Long Exposure Shutter Speeds?

[n30_mkii]

Silly question I'm sure, but here goes anyway;

If I want shutter speeds for night shots that are longer than 30secs, I can obviously use bulb mode and a remote shutter release. But how do I know how long the exposure should be? is it just guess work? Thanks

 

[CT]

Re-arrange...

watch/wrist.

Seriously - that's it. A second hand helps.

 

[CT]

Re-arrange...

watch/wrist.

Seriously - that's it. A second hand helps.

I think I've misunderstood you though Duh!

If you can get a reading with the lens wide open within your 30seconds, then you simply double the shutter time each time you stop down an aperture.

If you can't get any sort of a reading at all then it's a question of guessing a starting exposure and take it from there. Night exposures in very low light usually involves a bit of trial and error.

 

[dazzajl]

You can adjust the settings so that the camera can get a meter reading and then work it back again.

So if you were shooting at f16 but the camera set a 30sec exposure with f4, you can work back the four stops difference to a shutter speed of 8 minutes.

You can obviously do the same thing by playing with the ISO.

Or of course just guess but at 6, 8 or 10 minute exposures, if you're going that long becomes a long time to wait and see if you're right.

 

[n30_mkii]

Yeah guessed there would be some way of calculating exposures within a certain time by stopping down using ISO and aperature. Thanks for the help!