Crop Factor, Low Light and Aperture with m4/3 lenses? Part 2

Started Jun 16, 2014 | Discussions thread
Just another Canon shooter
Just another Canon shooter Veteran Member • Posts: 4,691
Re: Reply to Just another Canon shooter

knickerhawk wrote:

Let me repeat that the St.Dev. cannot tell you anything at all about the character of the noise or even if it can be qualified as noise.

Nonsense. The Std. Dev., especially when broken out in LAB tells you a lot about the character of the noise for what is ideally a uniform patch with 0 deviation. We do not disagree that the number tells you nothing about the spatial distribution of the noise, but spatial distribution is only one element of noise.

You still do not get it. St. Dev. tells you absolutely nothing about the character (statistical distribution) of the noise. I can easily generate an absolutely noise free image (by human standards) that will have the same mean and St.Dev. Going back to noise, if you know the type of the noise, then yes, St.Dev. tells you about its strength.

and my own two eyes confirm that the character of the noise (the look) is different between these two cameras and the two converters but that's hardly a surprise and certainly not evidence that Adobe is somehow inappropriately tipping the scales in favor of the Oly (and only the Oly) with respect to noise reduction. Your speculation on that point is meritless.

I did not say "inappropriately". And you did not answer the question, which was very simple. Does the lower right square look more NR'd than the rest or no? As simple as that.

I answered your question in detail. It's just that my answer wasn't the admission you were looking for. To repeat, there is less luminance variation in the LR Oly patch but more color variation relative to the DXO Oly patch. The spatial distribution and color "pattern" you keep referring to is very similar between the two patches. This conclusion is supported by the Std. Dev. numbers and examination of the individual channels for the two patches in LAB. Your characterization that LR "clearly...applies more NR (or whatever you want to call it to the color to the Oly than DXO" actually has things turned around. The character of the noise is more luminance influenced in the DXO rendering and more color influenced in the LR rendering. The opposite of what you claimed. Unfortunately, your refusal to utilize readily available objective information to enhance your initial subjective impression (which is apparently weighted strongly toward better discrimination of luminance differences than to color differences) has biased your observational skills.

You miss the point again. The lower right crop has what is usually described as "blotchy" noise - areas with too much correlation between the pixels. You are fixated on the color values only.

By the way, according to DXO, the red channel is the least sensitive for both the 6D and the EM1.

What we see depends on the three RAW channels, on the values of the color matrix, etc. Canon's blue color filters tend to be not so "pure".

You said, "[Blue] is the noisiest color for the 6D." Now that seems to be evolving to "not so pure" whatever that means.

It means something about the RAW blue channel.

Here are the noise covariance ellipses for the 6D and the EM1, luminance=30, ISO=100.

6D, daylight

EM1, daylight

The 6D has the least noise at "red", RGB around 130/30/30, and somewhere between red and blue. They did not measure saturated blue - their "most blue" ellipse is at RGB 0/70/160. The worse is at some mixture of green and red, with G=R approximately. Switch to tungsten, and the difference is more pronounced.

I was talking about deep saturated blue, as in the crops above, under tungsten light. DXO do not compute anything there. How do I know that - just look at the color chart, it is obvious. Also, years of experience with Canon cameras and "blue hour" shots help. Finally - those ellipses are based on RGB values but do not reflect how sensitive we are to different colors.

BTW, I will stop replying about this topic - we got so involved into the technicalities that the main point was lost.

 Just another Canon shooter's gear list:Just another Canon shooter's gear list
Canon EOS 5D Mark II Canon EF 15mm f/2.8 Fisheye Canon EF 35mm F1.4L USM Canon EF 50mm f/1.2L USM Canon EF 135mm F2L USM +4 more
Post (hide subjects) Posted by
Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow