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Old Jan 12, 2007, 9:14 PM   #1
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I've wondered...is there a minimum shutter speed that can be used when the camera is in "continous exposure mode"? Let's say we're talking about 3 DSLRs...a 3 fps DSLR (e.g. Nikon D80), a 5 fps DSLR (e.g. Canon 30D) or a 8.5 fps DSLR (Canon 1D Mk II N). How would you determine the range of useable shutter speeds?

Thanks.
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Old Jan 12, 2007, 9:40 PM   #2
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DarkDTSHD wrote:
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I've wondered...is there a minimum shutter speed that can be used when the camera is in "continous exposure mode"? Let's say we're talking about 3 DSLRs...a 3 fps DSLR (e.g. Nikon D80), a 5 fps DSLR (e.g. Canon 30D) or a 8.5 fps DSLR (Canon 1D Mk II N). How would you determine the range of useable shutter speeds?

Thanks.
No, there is no minimum shutter speed needed to shoot in continuous "shooting"mode. The only thing will be, at lower shutter speeds you obviously won't be shooting at those maximum rates per second. You do have to shoot at or above certain shutter speeds to shoot a Canon 1D at 8 frames per second or any of those other models you mentioned at their maximum rates. You can pick 1/4 second and the camera will shoot continually at 1/4 second....you'll just get 2-3 shots per second instead of 8 if it's a 1D.

In order to get to those fastershutter speeds to shoot at the fastest possible ratesyou also need enough light to be able to get a good exposure, so light and/or the speed of your lens will alsodetermine the fastest possible shutter speed you'll be able to use. That's why you see all those sports photogs on the sidelines at football and baseball gamesshooting with 300mm f2.8 or 400mm f2.8 primes. You can't quite get the same amount or quality of light when you shoot a 70-300 f4.5-5.6 zoom. It all goes together.
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Old Jan 12, 2007, 11:19 PM   #3
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Greg Chappell wrote:
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DarkDTSHD wrote:
Quote:
I've wondered...is there a minimum shutter speed that can be used when the camera is in "continous exposure mode"? Let's say we're talking about 3 DSLRs...a 3 fps DSLR (e.g. Nikon D80), a 5 fps DSLR (e.g. Canon 30D) or a 8.5 fps DSLR (Canon 1D Mk II N). How would you determine the range of useable shutter speeds?

Thanks.
No, there is no minimum shutter speed needed to shoot in continuous "shooting"mode. The only thing will be, at lower shutter speeds you obviously won't be shooting at those maximum rates per second. You do have to shoot at or above certain shutter speeds to shoot a Canon 1D at 8 frames per second or any of those other models you mentioned at their maximum rates. You can pick 1/4 second and the camera will shoot continually at 1/4 second....you'll just get 2-3 shots per second instead of 8 if it's a 1D.

In order to get to those fastershutter speeds to shoot at the fastest possible ratesyou also need enough light to be able to get a good exposure, so light and/or the speed of your lens will alsodetermine the fastest possible shutter speed you'll be able to use. That's why you see all those sports photogs on the sidelines at football and baseball gamesshooting with 300mm f2.8 or 400mm f2.8 primes. You can't quite get the same amount or quality of light when you shoot a 70-300 f4.5-5.6 zoom. It all goes together.
Thanks for the reply.



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Old Jan 13, 2007, 2:26 PM   #4
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I had decided to bow out of this thead I created till I checked the Nikon D80 User's Manual PDF. Turns out Nikon recommends a shutter speed of at least 1/250s (or faster) to get 3fps. So in fact there is indeed a "minimum shutter speed" that should be used. The D80 is a 3fps camera.

The same was recommended for the D200. 1/250s or faster.

Just in case any one was interested.

Later people.
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Old Jan 13, 2007, 2:37 PM   #5
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So in fact there is indeed a "minimum shutter speed" that should be used.
Don't misinterpret the manual. It's only telling you that in order to maintain that frame rate, your shutter speed needs to be that fast ("to get 3fps"). . You can still use slower shutter speeds in continuous mode (and may often want or need to so that the image is exposed correctly).

The only drawback is that if you use a slower shutter speed, you may not be able to maintain 3fps (because the exposure time impacts the frame rate). The slower the shutter speed, the slower the frame rate below a certain shutter speed. So, if you were shooting at 1/10 second versus 1/250 second, you may only get 2.8 frames per second versus 3 frames per second. The mirror and shutter mechanism movement speed is limited, and any exposure time is going to take away from the frame rate.

The shutter isn't going to move faster to make up for staying open longer to keep the frame rate the same as it could maintain with a faster shutter speed. ;-)

The frame rate a camera can achieve is going to have multiple variables. For example, some of them will include the time needed to reset sensor registers, open mirror, open shutter curtains, close shutter curtains, lower mirror, read out sensor, reset it for next exposure). Most of these variables are fixed for a given design. The shutter time is not (how long the shutter remains open so that the image is exposed correctly). A slower shutter speed will slow down the frame rate.

That's why Greg Chappell gave you the example that he did using an 8 frame per second camera (i.e., you can use 1/4 second if you want or need to for correct exposure, but you're not going to get as many frames per second because the shutter is going to be open long enough to impact it).


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Old Jan 13, 2007, 3:39 PM   #6
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P.S.

I'm not sure you're asking the right questions for what you may want to know.

Frame rate is one thing, and it's mostly related to the speed of the camera's mechanical design (how fast the mirror can be flipped up and down, shutter curtains opened/closed) and processor speed.

Shutter speed is a separate variable (how long the shutter needs to stay open for proper exposure). Yes, it can impact frame rate (see my last post). But, I don't think that's what you're trying to ask.

Quote:
How would you determine the range of useable shutter speeds?
The camera may be limited to a certain range of available shutter speeds (for example, one camera's fastest may be 1/8000 second, another camera's fastest may be 1/4000 second, etc. Ditto for the slow end (the slowest speed available may be different between cameras). But, that doesn't mean you can actually use them (if you want corret exposure). ;-)

The shutter speed you want to use will depend on the amount of light, your ISO speed, and the aperture you have your lens set to.

If you leave the shutter open too long for the lighting, aperture and ISO speed, you'll get an overexposed (too bright) image.

If you don't leave the shutter open long enough for the lighting, aperture and ISO speed, you'll get an underexposed (too dark) image.

Three things control how long the shutter needs to stay open for proper exposure:

Lighting Levels - typically shown as EV for Exposure Value.

ISO speed - This represents how sensitive the film or sensor is to light. Each time you double the ISO speed, the camera can use shutter speeds twice as fast for the same aperture and lighting. This is the same thing as the old ASA ratings for film.

Aperture - Think of the aperture opening in a lens as a pupil in your eye. If you open up the aperture wider (smaller f/stop numbers), more light gets through, allowing you to expose the image faster for the same lighting and ISO speed (ISO speed represents how sensitive the sensor or film is to light).

If you use a smaller aperture (higher f/stop number), less light gets through (so it will take longer to "expose" the film or sensor, requiring slower shutter speeds for proper exposure for a given ISO speed and lighting).

Lenses are rated by their largest available apertures (smaller f/stop numbers), and for most (but not all) zoom lenses, you'll see two aperture ratings... the first one is for the widest aperture at the wide end of the lens (least apparent magnification), and the second is the widest aperture at the long end of the lens (most apparent magnification).

You can still use smaller apertures (higher f/stop numbers). Most lenses can go down to at least f/22 (and some can go all the way to f/45).

The largest available aperture (smallest f/stop number) will fall somewhere in between the two numbers you'll see for a lens' specs at focal lengths in between the two extremes.

Some zoom lenses can maintain a constant aperture throughout their focal range (with f/2.8 being the most common). Of course, a brighter zoom lens is larger, heavier and more expensive. For indoor use without a flash, a lens with a constant f/2.8 aperture is preferred in a zoom (but, a brighter prime is even better, allowing faster shutter speeds and/or lower ISO speeds for the same conditions).

Aperture as expressed by f/stop is a ratio, and is determined by dividing the focal length of the lens by the size of the iris opening.

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, etc. With each one stop move to a smaller aperture (represented byhigher f/stop numbers), you will need shutter speeds twice as long for proper exposure.

So, a lens with a larger available aperture (smaller f/stop number) is desired to get fast enough shutter speeds to reduce motion blur (either from camera shake or subject movement) in many conditions.

Of course, the downside to using larger apertures is a shallower depth of field. This can be a pro or a con, depending on what you're shooting. For example, for portraits, you may want a shallower depth of field (to help your subject stand out from distracting backgrounds). For landscapes, you may want more of the image in focus instead. So, you'd use a smaller aperture setting. Again, just because a lens has larger available apertures, doesn't mean you need to shoot that way.

See this handy online Exposure Calculator to get a better idea of how exposure works (and the same principles apply to both film and digital). Note that Film Speed in the calculator is the same thing as ISO speed:

http://www.robert-barrett.com/photo/...alculator.html

For more information on how aperture impacts Depth of Field, see this Depth of Field Calculator:

http://www.dofmaster.com/dofjs.html

Short Answer:

Frame rate doesn't have anything to do with the shutter speeds you may want or need to use (or the available shutter speeds for a given camera).

But, using slower shutter speeds might impact frame rate (as described in my previous post).


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