timthelder
December 7th, 2007, 04:09 AM
These are some "cut-n-pastes",and some info on CCD imaging I thought was interesting.
http://en.wikipedia.org/wiki/Quantum_efficiency
The absorption spectra are just a relative demonstration; this is not intended to be a rigorous "proof-of-performance". The camera’s aperture and color balance were established with the unfiltered solar spectrum and then each filter was held in front of its lens and an image was captured. You will notice what appears to be excessive transmission in the Hydrogen-Alpha regions of the UHC, O-III, and H-Beta modules. I attribute this to the extremely high Near Infrared (N.I.R.) Q.E. my camera’s CCD sensor, see for example:
1376137713781379
The filters do not exhibit this level of saturation when you look through them with my unaided eye. Interestingly, the Thousand Oaks filter specifications show transmission at the H-Alpha wavelength, Lumicon’s do not. The Deep Sky filter is supposed to transmit N.I.R. according to Lumicon’s published specs.
1380
This is the graph for Celestron's UHC/LPR filter.
http://en.wikipedia.org/wiki/Quantum_efficiency
The absorption spectra are just a relative demonstration; this is not intended to be a rigorous "proof-of-performance". The camera’s aperture and color balance were established with the unfiltered solar spectrum and then each filter was held in front of its lens and an image was captured. You will notice what appears to be excessive transmission in the Hydrogen-Alpha regions of the UHC, O-III, and H-Beta modules. I attribute this to the extremely high Near Infrared (N.I.R.) Q.E. my camera’s CCD sensor, see for example:
1376137713781379
The filters do not exhibit this level of saturation when you look through them with my unaided eye. Interestingly, the Thousand Oaks filter specifications show transmission at the H-Alpha wavelength, Lumicon’s do not. The Deep Sky filter is supposed to transmit N.I.R. according to Lumicon’s published specs.
1380
This is the graph for Celestron's UHC/LPR filter.