I wanted to compare 2 filters this evening as I have recently purchased the new Antlia Triband RGB Ultra filter. The original filter I had for the one shot colour was the ZWO Duo-Band filter.
As can be seen above the difference without a filter is quite dramatic (Top – No Filter, Middle – Antlia Triband RGB Ultra, Bottom – ZWO Duo-Band). There is more broadband light captured. The red nebula is less apparent and the background sky is much brighter.
The above image from the running man nebula, NGC 1977 demonstrates that without a filter a reflection nebula comes through best (Left – No Filter, Middle – Antlia Triband RGB Ultra, Right – ZWO Duo-Band). The ZWO filter gives a more green image over that of the Antila, which in itself reduces the reflection nebula but does start to pick up some of the red emission nebula within the Running Man.
The inverted background above gives a sense of the reduction in star luminance that is allowed through without a filter.
This image shows the background with the details of the readout from each of the pixel across the colour channels. Here you get a sense of the green seen in the ZWO filter is less the extra green coming through, moreover the lack of blue being allowed through. Without a filter the background sky is swamped with all colour channels.
With no filter the full effect can be seen above, much brighter background, nebula less colourful and less detailed.
With the Antlia filter above, the final single image I personally find is much more pleasing.
Finally with the ZWO filter you can see quite clearly the green effect.
So in summary I would say the ZWO filter is better than no filter except when imaging reflection nebula, however the best filter is the Antlia filter when paired with my one shot colour ZWO ASI2600MC camera.
Below is a random drawing of a scientist with a Tak laser beam.
