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Participating Frequently
September 15, 2021
Question

Sky Replacement problem

  • September 15, 2021
  • 4 replies
  • 372 views

When photographing aircraft at airshows there is often a problem if you expose for the aircraft the sky is overexposed whereas the opposite happens if you expose for the sky. I thought of using the Sky Replacement tool as a way around this by creating two versions of the picture in Photoshop. One with the aircraft adjusted to my liking and the other with sky as I want it. The latter is saved as a 'Sky Replacement' so the correctly exposed aircraft hides the underexposed aircraft when the two are combined using Edit/Sky replacement. So much for theory. The Replacement sky picture, despite being the same number of pixels, appears larger ( about 10%) so my under exposed aircraft is not hidden. The obvious answer is to use the 'Scale' slider but this only works in integer increments so that it is not possible to get an exact match between the two.

It might be possible to get an exact match by adjusting the pixel size of the main picture but this could be very tdious.

John

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4 replies

JohanElzenga
Community Expert
Community Expert
September 16, 2021

The reason is probaby that one wants to be able to move the sky a bit to get the best composition.

 

-- Johan W. Elzenga
rieleyjcAuthor
Participating Frequently
September 16, 2021

Oh dear, I was hoping to avoid having to explain what was being this..

First of all its the same shot with the exposure adjusted in Photoshop, not two pictures. The reason for not having a different sky is to do with being able to see the aircraft propellers. If I adjust the picture settings to get the underexposed aircraft the propellers, which are blurred, become very faint and tend to disappear when a replacement sky is added so I adjust the one to be used to act as sky, which is overexposed and featureless, to show some cloud texture. This causes the aircraft and its propellers to become darker. When that version is used as the replacement sky the aircraft is hidden by the correctly exposed version but the propellers are now visible.

I appreciate that there may be other ways around my problem but I am not sufficiently familiar with Photoshop to make use of them at the moment and my method seemed to offer a good way of dealing with the problem but I was thwarted by Photoshop increasing the dimensions of the replacement sky and I wondered what was the reason for this as I cannot see one.

John

c.pfaffenbichler
Community Expert
Community Expert
September 16, 2021

Please post a pair of sample-images. 

 

If Sky Replacement works (aside from the scale of the sky) I suspect you might be served as well by using Select > Subject and using the Selection as a Layer Mask for the plane against the darkened sky. 

JohanElzenga
Community Expert
Community Expert
September 16, 2021

You are making things unnecessarily complicated. Shoot the sky without any aircraft in it.

 

-- Johan W. Elzenga
PECourtejoie
Community Expert
Community Expert
September 16, 2021

Hello, if I understand, the plane has moved between the two shots, unless your bracketing is very fast...

I am wondering if erasing the plane on the correct sky, with the patch tool, would not be a step to add, and if the sky replacement tool is the correct job, you might just stack the images, select sky and use a blending mode to correct the sky...