<https://forum.affinity.serif.com/index.php?/topic/130322-halo-on-edge-of-selections/#comment-716828>
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"If this is the original no adjustments file (I switched them off) and I notice your aperture was an F11 which is reasonably wide, then all this is Chromatic aberation.  Mostly Blue.  If you take a look a look at the screen shot I took you will notice that there is no fringing between the two hills where I put the black arrow, but only where the light is hitting the mountains.  Wide aperatures tend to do this in these conditions, although not with every lens I imagine.  I have not looked but you should be able to get rid of this in the DNG when you first load it into A.photo.  And to my utter shock and horrow, I see no options for eliminating chromatic aberation in affinity, so I guess you have to do it the long way in photo itself.  I have not looked into this but there are plenty of youtubers who might have done this already in affinity  Photo.\n \n\n\n\tEDIT:  may I suggest you consider using a neutral grey filter in these conditions, where the darker part of the filter would be positioned over the sky and the lighter part over the land.  You will be surprised at how much less editing you will need to do with also a polarising filter. Also I always OVER expose my images even in bright conditions, a rule of thumb is that the camera always lies, in other words it attempts to reduce everything to neutral grey.  In film photography we UNDER expose, in digital, We OVER expose by at least 2/3 of a stop, check your histogram and get as much information as possible to fall all the way to the right of the histogram, it then becomes a simple matter of pulling back the highlights in the RAW editing stage.  You can not add information but you can always remove some is a rule of thumb.\n \n\n\n\t \n \n\n\n\t "
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