despite being a Sony I do use them) is currently taking new darks in the garage. First time in a year.

[Macavity]

I noticed that... Intelligent stacking software, plus a degree of "random variation"

in tracking (judicious post-processing?) eliminates hot pixels and many sins...

[George]

OSC for me, never regretted it and unless the UK's cloud cover record changes (not likely with climate change pumping more moisture in the air) I'll likely never go the mono route. As said the the Sony APS sensors don't require darks so I'm more than happy with my QHY8 when I actually get to use it.

Personally in the UK with our poor weather and imaging opportunities you are never going to get the best out of a mono/filter combination and even when you get clear skies they are mediocre most of the time. Unless your lucky to get night after night of clear skies I feel OSC will be better at getting the most out of limited opportunities. If I was lucky to live under dessert skies I'd obviously go the mono/filter route, in the UK they just don't cut the mustard for me.

Just my opinion

[Gonzo]

There is nothing wrong with black and white pictures

[Interested]

OSC for me, never regretted it and unless the UK's cloud cover record changes (not likely with climate change pumping more moisture in the air) I'll likely never go the mono route. As said the the Sony APS sensors don't require darks so I'm more than happy with my QHY8 when I actually get to use it.

Personally in the UK with our poor weather and imaging opportunities you are never going to get the best out of a mono/filter combination and even when you get clear skies they are mediocre most of the time. Unless your lucky to get night after night of clear skies I feel OSC will be better at getting the most out of limited opportunities. If I was lucky to live under dessert skies I'd obviously go the mono/filter route, in the UK they just don't cut the mustard for me.

Just my opinion

I like mono because it allows me to use NB filters. Ha is great for for me (see pic to the left (Crescent Nebula)). Bristol has a fair amount of light pollution and on many a clear night either the moon is up or neighbours lights are going on and off (not to mention the street light I have directly to the back and front of my house!!).

You pays your money, you make yourchoice!

Pete

[earth titan]

Some CCDs require darks (only the Sony ones are OK without) however set point cooling means you can take them once and reuse them again and again. You can even "stretch" them and take one duration only if you really want to.

My camera (despite being a Sony I do use them) is currently taking new darks in the garage. First time in a year.

Unless I had misread the thread, I thought the 314 didn't need darks - but is that cos it uses the Sony chip? Perhaps I've got to reread the whole lot - it's getting quite involved.

Typed by me on my fone, using fumms... Excuse eny speling errurs.

[RikM]

The 314L generally doesn't need darks if you use dithered guiding and a sigma reject stacking routine. You can use darks to make a bad pixel map though. You can also use darks normally if you want to and you take enough of them to get a clean stack at the correct temperature.

[Gina]

Atik cameras come with their excellent Artemis Capture software

[earth titan]

The 314L generally doesn't need darks if you use dithered guiding and a sigma reject stacking routine. You can use darks to make a bad pixel map though. You can also use darks normally if you want to and you take enough of them to get a clean stack at the correct temperature.

Head hurts now.

Sigma reject stacking..... Dithered guiding..... Soooooo much more to this than using a DSLR. Which should keep me out of mischief for a while!

Typed by me on my fone, using fumms... Excuse eny speling errurs.

[Tinker1947]

Head hurts now.

Sigma reject stacking..... Dithered guiding..... Soooooo much more to this than using a DSLR. Which should keep me out of mischief for a while!

Typed by me on my fone, using fumms... Excuse eny speling errurs.

If you then add, setting-up and learning to use the ATIK and PHD software, the extra care with balancing, the constant cloudy skys, you could be 6 months away from actually doing what you brought the new bits for imagine,,,my 6 months has been and gone and i'm still running tests ect ect....

[George]

I'm looking to move toward a reduced noise profile on my images and as such, feel cooled CCD is the only way forward now.

But I ask you!

Taking the images in four stages to get all the needed subs - is it really viable under UK skies? I've struggled to get 20 colour shots with my DSLR this winter let alone 20 for each colour plus luminence etc.

Thats my whole argument for going the OSC route

[ollypenrice]

Head hurts now.

Sigma reject stacking..... Dithered guiding..... Soooooo much more to this than using a DSLR. Which should keep me out of mischief for a while!

Typed by me on my fone, using fumms... Excuse eny speling errurs.

No. Not at all.

Sigma reject and dither would be a great help in sorting out the mess generally produced by DSLRs. It would have MORE benefit on a noisy, insensitive DSLR than on a CCD. It isn't necessary on either if you are not trying to produce a good result but, if you are, these routines would be extra beneficial on a DSLR shot.

What's all this fuss about darks? If you use a set point CCD you shoot a set of darks for various exposure times during the day, over dinner, watching telly or whatever. You average them into masters and file them and they last what, a year? Six months? Let's not turn this into a problem. You certainly don't waste imaging time on them!

George, it is precisely because of the bad weather in the UK that you should use mono! It is faster. And you can use it productively on moonlit clear nights to catch narrowbandto add to colour images. There is this crazy idea circulating that OSC is faster, which it simply isn't. How can it be? In OSC you are obliged to shoot colour all the time. In mono LRGB you shoot L (about three times as much light gets onto the chip as through RGB filters whether OSC or mono because you let all colours in at once.) Then you add colour. If you add the colour in bin 2 then you get it at about 1.6x times the rate of bin1. On another thread someone called OSC a 'One trick pony' and that is dead right. It can be fine but it is limited and it is slow. On some objects, like emission nebulae, it takes forever to get the Ha to play via a broadband red filter as found on OSCs.

Gonzo, you can take colour pictures with a mono camera.

Olly

[RikM]

Head hurts now.

Sigma reject stacking..... Dithered guiding..... Soooooo much more to this than using a DSLR. Which should keep me out of mischief for a while!

Typed by me on my fone, using fumms... Excuse eny speling errurs.

Dithered guiding just means the mount moves a few pixels between each exposure. Maxim has this built in, if you use APT and PHD, they will talk to each other and give you the same option. What it means is that the hot pixels move with the camera so end up in different places on the image.

Then in your stacking software, you choose a stacking option that rejects pixels that are much brighter than surrounding pixels and that are in different places once the frames have been aligned. (If you align all the stars, the hot pixels will be spread about the place by the dithering and so the stacking software can see they are hot pixels rather than stars and can remove them.) I normally use either Median Kappa-Sigma Clipping in DeepSkyStacker or SD Mask in Maxim. You do need probably 12 or more subs for this to work properly, but if you want a good image, you would need a decent stack size anyway.

[RobH]

Mono for me. It's just as quick to get the same quality pic with mono as with OSC. Ollypenrice has posted some good info on this. Worth a search to have a read of what he has to say. Also if you want to do NB it's really the only option.

Absolutely right. Although you'll grab all of your RGB at once with an OSC camera, they are a lot less sensitive so you end up needing lots if you want to get a good noise free image, and it ends up, in practice, that the time needed to get the required data with filters and a mono camera is not much more at all. In fact, compared to my SX M25C OSC, with my 460EX mono, I can get enough colour data for a decent image quicker than with the OSC. I had the M25C for a couple of years, and, even though it's a great colour camera, I've now sold it as, from my experience mono is just better from all angles.

[NickK]

I seem to recall that Mr Penrice is not the religious type...

Ahh he has a set of temples built on the top of a rock.. that track the movement of the heavens.. I didn't witness any animal sacrifice though..

[NickK]

Absolutely right. Although you'll grab all of your RGB at once with an OSC camera, they are a lot less sensitive so you end up needing lots if you want to get a good noise free image, and it ends up, in practice, that the time needed to get the required data with filters and a mono camera is not much more at all. In fact, compared to my SX M25C OSC, with my 460EX mono, I can get enough colour data for a decent image quicker than with the OSC. I had the M25C for a couple of years, and, even though it's a great colour camera, I've now sold it as, from my experience mono is just better from all angles.

For me it's the resolution. OSC seems to be a bit blurred compared to mono with filters.

[Zakalwe]

No. Not at all.

Sigma reject and dither would be a great help in sorting out the mess generally produced by DSLRs. It would have MORE benefit on a noisy, insensitive DSLR than on a CCD. It isn't necessary on either if you are not trying to produce a good result but, if you are, these routines would be extra beneficial on a DSLR shot.

What's all this fuss about darks? If you use a set point CCD you shoot a set of darks for various exposure times during the day, over dinner, watching telly or whatever. You average them into masters and file them and they last what, a year? Six months? Let's not turn this into a problem. You certainly don't waste imaging time on them!

George, it is precisely because of the bad weather in the UK that you should use mono! It is faster. And you can use it productively on moonlit clear nights to catch narrowbandto add to colour images. There is this crazy idea circulating that OSC is faster, which it simply isn't. How can it be? In OSC you are obliged to shoot colour all the time. In mono LRGB you shoot L (about three times as much light gets onto the chip as through RGB filters whether OSC or mono because you let all colours in at once.) Then you add colour. If you add the colour in bin 2 then you get it at about 1.6x times the rate of bin1. On another thread someone called OSC a 'One trick pony' and that is dead right. It can be fine but it is limited and it is slow. On some objects, like emission nebulae, it takes forever to get the Ha to play via a broadband red filter as found on OSCs.

Gonzo, you can take colour pictures with a mono camera.

Olly

To be fair though Olly, you have a permanent setup with awesome skies. Mono might be faster but with OSC you are getting a complete image with every single shot. If you miss the R channel then you are pretty much guaranteed to get it the next night. OK, you could do one L, then a R, G, B in sequence. In reality, you will might have to refocus between filter swaps. Of course, you could automate the focusing, but thats more money and complexity.

Plus you only have one set of flats to do with OSC, not 4 times as many with mono.

OSC is easier for a new imager. The processing is easier and the workflow has far fewer steps.

Mono is also a LOT more expensive to get into.

Its horses for courses. Personally I am glad that I started with OSC. I will move to mono at some point, but my restricted imaging time is a massive limit on my ambitions.

[nytecam]

I'm looking to move toward a reduced noise profile on my images and as such, feel cooled CCD is the only way forward now. But I ask you! Taking the images in four stages to get all the needed subs - is it really viable under UK skies? I've struggled to get 20 colour shots with my DSLR this winter let alone 20 for each colour plus luminence etc.

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