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Opening the OSC vs Mono CCD issue again.

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I've been getting great results with my modified Canon ES300D, so I'm now considering moving on to an astronomical CCD camera and have decided to purchase either the SBIG ST-8300 or the ATIK 383L+.

Currently using the Canon I can get a good result in one imaging session of about 2 to 3 hours using the following workflow

1. about half an hour setup, aligning on subject, focussing, taking test images

2. flat darks and flats, saved to CF card on camera (saves download time) in RAW format, usually I take 19 of each which are then used by DSS to make a master flat for the session. (I do observatory flats, taking short exposures of the inside of the dome shutters illuminated with white torch light (the shutters are also painted white on the inside)). I guess this takes about 5 minutes, although it feels longer.

3. lights (RAW format), usually 10 exposures of 4 minutes, sometimes 15, sometimes 5 minutes, downloaded to PC so that DSS Live can stack them and I get a view of the result.

4. darks (RAW format), same exposure as the light and I always take an odd number usually 11 and again saved to CF card on the camera. DSS makes these into a master dark.

2. about quarter of an hour take down time.

If I were to purchase a one shot colour CCD then I think that the work flow would be very similar and because the CCD would be more sensitive than the Canon I'd expect the results to be better (get more photons converted into signal). But the results would be even better if I were to go mono and use a fliter wheel.

So the question is would I be able to achieve a similar or better result with a mono setup in one session like I've described above? I recognise that the workflow would need to be adjusted because flats would need to be taken with each filter (LRGB) so that is four sessions of flats and that lights would also need four sessions. Flat darks and Darks would only need to be done once per run as these can be used with each. I think my workflow would be along these lines

1. Luminance flats

2. Luminance flat darks

3. Red Flats

4. Green Flats

5. Blue Flats

again I dont think that these would take any more than about 10 - 15 minutes

6. Luminance lights, say 9 or 10 off 4 min exposures

7. Luminance darks, I expect that I'd not need as many as with the Canon and once I'd built up a library of master darks at certain temperatures I'd not need to do these at all.

8. Red Lights, probably about a third the number as the Luminance lights, say 3 or 4 and binned 2 x 2

9. Green Lights, as for the red

10 Blue Lights, as for the red too.

I'm not overly concerned about the additional expense of the filter wheel or the filters but I think that going down the mono route is ultimately going to give me better results and greater flexibility with narrowband also coming into the equation. But if I'm not going to be able to achieve this without having to do multiple sessions on one subject (which might mean weeks needing to be taken to get the image) then One Shot Colour has to be the preferred route.

I need some advice to help me decide which route to take.

Thanks in anticipation.



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I can see this one rolling on :eek:....

For me, I wanted a mono camera because the advatnage of being able to do narrowband too. By far and away the most often used filter I use is my Ha filter as most of the time I find a clear night is also a moon-filled night too!


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Try doing SII with a OSC camera...:-)

Whole heaps of fun..

OSC's are superb for broadband colour imaging, ideally augmented by a mono H-A layer.. it's something I want (DSI-III) to complement the Atik 314L

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