From: Floyd L. Davidson on
"Wilba" <usenet(a)CUTTHISimago.com.au> wrote:
>DRS, I really admire your patience and tolerance.
>
>As a rule I try not to be _too_ insulting, but in this case I have to say,
>Floyd, you are ASTONISHINGLY thick and childish for someone who often sounds
>very intelligent. I can't recall the last time I've seen such a stupendous
>display of belligerant idiocy. You really are a champ.
>
>Ha, that feels better. Carry on.

Amusing what people say when a topic goes above their
level of skill or understanding. It's wonderful that
such posts make you feel good, but you'd be way ahead of
the game to patiently pay attention and *learn*
something. That would make you feel even better.

--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd(a)apaflo.com
From: Floyd L. Davidson on
"Wilba" <usenet(a)CUTTHISimago.com.au> wrote:
>Porte Rouge wrote:
>> Wilba wrote:
>>> Porte Rouge wrote:
>>>>
>>>> I set my exposure to slide the histogram to the right, without clipping
>>>> ( when I have time), to capture the most tonal levels . So, now when I
>>>> am editing the photos they are over exposed(not clipped). A sunrise is
>>>> a good example. The deep colors are washed out. The obvious fix(to me
>>>> anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
>>>> is, by reducing exposure in post, am I just ending up in the same place
>>>> (histogram to the left) as if I had just ignored the histogram when I
>>>> was shooting and set the exposure to properly expose the image using
>>>> my light meter? I guess in short I am asking if Lightroom or CS4 loses
>>>> tonal values when you reduce exposure in editing.
>>>
>>> Yes, reducing the exposure in Lightroom just puts your histogram back to
>>> the
>>> left, so that's a waste of time. To avoid having the deep colours washed
>>> out, you need to make use of the full tonal range available in the image.
>>> If
>>> you have done a good job of exposing to the right, your highlights will
>>> be
>>> pretty much where they need to be. So then all you need to do is raise
>>> the
>>> black point (e.g. using the Levels dialog in Photoshop), so that the dark
>>> tones in the scene end up as dark tones in the image. If you are using
>>> the
>>> Levels dialog in Photoshop, while you drag the black (or white) point
>>> slider, press the Alt key to see which pixels are clipped (or blown).
>>>
>>> (The following relates to my experience with a Canon 450D. YMMV.)
>>
>> Aha!
>
>:- ) Was that what you actually wanted to know?

None of it is correct though. What do you get, for example, if you shoot
a image that is mostly an 18% gray card, against a black background?

If you use ETTR to get the most dynamic range, the gray card will show
up as very close to maximum white in the raw data.

"If you have done a good job of exposing to the right,
your highlights will be pretty much where they need to
be. So then all you need to do is raise the black
point (e.g. using the Levels dialog in Photoshop), so
that the dark ..."

Obviously that is not true. The only time it will be
true is when there actually *are* highlights that are
"pretty much" at pur white. Not all scenes have such
highlights, and therefore not all image data will have
them "pretty much where they need to be".

And that is when you use a raw converter or an editor
for "reducing the exposure in Lightroom just puts your
histogram back to the left.", and it clearly is *not* a
waste of time.

....
>>> So if you are bracketing for the best possible exposure, go at least two
>>> steps over what the histogram tells you is "correct". The maximum
>>> possible
>>> dynamic range occurs at the point where photosites in the highlights
>>> begin
>>> to saturate.
>>
>> What do you mean by steps? Do you mean stops, or steps on the aperture
>> or shutter dials?
>
>No, nothing to do with the increments by which the camera's controls change
>the exposure - that's arbitrary. An exposure step is a doubling or halving
>of the amount of light that reaches the sensor. A stop is a step achieved
>via the aperture. Most people also say stop when they mean a step achieved
>via the shutter.

Yes, they usually say that because in fact it is the
same thing in the context that you have described, it
changes the amount of light reaching the sensor.

And how you can say "nothign to do with the increments
by which the camera's controls change the exposure" and
then describe camera controls changing the
exposure... is amusing.

>> In everyday raw shooting, you can be quite relaxed about having a small
>> spike on the right of the histogram - that's actually a good thing.

It is, assuming you want to clip the highlights.
Otherwise, it's a fatal error, because there is no way
to recover the lost data. On the other hand, if you
back off on exposure just enough to make sure no
highlights are clipped, the loss of 1/2 to 1 stop of
dynamic range probably will mean absolutely nothing
(given that you won't print out anything that can show
more than 5 or 6 fstops and the camera will almost
certainly be recording 8 or more).

--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd(a)apaflo.com
From: Wilba on
Floyd L. Davidson wrote:
> Wilba wrote:
>> Floyd L. Davidson wrote:
>>> Wilba wrote:
>>>> Porte Rouge wrote:
>>>>>
>>>>> I set my exposure to slide the histogram to the right, without
>>>>> clipping
>>>>> ( when I have time), to capture the most tonal levels . So, now when I
>>>>> am editing the photos they are over exposed(not clipped). A sunrise is
>>>>> a good example. The deep colors are washed out. The obvious fix(to me
>>>>> anyway) in Lightroom or CS4 is to reduce the exposure. Now my question
>>>>> is, by reducing exposure in post, am I just ending up in the same
>>>>> place
>>>>> (histogram to the left) as if I had just ignored the histogram when I
>>>>> was shooting and set the exposure to properly expose the image using
>>>>> my light meter? I guess in short I am asking if Lightroom or CS4 loses
>>>>> tonal values when you reduce exposure in editing.
>>>>
>>>> Yes, reducing the exposure in Lightroom just puts your histogram back
>>>> to
>>>> the left, so that's a waste of time.
>>>
>>> Yes for the histogram, but it is not a waste of time.
>>>
>>> Increasing the exposure adds signal, but the noise stays
>>> the same. In other words, if you take a shot of an
>>> object that is all grey, with nothing approaching
>>> "white" at all in the entire scene, you could
>>>
>>> 1) Expose to produce an histogram that matches
>>> the scene, showing all values to be in the
>>> middle of the graph. This will produce an
>>> accurately exposed JPEG too.
>>>
>>> or,
>>>
>>> 2) Expose to produce an histogram with the data
>>> pushed so far to the right that it is almost,
>>> but not quite, clipping. The JPEG produce
>>> will be "overexposed", and instead of grey
>>> the scene will be white.
>>>
>>> But we want an image made from the camera raw data, not
>>> the JPEG. And note that with either of the above
>>> methods the "noise" in the data will be the same. The
>>> Signal to Noise Ratio (SNR) for method #2 will be higher
>>> because the signal is higher.
>>>
>>> The final image is made using the RAW converter, or an
>>> image editor like Photoshop after conversion, to reduce
>>> the whites down to grey. And the same process will
>>> *equally* reduce the noise. Thus the noise in the final
>>> image will be *lower* with method 2 than with method 1.
>>>
>>> Reducing the amount of noise in the final product is
>>> probably *not* a waste of time.
>>
>> You're the only one who has suggested otherwise. This fibre is about
>> whether reducing the exposure in post-processing is a good way to
>> recover saturation. Please pay attention to the conversation.
>
> "Recover saturation" means what? Nobody has said any
> such thing. *You* need to pay attention.

Porte Rouge said (underlines added to emphasise the seminal phrases), "I set
my exposure to slide the histogram to the right, without clipping ( when I
have time), to capture the most tonal levels . So, now when I am editing the
photos they are over exposed(not clipped). A sunrise is a good example.
_The_deep_colors_are_washed_out_. The obvious fix(to me anyway) in Lightroom
or CS4 is to reduce the exposure. Now my question is,
_by_reducing_exposure_in_post_,_am_I_just_ending_up_in_the_same_place_(_histogram_to_the_left_)
as if I had just ignored the histogram when I was shooting and set the
exposure to properly expose the image using my light meter?"

> The statement (quoted above) was made that, "Yes,
> reducing the exposure in Lightroom just puts your
> histogram back to the left, so that's a waste of time."

Right, a precise and appropriate answer to Porte's question.

> That is not true. It does more than just moving the
> "histogram back to the left", and what it does do is
> reduce noise, which is not usually a waste of time.

I can see I'm going to have to insult you again very soon. :- )


From: Wilba on
Floyd L. Davidson wrote:
>> Wilba wrote:
>>>
>>> In everyday raw shooting, you can be quite relaxed about having a
>>> small spike on the right of the histogram - that's actually a good
>>> thing.
>
> It is, assuming you want to clip the highlights.

The highlights are only clipped in the JPEG. In my experience (with my gear,
my settings, my subjects), I have up to two more steps available in the raw.

> Otherwise, it's a fatal error, because there is no way
> to recover the lost data.

Just underxpose the raw in PP. It's only when the the raw values are clipped
that you can't recover. It sounds like you've never actually tried this.

> On the other hand, if you
> back off on exposure just enough to make sure no
> highlights are clipped, the loss of 1/2 to 1 stop of
> dynamic range probably will mean absolutely nothing
> (given that you won't print out anything that can show
> more than 5 or 6 fstops and the camera will almost
> certainly be recording 8 or more).

Conversely, if you clip 1/2 to 1 step in the JPEG it only takes 5 seconds to
fix in PP, so you don't have to get hung up on getting a perfect exposure in
the field. And that "apparent" overexposure will give you more DR.


From: Wilba on
Floyd L. Davidson wrote:
> Wilba wrote:
>>
>> DRS, I really admire your patience and tolerance.
>>
>> As a rule I try not to be _too_ insulting, but in this case I have to
>> say,
>> Floyd, you are ASTONISHINGLY thick and childish for someone
>> who often sounds very intelligent. I can't recall the last time I've seen
>> such a stupendous display of belligerant idiocy. You really are a champ.
>>
>> Ha, that feels better. Carry on.
>
> Amusing what people say when a topic goes above their
> level of skill or understanding. It's wonderful that
> such posts make you feel good, but you'd be way ahead of
> the game to patiently pay attention and *learn*
> something. That would make you feel even better.

If only you would. (Please consider this to be my follow-up insult, as
mentioned elsewhere.)