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Roy wrote:
The camera doesn't always capture the truth.
I was changing the numbering system of my camera and I took a test shot of my
dimly lit clothes closet. The original scene was dark with a green plaid shirt
visible in the middle. The 18% exposure jpg was bright with colors and
looked much better than the real scene thru my eyes.
In another
incident:
I took some pictures of a
purple magenta sky at day break. When looking back over these images the jpgs
looked too colorful to me. (the RAW files all looked dull)Since it was a while
back I couldn't remember what I thought the original scene looked like. The old
adage jumped into my mind close down 1/3 of a stop to "underexpose" the
slide film for the best color. Now I don't know whether these day break jpg
images represents the real color or not.
Roy
my thoughts :
With negatives having a great latitude of
tones able to be recorded the rule of thumb that worked best was expose for
the shadows, develop for the highlights. the shadows were of course the
thin parts of silver on the neg, the highlights were the densest parts - more
development meant more density and contrast.
For slide/positive/E6 it was expose for the
highlights (actually to control the highlights) - as too much light meant the
density of the film would be thin - if you exposed for the shadows everything
else would be too thin..
There was an exception to this a type of slide film
by Polaroid had a very broad range and could capture ranges of tones comparable
to negatives but this was an unusual film rarely used mainly because the large
range of tones had a very flat curve and captured so much of the tonal range the
results looked 'drab'.
Slides /E6 was effectively contrasty - with a very
steep curve that dropped shadows to black and highlights to white and if you
didn't get the exposure right (or *best*) you risked pushing too much detail
into the shadow or the highlight to be lost - this is why I've said shooting
jpegs is like shooting E6. get the exposure right and you've got a good
looking finished product ready to go.
Negatives with a broader range meant varying your
'post production' stage (the printing) you could tease out a whole range of
photos from dark and moody to well exposed with smooth tones to light and breezy
by changing which part of the negatives tonal range (curve) you choose to print
- and it's why I likened negative to shooting RAW. You can be off on
your exposure by quite a bit and still get very usable prints .
HDR changes this - I'd said before I felt HDR was
like shooting 2 negs and double exposing or sandwiching negatives during
printing - but I never tried doing this printing E6 or projecting E6 slides
sandwiched so I can't really say whether it was viable or not - someone
else may know?
I'd long suspected in my ruminations of digital
camera algorithms that some cameras brains (the magic beetles I referred to)
were doing some HDR trickery without the
photographer knowing to juggle tonal ranges and make better pictures from iffy
exposures selected by the photographer - but I could/can only guess. It
wouldn't have been difficult to pull off .. and there's have been benefits
to the manufacturers for not telling us they were doing it. First it would
make that manufacturers cameras look better to the consumers and secondly it
would confound competitors who wouldn't guess why CameraA was making better
images than their own product - giving manufacturer A advantage in the
market.
How would a photographer know if this were
happening? I did some experiments - I took a shot of a series of tonal
patches under reflected light with references from a spot meter and took some
shots of the scene at different exposures with the camera set on manual.
Then I took a range of shots of a fixed density object (grey card) through
a matt box masked up with a broad selection of neutral density filters yielding
a 7 stop range. Now truth be told it took me while to realize
this matt box was actually more of a method of determining the lens contrast
more than it was of use in making exposure changes, but with fixed lens cameras
it served the same purpose. Comparing the results and checking the
densities of the colours recorded with a colour picker in a non-adjusting image
program under a non-adjusting operating system (remembering modern OS's can and
do adjust visible densities for monitor display effect) I found varying and
mixed results. It seemed the camera I used even set totally on manual was
compressing the tonal range into a curve that produced acceptable tonal ranges
for the final image - that's to so say tones that SHOULD have fallen outside the
range of capture were recorded.
The effect was consistent but conflicted with
actual exposures made by altering the exposure on the camera - so if I made an
exposure that should have rendered a certain pair of tones black - they
were, but if I included other tones much higher up the range, the lower
tones *were* recorded and with different values. magic
beetles..
This isn't really a surprise, the same camera(s)
tested were capable of taking RAWs, why wouldn't the manufacturer be clever and
shoot jpegs as RAWs and do the fiddling with algorithms in-camera to yield the
best jpeg it could all while pretending to be simply shooting jpegs?
they'd be daft not to really. SO long back I concluded for the vast
majority of my shots I'd behave exactly as all E6 shooters did and shoot for the
best exposure and get what I got by shooting jpeg and for me it worked
well.. Lots of time saved avoiding faffing about post production with RAW
captures.. There were rare times when I shoot RAW, but these are
times I know I want massive tonal ranges to fiddle with or to create images
from composites - but that's really rare for me.
At the end of the day the cameras appear to serve
both consumers and pro's well - except that they're so good they continue to
push professionals out of the market.
My main gripe is as a pedantic
fiddler is the cameras are doing things I
cannot control and I cannot readily identify their characteristics - what it
is they're doing.
Should anyone care? nahh - just shoot delete and
shoot again ! for 99% of photographers these things are amazing!
They can add details the lens can't actually see, they can compress and include
tones that shouldn't be recorded, they can brighten colours and make them really
pop - their magic beetles are super clever and can give you great shots
almost every time.
Scientific photographers recording minerals, stress
patterns, medical images, horticultural or cellular photographers could have
issues though. I had a guy from the WA Herbarium in years back pulling his
hair out over the newest camera he'd bought which was recording the yellows of
Hibbertia sp. all wrong. 'my old camera got them right!' .. so I suggested he
used the old one for those yellows. We got talking - He'd tried masks,
macro curve adjustments and all manner of post-image trickery but none of them
did the job without mangling other colours in the images (especially other
yellows) and after our discussion he ended up settling on 6 cameras to record
the colours of various plants accurately . He was grumbling that he could
just change the film in one camera once.. I don't know any mineral photographers
these days, the geologists I know tell me they have never heard of a 'mineral
photographer' and just shoot photos in the field using their mobile
phones. The results may serve as memory triggers for them but they can't
be used for reference by any stretch of the imagination. I work
with some medical photographers who seem to think green casts and dark magenta
capillaries are OK but hey, most of them have never heard of IR photography use
for recording haematomas or in fact using anything outside the visible spectrum
for their work .. It appears the days when photograpy could be used in
diagnosis are long gone aside from radiography, though thermography seems to be
creeping back in - though I suppose some special side field in medicine will
claim diagnostic rights over interpretation of such images and then fuddle their
way through until they get it right.
k
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