First public beta test version of SharpCap 4.2 now available

[admin]

Hi folks,

at long last, a publicly available beta test version with a whole selection of new and improved features...

https://www.sharpcap.co.uk/sharpcap/sha ... p-4-2-beta

The page linked above has the download link at the bottom and a quick summary of the major new features and improvements. I will try to post more about specific new features here over the next few days to provide a bit more detail.

cheers,

Robin

[CarCarlo147]

Hi Robin,

Congratulations on the 4.2 beta release! I'm really looking forward to testing all the new features.

Since a new major version is in the works, I wanted to take this opportunity to suggest a small improvement to an existing feature that I use a lot: the "Corona Boost" under Solar Colorization.

The effect it provides is incredibly beautiful, but as you can see in the attached screenshots, the transition right at the edge of the solar disk is quite harsh. There is a sharp, jagged pixelation that creates a noticeable "stair-step" effect, which slightly detracts from the otherwise natural look of the prominences and corona.

Would it be possible to add a slight feathering or edge-smoothing effect to that boundary when Corona Boost is enabled? A gentle gradient to blend the transition between the disk and the background would fix this hard edge and make the tool absolutely perfect.

Thanks again for your continuous hard work and dedication to SharpCap!

Best regards,
Carlo Mollicone

Immagine 2026-05-07 184148.jpg (100.68 KiB) Viewed 679 times

Immagine 2026-05-07 184144.jpg (116.41 KiB) Viewed 679 times

[CarCarlo147]

Hi Robin,

I have a feature request that would enormously improve the workflow for users processing SharpCap captures in Siril.

As you may know, the new Siril 1.4.x has introduced Python scripting. The community is actively building great tools, particularly the AMSP (Automated Multi-Session Preprocessing) script by Cyril Richard.

This script fully automates the preprocessing pipeline (generating master bias/darks/flats, calibrating, registering, and stacking across multiple sessions and filters). Users just drag and drop their raw files. However, the script has a strict requirement: it relies completely on the FITS header having the appropriate keywords to identify the frame type.

I noticed that SharpCap currently records the frame type in the external .txt settings file, like this:

Plaintext
[ZWO ASI2600MC Pro]
CameraSerialNumber=2927D20A14010900
FrameType=Light
...
...
However, this information is missing inside the actual FITS header.

Siril's script looks specifically for the standard IMAGETYP keyword in the FITS header. Here is the exact line of Python code the script uses to read it:

info['imgtype'] = normalize_imagetyp(str(h.get('IMAGETYP', '')))

And here are the definitions it expects to map the files correctly:

Python
TYPE_INFO: dict[str, tuple[str, str]] = {
'light': (' Lights', '#5BA3FF'),
'flat': (' Flats', '#FFB347'),
'darkflat': (' Dark Flats', '#CC8844'),
'dark': (' Darks', '#BBBBBB'),
'bias': (' Bias', '#CC99FF'),
'unknown': (' Unknown', '#FF7070'),
}
My request is: Could SharpCap be updated to write the standard IMAGETYP keyword directly into the FITS header by default (using values like light, flat, darkflat, dark, bias)?

Since SharpCap already knows what type of frame is being captured (as seen in the .txt file), injecting this standard keyword into the FITS header would make SharpCap files 100% compatible out-of-the-box with these powerful new automated pipelines.

Cheers,
Carlo Mollicone

[carlomuccini]

Hi

Last night I dedicated the entire live stacking deep-sky photography session to version 4.2 without ever encountering any problems.
SharpCapInstall-4.2.14539.0-64bit.exe
ZWO ASI 294MM PRO - ZWO ASI FW 2"

I attach the LOG file if it can be useful

Carlo

[admin]

Hi folks,

I wonder if anyone *not* called Carlo is trying out the new version

To answer the individual points above...

* Yes, some sort of graduated start to the corona boost is probably a good idea - my last solar session prompted me to increase the range of the solar boost brightness, which probably makes it even more desireable. You can already tweak it a bit by using the radius offset control in the same section - that lets you move the point where the boost starts in or out a little from the auto-detected position. I find that out a little is my favourite with a small visible darker band before the corona boost kicks in.

* On the IMAGETYP header - the code exists to set that header in the FITS files, but for some reason it doesn't seem to be coming through in saved files - that's a bug and I will investigate and quite likely fix in both 4.1 and 4.2 if the fix seems relatively safe from introducing any new problems.

* Glad to hear that your live stacking session went well - I probably don't need to see log files unless something bad happened that needs investigation Did you try out any of the new things in deep sky live stacking like the arcsinh stretch or the improved colour?

cheers,

Robin

[admin]

Since SharpCap already knows what type of frame is being captured (as seen in the .txt file), injecting this standard keyword into the FITS header would make SharpCap files 100% compatible out-of-the-box with these powerful new automated pipelines.

OK, I've looked at this now and it is a bug in the current versions of SharpCap (4.1 and 4.2) that happens if you have set the option to save FITS files in 'Bottom Up' format (which is the default for FITS, but not the default for SharpCap).

SharpCap always works internally with images in top-down orientation, so it has to invert the image before saving to FITS when this option has been turned on. Additionally, the image must be copied before being inverted, otherwise if the timings came out oddly, you might see the inverted version on screen. That copy operation was not preserving the frame type information (and a couple of other minor pieces of frame metadata, which probably aren't actually important, but I fixed them all).

So, this should be resolved in the next update for both 4.1 and 4.2 - thanks for finding and flagging the problem.

Robin

[archer1960]

Well, I am using the beta, but haven't come across any problems in it that don't also exist in 4.1 (and reported elsewhere), but I'm glad I read this thread, because I've been messing with solar photography, and had never heard of the Corona Boost; I'll have to play with it now...

[CarCarlo147]

* Yes, some sort of graduated start to the corona boost is probably a good idea - my last solar session prompted me to increase the range of the solar boost brightness, which probably makes it even more desireable. You can already tweak it a bit by using the radius offset control in the same section - that lets you move the point where the boost starts in or out a little from the auto-detected position. I find that out a little is my favourite with a small visible darker band before the corona boost kicks in.

Hi Robin,

Thank you very much for your reply and for considering the suggestion!

I did give the "radius offset" control a try, adjusting it both inward and outward as you suggested. While it does shift the boundary, it unfortunately doesn't seem to apply any smoothing to the edge. The harsh pixel separation over the prominences is still quite noticeable and visually unappealing.

Additionally, I've noticed that this hard edge issue is made a bit worse because the auto-detected circle doesn't always seem perfectly centered on the solar disk.

If it were possible to implement a true feathering effect at that boundary, it would be absolutely fantastic. It would smooth out that hard edge beautifully and likely help mask any slight imperfections in the circle's centering as well.

Best regards,
Carlo Mollicone

Immagine 2026-05-08 190233.jpg (259.24 KiB) Viewed 646 times

Immagine 2026-05-08 190228.jpg (252.41 KiB) Viewed 646 times

[Gfischer]

Hi Robin,
Congratulations on 4.2 I’m livestacking while writing this. The arcsinh works great colors are vivid. The stretch is following the histogram from beginning to end of stack. Public star parties will love this. I tried the enhance color button and color is very saturated. White stars get a red and blue edge as if color refraction is taking place. The button for “ auto star based color calibration “ I assume is the same as calculate in color calibration tab. Would be nice if this button starts a periodic application of the color calibration tool. I currently do this in sequence. Finally when I get the histogram where I like it if I turn on zoom I can’t get the black level and mid in the screen together. Maybe lower zoom a little.

12” dob , nexus, lquad Optolong, asi 533mc pro

[Gfischer]

Robin,
I found I had the color level high at right in histogram. When center the enhance button works great.