||LinkBack||Thread Tools||Search this Thread|
|May 9, 2004, 3:50 PM||#1|
Join Date: Mar 2004
I love the DSC-V1 but there's something that's really troubling me:
I want to take an action shot, so naturally i set the mode to S and adjust the shutter speed to say 1/1000 of a second. This is where i run into problems, as the faster the shutter speed i select the darker the image gets When I focus the image (half-press the shutter) the LCD shows a properly lit subject momentarily, then back to the v v dark screen. I take the picture and it shows just what the LCD shows.
Is this a fault with the camera or am I missing something here?
|May 10, 2004, 5:54 AM||#2|
Join Date: Apr 2004
Having a fast shutter-speed reduces the amount of light entering the camera. You'd have to compensate by having a larger aperture (and probably ISO setting), although the result may still be dark.
|Aug 15, 2004, 9:36 AM||#3|
Join Date: Aug 2004
Keep in mind, when your getting to the faster shutter speeds like that, you can not hand hold you camera. It has to be on a tripod.
I've noticed that you don't have to go all the way to 1/1000 for action shots. Try doing it at a little slower speed. It will certianly effect the amount of light being brought in.
Hope this helps.
|Aug 15, 2004, 11:43 AM||#4|
Join Date: Jun 2003
Location: Savannah, GA (USA)
Just because your camera can use a 1/1000 shutter speed, doesn't mean that it will use a 1/1000 shutter speed. Also, if you select it manually, you must have enough light for proper exposure of the image.
The shutter speed the camera uses is designed to insure proper exposure of the image, based on the lighting conditions you are in. So, if the camera is picking a slower shutter speed, then the light must require it for proper exposure.
For example: if it is using 1/30 second shutter speed for proper exposure, and it tried to use 1/1000 instead, then the photo would be totally black (not enough light hitting the CCD Sensor).
This is what happens if you try to override the auto exposure using shutter priority or manual exposure,in lighting conditions not appropriate for a fast shutter speed.
Think of it's electronic CCD sensor as film. It must open the shutter just long enough to properly expose the image. If it opens it too long, the image will be too bright (washing out details). If it does not open it long enough, then the photo will be too dark.
The camera must also select an aperture (iris opening for light to come through). This is like the pupils in your eyes (opening wider in low light, and smaller in brighter light). In most cases, it's probably selecting the widest aperture it can in lower light already. Then, it sets the shutter speed so that just the right amount of light enters through the iris for proper exposure.
Unfortunately, what is bright to the human eye, is not to a camera's lens.
The amount of light that can go through the lens, is based on the lens aperture rating. Your camera has a maximum aperture of F2.8 at it's full wide angle setting (very typical for a small camera). When at full zoom, the aperture is only F4.0. The lower this number, the more light can get through.
With your model, twice asas much light can reach the sensor at wide angle, compared to when you're at maximum zoom (at the largest aperture the camera has available to it).
The lower the F-Stop, the larger the aperture (with more light reaching the sensor through the lens). The higher the F-Stop, the smaller the aperture (with less light reaching the sensor through the lens).
F/1.4 is twice as bright as F/2.0
F/2.0 is twice as bright as F/2.8
F/2.8 is twice as bright as F/4.0
The aperture scale (in one stop increments) goes F/1.4, F/2.0, F/2.8, F/4.0, F/5.6, F/8.0, F/11, F/16, F/22... With each one stop move to a smaller aperture, you will need shutter speeds twice as long for proper exposure.
Your lens has a maximum available aperture of f/2.8 at full wide angle, dropping down to f/4 at full zoom.
ISO Speed is linear (ISO 200 is twice as sensitive to light as ISO 100; ISO 400 is four times as sensitive to light ISO 100, etc.)
An understanding of these parameters is very important, especially if you need to shoot in "existing light" indoors.
Here is a handy chart that shows how Aperture impacts shutter speeds needed in various lighting conditions (see the table for Exposure Values, F-Stops and Shutter Speeds). Note that the chart is based on ISO 100. So, each time you double the ISO speed, you can also use shutter speeds twice as fast for the same aperture and lighting. However, increasing ISO speed also increases noise (similar to film grain), so photo quality can degrade as higher ISO speeds are used.
To prevent motion blur from camera shake, as a general rule of thumb, you want to use a shutter speed that is 1/focal length or faster. In other words, if shooting at 40mm focal length, you'll want a shutter speed that is 1/40 second or faster. If shooting at a 100mm focal length, you'll want a shutter speed that is 1/100 second or faster -- etc. You need to increase shutter speed as more zoom is used, because the increased magnification also magnifies any camera movement (resulting in blurred images if shutter speeds are not fast enough). So, a tripod is needed in some conditons to take camera shake out of the equation.
You also have to take subject movement into consideration. A moving subject will need fast enough shutter speeds to "freeze the action".
BTW, when using a flash, shutter speeds are not as critical, because the flash itself "freezes the action". This is because in most lighting conditons, the subject is only exposed properly for the length of the flash burst (usually 1/1000 second or faster). However, you must insure the subject is within the stated flash range for your camera, which will vary with the amount of zoom used (since less light can reach the camera's sensor thorugh the lens when more zoom is used).
Unless you know what you are doing, it's not advisable to use shutter priority mode. This is because if the camera does not have an available aperture that is large enough for the shutter speed selected, your images will be underexposed (which is what you were experiencing).
Instead, to get the fastest available shutter speeds for proper exposure of the image, use Aperture Priority Mode instead, selecting the largest available aperture (represented by the smallest f/stop number). Then, the camera will use the fastest shutter speeds it can for this aperture, insuring proper exposure of the image.
Although, in lower light conditions, chances are, your camera is already selecting the largest avalable aperture for the amount of zoom you are using anyway. BTW, the "Sports Mode" on most cameras does exactly the same thing (selects the largest available aperture).
Again, you can also increase ISO speed to help, but this will increase noise.
Staying closer to the wide angle setting when faster shutter speeds are needed will also help (since less light reaches the sensor through the lens when using zoom).
Also, if noise if preferable to motion blur in some conditions, and you choose to shoot at higher ISO speeds, there are some very good tools to reduce noise:
Neat Image: http://www.neatimage.com
Noise Ninja: http://www.picturecode.com
Note that Noiseware is a free product. It does have some limitations (for example, it strips out the EXIF information, which contains information about the camera settings used). However, it seems to do an outstanding job at reducing noise. I've recently seen some tests where it worked just as well as NeatImage (using default settings) -- and Neatimage is considered one of the best tools available.
|Thread Tools||Search this Thread|