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ISO Sensitivity / Noise levels (contd.)

In-camera High ISO noise reduction

Hidden away in the E-P1's menu system is the Noise Filter option, which defines the amount of noise reduction applied to its JPEGs. Unusually, this setting has an influence at all ISOs, so it's not a choice you only have to think about when shooting in low light or when using high ISOs to keep the shutter speed up.

As we've seen with previous models the difference between Normal and High (or Low for that matter) isn't huge, and it's obvious that Off, whilst a lot lower, isn't really 'off' at all (there's far too little chroma noise). Our advice when shooting at anything under ISO 800 is to stick to 'Off' (to get the maximum detail). Over ISO 800 it's going to be more a matter of taste, with 'Low' the best compromise between noise and detail in our opinion.

  Noise Filter Settings compared
Off
Low
Normal
High

Indicated ISO sensitivity is on the horizontal axis of this graph, standard deviation of luminosity on the vertical axis (note that the standard deviation scale here is magnified 2x compared to the graphs on the previous page).

In-camera High ISO noise reduction

  Off Low Norm High
ISO 100
ISO 200
ISO 400
ISO 800
ISO 1600
ISO 3200
ISO 6400
         

Unlike most cameras, which have optional levels of noise reduction at high ISO settings, the E-P1's 'Noise Filter' cracks down on the noise at all settings. How smooth or noisy you want your pictures is a matter of taste. It would be nice if there was a noise reduction setting that tackled chroma noise more aggressively than luminance noise, but that's something that's easy enough to apply in many RAW converters.

Noise reduction and fine detail

The biggest issue with noise reduction - especially luminance noise reduction - is that in the process of blurring away the noise it can also have a very destructive effect on the detail in an image, particularly the fine, low contrast detail you might find in hair, fur or grass. To better judge the effect on fine detail lost due to noise reduction we have shot our lovely model and produced crops from the feathers in the image.

To check the effect of noise and noise reduction on low contrast detail we shoot our lovely model framed as shown here, with the new added feature of feathers. The very fine detail in the feathers will help to better judge the effect of noise reduction on fine detail.

Raw vs in-camera JPEG noise reduction low contrast detail comparison

Here we've used Capture One as the comparison, since Adobe Camera Raw is not able to render the low contrast detail quite as well. As before we've had to trick Capture One into processing these files using E-30 parameters, so they may not be perfectly optimized for the E-P1 - but they work perfectly well for this comparison. The Capture One crops have had noise reduction reduced to its lowest settings but are, in all other respects, Capture One's default output.

As you'd expect, given what the noise reduction crops further up this page show, there is a significant loss of fine, low-contrast detail as soon as you turn the Noise Filter on. At ISO 400 and above, you have a choice between whether you want the finest detail masked by noise or by noise reduction - you can't retain the detail.

  Cap 1 RAW NR OFF JPEG NF-Off JPEG NF-Normal JPEG NF-High
ISO 100
ISO 400
ISO 800
ISO 1600
ISO 3200
SO 6400
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