Hi this is Graham from Jenham's Astro this is the third video in a series about
this telescope the Skywatcher Heritage 130p which is also sold as the AWB
Onesky now in the first videos we concluded that it's great value for
money and it'll make a great telescope to get started in astronomy with now in
the UK it sells for under 150 pounds and in the U.S. under $200 so if we're gonna
make any improvements to it we need to do that considering our initial outlay
so the idea of this video is to make a couple of budget improvements we're not
going to spend much cash and we're going to try to improve the telescope a little bit
so modification number one is to introduce a light shroud
what's that this one of these so if we go back to the basic telescope when it's
delivered you recall it looks like this it's a truss tube Dobsonian which means
that these parts here result in the front of the tube being open and
normally this isn't a real problem we're using the scope at night and this design
works very well and it allows you to shrink the telescope down to a small
size for storage but we can find this because this part of the tube is open
and you can experience stray light if you've got maybe a neighbor with a
security light close to where you're observing or more importantly you can
have problems where you get condensation onto the exposed secondary mirror now
mirrors they're real magnets for condensation they get cold and if you
use a telescope outside for not very long really especially during the winter
months then the condensation can can spoil your
view so the idea is to produce a cover or a shroud for the front of the
telescope and the main benefit is going to be to reduce the susceptibility of
the telescope to dew but it have an extra benefit of reducing the effect of stray
light
so how do we make a shroud for the scope well I went down to a local craft store
and I bought a few sheets of this now this is very lightweight it's two
millimeter thick foam sheets they sell it in A3 and A4 sizes so I
picked up a few a three sheets like this now in the UK these cost one pound each
so hopefully you can see straight away we're not looking to spend much money so
one of those sheets isn't quite enough to go we'll go around the outside the
tube but at this price you can easily pick up a few and experiment so that's
what I did initially I made a shroud that went all
the way around the outside of the tube involved sticking a couple of sheets of
the foam together and cutting out a couple of shapes here so allow you to
use the focuser and go around the red dot finder now with this arrangement the
shroud goes around the outside and I've just put a bit of Velcro
onto the edge so you get you get this sort of effect and it basically works
but it's not very pretty and secondly you got to take it on and off every time
you want to put the scope away if you want to shrink it back down to its
smallest size so there's a better solution and that's to produce a light
shroud that fits inside the tube so this is it again I've used two sheets of the
A3 it's actually really about one and a quarter sheet you need and I've made a
cut out for the focuser and a little one here for the secondary vane and that's
really it and I've got some Velcro on the edges as you can see here
it's all we're gonna do is roll up the tube and then put it inside the main
tube the telescope and then feed it forward as we as we unroll it some more
and then on the front of the tube line up the cutouts that we made for the
focuser and the secondary they line them up and I've put a couple of bits of
Velcro on to secure it like so and then the acid test really is to see whether
we can open and close the shroud so there you go nothing nothing snagging
all seems quite secure and if I turn it round hopefully you can see that it's
quite an effective shield obviously you've got a hole where you've got to let
the light come out from the secondary mirror to the eyepiece which is here but
generally it's cut off a lot of the sources of stray light and it should
improve the tolerance of the scope to dew so it's cost us all of about two pounds
with maybe another couple for wastage for the first version that didn't make
the cut but it's a very cheap way of improving a telescope okay so the second
modification is to the focuser now you might recall that this is a slightly
unusual design it's called a helical focuser and as you turn the focuser the
eyepiece moves in and out on some threads now a lot of talk about
improving this whether you could replace the focus are entirely with a more
conventional rack and pinion arrangement or whether you could whether the tube is
strong enough to take any weight or something like that and I say don't
bother for the price of this scope you've got a bear in mind that nothing's
perfect so you want to look to make whatever improvement you can make with a
minor investment so what we're going to do is we're going to try to reduce some
of the play the in this mechanism so what do I mean well
if you're focusing on an object is quite close to the quite close to telescope
maybe during terrestrial observing then you'll notice that the eyepiece is going
to reach focus quite a long way outside the tube like this so then the eyepiece
rocks on those threads so we're going to try to improve that it's all we're gonna
do is we're gonna get a roll of PTFE or plumber's tape and we're gonna wrap that
around the threads of the focuser so the idea being that the tape will go inside
the threads like so and it will take up some of the play that's inside the
mechanism so when we finish we're gonna put the focuser back inside the tube and
we're gonna tighten it down and straight away you can feel that there's less
play as you might expect and then if you give it a few turns just to bed it in
like so then let's see how it compares take an eyepiece good it focuser and put
it in a similar sort of position that we have before and clearly the side-to-side
play is quite reduced so definitely a little bit of tape like this can improve
this part of folks movement
so that's it a couple of simple mods for hardly any money
we started with a good telescope and we made it just that little bit better.
I hope it's been useful if you might see more astro videos from the Jenham's
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watching