hi this is Graham from Jenham's Astro right now there are lots of
opportunities to image the planets we've got Venus Jupiter Saturn and Mars all
visible at different times of the night this video pulls together some of the
lessons I've learned when trying to image with a small telescope so it's
basically a list of do's and don'ts hopefully it will be of some use so say
one of the main bits advice is to prepare all your kit in advance don't
just rush out there on the night and screw it all together having not done a
bit of planning do a bit of preparation I'd suggest if possible use a webcam
rather than a digital SLR the webcam is going to capture a much smaller area of
sky you're going to produce much smaller more manageable files having a dedicated
planetary Astro camera is I would say a nice to have it's definitely not an
essential you can produce some really good images just using a cheap webcam
you can buy adapters or buy kits to allow you to adapt them into the
focuser draw tube for your telescope
this is one of the main lessons I've learned is to line up whatever finder
scope you've got whether it's a red dot finder or telrad or a conventional
optical finer scope line it up with the main telescope do this very precisely
check it and check it again do it during the day if you have got something like a
webcam and you don't have a good alignment you can waste a lot of time
not even finding the planet that you're trying to image you can you'll be
sweeping back and forth unless you've got a go-to scope if you haven't you can
waste a lot of time you can avoid that by lining up the finder scope in advance
and making everything nice and rigid so that you know that you can rely on that
pointing accuracy
next thing pretty obvious charge up any camera or laptop batteries in advance if
you've got batteries in your mount do the same thing get those all ready to go
use a good Barlow lens I've got two times and three times lenses get
familiar with them make sure you're happy with the quality of the image that
you get if you've using too much magnification then you're gonna have a
problem getting a good image clean out any dust from both the Barlow and maybe
from the sensor you have on the webcam before you go and set up now you can do
this just by pointing the your camera using a sort of live view arrangement on
your laptop look at the bright sky during the day and just make sure you
haven't got any obvious specks of dust in the in the field you're aiming to get
a focal ratio of around F thirty so for example if you have an F ten focal ratio
telescope then and a three times Barlow then that's getting you to that ratio of
the magic number F thirty and why is that important well really we're just
trying to achieve a certain image scale which means a certain number of pixels
across the face of the planet when you image it if there aren't enough pixels
then you get a pixelated image and it's just not pleasing so aim for F thirty
use an app to figure out where the planets going to be I use sky guide
but there are plenty of alternatives and it allows you to think in advance to
look hold up the phone to the sky and see where you think the planets going to
to rise see what time it is see what other features are going to be in the
sky that might help you to find the planet if it's not a bright one use an
app on your phone to do that and then on the night use the information you've
learned from the app to put the scope in the right place you're trying to avoid a
situation where the planet rises and goes immediately behind a tree you could
avoid that with a little bit of advanced planning
now these aren't quite so obvious but when you're trying to image the planets at
high magnification one of the major factors that influences the quality of
the image is the stability of the air that you're looking through now some in
some days you can't have any influence on that but there are some pitfalls that
you can avoid so don't image over the roof of your neighbor's house unless you
can avoid it don't image over a parked car especially one that's been sat in
the Sun or has been being driven it's going to radiate off a lot
of heat and it's going to disturb the air above the car and also don't image
over a hot surface so we've got a barbeque here or a big expanse of tarmac
or a road ideally image over a surface perhaps grass okay so let your scope
cool down different telescope designs need more or less time to cool down
certainly if you've got something like a maksutov I use a celestron c90 for lots of
the videos on this channel make sure you let it cool down for half an hour
after you take it outside some of the designs of scope you don't really need
to do this do a basic alignment now you can if you're doing a minute or two of
planetary video capture at a time you don't need a perfect alignment like you
would do for long-term deep sky Astro photography so do a basic alignment line
up the mount with Polaris you can use a compass app on your phone for example and
then you can approximately line up a mount good enough for purposes of
capturing a minute or two a video but it is worth lining it as we'll see if you
don't have basically good alignment then you can have problems when you're trying
to keep the image of the planet within the field that you're capturing now this
has to be the main rule of planetary photography focus focus focus
it's quite difficult to focus on what can be a wobbly blurry planetary image
that you get on the video so what I tend to do is I slew the telescope towards a
bright start that's in a similar part of the sky and then I focus on that very
very carefully you can do that with a live view app for example on your PC or
and then you can use certain tools like a Bahtinov mask which goes over the
front of the telescope and produces a nice diffraction image that helps you to
precisely focus but the point is to spend time getting a precise focus that
is probably the one aspect of planetary imaging that will make the most
difference. again capture video rather than stills well we've
mentioned that already so there should be no surprise it's worth
reviewing a few of the video files whilst you're outside you can do it very
quickly takes a few seconds click on the file I even run an the odd Registax
cycle through some of the files just to get a basic idea and while on the right
lines this is something that's is the focus
good or is it is it way off it's worth doing that only takes a minute or two
you can do that outside I've mentioned Registax but there are other programs
to process video files don't waste your time if the image is very unstable you
can't always tell when you go out overnight whether the night is gonna be
a good one if you find that you can't get a stable image then maybe wait an
hour or give it another try another day
okay here's a few examples of these pitfalls these do's and dont's I've been
talking about so in this first video Saturn is drifting towards the bottom of
the frame basically the mount he's not well enough aligned for the job we need
to do this time the same drift is apparent
I've used the manual slow motions to centralize the image and let it drift
again maybe I'll get more time sufficient time to capture the a good
image but you can process a file at this and centralize the planet in each frame
but it's better to just align the mount this time it's looking good good image
brightness more stable but the image is fading is it a cloud no it's gone behind
an obstruction this time everything is looking good
brightness is good but I think there seems to be some noise so stop and
process the file and you can see that there is some noise I don't know why
it's there but it gives you example of why it's worth processing sometimes you
go along and then finally for Saturn this is looking the best of all of them
good view of the Cassini division good level of exposure and planet is stable
in the frame so this was the best of a long evening of trial and error and
if you put this file through Registax without being an expert in wavelets
and one of those things I'm pretty happy with the result from a 90 millimeter
scope so moving on to Jupiter here's an example of a decent-enough night it's
not the best but you can see the red spot you can see so in equatorial bands
and you can see belts rather and you can see a moon over to one side of the
planet this is enough to know that it's worth processing and here you go the
Registax image is pretty good it brings out a lot of detail that you
really can't see in real time but there are enough good frames within the file
that you can stack and get a good result and finally moving on to Venus if you've
got a bright planet that's low in the sky you're gonna get all sorts of
turbulence and you can get color separation as you can see in this video
but sometimes it's worth persevering you can stack and align and you can get rid
of a lot of that noise and produce a decent result so hopefully this video is
useful I'm definitely not an expert in imaging but it shows you that if you
avoid some of the the obvious mistakes then you can get some half-decent images
of planets with a small scope and it's quite good fun so thanks for watching