Purple colouring to photo of stars

[jhallettbc]

I just recently got the Z20 f1.8 and am in love with it. Scenics are so incredibly sharp. A few nights ago, when away from the city and on an island that has very little ambient light, I tried some star shots. This is very sharp but I'd like to know what caused the purple colouring in the background. Any ideas?

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[DRwyoming]

How did you set white balance in the camera and did you change it all when you imported it into your post processing tool?

You can get some color shifts if shooting in an auto white balance mode. I usually use a fixed white balance around 5500K for night time shots. You can always change the WB in post when shooting RAW but it's nice to have it come into post processing from a known point.

 

[jhallettbc]

I just left it at auto white balance in the camera and in LRC. Thanks for the advice about 5500K. I tried changing the colour balance in LRC from 5500 to 4300 and the purple tint was always there. Might it have something to do with me having to increase the exposure in LRC because I had under-exposed it in the camera?

 

[jhallettbc]

This is one I took the night before the one above. There is less purple in it but it is noticeable in the bottom right and that was where there might have been some ambient light coming from Vancouver. The WB as shot was 3800K.

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[DRwyoming]

It could be, but I’d put it down to running auto WB in-camera. It sounds like the tint which should tend a bit to the green for night sky shots shifted towards the magenta side.

I’d probably work the tint slider more than the temp slider in LR unless there’s a clear blue or yellow cast to the image. One trick is to temporarily run the saturation sky high to pick up on color shifts remembering that the night sky isn’t blue and has more of a green tint and not so much magenta.

 

[jhallettbc]

I will experiment.