Timeline for Which cameras can sync at faster than 1/250?
Current License: CC BY-SA 2.5
10 events
| when toggle format | what | by | license | comment | |
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| Apr 7, 2011 at 11:45 | comment | added | mattdm | It is pretty cool that CHDK can be used with cheap hardware to get very short electronic shutter speeds. I'm just skeptical of that particular high number, based on the skepticism in the reference for it. | |
| Apr 7, 2011 at 10:14 | comment | added | user2719 | The actual flash duration is not outside of the realm of possibility -- Harold Edgerton built an entire career on that sort of exposure, after all. It's even possible that real-time metering for durations that short can occur (a luxury Edgerton didn't have); a nanosecond is a lifetime in modern electronics. But "actual shutter speeds" of 1/40000s (or 1/600000s) are all-electronic, not mechanical, shutters, and it seems that it's the CCD shutter strobe and not the camera flash that is being controlled in these CHDK examples. | |
| Apr 7, 2011 at 5:17 | comment | added | jrista | @rfusca: They just measured the blurred arcs of brighter materials in the cutting disc. If it had gone around 360+ degrees, the arcs would have been full circles, not just little arcs. I am not sure how they go from a 0.9 degree arc to a shutter or flash speed of 1/224,000. Seems like some oddball extrapolation to me, and some hard facts about the actual rotational speed, the actual electronic shutter speed, and the exact pulse time and power of the flash would need to be involved. | |
| Apr 7, 2011 at 4:41 | comment | added | rfusca | @mattdm - i not sure what you mean about about a blurred marker such that it would prevent b. Seems to me like it'd be difficult to tell if it went around 360.9 degrees - but I may not be visualizing correctly. | |
| Apr 7, 2011 at 4:24 | comment | added | mattdm | @rfusca: I assume the measurement is from the start to end of a blurred marker on a spinning disk, ruling out "b" as a problem. But "a" is a concern. As noted in the quote, we're not the only ones who are skeptical. | |
| Apr 7, 2011 at 3:39 | comment | added | rfusca | This links to a comment saying he was observing a dremel disk which is a: extremely unpredictable and not at all guaranteed to be spinning at a precise speed and b: how does he know it didn't spin around more than once? | |
| Apr 7, 2011 at 3:08 | comment | added | mattdm | "... Later tests, however at f/8 and with full flash, show a 6-degree rotation on a dremel disk turning at 33,000rpm. A quick calculation shows 1/32,520 for the shutter time. At minimal flash, the disk is rotated by just 0.9 degrees, which means a 1/224,000 shutter/flash time. Someone might want to verify these values some time soon, as they look pretty extreme." | |
| Apr 7, 2011 at 3:08 | comment | added | mattdm | The numbers come from here: chdk.wikia.com/wiki/CameraFeatures. The ¹⁄₂₂₄,₀₀₀th claim comes with the following footnote... | |
| Apr 7, 2011 at 1:46 | comment | added | Evan Krall | [citation needed]. I've never heard of either a flash duration or a shutter speed of a quarter-millionth of a second. | |
| Apr 6, 2011 at 22:07 | history | answered | Handy Andy | CC BY-SA 2.5 |