Long exposures during daylight.

[becky_stead]

Hi im wanting to try out some long exposures during daylight. Subjects such as streams, waterfalls and the ocean for example. I have a Canon EOS350D and was wondering what type of settings i would need and maybe filters?? I have searched the net, but havent really found much that helps and you peeps have been very helpful to me in the past with my newbie questions lol! Thanks for your time everyone.

Becky

[gemmf]

You'll need a x64 ND filter which will give you extra 6 stops. (You might get away with x8 on a dark cloudy day though) Then you'll probably have to set the camera to lowest ISO, then smallest aperture in order to get the longest shutter speed as possible. And solid tripod is also essential. If the shutter speed is still not slow enough and you want to squeeze in a bit more, you could over-expose the image just a little in desperate situations.

[ghsmith178613]

Hi im wanting to try out some long exposures during daylight. Subjects such as streams, waterfalls and the ocean for example. I have a Canon EOS350D and was wondering what type of settings i would need and maybe filters?? I have searched the net, but havent really found much that helps and you peeps have been very helpful to me in the past with my newbie questions lol! Thanks for your time everyone.

Becky

basics first - a formula exists for computing this. if you google for "basic exposure constant," you will see the reciprocal values between iso/asa, shutter speed and aperture openings.

notice from you google search that reduced light situations will allow you to use slower shutter speeds. lower light conditon settings can be computed through the formula.

longer exposures result in blurred motion. longer exposures can be achieved by using smaller apertures (bigger f number) on the other hand, smaller apertures result in greater depth of field. a tripod (as mentioned) is absolutely critical to avoid unwanted blurring.

you didn't mention which lenses you have for the 350d. the "hobby" 18-55mm will close to f/29. (not a "standard" aperture). by the formula, an exposure on a bright sunlighted day is f/16@1/iso (f/16@1/125), you lens will only allow you to work at f/22@1/2/iso. (f/22@1/60)

filters are assigned "filter factors." these are additive as they affect light reduction or loss. that is, stacking a bunch of neutral density filters together will be the same a single of the larges value you will need. although most manufactures have omitted the filter factor from the data sheet, the value can be tested using the above formula.

physics - can't live with it, can't live without it.

happy shooting,
g. smith
assoc. prof. photo. tech.

[philway]

Try a Hoya ND400 filter that reduces incoming light by 9 stops
or a B+W ND110 filter that reduces incoming light by 10 stops.

For example a 1/1000s exposure allows you 5s with a 9 stops filter so you can use your lens at his best aperture, before diffraction generally sensible after F11.

Nota : a ND8 is only 3 stops.

10 stops=1/(2*2*2*2*2*2*2*2*2*2)=1/1024 light
9 stops=1/(2*2*2*2*2*2*2*2*2)=1/512 light
3 stops=1/(2*2*2)=1/8 light

[halesr]

Another way to slow the water and leave everything else that is not moving down is to use a tripod and make multiple exposures and then combine the images.

I learned about this is a workshop when I was using film and you did the multiples on the same frame of film with the exposure compensation adjuted for the number of exposures. You camera manual should have the instructions.

BUT, if you are using digital, you can shoot all at same exposure and compensate in your image editing program. I have read several discussions as to whether you should adjust exposure when shooting or just take care of it in the editing process. I think the editing method came out on top. Let us know how it goes.--Rene

[mikelong]

One quarter second for silky water is my minimum. ND filters are not required although could make for interesting results - I use only a polarizer to eliminate reflections. Equations for reciprocity failure? Keep it simple and simply add a little time on long exposures of one quarter second or more, then bracket your shots.

http://www.pbase.com/mikelong/image/64371549

http://www.pbase.com/mikelong/image/49633621

http://www.pbase.com/mikelong/image/41651125

http://www.pbase.com/mikelong/image/52246987

http://www.pbase.com/mikelong/image/49251050

[becky_stead]

Thanks everyone for your help. To be honest i dont really understand a lot of the above (self taught amature with not a lot of theory knowlage lol). I kind of get some of it and in the past have taken a couple of shots where the water is silky and the image is not over exposed, but just by fluke and cant remember what settings i used. Anyway hopefully i will be out on friday with my camera so if i come accross any streams im going to try and put some of this to practice. Thanks again everyone for your help. Where would i be without you??

Thanks again

Becky

[halesr]

Mike's shots are great. Take his advice and keep it simple. Do you have TV mode on your camera. Set the time for the shutter there and it will adjust for the f stop. That at least would be a starting point.

Great thing about digital, you can take a shot, preview and adjust based on what you got with the first shot. Take a pad, and make notes.

Settings Results Notes

Then make a change and do it all over again. Using up a few kilobytes on your card won't hurt anything.--Rene

[mikelong]

Take a pad, and make notes.

This is really important, a vital part of my learning curve early on...and still today! When you get your shots onto the computer check them against your field notes and make further notes regarding what you like or don't like about the image. Your failures are equally as important as your successes.