Re: [Leica] waterproof bag/M : back from bath tub testing

["saadi lahlou" <saadi.lahlou@wanadoo.fr>]

Thanks John & Dennis.
I'll follow your advices for the damp cloth to wipe the M6 when back on
base.

Now more about the underwater stuff.
John Collier, I followed your advice and tested the autofocus of the GR1 +
aquapac in a bath tub before going. I just did it and my hair is still wet.
Well, it is more easy to advise than to do, mind you. As I realized, this
means getting into the bath tub WITH a snorkel and the camera, because I had
to check in the viewfinder whether the camera actually focusses : the GR-1
manual says that the small frame in the viewfinder blinks if it cannot
autofocus.

I can tell you it is a very uncomfortable testing process -unless may be you
have a huge bath tub, which is not my case. The camera AND the operator's
head have to be fully immersed. And as you wear goggles it gets difficult to
see the small prints and frames in the viewfinder, and then you need to
focus on something not to close so as to be within proper distance for the
autofocus. In fact this can be achieved only if the whole operators gets
into the tub.
Even so I had try many positions, eventually breathing water through the
snorkel. When my wife saw that, she rushed for my Leica with the intention
of sending the picture to the whole LUG, she told me. Fortunately I had
carefuly hidden all cameras beforehand. I hope some people with more testing
capacities than I will tackle with this problem in the future. May be
someone can convince Erwin ?

Now for the results. The GR-1 has a sophisticated autofocus mode, and also
three ways of turning off the autofocus. One is fixed at infinity (infinity
mode). Another is fixed at hyperfocal distance ("snap mode"). The third is
"fixed focus", and it is a way of fixing the snap mode at a specific
distance provided that you are able to focus on a given object (it is some
kind of autofocus memory, designed to reduce the time lag between the time
you press the button and the actual shutter release when you do candid
phatography, by avoiding the autofocus to switch on and steal precious
milliseconds). As I read the manual again, I realize that this GR-1 is a
clever camera. Why did I use it so little lately ? Oh! since I have an M6.

Well, mechanically, underwater the camera seems to be able to focus in
autofocus mode. It takes longer than in air, the frameline blinks for a
while, but finally the shutter operates. In fixed modes, of course it works
also. So I guess the camera manages to focus on something, but probably at a
"wrong" distance for good focus on the film plane. As this first test was
done without film, I still have to test the results, but I will do that on
site.

The most important outcome was that I discovered that the Aquapac leaks :-O!
I would not have discovered that if I had not stayed a long time in water.
So thank you very much John for making me do this test, I can still go back
to the shop and change the Aquapac before leaving ! And it was a fun
experience ;-)

Anyway I suppose I will keep to fixed focus modes. BUT. And here comes an
optical problem.
The snap mode "fixes focus at a distance of about 2 meters". Does this mean
that in the water this distance will be different ?  I have always had the
subjective feeling that in the water things are bigger, i.e. in a way
closer. So if the focus is set at 2m in air, what will be the corresponding
distance for things in focus in the water ? Does anyone have a rule of thumb
?

Also : what about the flash ? Should I set exposure compensation in the
water ? I do not know how the AE works, and it is not specified in the
manual what kind of link between the flash and the shutter, i.e. if there is
TTL measurement for the flash.

Thanks again for helping me digging the subject.

saadi

>John Collier wrote:

> Underwater the lens's angle of view tightens up quite a bit. Your 28
> underwater will have the coverage of a 35 on land which should be just
about
> right for most below the sea shooting. Focusing will be a problem
underwater
> as I do not think the auto-focus will work. Test in your bath tub tonight
> and see:-). I am not joking! Can you lock the focus some how? Make sure
you
> check this out as you do not want a bunch of rolls with everything fuzzy.
>
> I use my Ms around sea water with no worries. If it gets wet rinse it as
> soon as possible with fresh water. Regardless when you get back to base,
> wipe all your gear down with a damp cloth. Your cameras will be salty even
> if they do not get wet.
>
> John Collier

Dennis Painter <dennis@hale-pohaku.com> wrote:

>At the ocean shore what happens is salt spray dries in the air leaving tiny
>'floating' salt crystals, they land on  everything and can drift into
everything.
>Just always wipe off your gear with a damp cloth, everywhere you can reach.
No
>problems if you do this.

>I don't think any autofocus works underwater though I have seen housings
for all
>sorts of cameras. I would think the change in refractive index is the
problem.
>This is why that 28mm lens' angle of view is different underwater. As John
says
>it's more like a 35mm lens when underwater.

>Dennis