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

["Sonny Carter" <sonc@sonc.com>]

We thank you for the fine controlled testing you did on this situation. The
question begs; What object, pray tell,  were you focusing on, by yourself,
in the bathtub with your "underwater camera"?

Were you able to send the resulting film to a minilab?

Regards,
SonC





- ----- Original Message -----
From: "saadi lahlou" <saadi.lahlou@wanadoo.fr>
To: <leica-users@mejac.palo-alto.ca.us>;
<leica-users-digest@mejac.palo-alto.ca.us>
Sent: Sunday, July 22, 2001 5:34 AM
Subject: Re: [Leica] waterproof bag/M : back from bath tub testing


> 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
>
>