Hi this is Graham from Jenham's Astro if you watch my channel you probably
realize that a lot of the Astro photos I take use one of these a Canon EOS
digital SLR and for most of those photos the cameras connected to one of two
things it's either connected to a prime lens that's to say a lens of a single
focal length like this one here the 50 millimeter Canon F 1.8 sometimes it's
connected to a wide-angle lens like this one the samyang 14 millimeter and now and
again you may have seen that you can produce
pretty okay results using a cheap old lens like this one so this is a 200
millimeter lens. For the rest the time the camera is connected to the back of
one of my telescopes like this one the Celestron C90. It occurred to me that
I've got one other lens that I've never used for astrophotography and it's this
one this is the kit lens that was provided with the camera when I
originally bought it and it's really stayed in its box and never been used
it's an 18 to 55 millimeter lens and even though this isn't the latest model
of the lens I've dusted it off and the idea of this video is to see whether we
can get some good Astro photos using a lens that you might already have lying
around or that you may have overlooked so what can we say about the kit lens or
other this range of focal lengths I'd say the first obvious thing when you
pick it up is that it's light it weighs under 200 grams and it feels like it's a
lump of plastic that is largely because it is a lump of plastic but that isn't
to say we're gonna dismiss it optically based on that we've got to give it a
test and find out how it performs in terms of focal ratio the lens can
operate at f/3.5 when it's operating as an 18 millimeter lens that's the fastest
ratio can operate at is most wide-angle setting and if you've got it operating
like a normal kind of lens a 55 millimeter setting then its speed is no
quicker than f/5.6 so what does that mean well if
we compared it as an 18 millimeter lens to this dedicated prime lens which is 14
millimeters so pretty similar then this one operates at f/3.5 whereas this one f/2.8 so on the face bit not a huge difference but I guess we're going to
expect quite a difference in performance just due to the different price but
we'll see and then at the other end of the scale if we operate it as a 55
millimeter lens and compare it with this 50 millimeter nifty 50 as it's called
which is a well-known good value and versatile lens from Canon then this lens
can operate at f/1.8 whereas the kit lens is operating at f/5.6 so that is a
pretty key difference between the two lenses
essentially the kit lens is relatively slow so compared to one of the prime
lenses here it's going to take more time to capture a given amount of light and
we'll see if that is a problem when we try to use it later on okay other things
to know well the main thing is that the kit lens is from a series called the EF-S
range now I'm not a lens expert you can probably gather that but one of the key
differences between that range of lenses and the other lenses that I've been
showing here today relates to the size of the lens when it's mounted on the
body of the camera so if you look hopefully you can see that the lens the
kit lens here it is going to protrude further into the camera body than this
prime lens now why is that significant well it's only significant if you have a
filter that you put inside your Canon EOS so often I use a clip filter which
is a light pollution filter which actually clips inside the camera so
it's inside the body and then normally a lens like this will screw onto the body
no problem if you try to do it with with this
lens that extra distance will foul the filter and you can't actually engage the
bayonet on the front of the camera so basically the kit lens will not work
with clip filters so if you're somewhere where you have a lot light pollution and
you generally rely on a filter of that type that you've already got then maybe
that's a proble. Of course if you've got another kind of filter arrangement maybe
one that fits over the front of the lens with a step down ring then that's not
an issue but for me it is a limitation because I use the clip filter quite a
lot. So what sort of results have I got using this kit lens well I started off
with Orion because it's the middle of the winter and I know from
using the nifty 50 that it's a good sort of size a target to capture in the field
of view so on the left this is a single first second frame using the kit lens
where it's operating around about what we might call the normal and normal lens
focal length so 55 mil and this is a comparison between the kit lens and the
nifty 50 and I say looking at it at that scale it gives pretty good results
you've got the Orion Nebula here and got reasonably good rendition of the stars
if we zoom in a bit closer I've cropped the entire nebula from each of the
frames and this is where you start to see some of the issues so for the 55
millimeter setting on the kit lens the brightest stars start to show a little
bit of purple or blue fringing around them and generally they're not very well
defined if we do the same for Orion's belt we see again the blue fringes
chromatic aberration around the brightest stars which is a little bit
distracting and then if we go to the extreme we look in one of the corners of
the field this is Betelgeuse it's pretty distorted in the kit lens and you can
see quite a lot of the other stars in that region the frame have got quite a
bit of distortion
so from then I moved on to looking at Cassiopeia and pointing the camera much
closer to the zenith at this point and this gives you an idea of the field of
view so you can capture all of the W and quite a section over towards Perseus and
the double cluster and we're going to zoom in on a couple of sections of that
frame so firstly near to Cassiopeia this is Delta Cassiopeia on the right there
so here we can see from this cropped frame we've managed to capture three
deep sky objects clusters within Cassiopeia and it's I'd say reason we
were to find with the exception of the bright star in Cassiopeia the chromatic
aberration is not as noticeable on the fainter stars and if we move on to the
double cluster well if you consider that this is a zoomed in section of the frame
of a kit lens it may have cost you nothing then I think that's quite a
decent result for the Perseus double cluster if we're going to get critical
we look in the corners as we did before the Orion image and we can see quite a
lot of aberrations these are not the sort of nice round star images that
you'd hope to see in your perfect camera lens so there you go
pays your money who takes your choice or maybe you don't pay any extra money but
it's not going to work so well at the corners of the frame and then moving on
to using the kit lens at its widest setting so this being at 18 millimetres
running at F 3.5 so it's a big field of view as you might expect you can capture
or eager Taurus and over here we can see I think pretty good rendition a nice
wide angle view of this part of the sky and then looking a bit closer onto the
Seven Sisters it I think records reasonably well we don't see such
noticeable chromatic aberration here at the 18 millimeter setting I think
that's quite a pleasing crop from the frame and then looking at the kit lens
18 millimeter setting looking at the corners the aberrations are still
present to some extent but not in any way as pronounced as when you're using
the lens at 55 millimetres so overall some good results
amongst the bad. So conclusions, kit lens for me if you've already got one of
these in your cupboard in your camera box or in your box of stuff that
you hardly ever use I'd say give it a try I wouldn't go out and buy it
specifically if you're looking to get an extra lens probably there's better homes
for your money but if you've got it already plug it in and give it a try for
me it's worked better its widest angle setting with a focal length of 18
millimeters and I think you can get some quite nice views at that setting
having said that 55 millimetres especially if you cock a bit of the
frame it can be okay to that made difficult using this lens I'd say is
because it is quite a slow focal ratio lens quite hard to focus so you've got
the combination of it being quite slow so if you're using live view which is
what I recommend it's quite hard to see any stars unless the the lens is quite
close to to the right focus point and when you found them the actual
adjustment of the focus ring is really fine and once you've got it right if you
move the camera around too much your nudge it and you'll lose focus so I'd
say that the focus itself is a bit fiddly but having said that the Nifty
Fifty which is a fantastic lens in my opinion great value for money is also a
bit fiddly and that is why you can see this fine piece of paint on the side of
it here to allow me to find the focus easily and even then it's a bit fiddly
so kit lens is the same don't expect it to be a 10 second setup you'll have to
play around with it focus it but if you do that and use it
maybe at the 18 millimeter setting I'd say you can get some good shots. Okay I
hope it's been useful thanks for watching and please subscribe to Jenham's Astro
bye for now.