Live Stack with Flat Frame Bug?

[admin]

Hi Chris,


Because you are using a dark frame when capturing, the offset value that gets written to the end of the flat frame filename will not have any effect on your result. That means that the only change between 6128 and 6173 is the use of a slightly shorter bias frame if the minimum exposure for your cameras less than 0.1 ms (I've checked the code for any other changes between these two versions that might apply to flat correction and I can't find anything else).

The only thing I can think of is that your camera may be giving weird results when taking bias frames that are close to the minimum exposure value that may be upsetting the flat frame correction. I will undo the change that makes the bias frame shorter for the next uploaded version and we will see if that makes any difference.

Cheers, Robin

[BlackWikkett]

Thanks Robin

Just to make sure we're on the same page I'm not using dark frames during the flat creation only during imaging, specifically live stacking. I'll be sure to test once the next version is available and I' have skies.

-Chris

[admin]

Yep, darks for taking lights and bias for taking flats was what I was expecting. Should be OK (unless your flats are using long exposures... >2s or so)

cheers,

Robin

[BlackWikkett]

Just tried new version 6183 64bit, crashes at startup, uploaded error report.
-Chris

[donboy]

Same here on crashing but 32bit version.

Don

[Excalibur]

Both 32 & 64-bit versions of 3.2.6183 crasches on startup with null-pointer exception (Livestack Guiding), craschreports are uploaded.

Uninstalling proved difficult from Windows, but was eventually successfull by using uninstall-option of setups. Uninstalling from windows only seemed to uninstall the installer-package and did not actually uninstall the program - with an error-message when trying to reinstall older version (3.2.6173) that a newer version was already installed.

Clear Skies,
Magnus

[admin]

Hi Magnus,

Sorry about that – I was trying to fix a crash related to stopping live stacking while the dither was in process and ended up making things worse. I will have a new build uploaded within the next 30 minutes or so. Oddly I didn't see any problems with rewinding back to previous build – I uninstalled the 32-bit version and then managed to reinstall the previous version without issue.

Cheers, Robin

[admin]

Fixed version (3.2.6185) uploaded.

Robin

[BlackWikkett]

Reporting back findings. I see you made a change in v6185 but since then you published v6194. I'm assuming the 6185 change was present in the latest version also? I've completed testing flats with live stacking in 3.2.6194 and flats are not applying correctly in this build. I generally use the 64 bit version since I can allocate more memory for live stacking. v6194 64bit created flat and also v6128 32bit created a back up flat

Here are results of the different flat version and build version. You can see that flat are not apply correctly until I uninstall v6194 and install 64bit v6128 and create a new flat.

This is v6194 using flat created in v6194
IC1795-v6194-Stack_6frames_180s_WithDisplayStretch by Black Wikkett, on Flickr

Flat-v6194-19_15_40_offset=-0.024% by Black Wikkett, on Flickr

This is v6194 using back up flat created in v6128 32bit
IC1795-v6194-w6128flat-Stack_5frames_150s_WithDisplayStretch by Black Wikkett, on Flickr

Flat-v6128-19_18_43_offset=0.234% by Black Wikkett, on Flickr

This is v6128 32bit using the backup flat created in v6128 32bit. This looks better but vignetting still evident. Seems as though other version of software installed on the same machine are sharing under hood.
IC1795-v6128-w6128flat-Stack_6frames_180s_WithDisplayStretch by Black Wikkett, on Flickr

So at this point I was at a loss as v6128 was showing issues. I uninstalled v6194 and installed 64 bit v6128 and created a new flat and tried again. This time success! No vignetting or flat issues, back to normal!
This is v6128 64bit and new flat created in v6128 64bit
IC1795-v6128clean-v6128flat-clean-Stack_11frames_330s_WithDisplayStretch by Black Wikkett, on Flickr

Flat-v6128-64-clean-19_55_46_offset=0.243% by Black Wikkett, on Flickr

Once everything was working let this one stack up a bit. This is raw from SharpCap no Photoshop clean up.
Stack_85frames_2550s_WithDisplayStretch by Black Wikkett, on Flickr

All the flats look more or less the same, only difference being that the offset= is different from flat to flat and which version of the software it was created in. I'm hoping the 6185 change wasn't brought froward to 6194 and once it is things will be back to normal. If I was to test with 6185 first before pushing this to future builds then sorry for the misunderstanding. Also could one version of SC effect other versions of the software installed on the machine?

Thanks for having a look, Chris

[admin]

Hi Chris,

I've just been through the changes made between 6128 and 6194 again and as far as I can tell there are *no* changes to the way flat frame correction is calculated. There are changes to the creation of a flat frame as I've already described, but those would have no effect if you are using your flat from 6128.

Do you have the raw frames saved that you captured in 6128 to make the last stack (the one that worked)? Can you run them through the folder monitor camera in 6194 using exactly the same dark and flat that you used in 6128? If that shows a problem then I'm wrong and the processing is different somehow. If that shows OK then we have to start suspecting that it might be that the captured data is different somehow.

Cheers, Robin