Mar 28 2026 APP 2.0.0-beta40 will be released in 7 days.
It did take a long time to have the work finished on this and it will have a major performance boost of 30-50% over 2.0.0-beta39 from calibration to integration. We extensively optimized many critical parts of APP. All has been tested to guarantee correct optimizations. Drizzle and image resampling is much faster for instance, those modules have been completely rewritten. Much less memory usage. LNC 2.0 will be released which works much better and faster than LNC in it's current state. And more, all will be added to the release notes in the coming weeks...
Update on the 2.0.0 release & the full manual
We are getting close to the 2.0.0 stable release and the full manual. The manual will soon become available on the website and also in PDF format. Both versions will be identical and once released, will start to follow the APP release cycle and thus will stay up-to-date to the latest APP version.
Once 2.0.0 is released, the price for APP will increase. Owner's license holders will not need to pay an upgrade fee to use 2.0.0, neither do Renter's license holders.
Hello Mabula. I am having an issue with amp glow not being fully removed from stack with ZWO 183MM Pro camera. I am taking 300" photos with 6nm narrowband filters and have tried gain of 53 and 111 based on Cloudy Nights forum by John Rista. I used offset of 7 with gain 53 and offset of 11 with gain 111 and typically dither every other frame. I will be trying a higher gain and offset based on a couple of other people's suggestions as soon as winter is done. I use darks, flats and dark flats. Any advice would be great. Let me know if you need any more information. Photo is OIII filter with gain 53 and offset 7. Thanks, Tom
Hi Tom @tfergu01,
Thank you very much for your question.
The sensor in your camera, the ZWO 183MM, is known for having clear amp-glow. The keys to get rid of it properly is:
- do not use a too low sensor offset, I guess your's will do, but increasing the offset to 20 will not harm your data at all and will be safer, so it's definitely something you can try going forward.
- Now the most critical part is this: the CMOS sensor in you camera has amp-glow which is a non-linear signal in the dark current of your sensor. To remove it completely in the calibration process, the light frames must be calibrated with darks that have the same temperature, same exposure length, same sensor offset and same sensor gain. If you manage to create completely matching darks, the amp-glow should be fully gone in a single calibrated light frame. If it is not, then either the darks are not matching the proporties of the lights, or you have a more serious issue, like a light leakage in your optical train.
- Lastly, make sure that in 2) Calibrate, you have the option of adaptive pedestal/reduce Amp-Glow enabled.
Let me know if this helps 😉
Mabula
@mabula-admin Hi Mabula,
My darks all have the same settings as the lights so that should be good. I don't think it is a light leak as the issue is right where the amp glow is. I am in the process of taking new darks for the upcoming year with a higher gain and offset. I will see if that helps once winter is gone and I can begin taking some photos. Thanks for the advice, Tom
I even use bias instead of flat darks with my 183MM Pro and don't see any remaining amp glow. Though perhaps you have a more discerning eye than me. My first reaction was the same as Mabula's, I found that unless the darks matched EXACTLY it would show up. I'm using an offset of 50 now myself, just to be absolutely assured that I'm not missing the low end. I was reluctant to do so at first -- that sensor doesn't have a ton of headroom to begin with -- but it seems to work fine.
Hi Rick, we chatted on this forum a month or two ago when I think you had posted something about the 183MM. That chat and someone I follow on Instagram are why I am going to try a higher offset to see if that will help. I have tried just about every combination of bias and dark flats but they all seem to turn out the same to me. I think some of it may have to do with 6nm narrow band filters just not allowing enough light pollution through so any noise pattern or residual amp glow can be seen if stretched enough. Plus the OIII signal is usually not very strong on most nebulae so that doesn't help. Nothing like an Ha. Thanks for the advice Rick. Tom
Hi Tom @tfergu01,
Please let me know if things are better going forward with your data and amp-glow issue.
Regarding the sensor offset, it is definitely worth trying a higher offset, it will not harm the data and might solve your issue 😉 You can also visually check if the offset is high enough. Look at the histogram of your darks, it must not clip on the black/zero/0 level at all. The black level is the left side of the histogram. We have tested a lot with the 183 sensor, because it's amp-glow is very strong. We know from this testing, like Rick @rickwayne indicates, that the darks really must be identical for sensor gain, sensor offset, exposure length and temperature to work as expected. Any deviation in these parameters will result in visual residual amp-glow, because the amp-glow signal of the 183 is a very non-linear signal. Non-linear means that twice the exposure time does not give twice the amp-glow, the amp-glow would be much more than twice actually.
Mabula
Hi Mabula,
All my calibration frames are identical to the light frames. I think some of it may have to do with the 6nm narrowband filters and so there may just not be enough light pollution to swamp the read noise or any small residual amp glow. I will try the higher offset when winter is done and let you know if that helps any.
Thanks, Tom
Hey Tom, I just got an Antlia 3nm H𝛼 filter for Christmas -- weather has been terrible in Wisconsin so I only just managed to capture some data this past couple of nights. I will let you know if I see any differences in calibration versus the ZWO 7nm filter I had been using.
Hi Mabula,
All my calibration frames are identical to the light frames. I think some of it may have to do with the 6nm narrowband filters and so there may just not be enough light pollution to swamp the read noise or any small residual amp glow. I will try the higher offset when winter is done and let you know if that helps any.
Thanks, Tom
Hi Tom @tfergu01,
Okay, please let me know if all is okay with the higher offset.
In my experience and also from a theoretical/mathematical viewpoint regarding the astronomical data calibration using darks, flats etc... the light pollution and read noise will have nothing to do with removing the amp-glow from the lights. If the darks really match properly, the amp-glow should simply be gone.
So if you are 100% certain that the darks match perfectly with the lights, then another more serious issue could be interfering here... if you have a light leak in your optical train, even a very slight one... then it will create issues like this as well. So please double check that as well. You expect the darks to be a the same ADU level as bias frames, if they have a clearly higher median/average value than bias, you could have a light leak.
Mabula
@mabula-admin Hi Mabula. So I finally got around to getting some more narrowband data with my 183MM pro. I increased the gain to 150 and the offset to 30 to see if that might help the ampglow. I am still seeing ampglow remnants mostly with the 7nm OIII filter using the 30% stretch in APP (first photo). I was able to minimize it with light pollution reduction (second photo). I am pretty sure there is no light leakage but can I test this by taking a dark frame and a bias frame and checking the median average value of the two of them? Any suggestions as to what I might test next? The final starless photo looks OK but I still see a little extra blue where the ampglow was even with a little extra cropping on that side (third photo). Hoping to add some RGB stars this week.
Thanks, Tom
