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MediumSizeUnavailable (e2 Member)

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7 May 2010 - 7:02 PM

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shutterspeed. well, you click the button to take a photo. that means (basically) that in your camera a little door opens... and then closes again. The time your little door stays open, would be the shutterspeed. if the shutter speed is on - for example - 1/1000 (of a second), then that means the door is open only for an extremely short time. For - for example - sports, often these high shutterspeeds are used to "freeze" the action. low shutterspeeds would be more useful if you would want to show motion (rather than freeze it). Those landscape photos with misty or milky water were taken with very slow shutterspeeds. You can even choose a shutterspeed of 20 seconds. Meaning that door will stay open 20 seconds and record everything that happens within that frame during those 20 secs. All on one frame. obviously people in that case use a tripod. so in those landscape shots the rocks (who would not move during the 20 secs) remain perfectly sharp, where as the moving water will get this milky effect because of the motion in it. also, the shutterspeed indicates how long you allow light to enter the camera. 1/1000 means that only for 1/1000th of a second light enters the camera. So to take photos at such high shutterspeeds, you generally need a lot of light (very sunny conditions). 1/20 means that 1/20th of a second light enters the camera. Which is a lot more in comparison. So you need less light. But at 1/20 you probably need a tripod, as any small shake from your hands holding the camera during these 1/20 of a second will show as camera shake.

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Pete (ePHOTOzine Staff)

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7 May 2010 - 7:20 PM

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Quote: I guess an aperture of 22 would be good ? Its pretty shaded so an ISO of 200 or 400 ?

ISO 400 would be fine. f/22 is the smallest aperture (letting less light to the CCD/film) so a longer shutter speed would be needed. It would probably be too long to hand hold so you would need to support the camera. If you use an aperture-priority setting on your camera (marked AV on the mode dial) the shutter speed will be automatically set and the speed would be displayed in your camera's viewfinder.

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csurry

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7 May 2010 - 7:29 PM

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Isn't the point here that very few people could look at a scene and estimate both the aperture and shutter speed. Even when working in manual mode the photographer either takes a reading from a known element, like grass or a grey card and then dials in the settings as read from the target.

For me I tend to work in aperture priority mode. I set the aperture that will give the image the look I want, which is normally quite easy as I like shallow DOF. Then because I am in aperture priority the camera sets the shutter speed. The only thing I have to do is adjust the ISO if the shutter speed is too high (decrease ISO sensitivity, say 400 to 200) or too low (increase sensitivity, so say 400 to 800).

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RogBrown (e2 Member)

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7 May 2010 - 7:54 PM

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As a rule of thumb, if you set your shutter speed to the same as your ISO, then bright sun will be f16, hazy sun f11, cloudy bright f8, cloudy dull f5.6, really dull f4. Using that as a base, you can then adjust the shutter speed/aperture combination as necessary.

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ecowarrior

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7 May 2010 - 8:23 PM

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If it helps, dorney, you're no different to many others in terms of having to have things explained a few times. I've only just recently got back into photography and spent a hell of a lot of time reading, asking, watching (youtube has plenty of tutorial stuff), and practicing before I really 'got' it.

This is how I understand it:

To make an exposure you have three things to set - Aperture, Shutter Speed, ISO. If those three things are set correctly for a particular scene, then you will get the correct exposure - ie. the right amount of light will get into your camera in order to take the photo correctly. However, while one combination of settings may correctly expose the scene, there are perhaps 5 or 6 other combinations that will also expose the same scene correctly. So it's not just a case of getting the right exposure, but getting the right SORT of exposure. To understand shutter speed, you need to understand how that ties in with exposure.

Now deciding on what combination of values you would use for the right sort of exposure depends upon the situation and scene you are trying to capture. Here are some scenarios for example.

1. A photo of a flower, where the flower is in a field of other flowers but you only want that one flower in focus and the background all out of focus. This is called having a shallow depth of field. To do this, you would use a large aperture (small f stop) - something like f/2.8 perhaps, depending on the capabilities of your lens. Now if you're out in the sunshine trying to get this photo, and your aperture is wide open like this, then light will stream through the lens very quickly and very soon your photo will become OVEREXPOSED. To prevent this, you would use a very short shutter speed - literally, the shutter will open and close very rapidly. Perhaps 1/500 second or even shorter. Extremely fast anyway. In this sort of combination you could simply set your ISO rating to it's lowest value - ISO100 perhaps. That way your sensor would work at it's optimum sensitivity rating.

2. Taking a landscape photo where the whole scene must be in focus. For this you'd want a very small aperture, say f/18 or f/22. This would give you the greatest depth of field (ie. everything in focus). Now your aperture is open only a very tiny amount, so for the correct amount of light to be able to squeeze through to hit the sensor, you may need a very slow shutter setting. The other morning I was taking a photo in Ashridge wood of the bluebells and I ended up getting the correct exposure using f/18 for 30 seconds! With this sort of photography, especially with that shutter-speed you would use a tripod. ISO 100 worked for me in this situation.

3. Hand-held portrait shot inside a room. Let's assume for now you aren't using on-camera flash, but the room is only reasonably lit. For this, you would need to be a bit smarter with your combination of settings. For one, too small an aperture will mean a slow shutter speed - too slow for handheld, meaning you'll get blurry shots. Too large an aperture may give you too shallow depth of field so not all of the subject's face is in focus front-to-back. So for this you may try f/1.8 and see what the camera recommends for shutter speed. Perhaps it recommends 1/60 second, which is fast enough to cope with you using the camera hand-held, but then you see your subject's face isn't quite all in focus. So you make your aperture wider (f2.8 perhaps) and now your camera is saying something like 1/30second (twice as slow as 1/60 sec). Too slow for hand-held. In this instance you could try to increase your sensor sensitivity to something like ISO200. Now your sensor is twice as sensitive, meaning that you can get away with half the shutter speed required (so back down to 1/60sec). At f/2.8, shutter 1/60 second, ISO200, your photo looks fine.

4. Hand-held moving subject (say a car). Shutter speed is all important here - you need a fast enough shutter speed to ensure the car is captured without blurring, so you would start off with a very short shutter speed (1/1000sec perhaps) and then adjust the aperture accordingly to the right exposure. If the aperture was too small - say f/2.8 when you find you need something smaller to get the whole car in focus, say f/5.6 or f/8, then you would need to determine if you can get away with a longer shutter time. If you can't, then again you'd tweak your ISO setting until you got the right combination.

All of the above assumes a lot - that you understand how to take a meter reading properly (definitely worth taking the time to learn this!), that you're not using a flash (a whole subject on it's own), and that perhaps you can get away with a slower shutter speed than normal if your camera has something like VR (vibration reduction on Nikon) or OS (optical stability on Canon) or whatever. But you get the idea. Some photos require APERTURE to be the setting that's most important, others require SHUTTER SPEED. The Aperture priority and Shutter priority settings on a camera can help here because they will help you determine the correct exposure settings based on the priority value (aperture or shutter) you choose.

Don't despair though - once you 'get it', it's a great feeling of achieving something. And then it's all down to practice!

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