Astronomik CLS-CCD vs. Astronomik CLS filters
Posted 20 February 2013 - 02:59 PM
From the Astronomik web page:
Technical Data CLS-CCD
• 95% transmission at 486nm (H-beta)
• 95% transmission at 496nm (OIII)
• 95% transmission at 501nm (OIII)
• 97% transmission at 656nm (H-alpha)
• pass from 450 to 520nm and from 640 to 690nm
Technical Data CLS
• 92% transmission at 486nm (H-beta)
• 92% transmission at 496nm (OIII)
• 92% transmission at 501nm (OIII)
• 97% transmission at 656nm (H alpha)
• pass from 450 to 540nm and beyond 650nm
My understanding is that the major difference between these two is that the CCD version adds a filter to block IR beyond 690nm (ie: does not block H-alpha). Given that the 60Da is not a full spectrum detector like most CCDs are and yet has an extended detection window, it isn't obvious to me which is going to give me better performance. The transmission percentages for the CLS-CCD are somewhat better than the CLS, but since Astronomik does not publish their entire transmission spectrum (does anyone have this, by the way?) it might be that the CCD version is more transparent across the board and this isn't a real advantage.
Can anyone help me make this decision? The CLS-CCD is somewhat more expensive, but the difference in price does not concern me.
Posted 20 February 2013 - 04:23 PM
Posted 20 February 2013 - 08:33 PM
The transmission charts are on their site. At the top click on Datasheets.
Thanks! I don't know how I missed that before, I thought I had looked all over for them, but I guess not.
It looks to me like there isn't a huge difference between these but possibly the CCD one would be slightly better over all.
Does anyone else have thoughts on this?
Posted 20 February 2013 - 10:52 PM
cls i use for video... don't do visual..
Posted 21 February 2013 - 12:04 AM
Posted 21 February 2013 - 04:34 PM
Posted 25 July 2013 - 11:05 AM
Posted 25 July 2013 - 11:12 PM
A mirror lens newtownian will not have problems with star bloat so the cls would be fine for mirrors.
Not quite true. CCD chips dont perform really that well into the deep infra red unless they are explicitly designed to do so.
Don Goldman's analysis
Your best bet is to always get the filters that attenuate the UV/IR range of the spectrum if you are imaging.