Why is there so much noise in the sky, and how can I reduce it next time?
Asked 1/2/2017
7 views
2 answers
0
I photographed an eagle in flight and the final JPEG shows a lot of visible noise, especially in the smooth sky background. My settings were ISO 900, 1/4000 sec, and f/9. The bird looks acceptable, but the sky became noisy after processing the RAW file. What likely caused this, and what camera settings or editing techniques would help reduce sky noise in future shots?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
9y ago
2 Answers
3
Some of the below repeats parts of other answers. Apologies for that...
The higher the ISO, and the longer the shutterspeed, the more noise you're going to get.
Some cameras are better than others. Cameras with larger sensors tend to have lower noise and better high ISO performance. A high end full frame 35 mm DSLR with good high iso performance would make a big difference.
Given your current setup, shoot with the fastest lens you can get, with the lowest ISO you can. You might try using a larger aperture.
The good news is that the noisy parts of your image are out-of-focus.
If it were my shot I would open the raw image in Photoshop, select the bird and the tree, and then invert the selection to select the sky and apply moderate gaussian blur to the sky. That would hide the noise quite effectively. You could also use the same technique to select the sky and then apply a variety of other noise reduction techniques, but for an out-of-focus sky, blurring would be easy, effective, and give very natural-looking results.
I downloaded your image and took the liberty of doing what I describe. Here is a 100% crop of just the eagle so you can see the effect:
I would NOT use global noise-reduction software, as that tends to destroy detail in the parts of the image you want (the bird and the trees.)
Originally by user32419. Source · Licensed CC BY-SA 4.0
user32419
9y ago
0
Generated from our catalog & community — verify before relying on it.
The main issue was likely underexposure combined with a fairly high ISO. Bright, smooth areas like sky make noise especially obvious, and lifting exposure in RAW processing can make that noise look worse.
Your shutter speed of 1/4000s is very fast for this kind of shot, and f/9 is relatively narrow. That combination forced ISO upward. In many cases, you could reduce noise by:
- using a slower shutter speed if motion blur will still be acceptable
- opening the aperture wider
- keeping ISO as low as possible
There’s often a tradeoff: for birds in flight, you may need a fast shutter speed, so some noise can be unavoidable.
For editing, apply noise reduction selectively to the sky/background so you preserve detail in the bird. Since the sky is already out of focus, moderate blur or noise reduction there can work well. Also, noise is often more noticeable on screen than in prints.
In short: expose well, avoid unnecessarily fast shutter speeds or small apertures, and use selective noise reduction on smooth background areas.
Recommended products
UniqueBot
AI9y ago
Your Answer
Related Questions
How can I avoid sky banding/posterization when denoising RAW files in Darktable?
How can I reduce red noise in deep-sky galaxy photos?
How can I keep a small bird from looking dull when shooting against an overcast sky?
How can I reduce digital noise in Lightroom exports and when shooting?
Why is my video noisy at ISO 200 on a Sony A58, especially in dark areas?