Re: Look Ma, No Flash

On Tue, 12 Dec 2006 20:39:12 -0500, Dan Bracuk <bracuk@pathcom.com>
wrote:

>Last week I tried something new - new for me that is. I took all my
>photos with natural light only. The good news is that the good ones
>were much better than they would have been with flash. No shadows and
>no backscatter.
>
>The bad news is that I left the camera on fully automatic, except for
>the no flash part. That meant that in pretty well 100% of the low
>light situations, the shutter speed, or whatever you call that with
>digital cameras was too slow and my pictures were blurry.
>
>Next trip, manual f-stop and shutter speed settings. Anybody got any
>suggestions for something that might work? The camera is a 4
>megapixel Sony point and shoot.
>
>Dan Bracuk
>If we don't succeed, we run the risk of failure.

Here's what works for me with great results (Olympus 5050 camera):
- pump up the ISO sensitivity a little
- turn off the flash
- turn on manual white balance, and set it at depth by pointing the
camera at a white diving slate when setting it
- in Photoshop click on auto levels to bring out the true colors that
you captured by setting the white balance but which are overshadowned
by the stonger blue channel

I've taken available light pictures down to 70 feet with this
technique with very good results.


Jon Weinberg

| email: jon at JonWeinberg daht com
| web: www.JonWeinberg.com

Dan Bracuk wrote:
> Jon Weinberg <jon@JonWeinberg.com> pounded away at his keyboard
> resulting in:
> :I've taken available light pictures down to 70 feet with this
> :technique with very good results.
>
> If you are at 70 ft on a cloudy day, can you photograph a swimming
> turtle and end up with an unblurred image? That's what I'm trying to
> accomplish.

Dan, aren't the options pretty limited?

I think you could raise ISO so a motion-freezing shutter speed could be
used, but that would increase the equivalent graininess. On my Olympus
4040z, increased ISO produces a lousy image, and it doesn't
color-correct well.

Otherwise, how about setting your shutter fast enough to freeze motion
and correcting underexposure later? That's just a thought, as I haven't
done much lightening of images and don't know how much would be lost.

Other than adding light, is there another option? Please tell me if I'm
missing something here.

What I was trying to suggest in my earlier post was that there's a
slight chance your camera, in automatic mode, may be biased toward
maintaining mid-apertures at the expense of faster shutter speeds. I
don't think that's the case, but it would be pretty easy to find out as
I described.

To find out, can't you just check the camera's automatic settings of
aperture and shutter in some low-light environment at home?

If it's chosing too slow a shutter speed, but still hasn't opened the
aperture fully, you'll be able to increase the speed and widen the
aperture, right? Maybe then you'll have enough speed for those
underwater action shots.

> I don't know for sure, but you might be doing unnecessary work with
> that in-water camera adjustment. I don't do any of that and get
> similar results with the Adjust Levels feature of Microsoft Digital
> Image Pro. Mind you, I'm using a filter so that may be significant.
> One day you might want to skip the initialization and see if it makes
> a difference. Worse case scenario is that some photos won't turn out
> as nicely as they otherwise would have.

That's what I think, too.

I found tinkering with manual settings of white balance with my Oly
4040z yielded very unpredictable results and I was better off using
Auto white balance and color correcting later. I even tried using
"Cloudy" white balance and other white balance settings, but came back
to Auto, which corrected pretty well.

Mind you, this experimentation was in green North Atlantic and
Northeastern US lake waters, but, in tropical waters, I used Auto White
Balance and color-corrected later, with adequate results for my
"snapshot" quality pics.

Maybe I need to experiment more with manual white balance settings, but
I think I've come up against the limitations of my camera and/or the
limitation of water conditions here in the northeast. 8^)

Dave C

Dan Bracuk wrote:
> Dan Bracuk <bracuk@pathcom.com> pounded away at his keyboard resulting
> in:
> :WRT lightening images, Microsoft Digital Image Pro, which I use has a
> :Add Flash feature. It works really well with underwater shots in that
> :not only does it add light, it also brings out the colours. I'll show
> :you guys a before and after example in a little while.
>
> Here is a photo enhanced 3 times. Two of the enhancements were done
> using techniques mentioned in this thread.
>
> http://www.pathcom.com/~u1072675/x/
>
> Dan Bracuk
> If we don't succeed, we run the risk of failure.
>
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There is a pretty reasonable improvement with the levels fix. You might
want to have a go at some more complex colour correction. If you have
photoshop then there are loads of resources on the subject. If not you
can download GIMP free of charge and most of the techniques can be used
but you might have to figure out what the photoshop term for a function
is in GIMP. Here is a link to a fairly comprehensive colour correction
resource http://www.scubaboard.com/cms/article18-doc5.html. The
Mandrake method is one that I have found particularly useful in the
past. I had a go using it on a couple of your shots and in my eyes it
gives them another boost to what I imagine the scene looked like when
you pushed the shutter.

jon

Dan Bracuk wrote:
> "Dave C" <dcalderbank@top.monad.net> pounded away at his keyboard
> resulting in:
> :Otherwise, how about setting your shutter fast enough to freeze motion
> :and correcting underexposure later? That's just a thought, as I haven't
> :done much lightening of images and don't know how much would be lost.
>
> That's what I had in mind all the time. Has anyone done this before?
> What shutter speed did you use? Did you also keep a constant f-stop
> or did you keep that on automatic? How were the results.

The minimum shutter speed required to adequately reduce blur will vary,
of course, but I would try 1/60 or faster.

You apparently were talking about 70' in tropical water, so perhaps you
were only missing by a stop or two.

Any idea what your camera chose for shutter and aperture for those
blurry shots you talked about?

You might as well use shutter priority and let the camera choose
aperture automatically. This will mean that the dimly lit moving
subjects will be less blurred, but may be underexposed to varying
degree.

Try a few shots at home in dim light and then try to correct the
underexposure after the fact. Your dog's wagging tail might be a good
test subject. 8^)

If we're only talking about a couple of stops of underexposure, maybe
the correction will look okay to you.

If I were to use shutter priority set at 1/60th in my local waters, as
I get below 40', the diminished ambient light would give me at least a
4-stop degree of underexposure. I think that's a lot to correct, but I
might check that out next time I dive. Can't be much worse than getting
a blurry image!

Dave C

"Zen Diver" <spicedhamme@yahoo.com> wrote in message
news:S9udnXZEMKsVERnYnZ2dnUVZ8tOmnZ2d@pipex.net...
>
> I had a go using it on a couple of your shots and in my eyes it gives them
> another boost to what I imagine the scene looked like when you pushed the
> shutter.

Can you send a link so we can see them? Thanks for the link to the
photoshop information.

Dave C wrote:
> Dan Bracuk wrote:
> > "Dave C" <dcalderbank@top.monad.net> pounded away at his keyboard
> > resulting in:
> > :Otherwise, how about setting your shutter fast enough to freeze motion
> > :and correcting underexposure later? That's just a thought, as I haven't
> > :done much lightening of images and don't know how much would be lost.
> >
> > That's what I had in mind all the time. Has anyone done this before?
> > What shutter speed did you use? Did you also keep a constant f-stop
> > or did you keep that on automatic? How were the results.

I'm still shooting film UW, but for Cayman, my general rule of thumb
manual setting is 1/60sec at f/8 for ISO 100. This is generally good
for a sunny day, down to around 40-50fsw. Deeper than that, it depends
on conditions, but is time to pick up a stop by 80fsw, usually by going
to f/5.6, and at 100+fsw, I'll go to 1/30sec to pick up a second stop.

On digital P&S's, I've found that boosting the ISO is generally the
easiest way to keep the shutter speed short. On one dP&S we have, the
Manual camera mode automatically knocks the ISO all the way down to ISO
50, so overriding it to set it to ISO 400 does compromise noise some,
but it picks up 3 stops, and is usually worth it for night photography

An Example:
http://www.huntzinger.com/photo/2006...om_night1a.jpg


> The minimum shutter speed required to adequately reduce blur will vary,
> of course, but I would try 1/60 or faster.

1/60 is a good starting point, particularly for normal or wide angle
lenses. With an extremely wide 15mm lens on film, I find that I can
'get away' with slowing down to 1/30 sec, as this is still faster than
the "1/(length)" sec rule of thumb and I have reasonable technique for
not jerking the shutter release. It does, of course, depend on if the
subject's moving or not. With a dP&S, the trick might be to figure out
what the 35mm equivalent focal length is, since your CCD/CMOS sensor
chip will definitely be smaller than (24x36mm) film, so you can't just
read the number on the lens. My guess is that you're probably a 35mm
lens equivalent, which is borderline for dropping down to 1/30sec.


-hh