which one?

[cosmicdonkey]

hi guys i want too upgrade my uv/ir cut filter. (i just have the cheap standered one from morgans). I use a spc900 with a 127mak. I have seen these 2 filters on the flo website.

First Light Optics - Baader IR-Pass Filter

and

First Light Optics - Baader UV/IR Cut Filter

my question is one of them is an ir pass filter and the description says its good for planetry. Is this what i need? or should i be going for the uv/ir cut filter?

any help is much appreciated:D

[FrankieValley]

Hi,

The IR 'cut' filter is what you need for the SPC900 ( which is a colour ccd). The IR 'pass' filter is useful if you have a monochrome CCD. You would use the IR pass filter to give a luminance image that you would then combine with red, green & blue images to make a final LRGB image.

Another way of looking at it, is that the IR pass filter will exclude (cut) RGB wavelengths and 'blind' a colour ccd.

This link has a wavelength diagram - First Light Optics - Baader LRGB CCD Filter set

It's not that obvious, but the L (or IR Cut) passes only the wavelengths to the right of ~650nm. The 'Clear' filter passes both visible and IR wavelengths.

IR Cut is another term for a Luminance filter that provides extra detail to enhance an RGB image when imaging with a monochrome ccd.

Regards

David

[cosmicdonkey]

Perfect thank you very much. Much appreciated

[FrankieValley]

No problem and thank-you for not pointing out my mistake. I knew I'd get the 'pass' and the 'cut' round the wrong way somewhere....

"......the L (or IR Cut) passes only the wavelengths to the right of ~650nm. The 'Clear' filter passes both visible and IR wavelengths."

That should've said "....(or IR Pass)......"