:-)..........haven't heard that word in years.
----- Original Message -----From: Chuck Norcutt
<chucknorcutt@xxxxxxxxxxxxxxxx>To: Olympus Camera Discussion
<olympus@xxxxxxxxxxxxxxxxx>Sent: Thu, 15 May 2014 19:32:19 -0000 (UTC)Subject:
Re: [OM] (OM) Rendition of red colours by OM digital cameras
Silvernose nattering. Send real data.
Chuck Norcutt
On 5/15/2014 10:56 AM, Ken Norton wrote:>> Repeat when you have a side-by-side
of the same subject taken at the same>> time in the same light.>> To a certain
extent I agree with you. But in actual practice, the> difference is quite real.
If a person photographs test charts you'll> see zero significant difference.
However, depending on the light, the> E-1 responds is a VERY unique manner.
This is related to three primary> contributors:>> 1. The red sensel sensitivity
is shifted more to the IR. The IR cut> filter is not quite as strong. Some
flowers actually extend into the> near IR which the eye sees, but sensors
usually don't.>> 2. The red sensel sensitivity has a secondary bump in
violet.This> means that the E-1 is actually able to reproduce violet. (purple>
flowers may be purple (red+blue) or violet. Most cameras will only> properly
capture the purple flowers and will shift the violet ones to> blue. The E-1
fakes this by having the red sensels see the near UV> colors and th
en gives you a red+blue to mimic violet. This can be> tested with a prism.>>
3. The red sensel sensitivity doesn't extend as deeply into the> yellows. Most
cameras capture yellows better than the E-1 at the> expense of the reds. This
narrower spectral response (actually, it's> about the same width as the others,
but is just shifted more towards> IR) means that the red channel is less likely
to blow out with more> yellow content flowers. This maintains more tonal
gradiation in the> highlights of the red sensels themselves.>> On the flip side
of all this is the green sensels have their issues.> Unlike normal sensors, the
E-1 sensor MUST use a 4-pixel mix. Most raw> converters can work with the
sensor data on a 3-pixel mix. No, in most> cameras, it does NOT combine two
greens with one red and one blue. It> combines one green, one red and one blue.
Everybody assumes 4 pixel> mix and comes up with all sorts of crazy
explanations as to why there> are two greens, but if you look at
the matrix and see how you can> combine data at a single pixel location, you
do so with just a triad.> If you go with a quad, you lose a lot of
detail--which is what has> happened with the E-1. There are many versions of
raw converters, but> nearly all ones (especially the Adobe ones calibrated for
use with> Nikon and Canon cameras), they actually use a triad.>> However, due
to the 4-pixel mix, the way the two greens have different> color/sensitivity
responses, AND the added noise dithering, the> effective dynamic range of the
E-1 is massive. The E-1 is about the> only camera that you can recover a 4-stop
underexposed raw file and> still end up with a usable image. The
anti-grain/noise freaks say that> all E-1 images are unusable, so keep this
comment in mind as you read> my claim. But I've certainly used 3-stop
underexposed images in> wedding albums without grief. This happens when you get
a flash> misfire.>> The E-1 also has two other traits worth noting:>> 1. Skin
tones.
The extended near-IR response of the red sensels tends> to lighten skin tones
a little bit, however, not so much that the skin> turns waxy. This has the
great benefit of smoothing the skin out a> little bit AND it also helps make
zits and blemishes fade.>> 2. The narrower red response in the visible spectrum
combined with the> two green sensels of varying response makes for what appears
to be a> greater midtone tonal contrast. So, there is a natural "S-Curve">
applied to the image without an actual "S-Curve" being applied to the> image.
There is a lot of mathematical explanation that I could go into> on this, but
you can't argue with the results. While you can always> adjust in post to mimic
a lot of this, that requires bit-bending and> any time you are bit-bending you
effectively end up with a lower> bit-depth per color channel. There are a
number of medium-format> digital backs that have this trait as well as the new
Fujifilm X-tran> sensor. But it certainly is something
that I have not seen with almost> any normal CMOS DSLR. The E-1 files, even
SOOC jpegs, have better> midtone contrast than nearly any other camera.>> Yes,
I do miss mine.>>--
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