Struggles with Stars in Startools

[xonefs]

I face the same issue with broadband stars…. M45 and now m44 just don’t look right to me with these points and halo like blobs

[admin]

I face the same issue with broadband stars…. M45 and now m44 just don’t look right to me with these points and halo like blobs

At the end of the day, you are free to to process your images in any way you wish, and StarTools imposes no limitations in that respect.
My only wish is that any refusal to render stars correctly (e.g as the point lights they are) comes from a conscious decision not to, rather than some misplaced dogmatic understanding of "what is right".
StarTools - by default - follows and implements the laws physics/optics. If that is not your cup of tea, power to you, and you can choose from an infinite array of alternative settings/parameters/techniques within StarTools. These will invariably be more laborious and subjective (e.g. will require the levels of manual intervention seen in other applications) simply because a robust signal processing flow cannot be maintained.
Your conscious decision and deeper understanding will hopefully also trigger a desire to optimise your optical train and/or stacking techniques that may influence star appearance, rather than "paving over" any such problems in post-processing; as has been repeated many times across this thread and this forum; what is happening to your stellar profiles, is happening to to all detail in your image.

[xonefs]

I like point source stars… it’s the circular halo/glow I get around them that bothers me and doesn’t look right with how it transitions. It’s only in broadband. So what is that from exactly and how can it be tamed?

[admin]

I like point source stars… it’s the circular halo/glow I get around them that bothers me and doesn’t look right with how it transitions. It’s only in broadband. So what is that from exactly and how can it be tamed?

I see. Would you be able to post an example of one of your narrowband sets?

If you find this is happening depending on the spectrum you are imaging in, then - all things kept equal (e.g. ST workflow and atmospheric conditions at the time) - this may indicate a problem with the filter coating.

Poor transparency (e.g. the presence of from dust, smoke and haze) is, however, a more common cause of this sort of look. Looking at the tightness of the cores and the size of the the surrounding profile ("halo"), the profile is indeed disproportionately large.

A good experiment would be to shoot both broad and narrowband in the same night. This should roughly keep transparency the same across the datasets, eliminating it as a factor, leaving only the optical train (e.g. filters) as a possible culprit.

[xonefs]

I suppose it could be filters and the way ST tried to render them it reveals the washed out area. It does not look like this when shooting and transparency is good and from multiple different nights ive had this in broadband,

I did shoot narrowband last night too and no halos like that (just normal expected antlia oiii filter halo here- this filter does that but it is different from the rgb)

This is oiii shot right before the broadband posted above

The RGB filtes are astrodon gen2 e series, so by no means bad

Narrowband is antlia 3.5nm

I guess maybe rgb could just need a lot more data then it would look more natural. I did shoot one nice lrgb project of horsehead/flame and the glow around alnitak and the other bright stars looked natural and transitioned smothly with a lot of integration and then processing in ST- https://www.instagram.com/p/CYhDIXfuc5U ... =copy_link

Example rgb above is only just over an hour

[admin]

Good signal on a bright-ish star may allow diagnostics through deconvolution as well; if the halos resolve into a diffraction pattern, we are looking at a limitation of the optics. If not then the issue would more likely be in the realm of atmospheric conditions or filter-related peculiarities (though the Astrodon filters have a deservedly good reputation, my money would still be on that being the issue).

What sort of sensor are you using?

Is the full-spectrum image the result of an LRGB combination or just an RGB combination?

EDIT: Also, what is the focal ration "f/" of your optical system?

[xonefs]

The broadband is just RGB no l. It’s an f5 system sharpstar sca260. Though ive experienced the same with my f5.2 refractor. Zwo 2600mm. I am going to try to get my a7r4 running soon it will be interesting to see how OSC compares without dealing with separate filters

If it stay clear i will try shooting more on m44 later tonight

[admin]

The broadband is just RGB no l. It’s an f5 system sharpstar sca260. Though ive experienced the same with my f5.2 refractor. Zwo 2600mm. I am going to try to get my a7r4 running soon it will be interesting to see how OSC compares without dealing with separate filters

If it stay clear i will try shooting more on m44 later tonight

If you have an L filter, would you be able to shoot some data with that and see if the problem happens in there as well?

If the problem is a filter-related issue, the halo size will appear similar if the focal ratio is similar (+ if distance of filter to sensor is similar as well).
The OSC is a great idea. Please keep us up to date - this sort of stuff is incredibly useful for others as well!

[hixx]

I am going to try to get my a7r4 running soon it will be interesting to see how OSC compares without dealing with separate filters

Hi xonefs,
I used Sony A7 II and a modified a7 III as well. I noticed similar star halos as well on the unmodified A7 II but the modified cam (with red filter removed) is much better. It seems the Sensor IR Filter / cover might produce these reflections internally. These filters usually are built like sandwiches with multiple layers. The A7 II only has UV/IR filter left, which is much thinner than the usual green filter (to dampen reds). If you can, try to have your A7r4 modified. It's a great cam for sure!

cheers,
Jochen

[hixx]

... sorry I meant my mod A7 III has the green filter removed and only UV/IR cover glass left which is much thinner causing less internal reflection Lookingat the sensor it does not look green any longer , but rather grey. I hope this clarifies

Jochen