วันอังคารที่ 5 มีนาคม พ.ศ. 2556


High ISO noise and detail

High ISO noise reduction settings

The EOS 650D adds an extra stop of ISO sensitivity compared to its predecessor, the EOS 600D, with in-camera noise reduction settings that have been tweaked sightly, as you can see on the noise performance page of this review. And for the most part, the 650D maintains the well-considered balance between noise suppression and detail in JPEG mode we're used to seeing from Canon's entry-level DSLRs.
The one minor exception to this occurs once you venture beyond ISO 6400. As you can see from the shape of the graph on the noise performance page of this review, the 650D switches to a more aggressive approach to noise suppression at ISO 12800. The real-world ramification is that in some instances, this heavier-handed approach can obscure a bit more fine detail at the default NR setting. Below we've shot a low light scene at ISO 12800 in order to compare the 650D's NR settings. For a look at the 650D's new multi-shot NR mode, see the image quality tests page of this review.
ISO 12800 NR Standard (default)NR Low 100% crop
NR Standard 100% cropNR High 100% crop
In the crops above, you can see that at ISO 12800 very fine detail like the mesh netting begins to be smeared away at the default NR setting. And for this detail loss, neither of the two higher NR settings are reducing the appearance of chroma noise to any greater degree. As such, we'd suggest that when you do find yourself shooting at such a high ISO, you can hold onto slightly more detail by using the 'NR Low' option.

Compared to Nikon D3200

On the noise performance page of this review we've measured noise performance of the EOS 650D against both its predecessor and its peers in our studio test scene. Here we provide you with a real world comparison of high ISO performance using a still life scene. It was shot under low color-temperature (approx. 2600K) artificial light, designed to be representative of typical indoor lighting. This accentuates the appearance of noise due to the low level of blue light in the spectrum of the light source. And to achieve accurate white balance the blue channel has to be amplified strongly, and the green channel to a lesser extent - thereby increasing the visible noise.
Both cameras were shot at ISO 6400 in Raw mode and the files were processed via ACR 7.1 with sharpening and noise reduction both set to '0'. The D3200, which boasts a higher resolution of 24MP (versus 18MP for the 650D) was downsampled using Photoshop's Bicubic algorithm to match the pixel width of the 650D. Identical amounts of low-radius sharpening were then applied to all both images in Photoshop.
Canon EOS 650D
ISO 6400 ACR 7.1 Raw
Nikon D3200 (downsampled)
ISO 6400 ACR 7.1 Raw
NR Standard 100% cropNR High 100% crop
NR Standard 100% cropNR High 100% crop
NR Standard 100% cropNR High 100% crop
Looking at the samples above, the EOS 650D compares very favorably against the Nikon D3200. While the 650D shows greater chroma noise in areas of solid black, it also retains a touch more color saturation. Other than that though, there is very little to separate these two APS-C cameras in terms of detail retention.

ไม่มีความคิดเห็น:

แสดงความคิดเห็น