Effect of L-eNhance Filter -- M27

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donstim
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Effect of L-eNhance Filter -- M27

Post by donstim » Tue Jun 30, 2020 5:08 pm

Here is a comparison of an M27 I captured a couple of nights ago using an L-eNhance filter: https://photos.app.goo.gl/eHH4iqvu2VYspsZJ9

compared to one I took last year without any filters: https://photos.app.goo.gl/p5Bg71fwemb4pTR2A

Both were taken with a Celestron Evolution 8 with a Celestron 0.63x focal reducer/corrector using a ZWO ASI294MC Pro camera. They are saved live stacks from SharpCap with some limited post processing in GIMP. The first is 60 frames at about 20 seconds exposure with 300 gain, while the second is 120 frames at 20 seconds exposure with 210 gain.

Although the L-eNhance filter version is interesting and really brings out the red portions of the nebula, I prefer the version without the filter. Is there something I should be doing differently when using the filter? I know I was having trouble trying to adjust the colors while live stacking, but aligning the color peaks didn't seem to give the right balance. As I recall, I think I ended up with the red peak being pretty far to the left of the blue and green peaks.

Don

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Re: Effect of L-eNhance Filter -- M27

Post by umasscrew39 » Tue Jun 30, 2020 8:48 pm

Interesting- both are nice and many folks produce each version. I like the blue M27 version without the filter but I would struggle to get a nice image with no NB filter. I use the L-eNhance filter a lot and just imaged M27 on the 2600 but did it last year using the 294 (a gain around 200) which you are using. In my case, neither M27 looks like yours. Did you save them as seen on the screen or save as FITS files? I am assuming the former. I save as FITS and then PP - not in GIMP but PI.

I can make my version look somewhat like your blue version in PI but I would think you can play with the color levels in SC prior to saving to perhaps get it closer to the non-filter version.

In any event, I think they are both very nice images.
M27v2.jpg
M27v2.jpg (399.24 KiB) Viewed 165 times

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Menno555
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Re: Effect of L-eNhance Filter -- M27

Post by Menno555 » Wed Jul 01, 2020 7:57 am

One of the things I learned (also with a lot of info from this forum) is that altering the white balance can give nice results but also can cause bad results. I too have the L-eHance filter and id found that especially with that filter, the best results are with white balance on the default setting of Red 52 and Blue 95. I think that that is also the default setting for your camera. All the colors are captured in the right way then and with processing afterwards, you then can alter it.
I tried also the Red 50 and Blue 50 setting. Works nice with normal or no filter but with the L-eNhance it didn't work that well.
Also, this filter is a multi narrowband filter (H-Alpha, H-Beta and OIII) so the colors will always be a bit "off". There is the L-Pro filter too and that allows passing of some more bandwidth and has more blue in the capture.

See an example here: https://www.cloudynights.com/topic/6701 ... le-9-zone/ ... you'll see that the L-eNhance blocks more blue and that's because it only lets through a bit of the blue H-Beta band.

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Re: Effect of L-eNhance Filter -- M27

Post by umasscrew39 » Wed Jul 01, 2020 12:23 pm

Actually, I brought the topic of R/B white balance up on this forum. The effects are dependent upon whether or not you are using the ASCOM or native camera driver, how you are saving the image, and how you post-process it. I don't think it is just one factor like what filter you use. On CNs, you will find folks using 50/50 and the default of 52/95. I have used both settings with the L-eNhance filter and the final images show very little difference.

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Menno555
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Re: Effect of L-eNhance Filter -- M27

Post by Menno555 » Wed Jul 01, 2020 12:45 pm

Ah okay, I wasn't aware that those factors can also be a cause. Another thing learned :)
If I use 50/50 normally, then the FITS are very green saturated. Can be altered in processing ofcourse. And 52/95 gives almost natural.
With the L-eNhance and 50/50 it was just ... weird. The histogram in PS was all over the place and it was very hard to stretch. But with 52/95 it was okay, histogram in PS had good curves and stretching was easy.

donstim
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Re: Effect of L-eNhance Filter -- M27

Post by donstim » Wed Jul 01, 2020 7:01 pm

Thanks guys for the discussion. In response to your first post, Bruce, I am basically doing EAA with a little post-processing. I save the stack from SharpCap "with adjustments," not the individual FITS files. All the adjustments I make in SharpCap are with the sliders in the livestack window, not from the right side panels (except for gain, exposure, and brightness).

Where did you guys get the info that the default white balance for the 294MC Pro is 52/95? 50/50 is what comes up for me in SharpCap, which is consistent with what I have read elsewhere. I prefer to use the default color balance (whatever that is) and make all the color adjustments using the livestack sliders just to make sure that I capture what I see when using the "save with adjustment" options and to still hopefully not need to use extreme settings on the color sliders to get a good color balance.

Another oddity that came up with this session was the livestack histogram. Here is a screenshot of SharpCap partway through the capture:
Screenshot (5).jpg
Screenshot (5).jpg (323.45 KiB) Viewed 107 times
As you can see, there is no "peak" to the Livestack histogram, but there is one in the "small display histogram stretch" right side panel (although no stretch had been applied in that panel). You can see that I have really boosted the red channel and lowered the green, but I still cannot get the red histogram peak (or line) to match the blue and green peaks (and lines).

The histograms indicate under-exposure, but stretching or boosting the exposure quickly blows out the nebula detail. I had the same general histogram behavior in imaging the Cat's Eye Nebula earlier in the same session.

Don

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Menno555
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Re: Effect of L-eNhance Filter -- M27

Post by Menno555 » Wed Jul 01, 2020 8:19 pm

donstim wrote:
Wed Jul 01, 2020 7:01 pm
Where did you guys get the info that the default white balance for the 294MC Pro is 52/95? 50/50 is what comes up for me in SharpCap, which is consistent with what I have read elsewhere. I prefer to use the default color balance (whatever that is) and make all the color adjustments using the livestack sliders just to make sure that I capture what I see when using the "save with adjustment" options and to still hopefully not need to use extreme settings on the color sliders to get a good color balance.
As coincidence wants it: I just received my ASI294MC Pro yesterday :)
When I hooked it up and checked it in SharpCap (so a clean camera install if you will), it gave Red 52 and Blue 95 as default. The same value was there in FireCapture.

Menno

donstim
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Re: Effect of L-eNhance Filter -- M27

Post by donstim » Wed Jul 01, 2020 9:19 pm

That's funny. I deleted by default 294MC Pro initialization file in SharpCap, restarted it, and it showed 50/50. Just to make sure, I downloaded FireCapture, installed it new, and it also shows 50/50. I don't know if it matters, but which version of the ZWO camera driver are you using? I have been using v.3.0.0.8. Noticed they just released v.3.0.0.9, so I installed that one. No difference. Still 50/50.

Also, SharpCap is supposed to load the default settings if you hold the control key down when selecting the camera. I did that and still get 50/50.

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Menno555
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Re: Effect of L-eNhance Filter -- M27

Post by Menno555 » Wed Jul 01, 2020 9:38 pm

I did a bit of searching and found this on the Zwo forum: https://bbs.astronomy-imaging-camera.co ... php?t=7682
Zwo itself indicates there that there is no white balance applied when the Zwo Ascom driver is used. So that would translate in a Red 50 and Blue 50 setting.
I do not use the Zwo Ascom driver but the native SharpCap support and (somehow) that gives Red 52 and Blue 95. The same goes for FireCapture. Why, I don't know.
But either 2 works fine: with the 50/50 I got a lot of green but that is fine to remove in processing. And with the 52/95 setting I got more "natural" results but with some red lacking. This is my preference.
That is also what I learned here: look what your preference is and use that :) I tried 50/50 with the L-eNhance and that just didn't work for me. But that doesn't mean that it isn't working overall.

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Re: Effect of L-eNhance Filter -- M27

Post by BlackWikkett » Wed Jul 01, 2020 11:21 pm

@donstim

The 50/50 is default for all ZWO camera (may apply to other brands also) using the native driver. Red 52 and Blue 95 would be meaningless to you unless you are using the same exact scope, filters and have the same sky brightness (light pollution) as Menno555. I suggest not changing the 50/50 but if you want to do some testing do the following. Set your exposure, gain you want to try also I'd start at 10 brightness and adjust the brightness to move the peak of the histogram away from the left edge. As it is now with your brightness setting of 4 you're clipping the black point. Don't use Live stacking for now but turn on the smart histogram. Then adjust the red and blue values to align with the green channel. The white, emulated luminescence channel, will align as you get the other color closer.

Can't remember the title of the post but there's a long discussion about brightness setting and using fits liberator to find the correct setting. The post is here on the SC forum. I've just always used 10 brightness and adjust from there based on the histogram shape and not clipping.

-Chris

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