millimeter is normally the first fast prime that people buy if you're on a
crop sensor it's around about 80 millimeters depending on how cropped
your sensor is but if you're on a full-frame you get a decent amount of
coverage normally because it's a prime lens it's also very fast it does give
you a decent amount of coverage on a full-frame camera just about enough to
shoot the core of the Milky Way normally when doing Astro photography I
like really wide shots with the Milky Way streaking across the sky or lots of
stars filling the sky so I use a 14 millimeter and a 24 millimeter but today
I've taken the 50 millimeter out just to see what I can get and just to see the
issues I have with the 50 millimeter so if this is your first fast prime you can
go out and try and get some shots with it as well taking the five hundred rule
into consideration with a 50 millimeter lens I can only keep my shutter open for
10 seconds after this the stars will start to streak I went out the other
night and I shot with the 50 millimeter the Milky Way was quite high in the sky
so it was really hard to get any kind of landscape in with the Milky Way this is
one thing to take into consideration you can use photo pills to work out when the
Milky Way is going to be low in the sky as long as there's not too much air
pollution you should be able to get a big chunk of the Milky Way with say a
mountain or something like that in front of it I use the f1 point for 50
millimeter from Canon with a sigma MC 11 adapter on my a 73 and a 7 r3 obviously
because I'm shooting at night I have to have it on manual focus the 50
millimeter has this little window on the top so I can work out where the infinity
point is before I've even turned the camera on so one thing I found with this
lens is at one point for at the edges of the shot concede you get these weird
sort of butterfly shaped stars there you can really see it now and
happens all the way around the shot so if I come down to the bottom it's the
other way around so you can see this is an issue with this lens at one point for
when I go to F 2.8 you can see these are pretty much gone even when I have the
full frame on the screen you can see the difference so if you look up here in
this top right hand corner look at the stars at 1.4 and at 2.8 at F for any
kind of aberration like these has gone the only downside is because it's a 50
millimeter lens and I can only shoot a shutter speed of 10 seconds I then have
to bump up my ISO but at F 2.8 this is okay so I tried a varied amount of shots
from ISO 16,000 down to ISO 6400 again this is iso 5000 at 10 seconds at f 1.4
we can see these aberrations around the size there are a few other observations
that are found one of them is if there's light pollution in the direction that
you're shooting you'll tend to lose the stars on the horizon this is in quite a
dark area but there were a few towns just to the south where I was shooting
the Milky Way is just out of shot so this shows with this focal range you
really need the Milky Way down on the horizon you need there to be no light
pollution in the direction that you're shooting and also the air quality has to
be good also I was shooting wide open with this shot as well and it's shown
these strange aberrations with the stars towards the edge of the lens again with
this one there was a lot of light pollution about but I was able to pick
up the stars I shot this at f/4 and ISO 16,000 at 5 seconds I shot this one on
the a7 3 and for 16,000 ISO that's pretty clean so when shooting Astro
shots with a 50 millimeter lens you want to make sure that the Milky Way is low
in the sky if you want to get that in the shot you can work this out with apps
such as photo pills or the photographer's ephemeris secondly you
want to make sure there's no light pollution in the direction that you're
shooting the third thing is to make sure the air quality is good where
the air is a little bit thick when this pollution about or dust or sand in the
air as you get closer to the horizon the stars will start to disappear this is
because the atmosphere is thicker and the light from the stars can't get
through if you shoot in places like Iceland or New Zealand the air quality
is cold and crisp there's a lot less dirt in the air especially after a storm
so that's the time to shoot and this is why I like to take a 14 or a 24
millimeter lens out with me when I'm shooting the stars when the Milky Way is
in the sky with a 14 millimeter you can get some great shots with a milky way's
sweeping across the shot so if you look in this shot you can see I've parked my
car and I've got the Milky Way coming above it I've licked my car with a torch
however with a 14 millimeter there is quite a lot of distortion so my car does
look a slightly strange shape in doing this little test I'm definitely going to
shoot more shots with a 50 millimeter all you need to do is plan those shots
properly and it'll be really nice to get a shot of say a mountain with the Milky