Am i ready for lightning photography? - Creative Uses of CHDK - CHDK Forum
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Am i ready for lightning photography?

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Offline Coutts

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Am i ready for lightning photography?
« on: 15 / April / 2008, 18:26:45 »
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So i've been messing with the motion detection script on my SD1000, so far my reaction times are averaging between 200-300ms, so i did some tests.

Threw a shoe infront of the camera:


Looked at a youtube video with lightning and it looks like it can capture the lightning in it!!






so does this mean ill be able to get pics durring a lightning storm?
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Offline mrproper

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Re: Am i ready for lightning photography?
« Reply #1 on: 15 / April / 2008, 19:01:50 »
LOL @ Youtube!!!

High speed videos (examined frame-by frame) show that most lightning strikes are made up of multiple individual strokes. A typical strike is made of 3 to 4 strokes. There may be more.

Each re-strike is separated by a relatively large amount of time, typically 40 to 50 milliseconds. Re-strikes can cause a noticeable "strobe light" effect

Lightning - Wikipedia, the free encyclopedia
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Offline fbonomi

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Re: Am i ready for lightning photography?
« Reply #2 on: 16 / April / 2008, 06:46:34 »
wonderful idea, capturing the youtube lighting!
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Offline whoever

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Re: Am i ready for lightning photography?
« Reply #3 on: 16 / April / 2008, 09:10:13 »
Quote from: Coutts on 15 / April / 2008, 18:26:45
So i've been messing with the motion detection script on my SD1000, so far my reaction times are averaging between 200-300ms, so i did some tests.

so does this mean ill be able to get pics durring a lightning storm?

Your cam should be capable of at least 150ms, as most people report for most cams (e.g., see here). And yes, you can catch thunderbolts with this response time. What script are you using? Try "MD LightningB" or those based on it.
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Offline Coutts

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Re: Am i ready for lightning photography?
« Reply #4 on: 16 / April / 2008, 15:29:33 »
Quote from: whoever on 16 / April / 2008, 09:10:13
Quote from: Coutts on 15 / April / 2008, 18:26:45
So i've been messing with the motion detection script on my SD1000, so far my reaction times are averaging between 200-300ms, so i did some tests.

so does this mean ill be able to get pics durring a lightning storm?

Your cam should be capable of at least 150ms, as most people report for most cams (e.g., see here). And yes, you can catch thunderbolts with this response time. What script are you using? Try "MD LightningB" or those based on it.
im currently using MDLightning6, i tried 7 and B but 6 seems to work best (sometimes have the problem of it not refocussing, and then it just stops taking pictures). Just trying to get the hang of these settings still.
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Offline Coutts

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Re: Am i ready for lightning photography?
« Reply #5 on: 16 / April / 2008, 15:50:17 »
excellent! after repeating the tests without using the flash, my reaction times are averaging between 140-200ms now. 140 seems to be pretty consistant though :) w00t im pumped. any more info as to what the settings do? (particularly compare interval?)
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Offline fudgey

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Re: Am i ready for lightning photography?
« Reply #6 on: 16 / April / 2008, 16:17:27 »
For lightnings, you should probably set compare interval to be as short as possible to minimize delay of detection. AFAIK, anything between 0 ms and 9 ms can be condidered "as short as possible". Use a threshold which doesn't trigger accidentally. Use a fair pixel step like 6 (too small and your detection slows down, too large and you'll start missing lightnings unless it's dark and they light up the entire sky).
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Offline Coutts

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Re: Am i ready for lightning photography?
« Reply #7 on: 16 / April / 2008, 16:45:44 »
Quote from: fudgey on 16 / April / 2008, 16:17:27
For lightnings, you should probably set compare interval to be as short as possible to minimize delay of detection. AFAIK, anything between 0 ms and 9 ms can be condidered "as short as possible". Use a threshold which doesn't trigger accidentally. Use a fair pixel step like 6 (too small and your detection slows down, too large and you'll start missing lightnings unless it's dark and they light up the entire sky).
ah cool. so i calculated that at a shutter speed of 1/15th of a second in my tests earlier (without flash), and reaction times averaging about 140ms, the actual reaction time of the camera between the time of seeing the motion and opening the shutter was about 75ms. then it was about 65ms exposure time (1/15th of a second) which all adds up to 140ms total. 75ms is pretty [admin: avoid swearing please] fast for a reaction speed, the average human reaction speed is about 250-300ms. This stuff is awesome!
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Offline Barney Fife

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Re: Am i ready for lightning photography?
« Reply #8 on: 16 / April / 2008, 18:17:30 »
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« Last Edit: 22 / April / 2008, 18:05:33 by Barney Fife »
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Offline PhyrePhoX

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Re: Am i ready for lightning photography?
« Reply #9 on: 21 / April / 2008, 16:07:26 »
by the way i just tested MD during video recording. works like a charm. this actually means you can record a video of a storm and also have nice pics of lightnings.
the other benefit could be that you can find out your camera's MD-"time" easily, just by opening the video in an editor and look at the frames and count them.
of course this makes more sense on s-series cams as they can shoot pics during video recording, but the MD itself will also work on other cams during recording. video will stop though, once motion is detected (because it presses the shutter, which stops the video on a620 for example).
edit: basically what you do is start video rec, enter altmode, start MD script.
« Last Edit: 21 / April / 2008, 16:09:37 by PhyrePhoX »
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