4
$\begingroup$

I observed color in a nebula for the first time this past weekend when looking at the Ring Nebula through my Orion XT8. I noticed a bit of red on the outer edges. I placed my Orion Ultrablock Narrowband filter on to attempt to observe more detail when I realized that it washes the field of view out in green, so I could no longer see the red.

Is this normal? Are there any other narrowband filters that preserve color?

$\endgroup$
7
$\begingroup$

By definition, a narrow band filter is exactly that, a narrow band. That means that it only lets light of a very small wavelength range through the filter. Since wavelength corresponds to color, all narrow band filters are only going to let through a very narrow color range and will "tint" the image accordingly.

In your case, I suspect the filter you used is centered on the [OIII] lines which are in the green part of the spectrum and so the filed appeared green as that is the only color that would get through. If you were using a narrowband H-alpha filter, it would have all appeared red as that is in the far red portion of the spectrum at 6563 Aangsroms.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy