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10-05-2010, 06:13 AM   #31
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Back on your original question. A couple of nights ago I too was out photographing lightening. I was in several of the modes at ISO 100 and then turned to B, took a image, fortunately checking it and saw the graininess in a very semi daylight image. The ISO was at 3200. I had forgot that the K20 has iso associated with different modes.

I don't have an *ist, but I would check the iso speed associated with the Bulb mode and set it to where you want it.



10-05-2010, 06:35 AM   #32
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QuoteOriginally posted by interested_observer Quote
Back on your original question. A couple of nights ago I too was out photographing lightening. I was in several of the modes at ISO 100 and then turned to B, took a image, fortunately checking it and saw the graininess in a very semi daylight image. The ISO was at 3200. I had forgot that the K20 has iso associated with different modes.

I don't have an *ist, but I would check the iso speed associated with the Bulb mode and set it to where you want it.

*istD does not have ISO modes, ISO is set once for all modes.

I know what you mean with later cameras, K10D can have at least 3 different ISO settings as a function of mode used. Manual is one, User is a second, and you can have the auto modes set to Auto ISO. I have not looked to see if Bulb has an independant setting of its own on the K10D.
10-05-2010, 09:53 PM   #33
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I had actually forgotten about this, as I essentially had everything set to 100. The K20 was repaired (new electronics and sensor), so as I use it, I am finding that things need to be setup again.
10-06-2010, 01:23 AM   #34
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As an electronic engineer I find this thread very interesting. I would couple the photodiode to a IR bulb and use that to take the picture (though you'll probably need a PLC too), rather than take the shutter button apart if your camera doesn't have a wired shutter release. I also wonder if you won't maybe get a stronger current from small solar panel than a single photodiode.

10-06-2010, 02:22 AM   #35
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QuoteOriginally posted by kari Quote
As an electronic engineer I find this thread very interesting. I would couple the photodiode to a IR bulb and use that to take the picture (though you'll probably need a PLC too), rather than take the shutter button apart if your camera doesn't have a wired shutter release. I also wonder if you won't maybe get a stronger current from small solar panel than a single photodiode.
There is no need to "take anything apart" all pentax DSLRs have a wired release using a 2mm 3 connection headphone plug. The reason for using a photo diode is because there is no need to supply current, the camera's shutter release circuit does this by way of a resistor in series with the release contact. It is looking for a short to the common to trip the shutter. As for functionality the scheme works and using a commercial plash slave (schematic shown above) it os possible to trip the shutter with a camera flash. To create a lightning trigger simply requires changing the base emitter resistor to reduce the current necessary to turn on the transistor i.e. To increase the sensitivity. Too many people are looking for a complex solution when using these three simple components is all that is needed
10-06-2010, 03:56 AM   #36
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QuoteOriginally posted by Lowell Goudge Quote
all pentax DSLRs have a wired release using a 2mm 3 connection headphone plug
please forgive my ignorancy.
does k-x has??
10-06-2010, 04:40 AM   #37
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QuoteOriginally posted by akanarya Quote
please forgive my ignorancy.
does k-x has??
No, mine doesn't. I don't think the K-m or the K-r has it either.
10-06-2010, 05:03 AM   #38
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Digitalis, that picture should be in PPG if it isn't!

Regarding the original question, my technique has been to expose for 30 seconds, allow the K20D to substract noise (weak filter). I used the FA 50 macro, with a polarizer and an ND filter stacked so I could use a decently wide aperture and avoid seeing the window behind which I was standing. Got through in the PPG with that one:



10-06-2010, 11:22 PM   #39
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QuoteOriginally posted by bdery Quote
Digitalis, that picture should be in PPG if it isn't!

Regarding the original question, my technique has been to expose for 30 seconds, allow the K20D to substract noise (weak filter). I used the FA 50 macro, with a polarizer and an ND filter stacked so I could use a decently wide aperture and avoid seeing the window behind which I was standing. Got through in the PPG with that one:
was it a daylight shot?
10-07-2010, 12:20 PM - 1 Like   #40
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Daylight Filter

Another technique to photograph lightning in the daytime is to use a filter. Years ago, I used an automated 35mm film camera with a 180-degree fish-eye and an infrared filter as part of a lightning investigation on power lines. Lightning has very strong light emissions in the infrared spectrum (especially hydrogen-alpha). I currently use an inexpensive infra-red filter that enables 15 to 30-second daylight shots.

Triggers that use the electric field change from lightning are preferable to optical triggers if you want to capture the early part of a flash (all those pretty branches!). The optical triggers work fine, but you'll generally only capture subsequent strokes in a multi-stroke flash. Good for engineers, but not so good for artists!

Mike

(who plays with lightning for a living)
10-07-2010, 04:09 PM   #41
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that image was not taken during daylight hours.
10-07-2010, 04:56 PM   #42
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QuoteOriginally posted by Stringmike Quote
Triggers that use the electric field change from lightning are preferable to optical triggers if you want to capture the early part of a flash (all those pretty branches!). The optical triggers work fine, but you'll generally only capture subsequent strokes in a multi-stroke flash. Good for engineers, but not so good for artists!
Can you elaborate on the E-field triggers?.
I mean, can you educate us on the E-field triggers?.
10-07-2010, 05:21 PM   #43
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If you want to trigger from the electric field the easy way is to look for static pulses on the AM radio band and feed the speaker or earphone to the transistor in the flash trigger circuit. The problem I see is being too sensitive. You will trigger on static fromiles away. You are better triggering on what you can see not what the radio can pick up. But I agree you may be able to trigger during the stepped leader process before the complete formation of the ionized channel and the main stroke. I will need to think about this
10-07-2010, 05:40 PM   #44
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I agree on static messing things up.
Was not really thinking about an AM radio as a trigger device. Your next electric pole with a leaky insulator will set that off, hardly useful as a lightning trigger.
10-07-2010, 05:51 PM   #45
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Getting back to real E-field detectors, as those that count lightning strikes as sen on The Weather Channel. Again , how much delay?.
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