Astro Photography

For that image a 5" refractor to get the necessary wide field but not using the particular CCD camera shown in the first photo..



Instead I used this camera to capture the widest possible field (with my kit), it's a Moravian G4 16000.



If I need to image smaller objects (effectively requiring longer focal length) I go with this 12" ODK scope:

 
wowow awesome! i had a telescope when i was younger, i'd stand out in the cold looking at stuff.
Now im more into photography, astro is on my todo list one day if i ever have time, I have a 500mmf4 camera lens so was thinking a sky tracker would be a good start ? :)
 
Mr Spoon said:
wowow awesome! i had a telescope when i was younger, i'd stand out in the cold looking at stuff.
Now im more into photography, astro is on my todo list one day if i ever have time, I have a 500mmf4 camera lens so was thinking a sky tracker would be a good start ? :)
Click to expand...

Sky trackers work well for wide-field stuff, but you need to take care to polar-align it. 500mm is a fairly long focal length and will cause you problems unless the mount is very precisely aligned. For example, ^that refractor is only 540mm focal length and it needs that huge mount to track well (you could make do with less mount than a 10-Micron but accurate tracking is everything for astrophotography). A lens around 100mm focal length would be much easier to work with!
 
ChrisLX200 said:
Sky trackers work well for wide-field stuff, but you need to take care to polar-align it. 500mm is a fairly long focal length and will cause you problems unless the mount is very precisely aligned. For example, ^that refractor is only 540mm focal length and it needs that huge mount to track well (you could make do with less mount than a 10-Micron but accurate tracking is everything for astrophotography). A lens around 100mm focal length would be much easier to work with!
Click to expand...

ok thanks for the tip
 
Hello :)

^^ serious kit :)

I have a simple Pentax 105SDP with a number of ATIK CCDs, off axis guided, 2” filters all sat on an NEQ6 mount.

however I’ve not done any for about 5 years due to work demands.
 
MartinPrince said:
That's a bit of an understatement! ;)
I had a look through your flicker album. Amazing photo's. Do the images originate in greyscale and then get 'colourised' in post?
Click to expand...

Yes very few are taken as 'one-shot colour', although better (more sensitive) cameras are available these days for doing simple RGB images of brighter objects as single colour photos. However, for colour-mapped 'narrow band' images such as that one shown the data is collected using 3 separate filters (having a very narrow 3nM bandwidth) and a mono camera. The colours are mapped as Green=Hydrogen alpha, Blue=Oxygen III and Red= Sulphur II and the filters only let through light matching those wavelengths. These are the ionised states of the three elements which glow at those wavelengths when stimulated by radiation from nearby bright stars. Further, each colour channel consists of multiple sub-frames which are stacked together to reduce noise in the image. In all, there may be 30 sub-frames ('subs') each of 20-30 minutes length, that's 10 for each channel, so a total of perhaps 15 hours exposure spread over several nights to generate that one image. Some images require much longer total exposures because the object is so faint.

Some images use RGB (Red/Green/Blue) broadband filters so the resulting images are called 'true colour', i.e., what your eye would see if it was sensitive enough to pick up the very dim light being emitted. An exmaple of an RGB image is below, the HorseHead and Flame Nebula region in Orion.:



Bet you wished you hadn't asked now lol
 
ChrisLX200 said:
Yes very few are taken as 'one-shot colour', although better (more sensitive) cameras are available these days for doing simple RGB images of brighter objects as single colour photos. However, for colour-mapped 'narrow band' images such as that one shown the data is collected using 3 separate filters (having a very narrow 3nM bandwidth) and a mono camera. The colours are mapped as Green=Hydrogen alpha, Blue=Oxygen III and Red= Sulphur II and the filters only let through light matching those wavelengths. These are the ionised states of the three elements which glow at those wavelengths when stimulated by radiation from nearby bright stars. Further, each colour channel consists of multiple sub-frames which are stacked together to reduce noise in the image. In all, there may be 30 sub-frames ('subs') each of 20-30 minutes length, that's 10 for each channel, so a total of perhaps 15 hours exposure spread over several nights to generate that one image. Some images require much longer total exposures because the object is so faint.

Some images use RGB (Red/Green/Blue) broadband filters so the resulting images are called 'true colour', i.e., what your eye would see if it was sensitive enough to pick up the very dim light being emitted. An exmaple of an RGB image is below, the HorseHead and Flame Nebula region in Orion.:



Bet you wished you hadn't asked now lol
Click to expand...
I am glad they asked :)
Great explanation for some one like me who knows nothing about the work behind those
Incredible images so thanks :):)
 
I've just bought my first "proper" camera in 35 years, have always had an interest in astrophotography and with tonight being the first time since I bought the camera the sky is clear. I had a go and getting some photo's or the Orion Constellation. This is using my FujiFilm X-T200 with the 15-45mm kit lens.

I'm just beginning the learning process. Also I'll worry about learning the editing side of this once I get a little more used to taking the photo's.

First attempt with far too long shutter speed and too high ISO (it was dark outside).
65wfcXb.jpg

Happier with this one but a very long way to go and I intend to but a better lens for this. I had to lower the tripod and kneel on the drive as the streetlight directly below Orion was being a git. Going to buy a light pollution filter I think.
z7ZC9p7.jpg
 
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