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|Oct 27, 2006, 4:31 PM||#1|
Join Date: Jan 2005
Looking for a camera for my college-age son going on an European vacation summer of 2007. I own a Canon A530 which I really like except the slow shutter speed. Wanting a 5-6 mp, easy to use, fast shutter speed, not too bulky or heavy, high quality 4x6 photos. Any suggestions?
|Oct 28, 2006, 12:45 AM||#2|
Join Date: Jun 2003
Location: Savannah, GA (USA)
Most models are capable of relatively fast shutter speeds (for example, your Canon can use shutter speeds up to 1/2000 second).
But, just because they have that ability doesn't mean that you can use it if you want properly exposed images.
If you keep the shutter open too long, you'll get overexposed images (too bright). If you don't keep the shutter open long enough, you'll get underexposed images (too dark).
Three factors determine how long the shutter needs to stay open for proper exposure:
1. The Amount of Light (and what you think is bright indoor lighting is very dim to most cameras). The Human Eye adjusts well to typical interior lighting, but it's still very low to a camera's lens.
2. Your ISO speed (this is how sensitive the camera's sensor is to light). Your A530 has ISO speeds up to ISO 800 available (which is pretty high for a model in it's class). You don't want to set it to any higher than needed (since increasing ISO speed also increases noise levels). Each time you double the ISO speed, the camera can use shutter speeds twice as fast for the same lighting and aperture.
3. Your Aperture Setting. The largest available apertures (represented by smaller f/stop numbers) are printed on the front of the lens with most lenses, and are also shown in the specs.
Aperture when expressed as f/stop is a ratio between the focal length of the lens and the area of the iris opening diameter.
With a zoom lens, you usually see two apertures listed (the largest available aperture at wide angle zoom setting, and the largest available aperture at the full telephoto zoom position). Smaller numbers are better (larger openings).
When in between the widest and longest focal length of the lens, the largest available aperture will fall somewhere in between the apertures shown in the specs (and printed on the lens).
Your Canon's lens is more than 3 times as bright at it's widest zoom setting (least apparent magnification) versus it's longest zoom setting (most apparent magnification). This is typical for it's class of camera. So, don't zoom in any more than necessary in less than optimum lighting if you can't use a flash and stay within it's rated range, or use a tripod (and a tripod won't help with motion blur from non-stationary subjects).
Some higher quality zoom lenses can maintain a constant aperture throughout their zoom range (with f/2.8 being the most common). But, most lose brightness as more optical zoom is used.
When you vary the aperture, you're controlling the iris in the lens (which like a pupil in your eye, can be opened up to let in more light or closed down to let less light in). Larger available apertures require a lens to be larger for a given focal length, too.
So, lens brightness (largest available aperture) impacts the shutter speeds you'll need for proper exposure (since more or less light is getting through to the sensor). Hence, the term "fast" (as in faster shutter speeds) for a lens that's brighter (larger available apertures, represented by smaller f/stop numbers).
The aperture scale in one stop increments goes f/1.0, 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 (represented by higher f/stop numbers), you will need shutter speeds twice as long for proper exposure for the same lighting and ISO speed.
In lower light conditions, even shooting in Programmed Auto (P) Mode with your Canon, the camera will automatically use the largest available aperture for the focal length you're using (don't zoom in any more than needed if you want the fastest shutter speeds).
So, about the only other thing you can do to influence it without influencing image brightness is to increase your ISO speed. This will increase noise levels (similar to the way using higher ISO speed film will give you more grain).
You can use software to help reduce the grainy appearance (with the loss of some detail). Popular products include Neat Image and Noiseware
Note that the trial stand alone version of Neat Image doesn't expire and is free for home use. You'll also find a free "Community Edition" of Noiseware on their download page.
Now, I realize that was a bit "wordy". But, when I noticed from your posting history that you've mentioned not liking the "slower shutter speed" from your camera in more than one post you've made, I figured that perhaps I should clarify why it uses the shutter speeds it does.
If you're interested in learning more about how exposure works, any good book on basic photography at your local library would also cover some of this type of thing (and it doesn't have to be specific to digital, as the same concepts apply to film cameras).
Your best bet with most smaller cameras is to use a flash in less than optimum lighting, and stay within the rated flash range. Then, shutter speed won't be as critical.
If you're outside of the flash range, turn the flash off (otherwise it may try to use shutter speeds that may cause underexposure, since it's expecting you to stay within the flash range). Most models default to a shutter speed of around 1/60 second indoors with flash (since the light is usually not good enough to expose a subject at that shutter speed, so the flash burst itself freezes the action).
Since the flash burst length is usually around 1/1000 second or faster, shutter speed isn't as critical, since the subject is only properly illuminated during the fast flash burst (as long as it's not so slow as to allow your subject to be exposed by ambient light in the room, and at lower ISO speeds, 1/60 second is usually a good default for most smaller models).
After turning your flash off (if your outside of the flash range), increase your ISO speed. Each time you double it, the camera can use shutter speeds twice as fast for the same lighting and aperture (and it will be using the widest aperture it can indoors in low light for the amount of zoom you're using, even in Programmed Auto modes).
If you need a model that can do significantly better in low light, and you can't use a flash, I'd suggest looking at a DSLR model with a bright lens (not a kit lens). These models have higher usable ISO speeds compared to non-DSLR cameras, since their sensors are much larger. So, the photosites for each pixel have a larger surface area and can generate a stronger signal, requiring less amplification for any given ISO speed.
In smaller cameras, the little Fuji F10, F11, F20 and newest F30 models have higher usable ISO speeds compared to most similar cameras. But, they'll have some limitations in other areas, and like your Canon, their lenses lose a lot of light if you zoom in much.
Steve usually comments on things like noise levels in models reviewed here in their Conclusion Section. That's the last page before the sample images in each model's review.
I'd suggest looking through the Best Cameras List as a starting point for models you may want to consider for your son.
If a model with significantly better performance compared to your Canon is needed, look at the DSLR categories.
|Oct 31, 2006, 3:04 PM||#3|
Join Date: Jul 2006
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