CCD Security cam for astrophotography

[Ewan]

I am doing a lot of research regarding imaging & was thinking about an 'alternative' to the more expensive Astero cams you can get but i also understand they may either not work in some cases & the picture quality may not be as good as my DSLR.

Anyone have any thoughts at all on these ? :-

http://www.ebay.co.uk/itm/HD-Array-IR-Led-1-3-Sony-Effio-700-TVL-CCD-Indoor-Security-Camera-CCTV-System-/120949664466?pt=UK_CCTV&hash=item1c29296ad2

http://www.ebay.co.uk/itm/1-3-SONY-480TVL-CCD-Color-Video-3-6mm-Lens-CCTV-Security-Camera-Board-PCB-C4-1-/280870319812?pt=UK_CCTV&hash=item41652cf6c4

http://www.ebay.co.uk/itm/MINI-METAL-OUTDOOR-BULLET-SPY-SECURITY-CCTV-CAMERA-1-3-SONY-CCD-480TVL-9-LED-IR-/180888838944?pt=UK_CCTV&hash=item2a1dd0a320

http://www.ebay.co.uk/itm/540-TVL-PAL-CCTV-PCB-Board-Camera-Sony-CCD-Super-HAD-low-lux-spy-/170865188127?pt=UK_CCTV&hash=item27c85bdd1f

http://www.ebay.co.uk/itm/700TVL-1-3-SONY-Effio-E-CCD-Video-3-6mm-Lens-CCTV-Security-Camera-Board-PCB-C7-1-/280913547341?pt=UK_CCTV&hash=item4167c0904d

I know there are a few there sorry , i dont mind doing a bit of soldering & adaption, it just seems like there are some good cheap ccd sensors begging to be used for astro work

Any ideas / info please & thank you as always

[pete_l]

Let's take a second to review how an security CCTV camera works. Essentially, the following happens.

• Start the exposure
  
• Gather photons for a set period of time
  
• stop the exposure
  
• convert the CCD signals to digital format, this adds a bit of uncertainty - or noise, to each reading
  
• modulate the digital signal to analog CCTV format, possibly altering the lines/resolution of the resulting picture
  
• Repeat this, 25 times a second
  

Now with astro-cams, there are far fewer operations - typically the cycle runs once every few, to few hundred, seconds, so there's less noise added from the fewer digital conversions.. Astro cams also to not have the lossy analog modulation stage and, as the cameras are cooled, add far less noise at each stage as well. If you stick your finger on the chips of a security camera (I have some of the little board-cams), you've be aware that they do run quite hot.

So, in short, security cameras are designed to give real-time video at high frame rates. The human watchers of their screens aren't looking for static objects like stars, they're looking for moving objects like criminals - so they aren't too concerned with the level of video noise.

It is possible to capture the video and integrate / stack it, but the quality of the picture you get, compared with the quality from an equally long astro-cam, is much much worse. These cameras are designed to do a different job. And although they appear to have a lot of the same function as astro-cams, they are not intended to produce the same quality from static scenes and so aren't a great solution to seeing dim objects through a telescope.

[Ewan]

Thanks Pete for a very quick answer, oh well i like to look at all avenues :-) but i wont be going down that one

[Space Cowboy]

Maybe of interest for those looking for a cheap Planetary cam? Looks like they use auto settings so maybe not?

[Ludd]

Can I chip in with a comment about Mintron cameras? Yes, low definition and quite noisy, but have a look at what they can do with frame integration: I was watching M13 on a 32" TV screen last night, with a myriad of stars right down to the core, all captured through a diddy 70mm scope and a second hand unmodified CCTV camera.