Beginner Talk to me about long exposures...

crundi

crundi

Suspended / Banned
Messages
8
Edit My Images
No
I attempted to capture a flowing waterfall the other day and although I understood a slow shutter speed was required to get that smoooth look, I was restricted in so far that the image started to become over exposed - of course! So how do I take a silky water shot without blowing the rest of the image? Are we talking bracketing here or am I missing something?
 
I believe your answer lies in ND filters to darken the scene, giving you the ability to dial in a longer exposure time.

Edit: Beat me to it!
 
presume you are already using lowest ISO and a small aperture (f16 or above).
 
Dawn or dusk (for lower light levels) or a polarising filter would be the cheapest way to go (if you have a polariser, if not, get one - it's pretty much the only filter that can't be replicated in PP).
 
The reason for the over exposure is you are increasing the amount if light of the exposure by extending the time the shutter is open for but not compensating for it by reducing the amount of light reaching the sensor in another way (reducing the aperture or ISO).

Like others have said a ND filter is the best way to achieve the silky water look. You need to keep the shutter open for around 10-30 seconds depending on the speed of the water. If your unfiltered shutter speed was 1/50 then a 6 stop nd filter would give 1.3 secs and a 10 stop nd filter would give 20 secs. If you were out at sunset or sunrise the light levels would be lower so shutters speeds would be longer.

A circular polariser would cut down light through it by a stop or two and extend the shutter speed but probably by not enough to get the silky look you want.. A ND filter can be purchased in various strengths and selected as required depending on unfiltered light levels. Both ND filters and polarisers give an effect that can't be replicated in post processing.
 
Last edited:
Thanks, that all made sense. I'll look into a cheap filter to get me started then!
 
Agree with a cheap ND first.. I bought one and have been 'playing' but not managed anything worthy of posting up yet! It takes some time to get right, but I'm really new and still learning something every time I get the camera out...
 
Try a 3 stop (or nd8) filter first. You probably won't need a 10 stop filter for waterfalls
 
Agree a 10 stop can be a bit much if you can't open up aperture or increase ISO to suit. Other dodges include switching to ISO50 if you have it, which gains you another doubling of duration. Another consideration, is that you may wish to invest in a timer release - a lot of cameras max out at 30 seconds exposure, so if you start to play with ND filters (not necessarily with waterfalls, but for really long exposures), a timer release can be a godsend (though is not essential). You can also use multiple exposures to achieve a longer duration if you haven't got a timer and layer up the image.
 
A 10 stop is a bit overkill for water which is already moving fast.

Shooting after the light has gone will also give you much longer shutter speeds without over exposing.
 
iso 50 (if possible)
f16+

or take the shot at night.

A lee little stopper (6 stop) would work a treat but they are not cheap.
 
I agree with what's being said in this thread. Have the lowest ISO and the lowest usable F stop to create more time if you don't have an ND filter to use. If you get an ND filter I'd do some research as the cheaper brands can have harsh colours hues introduced to the image. I use the Lee Big Stopper. It introduces a blue tint to the image but can easily be removed by increasing the temperature of the photo. Other brands aren't as easy to do this. Lee Filters can be expensive though so use what's best with your budget.

When I first started exploring with this idea it was mentioned to try out some welding glass. You can get it on Ebay etc. I don't know how good it is but it could be a cheap intro if you're on a budget or not wanting to shell out for something you want to do once or won't use again.

Something else to add is that if you're using Canon that you can use live view and it'll show you what the image exposure will look like based on the settings you currently have set. Nikon doesn't have this feature as it's something to do with the internal architecture that prevents this.
 
If you're in that situation again and you don't have a filter on you but you've got sunglasses, as an emergency, you can hold them in front of the lens - it might get you the shot that would otherwise be missed.
 
You must log in or register to reply here.
Back
Top