Can a circular polarizer make photos look noisy?
Asked 10/16/2013
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I’m using a Canon 450D with a Canon 17-85mm lens, and my photos seem much noisier when I attach a circular polarizer (CPL), especially when shooting RAW. Is this normal, or could it mean the filter is poor quality?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
13y ago
2 Answers
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A circular polarizer wouldn't directly create noise. The noise is a function of the sensor and exposure settings. Better filters help capture better images but better filters don't prevent noise.
In this case, underexposure (an effect of the polarizer) may be the reason for noise in that sample image. Additionally, if you're noticing it more when you shoot RAW, that could be because RAW retains more noise than a JPEG that has had in-camera noise reduction already applied. Which is to say: you may be noticing the noise on a RAW image because the RAW file hasn't had any noise reduction applied and the JPEG almost certainly received some in-camera noise reduction.
Originally by user22737. Source · Licensed CC BY-SA 4.0
user22737
13y ago
0
Generated from our catalog & community — verify before relying on it.
A CPL should not directly create sensor noise. What it does do is reduce the amount of light reaching the sensor, often by around 1–2 stops. If exposure isn’t adjusted to compensate, the image can be underexposed, and underexposure makes noise more visible—especially in darker areas and when you brighten the image later.
RAW files will often appear noisier than JPEGs because RAW keeps the original sensor data, while JPEGs usually have in-camera noise reduction applied.
A poor-quality or dirty filter can still degrade image quality in other ways, such as haze, flare, lowered contrast, or smeared-looking highlights, but that’s different from true sensor noise.
What to check:
- Compare the same scene with and without the CPL
- Compensate for the light loss by using a slower shutter speed, wider aperture, or higher ISO if needed
- Make sure the filter is clean
- Don’t judge RAW vs JPEG the same way unless you apply similar noise reduction in processing
So: a CPL isn’t supposed to add noise by itself, but it can indirectly make noise more noticeable if it causes underexposure.
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