Hi all,
I'm currently constructing a digital filter. A digital filter you may ask?
Well I'm getting fed up with swapping from filter to filter, having to remove the eyepiece everytime, paying high prices for expensive filters etc...
I have been experimenting with LCD screens to construct a digital filter which mounts in front of the focal path of most telescopes (in front of the primary lens etc...).
I currently use a 4" Mak (Celestron 4se) and hope to have an 8" Saxon Mak soon up and running on a EQ6 skywatcher mount.
I have found that by dismantling a high resolution LCD screen and removing the backlight, I can create a digital color filter mask. I can turn on desired pixel combinations (through software I have created) and create color windows which allow only programmed wavelengths of visible light to enter the aperature of the telescope.
The system is only in it's infant stages at the moment, but basic accurate colour filtration has beeen accomplished! I don't have to say what a great device/system this could be if it's made available to all amateur astronomers.
This is why I'm putting my findings out there!
I must point out though that this method I have found to filtrate color is not 100% accurate with all LCD panels on the market. High resolution computer monitors work best. The reason being is that some LCD panel inter-pixel distances still have some space in between and allow some of the original light to get through this space, this I have found is not as bad as it seems though, and the benefits still outweigh the downfalls. Basically if some of the original light still gets through, the additional colour filtrated light just sumperimposes and inhances the view. The potential for filtering/enhancing important OIII, H-Alpha and H-Beta lines etc... can be done!!!
I've had ideas of creating a smaller version of the digital filter that fits in an eyepiece. I plan using a small inexpensive keyring LCD photo display gadget. Cost is about $7, LCD size is about 1.5" and basically loading the photos as plain colour, full frame images. By placing the LCD before the eypiece this would work as a basic digital colour filter. If you new the exact colour of OIII wavelength of light, you could create an image file which is just that colour. This would allow mainly OIII light to enter the eyepiece and greatly enhance OIII lines in the view etc...
The eyepiece version could also be used for solar observations using the addition of a Ba'ader White Light Solar filter for visual use. By creating the desired filter image colour such as expensive Calcium K-line filter. Of course emulating complex filters that allow multiple bandpass wavelengths of light to pass through to the eyepiece, would have to be created as individual colour image files that correspond to the colour of the desired wavelength/bandpass you want to allow through for video capture. The captured images would then be combined through software etc... Similar to the way LRGB images are combined to produce the final image, although many channels/bandpass/wavelength captured images may have to be combined rather than only 4.
The colour manipulation and filtering possibilities of such a device are extraordinary compared to fixed treated optical glass versions.
So.......I hope my findings stimulate other budding astro-experimenters out there to start experimenting, and if you would like to discuss any aspect of this project feel free to respond, interact or contribute in any way. If you know of anyone else that has worked on a similar project I would be very interested to get any feedback.
Since I had an idea to do this over 20 years ago, I presume I'm the only one who's experimented with and tried this so far (apart from possibly military, NASA etc....)
I know if this kind of technology fell in the hands of greedy commercialists we would be exploited, so let's try and keep it free for all to enjoy!