So you got tired of reading about Trump on ATS and decided to take a look at my other thread on Astrophotography, the pretty pictures have given you
an appetite for trying this out yourself. You've got a camera, and like that erik guy said: in today's world with digital cameras, I don't need to buy
film, pay for it to be developed, wait days or weeks for it to be developed. I can see it right away!
Let's head on out and do it! CHAAAAARRRRGE!!!
Woah there Hoss. Yer gonna need to figure out a few things first.
First up is: weather. If it's cloudy, even partly cloudy out, you are going to have some issues.
Second up is: Moon. Is the Moon out tonight? If it is and you want to take pictures of it, you're almost good to go. If it is, but you wanted to take
pictures of the stars......the light of the bright Moon is going to give you issues.
Third up is: Camera. What kind ya got? If it's a iPhone and you think you can just point it at the Big Dipper and you're good to go, you're going to
They do make devices that allow you to hook up your smart phone camera and other cameras like it to telescopes, and as long as you're looking at a
very bright object in the telescope (Moon, planets like Venus, Jupiter, Saturn), you can get some excellent pictures, or take videos of them. Even
some very bright nebulae like M42, Orion's Nebula.
But for wide angle lens photography of whole patches of the sky, you're going to need a camera like my DSLR that I have, because it allows you to
adjust things like the f-Stop, the ISO and most importantly: how long the shutter stays open (exposure).
"But erik, I got a DSLR camera, so shut up already and let me run out there and buy up all the equipment I want!"
Again: Woah there!
Most of us that do this pretty much dream of having a set up like this:
When in reality, if you're dirt poor like me, this is what you have instead:
Basically a camera on a stick.
Okay, don't fret. This is how you should be starting off first anyways. You need to get comfortable with your camera, lenses and learning all the in's
and out's. Especially if you've never done anything else, like actually owned a telescope, and used it to find things in the sky that your eyes can
Even so, you might already be comfortable with your camera and are ready to move on to the next step, which is mounting your camera in such a way so
that you can "track" the object you're taking a picture of, but you do not have the money to spend on some of the expensive equipment for a motor
mount. There is an answer for that too which I'll get to in a minute.
First: Static Mount vs. Tracking Mount.
When you're imaging the night sky, you have to keep in mind that you're going to take long exposures (measured in seconds and minutes). Bright objects
like the Moon are so bright, you don't have to worry about that. You can take exposures as fast as 1/250 of a second, just like you're taking images
during the day.
But those longer exposures we have a problem. It's called "The Earth Is Spinning At 1,000 Mph". The Earth's rotation causes the objects in the sky to
appear to move.
If you set up your camera and open up the shutter, then walk away for about an hour, then come back and close the shutter, you'll end up with images
These are called Star Trails, and can be very awesome and beautiful. If that's all you want to do, you can stop reading here as all it takes is a
steady camera (a tripod) and opening up the shutter for very long periods. You just have to be aware of the weather (clouds) and light pollution. Some
of these shots are the most beautiful I've ever seen:
Now, if you don't want star trails, but you only have a tripod, and don't have the money to blow on more expensive equipment, there are options.
If you just use a tripod, your option is limit how long you expose your frame for. How long is too long?
That's a hard question because it has a lot of "depends" on it. It depends on your lens (it's focal length), it depends on what you've set your ISO
and f-stop to, and it also depends on what direction you have your camera facing.....which depends on where you live too.
I'm going to skip talking about ISO's and f-stops. Right now the most important thing is your focal length of your lens and what direction you're
If you live in the northern hemisphere here on the Earth, objects in the sky when facing North will appear to move slower than objects in the sky when
facing South. The opposite is true if you live in the southern hemisphere. Keep this in mind for the next part.
Focal Length: There is a rule called the Rule of 500. You take your focal length of your lens and divide it into 500. The answer is the amount of time
in seconds you can open your shutter before the stars will move far enough to leave a trail.
So, for my EF-S 18mm to 55mm lens, if I have it set to 18mm, I'd divide 500 by 18 and the rounded answer is 27. So that means I should be able to do a
27 exposure and not get any star trails. If I set it to 55mm, the math says that I only have 9 seconds before I start to get star trails.
What about a 500mm telephoto lens? Do the math: 500/500 = 1
I can only expose the frame for 1 second. Which with stars and nebulae is not going to be enough time to capture anything in the frame.
Yet, if I attach a 6.5mm wide angle lens, I can expose the frame for a whopping 77 seconds before I get any trails!
Rule of thumb: The more you zoom in, the less time you have for an exposure if your camera is not tracking with the Earth's rotation.
Now, the Rule of 500 is not exact either. You will find that 27 seconds works perfect for the Big Dipper (pointed north), but if you do it with Orion
(towards the south), you end up with a little bit of star trails. Just back off the exposure by a second or so.
I don't have the money to buy a motor mount!
Never fear! Human ingenuity is here!
All you need to do is go to the hardware store and by some cheap things:
Quit yer laughing! It WORKS. I built one myself back in the 1990s. You have to align the hinge of the device with Polaris (the North Star), Or the
Southern Cross area for those of you downunder, and then slowly turn the screw (constantly) for a certain amount of time while you have the shutter on
your camera open.
If you don't trust your hands, and have a little bit more money to spend, you can buy a stepping motor and it will do the same thing for you:
Astrophotography on a shoe string budget, and yes, you can get some amazing shots this way:
The bottom line is, if you want to take images of other galaxies, nebulae, globular clusters, you will need a mount that compensates for the Earth's
rotation because their light is so faint, that you must make long term exposures.
I wouldn't complain though. In the old days with film......some shots you'd have to guide the camera with the shutter open for 45 minutes. Today's
DSLR cameras can do it in 5 minutes.
edit on 2/15/2017 by eriktheawful because: (no reason given)