# Image question



## MPCSound (Feb 29, 2016)

Hello group, I am a photography hobbyist and have been shooting with a Canon 700D(T5i) for over two years now. My first DSLR, and have been learning more about working in Manual Mode and understanding the relationships between my f/stop, Shutter and ASA. I have noticed how the night sky changes color with simple adjustments to the any of these. I understand that topic. 

My settings and camera setup... Canon 700D, Canon 18-135mm lens, UV Filter, 18mm, f/3.5, 15.0 sec, 400 ASA

Last week I was taking pictures of the night sky in Sequoia NP, and set up many shots with intention to paint the trees with some light. Sadly, I lost my flashlight in the trip, and had to resort to my iPhone to light. Not ideal, as you can see. However, with all settings being equal, the sky still changed color on me. Here's a shot with no light painting...






Here's the same shot, same settings, with my first paint. Not ideal, but here, the sky turns blue. 






And here is one where I backed off the light and got a decent coverage of the tree, that could be edited to make brighter. More even spread and better. The sky appears to be as it should. 






My natural deduction is that the kick from the light on the tree is what's causing the camera to treat the darks differently. As the sky came out as it should when I backed the light off. 

My questions is what is ultimately causing this phenomena? Would a full sensor treat this better? Would a different camera manufacturer treat this differently? Is it the lens? Is it the UV Filter(used simple to protect the lens)?

I appreciate any feedback you may provide. Thank You!

Michael P. Clark


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## Didereaux (Feb 29, 2016)

10- to 1 your camera is on auto WB.   thus it is reading and averaging from no phone light and then from the phone light   that will give you WB issues every time.


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## 480sparky (Feb 29, 2016)

Not sure why you think the sky shouldn't be blue.  A clear sky is _always_ blue.... day or night.


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## Derrel (Feb 29, 2016)

Didereaux said:
			
		

> 10- to 1 your camera is on auto WB.   thus it is reading and averaging from no phone light and then from the phone light   that will give you WB issues every time.



The above is what I think is the issue. These small images are missing EXIF information that would make it pretty easy to check the WB that was used.

Were these shot as in-camera JPEG images, or as .CR2 raw files that were later processed?


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## MPCSound (Feb 29, 2016)

I just checked my camera.....Auto-White Balance. (Slaps forehead)

Thank you for that. 

I do agree 480sparky, sometimes the sky plays well blue. But to my eye, it's much darker than this. This was more a question of why. 

Thanks again for the quick replies. 


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## spiralout462 (Feb 29, 2016)

I will add, the UV filter will cause more problems than it will prevent.  I will never use or recommend one for general photography.


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## GHK (Apr 8, 2016)

480sparky said:


> Not sure why you think the sky shouldn't be blue.  A clear sky is _always_ blue.... day or night.



I'm not really disagreeing but I suspect that, in the middle of the night, there may be very little colour.   The familiar blue is due to scattering of the white light from the sun and there may be very little effect when the sun is WELL below the horizon.
In the first image, the sky is not far from neutral although careful measurement shows that the hue is closer to blue than to any other primary.    The more obvious blue in the others may be down to the characteristics of the torch.


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