Re: ATM self contained vibration damper....

["benoit schillings" <benoit_schillings@hotmail.com>]

My scope is already about 400 pounds

-- benoit


>From: "Ken Hunter" <kb7h@onemain.com>
>Reply-To: "Ken Hunter" <kb7h@onemain.com>
>To: "benoit schillings" <benoit_schillings@hotmail.com>,<atm@shore.net>
>Subject: Re: ATM self contained vibration damper....
>Date: Tue, 27 Aug 2002 22:51:26 -0500
>
>
>Here we go again...
>
>Let's all build lightweight scopes and add 400 pounds of support to
>compensate for the 20 pounds we took off the weight of the scope.
>
>Doesn't make sense to me.
>
>Ken Hunter
>
>----- Original Message -----
>From: "benoit schillings" <benoit_schillings@hotmail.com>
>To: <atm@shore.net>
>Sent: Tuesday, August 27, 2002 2:07 PM
>Subject: ATM self contained vibration damper....
>
>
> >
> > One the major limitation I find when doing ccd imaging is that
> > in most cases, when imaging from the top of a mountain good seeing
> > is generally corelated with medium strength wind which of course
> > has a tendency (even with my semi-heavy scope) to counter the
>advantage
> > of good seeing.
> > I use my AO-7, but in many cases, the dominant vibration of the
> > instrument will be around 5 to 10 Hz which is hopeless to correct
> > with a tip-tilt mirror unless I was able to correct at 100 Hz or
> > so, something which is not common by virtue of lacks of bright guide
> > stars.
> >
> > I started thinking a while back at some lower tech way to dissipate
> > this high frequency vibration from my scope by using a long shock
> > absorber attached to the top end of the scope and connecting to the
> > ground somewhere around the scope, but decided that this was way too
> > much pain to be practical, it would also likely have a prefered
> > direction for the vibration reduction, something which is not always
> > doable of sufficient.
> >
> > I remember seing in an old s&t of the idea of having a chain
>attached
> > from the top of the scope and hanging into a bucked of oil... other
> > that the fact that this is yet again a difficult setup, this would
> > not work well if the scope is pointed toward the zenith... so I am
> > now wondering if one could build a self enclosed system which would
> > act in the same way but could just be attached to the top of the
>instrument
> > and dissipate some of that vibration energy.
> >
> > some of the q&d ideas I was thinking about was a cylinder partly
>filled
> > with oil, or maybe filled with two liquids which would not mixed...
> > another idea would be to have a mass held by 4 springs that would
> > be semi-tuned to the natural vibration of the scope, but I'm finding
> > myself out of my depth & area when it comes to what would and what
> > wouldn't work.
> >
> > Does anybody on the list has some idea of the subject, or better
> > experimented in that field ? It seems to me that the same problem
> > must exist for large dobs, and finding an easy way to kill a good
> > deal of these vibrations would allow us all to build lightweight
>scopes
> > which would be more resilient to wind & other vibration sources.
> >
> >
> > -- Benoit
> >
> >
> >
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> >




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