You'll start to notice that the signal strength in each channel varies from target to target. Ha is often the dominant channel compared to Sii and Oiii. When you do a straight SHO hubble blend the image will often look very green with magenta stars, because you just assigned the most dominant channel to green. DBE is not the tool to fix that. DBE helps you eliminate sky gradients and uneven illumination, but it's not to get the green out of a hubble image. You would need to focus more on color manipulation process, or change the blend in pixel math. The initial combination is just a starting point. Don't expect to get your final color balance with just the pixelmath blend alone.
There is a bit of a sledgehammer approach when it comes to reducing the green out of a sho blend. Hit it with SCNR green AFTER you stretch the image. Vary the SCNR amount to taste. To tackle magenta stars with the same hammer, invert the image and the magenta stars will now look green. Hit it with scnr green again, then invert the image back. No more magenta stars.
The color mask script is very helpful for narrowband. Instead of the SCNR approach you can create a mask of just the green in the image, then use the mask and curves to manipulate the green into something else.
You can also vary the blend for a starting point. Search for narrowband pixelmath blends. Lots out there. If you're looking for more of an RGB-ish look try out some HOO blends. Don't expect to get RGB stars and color palettes with narrowband, unless you add RGB star data later. Just take what the data gives you.
You will need to vary the total imaging time for each channel depending on the target. A heavy Ha target with weak Oiii might only need a few hours of Ha to look nice, but you made need triple or more that time in Oiii and/or Sii. Ha always integrates smooth with a pleasing noise profile. Sii always looks grainy to me, even with lots of integration time. Oiii has typically been the weakest for the targets I've shot (except for veil complex). A typical exposure time distribution for me would be something like 5-7 hours Ha, 10 or so sii, and probalbly 15-20 Oiii. Bottom line is a 1:1:1 ratio is probably not going to work for most targets.
I know you're still in the proof of concept phase of mono, but you do a lot of one-night images. You will probably need to commit to multiple nights on one target for the results you're looking for. Try shooting just one filter per night, for 3-5 nights. This will save you focusing since you won't be changing filters. Plan your Oiii around new moon. The results will likely blow your mind.
Here is your challenge: Pick a target that you can shoot all night that has all three channels present. Shoot just Ha on night one. Shoot just Sii on night two, shoot Oiii for nights three and four. Then post up your 30 hour integration. You'll have an image with amazing depth and smooth noise profile. You'll actually be able to zoom in and still like it.
Edited by Monkeybird747, 24 January 2020 - 07:31 PM.