Smart Histogram always way too dark, no matter what

[BlackWikkett]

About the noise: if I set that to 20% for example, that would result in brighter captures?

Menno

As a way of getting closer to expected results you are able to achieve using your settings. Your settings are generating more signal but also more noise. This is an easy thing to try.

The brains sky brightness measurement relies on a sensor profile. Did you create your own or are you relying on the profile provided by SC?

SC live stacking does not stretch prior to stacking as far as I know. There are several settings in Live stacking alignment tab that will increase detection and amount of stars used to stack the image. Alternatively you could just uncheck "Align Frames" and the images will stack will less than ideal results but will stack. I mention using live stacking as it's an easy way to test changes on the fly and not have to wait to save data to stack afterwards.

On the alignment tab increase "digital gain" first then play around with the settings until you start seeing the "star detection status" increase

Menno555-lsaligne.jpg (71 KiB) Viewed 1642 times

Hope this helps
-Chris

[oopfan]

I heard it through the grapevine, Menno, that you are trying to image NGC 5395. That star field is devoid of bright stars. In addition to that your telescope's field-of-view is narrow.

Deep Sky Stacker is infamous for needing at least 9 stars for alignment. And not only does it need 9 stars, it needs 9 bright stars.

You have three choices:
1. Increase exposure if you continue to want to use DSS
2. Try Siril (free)
3. Purchase AstroPixelProcessor

A 17.5-second exposure is not long enough to capture and burn-in 12th magnitude stars. Increase exposure.

SharpCap makes it easy to choose any exposure you want. Look over to the right where it says "Exposure". You can type it in.

[turfpit]

Menno

Can you upload a set of light frames somewhere and link to them? Without filter preferred, otherwise whatever you have.

Dave

[Menno555]

Thanks everybody! I have enough info on this now and will experiment further. Again, SC works great but was just curious on the Brain. Maybe also has to to do with something I discovered last night, see comment to Brian.

@ Chris
Will try that. And I did try both: my own and the one provided by SC. But also discovered another reason, see my comment to Brain.

@ Dave
Will do when I have them. Have nothing now cause deleted everything after posting the screenshots here.

@ Brian
Okay, here my newbie status is confirmed Discovered something last night.
You are absolutely right about the (faint) stars. I am pinned to my location here, have a south-west to north sky. But never realized that although it has some great objects, it is also less dense with (bright) stars, especially with my small FOV.
This became obvious last night when I could look at the Ring Nebula M57, it showed in my zenith here ... and I was blown away by it, literary staring at my screen for a long time. The object itself ofcourse but I never did see so many stars with this scope. I always thought that captures from others had so many stars because their bigger FOV ...
About the exposure time: the suggested 17.5 sec exposure was obvious for me that it wouldn't work, both for the stars and the object. And it's for that exact reason why I am wondering why the Brain is suggesting it. No criticism towards SC or Robin, just wondering.
Surely I do my own settings and that works fine. That thing called Exposure on the right side does wonders

[turfpit]

Menno

If you work within the Summer Triangle, it has the Milky way as a backdrop. Plenty of stars and objects of varying types to get you started in the constellations of Cygnus, Lyra & Vulpecula. Both M27 and M57 have higher surface brightness and are good objects to experiment with settings.

viewtopic.php?f=16&t=2779 at a Bortle 6 site.

https://www.astrobin.com/1graw1/0/ at a Bortle 4 site.

How much difference does the Bortle number make? At Bortle 6 (home which is North East of Manchester) I never see the Milky Way. At Bortle 4 (Anglesey, North Wales) the Milky Way is clearly visible. With your Bortle 8 life will be harder.

Looking for the Heron Galaxy on Astrobin, there are only 4 Top Picks and no Image of the Day - that tells me it is a difficult object to image.

Suggest you try both with and without the Neodymium filter so that you understand its impact on the histogram.

Dave

[oopfan]

Menno,

The exposure that the Brain suggests is what I call the "minimum exposure". It means that you really should not go below it because you will need to stack a lot more to get the same result. For example, if you take the suggested exposure then perhaps two hours later you will have a beautiful image but if you select a lower exposure then perhaps you will need to stack for three hours for the same quality. But nothing prevents you from selecting a longer exposure. The Brain is just saying that there is not much to gain from it, meaning that if you double the exposure you won't automatically cut in half the total integration time. Maybe you will reduce it by a mere 10 minutes. You know, something like that, I'm just giving examples. The Brain makes this suggestion based on the pixel value of dark space (which is never black because of light pollution.) The Brain is not looking at your star field. It assumes that there are enough bright stars to satisfy your stacking software. Unfortunately DSS is very sensitive. It wants at least 9 bright stars. Of course "bright" is subjective. It is obvious in this case that DSS is not satisfied with the stars from a 17.5-second exposure. So, increase it by 50% or more if necessary.

Brian

[donstim]

Menlo,
I think (hope?) you have your answer. The Brain's suggested max dynamic range exposure/gain settings (for the measured sky brightness, camera sensor analysis, min/max exposure limits, and desired read noise limit) will give you the best dynamic range in a stacked image. It assumes you will be able to stack the images, which will depend on the brightness and number of stars in your FOV (as well as how well your mount tracks so the stars are picked up as stars by the stacking program) and the parameters used in your stacking program to identify alignment stars. A single unstretched frame is likely to be very dark if you don't have any bright objects (e.g, brighter stars) in the FOV.

Changing the total stacking time has no effect on the suggested gain/exposure for best dynamic range in a stacked image with your selected read noise limit. Itwill, however, affect the dimmest object you can get in the image and the total dynamic range achieved.

Don

[Menno555]

Thanks all ... again

@Dave
I did send you a PM with a link.
The impact of the filter is known, I experimented with that. Without the filter the exposure times were a bit shorter but the objects were not as "expressive" as with that filter.
And sadly the Summer Triangle is obscured for me by buildings: it's in the East and I am kinda pinned on my location and that faces directly to the West. All of that is coming my way in the Fall and Winter.
And yes, that Heron Galaxy is challenging. And just that is attractive I know my scope is not really made for that but my mount is.

@ Brian
That minimum brightness makes sense. Did some experimenting (like usual) last night in that direction. Slowly but surely my brain is starting to get the Brain But in general for me I know that around 30 to 50 sec and Gain 150 to 250 works best. At least in this time of year with the sky I can see.

@ Don
Jah, starting to understand that it assumes it is stackable. I haven't been able yet to use the Brain with enough and bright stars. And if there were, there were only like 4. All in all I think that my small FOV a big part is of this: the Brain doesn't know that ofcourse and measures only the light received by the sensor.