Strange Hot Pixels on Final Integration

Mabula and Vincent, Thank you for the reply! I checked my dithering with the ASI533MC and it appears it is ON in Stellarmate/EKOS/KStars (and it says it is dithering) but PHD2 is not receiving the commands! So this is it. Thank you for your help. Will have to sort this out in EKOS>PHD2 then.

@petercpc Also Turning off local normalization rejection in the integration TAB got rid of almost all of these pixels. So when not dithering this seems like a reasonable solution for now.

@xs4allan Excellent! I learned something as well as I didn't know some sensors might "misbehave" in this manner. 🙂

Posted by: @petercpc

Re dithering. I always dither when using my Canon and BYE. However, when using my cooled ASI533 i find that noise is not such an issue and have been using it without dithering to save time on capturing lights. I use Sharpcap generally with the ASI533 and, so far, I can see no way to dither unless I do live stacking which is not something I do. I would rather stack in APP.

Peter

Dear Peter @petercpc, @xs4allan , @vincent-mod

Still, dithering is highly recommended allthough visually you think that it is okay not to do it because off less obvious noise patterns.

Any sensor has patterns that are bigger then several pixels large... only by dithering several pixels you will be able to completely get rid of that when you integrate your frames.

Noise analysis always confirms this, noise will go down more efficient in the integration if you dither ;-). If you don't dither, yes you will save some time, but your end result might still have higher noise with more exposure time because the patterns are burnt into the integration... I can not see a good reason not to dither to be honest 😉 It really improves the results and you will get far less issues like this. If your mount is slow with dithering, okay, maybe reduce the dither step somewhat so it goes quicker, but in my experience, you always want the dither step to be at least several pixels to get the best noise reduction. On my asi1600mm-c I dither 30-50 pixels even. If I do only 3-5 pixels, noise is not dropping as efficient and I have tested this on multiple datasets. If I don't dither, the result immediately is rather bad in terms of noise reduction. The difference is a factor of 10-40% in some cases, which is very clear to the eye.

Let me know if this makes sense,

Mabula

@mabula-admin

Hi Mabula

Yes, that makes perfect sense. As I said I am still trying to find a way to get Sharpcap to dither. If not I may be forced to use APT which I find unnecessarily complicated to use. If only BYE made an application for ZWO cameras.

Peter

@petercpc N.I.N.A. is free and also good software to image with.

@xs4allan

I find NINA even more complicated than APT.