Strange markings on images

[DeepThought]

Hi

Can anyone tell me what the strange "S" shaped markings could be on this crop of a stacked image? They appear to be all over it in varying colours but I have just zoomed in on a couple of them.

Thanks

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[Alien 13]

They look like hot pixels if you are using DSS try ticking the sigma clipping box in the stacking parameters, light tab.

Alan

[DeepThought]

Thanks. Is this normal then? The camera is under warranty if it's anything untoward.

[Alien 13]

It is normal and it may only appear on the odd sub, i had a similar problem and found if i only stacked half my subs it didnt show anything same if i did the second half but using the sigma clipping fixed it.

There is a method of remaping the sensor to remove hot pixels it involves runing the camera manual sensor clean routine, during this the camera disconects the sensor electricaly to prevent any static damage you wait 30 seconds then turn the camera off this remaps the sensor when next turned on.

There are a few topics on google this is one http://www.bluehoursite.com/articles/how-get-rid-stuckdead-pixels-canon-dslr-camera

Alan

[Astrosurf]

Take darks when you take images. They'll remove the hot pixels and noise for you.

Alexxx

[glowingturnip]

yeah, it's just hot or cold pixels, appearing in slightly different places in each off your subs, perfectly normal.

check your stacking routine used - a median stack will remove all those outliers but be quite noisy, an average stack will show them all, so not ideal either, but you should be able to use something like a sigma clip, which rejects outlier pixels and averages the remainder, then they will magically disappear