Extended exposure photography

[macroMe]

A quickie that has been bothering me - how do you take long shutter speed photos during the day?
Would I be right with this logic: meter for the light levels then using those settings as a basis do I move through the scale until I get to the desired shutter speed? eg: f/5.6 and 1/125 shutter can become f/22 and 1/8? (The scale that I'm talking about comes off a wheel that I found at http://www.uscoles.com/fstop.htm , it shows all of the identical exposure combinations from a single meter reading)
I have a hankering for a photo of moving water eg: a creek in flow, but I don't have night-time access and I don't know that I really want a night shot.
Thanks,
Aug

[wulf]

To increase the shutter speed, you need to limit the light getting to the sensor. The first step is making sure your ISO is as low as it can go. Next, you can experiment with increasing the exposure time and decreasing the aperture as you describe. It is worth doing some test shots with your lenses to see if there are any adverse effects from stopping down too far due to a side effect called "diffraction".

If you can't close down the aperture any further without losing quality, you then need to consider "neutral density filters". These are darkened glass and will reduce the amount of light by a calculated number of stops. At a push, you can just put a pair of sunglasses in front of the lens but this will require more trial and error and, depending on the quality of those lenses, may degrade your result.

Wulf

ps. any clouds in the sky? While being outside is generally bright, it is noticeably dimmer when the sun is behind a cloud, which will help your efforts before having to resort to filters.

[macroMe]

Seriously Wulf, is there anything you don't know
Thanks very much for the easy to understand explanation. Definitely gives me something to plan with. Would having the "stream" in the shade also help in the same way that a cloud would?

[fletch]

Originally Posted by macroMe

Seriously Wulf, is there anything you don't know
Thanks very much for the easy to understand explanation. Definitely gives me something to plan with. Would having the "stream" in the shade also help in the same way that a cloud would?

Having the stream in the shade can help with the exposure and make it easier to blur the water. However it can also create a flat looking shot with poor contrast to you need to be careful.

If you are shooting with a DSLR ND filters can be had relativly cheaply. Try searching for Cokin or looking on Ebay.

[macroMe]

Thanks for that fletch.
It's always interesting to see how my logic doesn't always work. Good to know about the flat-look. I'll check out ebay and see what I can find.
Cheers.

[OsmosisStudios]

If you really want some fun, B&W makes an ND1000 filter that offers 10 stops of stopping power. That's... alot

[fletch]

I've stacked my ND8 with my GND8 and a circular polariser before now. 30-40s exposures in bright daylight!. Shots came out really bad but was a bit of fun.

[dcclark]

Originally Posted by fletch

I've stacked my ND8 with my GND8 and a circular polariser before now. 30-40s exposures in bright daylight!. Shots came out really bad but was a bit of fun.

Nice... I've been known to stack my polarizer and ND8 to get 3-4 seconds, and it actually looks pretty decent. The main problem is that the viewfinder becomes SO dark that it's really hard to compose -- so do you composition first and add the filters at the last minute!

[macroMe]

Thanks guys. I am headed to the mountains over Easter (hopefully all the rain we've had will make the streams flow) so I will see if I can't get hold of ND filters before I go.
Looking forward to having a play to see what I can produce.
Great info.
Cheers.

Edit: Ordered filters - they should arrive tomorrow. Thanks heaps.