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Messages - Bobinius

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31
General / Re: Dark frames are not correctly subtracted
« on: 2019 April 22 02:54:11 »
I just saw that there are a few threads on this topic with the same problem. I'll do some experimenting and tell you if it works. The thing is I didn't notice this problem on all my deep sky shots, and I always stick to the same protocol.

If I understand correctly, if I remove "optimise darks" I don't need bias frames?

32
General / Re: Dark frames are not correctly subtracted
« on: 2019 April 22 02:19:26 »
Thanx. The thing is that it doesn't seem to be systematic. I tried to do it manually and it stuck. One way around it is to remove optimize darks (is dark optimisation done only for the flats? by definition darks have the same length as the lights).

As you can see in the image the glow (apparently it is called Starburst and it is not ampglow), was partially subtracted but not completely.

I was wondering if the flat settings could influence this. I am trying to take them using the same gain I used for the lights and darks, in colour, with the B/G bell around the middle (the flat panel I use is blueish).

I don't know how to take dark flats.

33
General / Dark frames are not correctly subtracted
« on: 2019 April 21 13:10:13 »
Hi everybody,

I am having this problem which seems to be reccurent during different sessions. I am using an Altair Hypercam 294C and Altair capture. After the integration using Batchpreprocessing, the image still has the sensor sideglow present and it seems that the dark frames did not subtract this signal completely.

Any idea what could be the cause? Pixinsight can correctly determine the duration of the darkframe (I capture fits). The glow goes away when I uncheck "optimize darks" but the image seems noisier (probably because the flats are no longer correctly calibrated).

Thanx

B

34
General / Re: White circular patch on the stars
« on: 2019 March 14 09:10:37 »
Ok, thanx guys, I'll let you if I manage to avoid this effect by modifying the masks.

35
General / Re: White circular patch on the stars
« on: 2019 March 13 12:09:32 »
Or is it the Global bright parameter in Deconvolution/Deringing ? I understand it as a protection for the peripheral bright artefacts around the stars not at their core.

36
General / Re: White circular patch on the stars
« on: 2019 March 13 12:06:42 »
Thanx Rob. So what is the solution for preventing that? I mean, what are the characteristics of a good deringing support image?

37
General / Re: White circular patch on the stars
« on: 2019 March 13 00:14:00 »
Ok, I used a star mask and enlarged the structures in order to capture the big stars. The problem is that since it is a Head Horse Nebula Alnitak is very big and not detected as a star. However, the saturated circular core patch is seen on other stars. I'll try to adjust with the range selection see how it goes.

Will deconvolution have a tendency to saturate the core? Ringing is pretty obvious as a side effect since it tries to improve the PSF and narrow it but does that increase the saturation of the core?

38
General / Re: White circular patch on the stars
« on: 2019 March 12 14:42:12 »
Thanx for your answers. Yes I used a local support image or a mask that is not a mask... I don't really understand the details of how this image interacts with the deconvolution process since it is not a mask (and it does not protect). So should I use a transformation of the support image with curves of Histogram transformation to make it more saturated ? How to you transform or adapt your local support images?

39
General / White circular patch on the stars
« on: 2019 March 12 09:22:05 »
Hello everyone,

I observed an artefact during post-processing which I believe it is due to an imperfect mask during deconvolution. The stars have in their center (visible on the big  ones) a solid white circular area which is homogenous and saturated white? Is it a known effect of some imperfect setting? How could I improve that ?

Thanx.

B

40
Great, very clear reply!

41
Thanx, you are right. The image is only zoomed, if I reduce it and overlap it on the original it fits.

For the second problem, I not trying to manually do DBE for each sub. I have two sets of subs with different exposures which I stack. I obtain two integrated images #1 and #2, do I perform DBE before combining them or after? Does it make a difference?

42
Hi everybody,

First post here. I have a problem with the background extraction process. After having applied the process, the new generated image is actually a cropped and larger version of the original one. I did  not modify the resolution during the settings and I tried with downsample at 1. Is there a default setting that reduces the size?

Second question: I have two series of subs with different exposures and ISO of M42. One has a gradient that is more pronounced a bit difficult to extract. Should I stack them in linear mode after having applied DBE for each and StarAlignment and then redo DBE on the final image or perform DBE on the stacked image before any treatment?

Thanx

B

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