hi this is Graham from Jenham's Astro, for those of you look at the videos in my channel probably
already know that I'm a big fan of the celestron c90 maksutov scope the first of this video is to
see if we can make a small improvement to that scope it using a simple and cheap material that
you can pick up quite easily and basically it's this it's called flocking paper and it is matte
black paper the idea being that it absorbs light and we're going to use it to try and improve some
of the image contrast that you get with the c90 okay so what problem are we trying to solve well
if we look down in front of the telescope towards the primary mirror hopefully you can see there is
pointing out from the back of the primary mirror there is a tube and that tube points towards the
secondary now if I move the scope you should be able to see a black a black plastic tube that
is the primary baffle tube and the purpose of that tube is to make sure that we don't get any
stray light reaching the eyepiece and effect an image okay so if we look from the eyepiece end
hopefully if I move the scope left and right a bit you can see as we look along that too that there
is some reflection from the inside of that tube basically because it is not matte black okay so
what do we do where we're going to try and use the flocking paper to stop that stop those reflections
so what I've done is a cut a small section of the paper and unrolled it into a tube so here we go
there's the tube you can do a better job than me but this is just going to give you an idea so if
you look at the amount of reflections before and then we're going to put the paper inside the scope
okay so hopefully you can see straight away that we've cut down on a lot of those reflections now
in my case I haven't done a very good job so I've not got a completely concentric - if you
do a better job and make sure that you're not cutting down any of there like that you do want
then I think it's pretty clear that that is going to absorb a lot of the light that's
touching that baffle tube and then we can see if that's going to lead to any improvement in
the image contrast so in daytime use on the Left we've got the original scope and on the right we
have the same same view with the flocking paper inserted same again here this is looking at a
very an object with a very bright sky background so we're going to expect to have a lot of light
potentially bouncing around on slides inside that baffle tube and then finally a view of some leaves
again before and after the modification hopefully the improvement in the contrast is quite clear
moving on to an astro target this is a view of the Sun there's not a lot of activity now
we're close to the solar minimum but I think you can see on the left and right
small difference in contrast and if we take a still image from each of those two videos
I think the improvement is evident the paper seems to have increased the contrast of this
particular sunspot then moving on to the moon in the early evening the difference is quite clear
the skies still quite bright at this stage and the papers giving us quite a good improvement
as the sky darkens in this particular example I'd say there is some difference but it's not
so great. so this modification works well does especially if you're going to use the C 90 in
conditions where there could be quite a lot of stray light so if you're using it as a spotting
scope during the day or if you're using it to view and maybe the moon or the Sun is setting then
you're going to see an improvement in the contrast if you use the scope during night time then I
think for a very bright target like the moon and extended object you'll see some improvement in the
contrast but you won't see any real effect if you use it on and other objects I haven't seen
any real benefit when I've used it on Jupiter for example overall given that this is a very simple
modification and it does yield some definite improvements in some circumstances I'd say give
it a go get some flocking paper and see if you get the same results as I do okay thanks for watching