UPDATE FROM MABULA
I have had a very rough 2 months unfortunately health wise. I was struck 3x in a row with bacterial infections. The second infection occurred  after a routine hospital checkup and I became very sick. I had to rest and take a lot of antibiotics. Once I was recovering and restarting work 1 month ago, I again became sick. The infection was not yet gone, so even more antibiotics and rest was needed. Needless to say, it took a lot of my energy and I needed a lot of rest.
Finally, the infection is really gone and my energy is coming back step-by-step now and I have started work again. I am terribly sorry to have kept you waiting for support. I will address all outstanding questions and e-mails step-by step and will be on the forum daily from today.
APP 2.0.0-beta47 will come soon as well, a lot of work was already completed before I became very ill, so the release is also nearly ready for you. Beta47 will be much faster actually. Many workflows will be more than 2x faster, mosaics can even be 10x faster than before because registration really received a major boost... all compared to beta46. Â Before I release it, I will make sure that everything is working properly and then I will release it.
I'm creating a master dark frame library for a new QHY 268M. To that end, I have a ton of dark data (more than 100GB by the time I'm done!) at varying exposures. Per exposure time, I only have 32 dark frames. But then I have many different exposure times since I'm creating a master library to re-use in the future in any conceivable situation.
For the purposes of creating a very good Bad Pixel Map, is it better to combine more data? E.g. 240 second, 300 second, 360 second darks for 96 frames total between 240 - 360 seconds? Or, is it better to stick to a single exposure time, e.g. just 32 frames of 360 seconds each?
Thanks!
Mabula's tutorial on BPM creation is indeed great! I've been following that advice for years. However, unless I'm missing something, it doesn't address the question that's the subject of this thread - whether mixing dark exposure times helps or hurts.
For the purposes of creating a very good Bad Pixel Map, is it better to combine more data? E.g. 240 second, 300 second, 360 second darks for 96 frames total between 240 - 360 seconds? Or, is it better to stick to a single exposure time, e.g. just 32 frames of 360 seconds each?
Hi @martinw89 & @carlesa25,
Mixing different exposure times for darks to detect hot pixels for your Bad Pixel Map will not give significant different results in my experience.
If you want to create a really good Bad Pixel Map to use for a long time, I would simply shoot darks at a long exposure time, like 600 seconds without camera cooling on if it is a cooled-camera. Then all pixels that don't behave linearly on the dark current, will stand out clearly ! Shoot at least 20 of those darks I would suggest, more is always better, but with 20 the statistics should already be really good to detect these hot pixels.
That BPM can then be used for all your data for a long time to great effect 😉 So you only need to do this once every 2-3 years in my experience (depends on the sensor quality and usage of course).
Mabula
@mabula-admin Thank you so much Mabula! That really changes the way I was thinking about creating a BPM to use for a long time. I was previously trying to just re-use my (cooled) dark frames, but this is a great way to think of just what's intended here - detecting hot pixels, and giving them more time + energy to go hot for statistical detection's sake. Thanks!
Indeed Martin @martinw89 !
So create that BPM just once, and use it in all your projects for more than 1 year easily 😉
Mabula
Hi Mabula,
I have a question about a BPM created with long exposure darks. Â My camera, ASI294MCP has amp glow -- and I am sure a lot of amp glow at 600 seconds uncooled. Â Is that amp glow a problem for a BPM to be used across the board for all exposures as you advise for 2 or more years?
Thanks
I think that shouldn't be a problem as a BPM is not destructive to your data, so if the amp glow changes a bit, it should still work. I asked Mabula to be sure.
Hi Mabula @mabula-admin
Hi @martinw89 & @carlesa25,
Mixing different exposure times for darks to detect hot pixels for your Bad Pixel Map will not give significant different results in my experience.
If you want to create a really good Bad Pixel Map to use for a long time, I would simply shoot darks at a long exposure time, like 600 seconds without camera cooling on if it is a cooled-camera. Then all pixels that don't behave linearly on the dark current, will stand out clearly ! Shoot at least 20 of those darks I would suggest, more is always better, but with 20 the statistics should already be really good to detect these hot pixels.
That BPM can then be used for all your data for a long time to great effect 😉 So you only need to do this once every 2-3 years in my experience (depends on the sensor quality and usage of course).
Mabula
I have one question - as I am quite confused from the recommendations for BPM creation over the last years:
- If I exactly do these 20 darks at 600 sec, uncooled, gain 0, offset 30 with ASI2600MC ...
--> I just load as darks, leave all parameters on default, check "create BPM" and then click "Create Masters & assign ..." ?
And I ignore what I read on flats needed, how to set the parameters etc. (I think, this was 2017, a tutorial from Sara).
Thank you, Michael
Â
Hi Michael @michaelacg,
Yes, just make a bunch of long darks uncooled with the same exposure time, that will create a good Bad Pixel Map for removal/correction of all the hot pixels in your lights with the created Bad Pixel Map. Indeed, Create Masters and Assign will create the Bad Pixel Map by default. Check the Bad Pixel Map settings in 2) Calibrate, the automatic BPM setting is fine 😉
The flats will only be needed if your sensor has cold or defect pixels, but these days, that rarely occurs ;-), so yes, for the ASI2600MC, just darks will be enough normally.
Hope this clarifies things?
Mabula
