Posted by
R. Ticle on
URL: https://www.es-forum.com/Camera-Motor-EMF-Cause-for-concern-tp1546119p1546141.html
Bill - can you please explain what you mean by a "linear motor", and
why they are difficult to shield?
I'm not sure how to tell if the field is parallel to the back of the
camera. It's kind of all around it, but seems more so to near where
the batteries are...
R.
--- In
[hidden email], "Bill Bruno" <wbruno@...> wrote:
>
> Ah- I just realized it probably has some kind of linear motor
> to move the mirror and shutter. These can be awful, and
> unfortunately not too easy to shield. If the field is parallel
> to the back face of the camera, try a piece of mu metal
> on the back, and wrap it around an inch or so on the edges.
> Cut out holes where needed. I have not tried holding mu-metal
> for long periods so you might need to put something else over it,
> or not keep your hand on it. But, I'm guessing you'll be lucky
> to get a factor of 2 or 3 improvement, which is worthwhile if
> you're set on this camera, but may not be enough to really
> make it safe.
>
> Bill
>
> On Sun, Mar 9, 2008 at 4:37 PM, rticleone <rticleone@...> wrote:
>
> > Hi Bill, it does indeed have manual focus, and I've been using it,
> > besides, I think it's good to be able to do that - auto this, and auto
> > that these days... - but it would be nice to be able to use autofocus
> > for low light or fast moving objects. Thing is, every time the
> > shutter gets opened to take a picture, there's the same magnetic
> > discharge, I guess because the shutter's electronically controlled.
> >
> > Still working on finding someone who can help. I can't imagine it'd
> > be too difficult to do with the knowledge of how to open one of these
> > up, I just need a willing person. I've sent out a lot of emails, but
> > the weekend's just ending here, so I've got to wait a bit.
> >
> >
> > Best,
> >
> > R.
> >
> > --- In
[hidden email] <eSens%40yahoogroups.com>, "Bill Bruno"
> > <wbruno@> wrote:
> > >
> > > Maybe it has a manual focus mode?
> > > Bill
> > >
> > > On Sat, Mar 8, 2008 at 4:13 PM, rticleone <rticleone@> wrote:
> > >
> > > > Hey Bill,
> > > >
> > > > There is a 2.5" screen on the back, but because this is an SLR
style
> > > > camera, it has to be held up to the head to "shoot", because
you look
> > > > directly through the optical viewfinder. The screen is always off
> > > > when taking the picture.
> > > >
> > > > I hear you - I don't feel anything from using the camera, and most
> > > > people here so far have said they probably wouldn't worry
about it.
> > > > It may not even go as high as it shows, because it's an outdated
> > > > meter. But - like I said in my last reply to someone else, I'd
still
> > > > rather shield it.
> > > >
> > > > Best,
> > > >
> > > > R.
> > > >
> > > >
> > > > --- In
[hidden email]
<eSens%40yahoogroups.com><eSens%40yahoogroups.com>, "Bill Bruno"
> >
> > > > <wbruno@> wrote:
> > > > >
> > > > > I have heard of people reacting to cameras.
> > > > >
> > > > > What's probably important is the field inside your skull,
> > > > > i.e. try to put the meter where you brain is, not right up
> > > > > to the camera. But I would not want 3 milligauss even.
> > > > > Short exposure is better than long, but pulses can be bad.
> > > > >
> > > > > Having a screen on the back may be better, although a smaller
> > > > > screen could be safer compared to the new big ones.
> > > > > Bill
> > > > >
> > > > > On Thu, Mar 6, 2008 at 6:19 PM, rticleone <rticleone@> wrote:
> > > > >
> > > > > > I have really gotten into photography in the last couple
of years.
> > > > > > With the advent of digital cameras, I am able to take pictures
> > without
> > > > > > dealing with developing chemicals, or the cost of many takes
> > in film
> > > > > > to keep one shot.
> > > > > >
> > > > > > I was recently gifted (birthday gifted) a Digital SLR
Camera. It
> > > > > > works very well and takes great pictures.
> > > > > >
> > > > > > First thing I did was check it's EMF output. Very low
electrical
> > > > > > fields. That can be dealt with simply. Great!, I thought.
> > > > > >
> > > > > > Then I check it's magnetic fields. And I thought, "sh*t!".
Because
> > > > > > naturally whenever the lens focuses automatically, or the
shutter
> > > > > > opens to take a picture, there is a burst of a magnetic field
> > from the
> > > > > > motor. I can't BELIEVE I didn't think of this before. Gah...
> > > > > >
> > > > > > It jumps to about 35 milligauss on average (meter up
against the
> > > > > > camera, just like the face of whoever's using it - this is the
> > kind
> > > > > > where you look through the viewfinder, it's not a point
and shoot
> > > > > > where you use the screen).
> > > > > >
> > > > > > Do I have reason to be concerned about these bursts of
magnetic
> > > > > > fields? I mean, it's not constantly against my head, and they
> > last for
> > > > > > perhaps a second or less at a time, only when the shutter
fires. I
> > > > > > can even get away from the motor focusing the lens most of the
> > time by
> > > > > > using manual focus and adjusting it by hand.
> > > > > >
> > > > > > Unfortunately, I can't just take this thing apart and try and
> > shield
> > > > > > the motor from the inside, myself. There is a very thin and
> > flexible
> > > > > > foil called Met Glas that sounds like it could be used for
such a
> > > > > > purpose, but it's the matter of getting it inside that's the
> > issue.
> > > > > >
> > > > > > Maybe I can find a technician who's willing to do it?...Hmm...
> > > > > >
> > > > > > I can theoretically shield some parts of the camera from the
> > outside
> > > > > > with this material.
> > > > > >
> > > > > > But - what are your thoughts on these brief magnetic fields?
> > > > > >
> > > > > > Best,
> > > > > >
> > > > > > R.
> > > > > >
> > > > > >
> > > > > >
> > > > >
> > > > >
> > > > > [Non-text portions of this message have been removed]
> > > > >
> > > >
> > > >
> > > >
> > >
> > >
> > > [Non-text portions of this message have been removed]
> > >
> >
> >
> >
>
>
> [Non-text portions of this message have been removed]
>