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Good targets for OSC + dual band filter


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Just wondering if anyone has any targets that they've found to produce good results with a dual (or tri or quad) band filter with a OSC camera, such as the Optolong extreme or enhance filters?

All the listings and materials use the veil as examples and I've found that the veil easily gives the best results, as the OIII is presumably strong enough and in a separate region to lead to the distinct red/blue colors.

Whilst I'm sure the SNR is improved on every target, everything else I've imaged ends up a slightly disappointing shade of red, like the pac man nebula below. Obviously there may be more one can do in processing, but I've struggled to do a lot more with this is in startools.

process_v1.jpg

PACMAN_PROCESSED_V1.JPG

Edited by rnobleeddy
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When using such filters with OSC camera - you are really just recording blue and red color.

There is little difference in Hb and OIII wavelength as one is 486nm and other is 500nm. In ideal world here is what you would get:

image.png.331a48daa356850acd53bd4a58ebc139.png

as these are the colors in RGB color space that are closest to actual red of Ha/SII (there is no difference between the two in color - SII seems a little darker to us), Navy blue of Hb and teal of OIII.

However, due to raw color space of OSC cameras and absence of color calibration - colors will often be a bit skewed with respect to above and there might even be less distinction between Hb and OIII - just blush color.

There is no way with these filters to separate actual colors Ha and SII signals will blend into red without ever having chance of separating them - and often Hb and OIII do the same - they create sort of blue/teal tone and that is it.

if you want to achieve look of Veil nebula on other nebulae - you'll need to separately process blue, red and green channels as often OIII signal is much fainter than Ha signal and needs to be boosted considerably.

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  • 2 weeks later...

You could try M27 ( Dumbbell ) Which is an easy target or NGC 2359 ( Thor's Helmet ) which is a little trickier. They give a nice colour contrast, here is my M27 from earlier in the year with the altair tri band, 130 p-ds and 294mc pro. This is a 15 second exposure  x 20 frame stack.

Stack_20frames_300s_WithDisplayStretch.thumb.png.7cf9a8e52479903dc50a1badb3be8fa2.png.03b90c740e92016e3c794a32222db644.png

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By far the best bi-colour result I have obtained to date with the IDAS NBX dual band filter and a OSC camera is the Veil Nebula. As you have indicated, most other nebulae I have targeted are predominantly red. I did capture some blue signal on the Spaghetti Nebula, which surprised me given my relatively short integration times.

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On 01/01/2021 at 00:00, barkingsteve said:

You could try M27 ( Dumbbell ) Which is an easy target or NGC 2359 ( Thor's Helmet ) which is a little trickier. They give a nice colour contrast, here is my M27 from earlier in the year with the altair tri band, 130 p-ds and 294mc pro. This is a 15 second exposure  x 20 frame stack.

Stack_20frames_300s_WithDisplayStretch.thumb.png.7cf9a8e52479903dc50a1badb3be8fa2.png.03b90c740e92016e3c794a32222db644.png

 

On 01/01/2021 at 00:23, tomato said:

By far the best bi-colour result I have obtained to date with the IDAS NBX dual band filter and a OSC camera is the Veil Nebula. As you have indicated, most other nebulae I have targeted are predominantly red. I did capture some blue signal on the Spaghetti Nebula, which surprised me given my relatively short integration times.

Thanks. The ring is now behind my house, but will give that a go when it reappears. Presumably other planetary nebula would be good too, but until I get a recently acquired 250PDS up and running, they're all a little small for my 130PDS.

 

As an aside, I got some data from the last few nights with a full moon using a dual band filter. The full dataset is hard to use due to strong gradients, but the red/ha channel is serviceable and led to some decent B&W images.

 

 

soul_20201230_ha_levels.thumb.jpg.be74c5163a4c6c9f6627e729628badba.jpg

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Heart Nebula, Soul Nebula, Witches Broom, North America, California, Thor’s Helmet, Helix, Wizard, Elephants Trunk, Rosette are all targets I’ve imaged/ on my list to image with the L-eXtreme. 

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Here’s a few. The Helix was very low down and I only got 4 subs but it looks to have plenty of OIII signal. The colourful  image of the North America Nebula is a composite of two images shot separately through the L-eXtreme and an IR/UV cut filter. Used the narrowband data as luminance file and the IR/UV for the rgb. That’s another way to use these filters..

 

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