What I've been doing with my Pentax (maybe a few NSFW?)

Started Jan 27, 2013 | Discussions thread
mike703 Veteran Member • Posts: 6,655
Re: What I've been doing with my Pentax (maybe a few NSFW?)

Simon Devlin wrote:

I was glad to see that you too were getting some grain/noise in your longer focal length shots. I thought it was my lens but hopefully someone can offer advice.

Hi - nice series OP!  Good catch on the osprey fishing.  The only time I've seen an osprey was about half a mile away.

Simon - the noise isn't directly lens related; it is a combination of cropping and the fact that the background is smooth green (most obvious on the last hummingbird shot).  The OP will be able to tell us how much those shots were cropped but it makes sense that cropping will be most necessary when the lens is already at its longest focal length, and that of course will magnify any noise... so the noise does become visibel at the longest FL but that's not the fault of the lens!

Smooth green / blue backgrounds (blurred foliage, or skies) show up noise particularly badly.  The red channel is inherently the least sensitive of the three primary colours (R/G/B) so shows noise most.  On a blue / green background when the red content is close to zero any small noise in the red channel will stand out.  Just google 'red channel noise'.  The good news is that it's very easy to remove with a NR plugin like Topaz DeNoise or something similar.

Best wishes

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