A DSLR camera, a tripod, a piece of card
– Manual mode
– Aperture F5.6
– Exposure 30s
– ISO 800
Find an object
Block the lens with the card and remove it when pressing the shutter button and.
Excerpt from Live View Focusing for Astrophotography
Finding the true aperture:
Aperture = Focal length / focal ratio.
So with our example of a lens with 18mm of focal length and a focal ration of f/3.5, Aperture = 18mm / 3.5. Therefore the true aperture = 5.1428mm.
Marcus Ian , Feb 08, 2012; 07:04 a.m.
Night is a ‘condition’ not a subject. But starfields are entirely doable with your kit lens, assuming you have a tripod, and preferably some kind of remote shutter release. Even your 18-55 has a manual focus option, and even though it doesn’t display a distance scale, with a little playing around you should be able to figure out which direction is near focus, and which direction is infinity. just leave it at (or almost at) infinity, and you’ll be fine focus wise. Be prepared to do exposure times of 4 seconds -> 30 sec depending on lighting and conditions. The longer your focal length (say if you got a 55-250) the shorter the max time (and therefore, less light) you can capture (due to starfield movement). Also, shoot at low ISOs to minimize noise, which can get very bad very fast.
Make sure you also set your camera so ‘mirror lock up’ is engaged, as the vibration can introduce a little bit of degradation otherwise.
Other than that, it’s a matter of getting out there and doing it.
In a nutshell, it’s not your lens, it’s your technique. The only advantage in this respect, a bigger, longer, faster, more expensive, lens is going to have is a distance scale, which is practically irrelevant anyway.
There is a rule of thumb for focal length and star movement. It is called the “600 rule”. Divide six hundred by your focal length and you will get the number of seconds exposure you can shoot without objectionable star elongation.
So a 50mm lens would be: 600/50=12, so a 12 second exposure. A 600mm lens gets you one second, a 17mm lens would be a 35 second exposure.
Bob Atkins , Feb 08, 2012; 01:11 p.m.
You might want to take a look at this – http://www.bobatkins.com/photography/tutorials/astrophotography.html
Your lens is fine. Not perfect but it’s certainly usable for star fields and star trails. Don’t use autofocus. Either focus manually or autofocus on some subject as far away as possible (“infinity”), then switch the lens to manual focus. Focus AFTER you zoom, since zooming will shift focus.
If you wanted a “better” lens the 50/1.8 II is your lowest cost option.
Put the camera on a sturdy tripod, point the lens at the sky, set ISO to something like 800, set the aperture to the maximum value (minimum number, f3.5 at 18mm, f5.6 at 55mm) and set exposure to 30 seconds.
From there on adjust your exposure time and ISO to give you the best image. Be prepared to do some editing work in PhotoShop (or whatever Image editor you use).