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01-26-2014, 10:02 PM   #1
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Bad Effects of Super High Shutter Speeds?

When shooting at large f numbers in very bright light, even at the lowest ISO settings, it's pretty easy to reach shutter speeds of 1/2000 or higher. Is there any negative effect from this on the photograph, like how very small f's cause diffraction softening? It seems like 1/4000 or higher would barely give the sensor enough time to capture a proper image, even in bright light. Is this just my imagination or any truth behind it?

The remedy would be to use an ND filter to bring the shutter speed back from the stratosphere to a healthy 1/500 or 1/250.

01-26-2014, 10:27 PM   #2
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QuoteOriginally posted by MadMathMind Quote
It seems like 1/4000 or higher would barely give the sensor enough time to capture a proper image, even in bright light. Is this just my imagination or any truth behind it?
It's you :-) Hi-speed photography (with flash) is on the order of 1/10,000-50,000th sec or faster.
01-26-2014, 11:00 PM   #3
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QuoteOriginally posted by MadMathMind Quote
When shooting at large f numbers in very bright light, even at the lowest ISO settings, it's pretty easy to reach shutter speeds of 1/2000 or higher.
High shutter speeds are really not much of an issue from a mechanical perspective. The actual velocity of the shutter curtains is much slower than you might think. What makes for the different speeds is the time between the start of the leading curtain travel and that of the trailing curtain.

In the old days (say 1/1000s max) the curtain velocity was the same for all exposure times with the leading curtain completing its travel in the amount of time indicated by the X flash sync speed. That would generally be 1/60s for horizontal run shutters or 1/125 for vertical run. On modern shutters the curtain velocity is stepped into two or more ranges to allow for consistent timing, but the idea remains the same.

The shutter on the vintage Zeiss Contax rangefinder cameras (and their clones, the Kiev), the vertical shutter is amazingly slow with the leading curtain taking about 1/35s to drop, yet the minimum exposure time is nominally 1/1000s. It is a marvel to watch.

As for the sensor...It reacts to the light that strikes it. That is the essence of exposure control. The same number of photons strike the sensor for f/8 @ 1/125s as for f/5.6 @ 1/250s and also f/1.4 @ 1/4000s for that matter.


Steve

Last edited by stevebrot; 01-26-2014 at 11:05 PM.
01-27-2014, 02:09 AM   #4
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QuoteOriginally posted by MadMathMind Quote
It seems like 1/4000 or higher would barely give the sensor enough time to capture a proper image, even in bright light. Is this just my imagination or any truth behind it?
What you are touching upon is the concept of exposure value (EV). A quote from Wikipedia:

In photography, exposure value (EV) is a number that represents a combination of a camera's shutter speed and f-number, such that all combinations that yield the same exposure have the same EV value (for any fixed scene luminance). Exposure value also is used to indicate an interval on the photographic exposure scale, with 1 EV corresponding to a standard power-of-2 exposure step, commonly referred to as a stop.

You may think of "yield the same exposure" as the combinations that allow the same number of photons (in identical scenes/situatations with same light intensity) to be captured by your sensor.

The capture process is "instantaneous" and thus, the sensor does have all the time it needs to capture the image.

Example: If you have a very bright light scene where you get a decent exposure at 1/250s and f/22, then you wil get the same exposure = capture the same number of photons at 1/4000s and f/5.6

01-27-2014, 07:06 AM   #5
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QuoteOriginally posted by MadMathMind Quote
When shooting at large f numbers in very bright light, even at the lowest ISO settings, it's pretty easy to reach shutter speeds of 1/2000 or higher. Is there any negative effect from this on the photograph?
With the K-3, the anti-moiré sensor-shake only operates for speeds of 1/1000 sec or lower.
01-27-2014, 09:47 AM   #6
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Back in film days, the response of film varied for very short as well as very long exposures (reciprocity failure), so you had to compensate exposure for these conditions. This is not generally an issue with sensors.
01-27-2014, 10:24 AM   #7
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The actual speed is no issue whatsoever - the sensor doesn't need any specific amount of time to register light. It just reacts to the number of photons that hit it, whether they arrive over a period of one second or all within a millionth of a second.

The one thing I can see as possibly affecting the image is diffraction and reflection effects off the shutter edges. At 1/4000s the 'slit' between the first and second curtain is of the order of just 1mm. I have noticed some minor vertical smearing at 1/6000 and narrow aperture on the K-30 but I'm not yet entirely sure whether it is actually because of the shutter.

In any case I think the effect, if it indeed exists, is minimal. Where I have seen it was only in some rather extreme conditions such as shooting straight against the sun and arc welding.
01-30-2014, 02:14 AM - 1 Like   #8
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QuoteOriginally posted by MadMathMind Quote
in very bright light, even at the lowest ISO settings, it's pretty easy to reach shutter speeds of 1/2000 or higher
Come to Scotland it's never an issue here.

01-30-2014, 03:49 AM   #9
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On a DSLR, due to only a small slit being exposed over the sensor at a rate of the actual sync speed, i.e. up to 1/180s for Pentax, you can get odd side effects with regard to fast moving objects. The best example is the blades on a straight propeller starts to look curved or disjointed.

High speed shutter is intended to cut ambient light. A side effect is freezing motion in many situations but it is not best suited to do so in all cases.

Most high-speed photography intended to stop action (bullets, popping balloons, water splash) is captured by a very fast flash. The shutter remains open for a very long time, (perhaps several seconds) in very low light allowing the full sensor to be fully exposed the whole time. Only light from the flash exposes the image and at a rate in the range of 1/10,000, 1/20,000 or much faster.
01-30-2014, 04:25 AM   #10
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QuoteOriginally posted by MadMathMind Quote
It seems like 1/4000 or higher would barely give the sensor enough time to capture a proper image,
Compare it with a bucket that you need to fill. Open the tap a little is equivalent to a closed aperture (e.g. f/16) or use of ND filters and you have plenty time, open the tap wide is equivalent to a wide aperture (e.g. f/1.8) and you have barely time to close the tap in time to prevent overflow In both cases however the bucket will be filled.
02-02-2014, 01:51 PM   #11
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So, yes, some odd visual effects may occur. There was an example of propeller blades. Another example is if you are under artificial lights, you might capture their "flickering"
Lights are not actually continuous, they just flicker very fast. If your shutter speed is faster than that, you might get dark lines across the frame.

And there are mechanical limitations, like flash sync or SR (becomes pointless at higher speeds anyway) or the anti-moiree.
02-02-2014, 01:59 PM   #12
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QuoteOriginally posted by kerrowdown Quote
Come to Scotland it's never an issue here.
So if someone tells me to 'Stick it where the Sun don't shine' I should stick it in Scotland?

Though I must tell you, Syracuse, NY ranks near the bottom in Average Days with Sunshine in the US. 46%.
02-02-2014, 04:13 PM   #13
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QuoteOriginally posted by boriscleto Quote
I should stick it in Scotland
Pretty much.
02-02-2014, 09:42 PM   #14
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QuoteOriginally posted by boriscleto Quote
So if someone tells me to 'Stick it where the Sun don't shine' I should stick it in Scotland?

Though I must tell you, Syracuse, NY ranks near the bottom in Average Days with Sunshine in the US. 46%.
Is the lack of sunshine why no one can get a decent picture of the loch ness monster?
02-02-2014, 10:19 PM   #15
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QuoteOriginally posted by mikemike Quote
Is the lack of sunshine why no one can get a decent picture of the loch ness monster?
Probably. I, for one, am tired of seeing grainy, foggy pictures that might be a neck or a flipper. Maybe.
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