Aperture/Shutter Speed/Exposure

[Andrew Khan]

Good Day, I have a Canon EOS Digital Rebel XT (3500) and, I was outside today, and was attempting to take some pictures of a small little creek, near my house. In doing so, I decided to take the longer shutter speed ones, where the water comes out looking like, silk, and it's very very smooth. So what I did is this; I set my shutter speed to the "Bulb" setting, and I raised my aperture all the way (up, to higher values to 22), in order to not let to much light in, since the sun was shining quite close to the location where in I was photographing. I had numerous trial and error sessions, and didn't end up with what I wanted at all. Even my ISO was at simply 100. I could not understand why they were getting so over exposed, even under 5 seconds of having my shutter open. I do not understand it. I eventually just walked back up to the house, unsuccesful, wondering why, and how to do it. I have seen so many other shots like this, what could I be doing wrong? I appreciate any help in resolving this matter.

[BTBeilke]

First, a disclaimer - I've never done this myself. I tried to this summer, but it was so dry around here, I couldn't find any running water.

If it is very bright, you may need to use a neutral density filter in order to reduce the light hitting your sensor.

[ohanapics]

Go earlier or later in the day when there is less light. You can also purchase some neutral density (ND) filters which will also block out some of the light allowing for longer exposure times. The ND filters come in varying strengths and usually can be stacked.

[cforslund]

Why would you use the "bulb" mode for this type of shot? Try shooting in TV mode and set your shudder speed to 1 or 2 sec. That should provide you with the effect you are looking for. Make sure of course you are using a tripod.

Chris

[ACDCROCKS]

Go earlier or later in the day when there is less light. You can also purchase some neutral density (ND) filters which will also block out some of the light allowing for longer exposure times. The ND filters come in varying strengths and usually can be stacked.

Aww, did type pf photography a million times, still dosen't get tiring..Simple soulution:You had bulb on too long...Pressing the shutter 1-2 seconds will do it. Use ISO 100,the aperature varies in the light....( but prbably need Min.F/8, again depends on the light.:D

[Justin Horne]

Well, sometimes, there simply is too much light, and you need a filter. AT F/22 in really bright light at ISO 100, a 2 minute exposure just wouldn't work. Filters are needed sometimes...
That said, try it on Tv mode, set it to the time you want, and let the camera do the other stuff.

[Mark_Cohran]

All good advice above. I've done this lots of times and you only need about 2-3 seconds to get the silky effect. If you do want to try longer exposures, you'll need a neutral density filter or a polarizing filter. The polarizer will also cut down on the amount of light hitting the sensor or film, but watch out, it can remove the reflections in the water and change the whole look of the photograph.

If you really want to try long exposures, the neutral density filter is a must. A handheld meter, especially one with a spot function can be useful, or just meter using your camera's meter and manually set shutter speed and aperture to obtain the desired effects. There are lots of ways to skin this cat.

[Andrew Khan]

Wow, all of your guys advice really helped me!

Just look at the results, taken just a few minutes ago: http://img386.imageshack.us/img386/3708/img09495ld.jpg

[DayHawk]

very nice, it might need abit of USM in photoshop but the picture is very nice :)

[R Hardman]

That's a pretty cool shot. Almost reminds me of how mercury flows over things.

[Dante King]

SCHWING! nice caputre. A little pp would make this shot outstanding.

[Dante King]

Hope you dont mind

[Dragos Jianu]

great effect. well seen!. hope you don't mind my interpretation :o

[Robert_Lay]

Good Day, I have a Canon EOS Digital Rebel XT (3500) and, I was outside today, and was attempting to take some pictures of a small little creek, near my house. In doing so, I decided to take the longer shutter speed ones, where the water comes out looking like, silk, and it's very very smooth. So what I did is this; I set my shutter speed to the "Bulb" setting, and I raised my aperture all the way (up, to higher values to 22), in order to not let to much light in, since the sun was shining quite close to the location where in I was photographing. I had numerous trial and error sessions, and didn't end up with what I wanted at all. Even my ISO was at simply 100. I could not understand why they were getting so over exposed, even under 5 seconds of having my shutter open. I do not understand it. I eventually just walked back up to the house, unsuccesful, wondering why, and how to do it. I have seen so many other shots like this, what could I be doing wrong? I appreciate any help in resolving this matter.

No matter how much you WANT the exposure to work, it is necessary to understand a fundamental relationship between the resulting amount of exposure and the three controls that govern that exposure - namely, shutter speed, aperture and ISO setting. That relationship is simple:
Exposure = A + T + ISO
where A = Aperture (in f-stops)
T = duration of shutter (in f-stops)
ISO = speed setting (in f-stops)

So, given an aperture setting and a shutter speed and an ISO that give the correct exposure, if you change any one of those values by one stop, then one of the other components must be changed by one stop in the other direction in order to maintain the same exposure.

Take a numeric example - using f/5.6 and 1/125 sec and ISO = 100, gives a correct exposure. You decide you want to use a shutter speed of 1/30 second instead. That would be an increase in exposure of 2 stops. Therefore, in order to maintain the correct exposure, you must either reduce ISO to a value of 25 (2 stops reduction) or you must change the aperture to f/11 (2 stops reduction), or you could reduce ISO to 50 and aperture to f/8 (one stop reduction, each).