Finding The North and South Celestial Pole

I'm sure all of you have seen those cool star trails photos of the stars spinning around a circle. Well that circle is either the North or South Celestial pole.

Now I don't know about you, but my astronomy is not that flash, and when I was out doing some photography the other night, I couldn't work out the axis that the stars rotated around so I could frame my shots.

I decided to do a bit of research to work out how to locate them, and here's the answer.

Enjoy
Brent

Night Shoot Number 3 - The Old Blast Furnace

Last Saturday my Old Man and I threw our swags into the 4WD and headed up to the mountains for a planned evening of night photography. It was a full moon so we figured the old Blast Furnace at Lithgow would be a great location for some long exposure work.

Got some interesting images.




This first one was a 12 minute exposure... my longest yet. I jumped down into the basement of the old gas works and camped out there in the dark to get this image.

We were lucky in the fact that a bunch of clouds finally came overhead to create some drama to this image of the ruins.





Starting to feel like I am getting the night photography sussed out... I've got a routine going to calculate exposures and to compose my shots and I seem to be making the captures correctly (hardly any noise and the amp glow hasn't posed a major problem).

I love the pace of night photography... lots of time to think and plan while the shutter is open. My new torch seems to work well, so I'll have to start doing more painting with light.

Brent

How Do You Calculate Night Exposures?

One of the most frustrating aspects of jumping into night photography was the exposure metering. Forget your handy-dandy in-camera meters, mine will only meter to 30sec and I expect thats pretty much standard.

So how do you work out your exposures? Hand held light meter? I don't think so...

Most hand-held light meters are only sensitive to about -2ev, so thats not going to help you work out your exposures.

Trial and Error - Yup, that works... but here's a way to get close to the right exposure out of the gate.

I came across an interesting article by Fred Parker called "The Ultimate Exposure Computer". If you haven't seen this, it's worth a read. Fred has published some exposure tables that allows you to calculate exposures under any lighting conditions, using any combination of shutter speed, ISO and Aperture.

What I have done is to distill the relevant information into a handy pocket card that allows you to get a pretty good starting point for your exposures. This is what it looks like.

You will see that it "hard-coded" to 200 ISO (because thats what the speed that I'm going to shoot all my night work) and the aperture ranges from f4 to f16 (because I'm unlikely to shoot outside that range).

So just look at what sort of moon you have, and then read off how many minutes you need to expose for at the various f-stops.

If anybody wants this chart in PDF format, just drop me an email, otherwise you can just print this article and cut it out.

Enjoy

Brent