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UK diy (uk.d-i-y) For the discussion of all topics related to diy (do-it-yourself) in the UK. All levels of experience and proficency are welcome to join in to ask questions or offer solutions. |
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#1
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Removing 100hz pulsing from mains lighting
The background is that I've been trying out a Canon Powershot digital
camera on a tripod with the Canon Zoombrowser software that lets the camera be controlled from a computer via the USB. This works well but illuminating the subject (a ragbag of documents and old pictures) with desk lights using ordinary GLS lights gives a visible pulsing of light which can be seen in the monitor due to the 50Hz mains frequency. [which means 2 flashes per sec or 100Hz] This isn't ideal as it clashes with typical camera exposure speeds. SFAIUI professional copystand lighting is expensive, so looking for a method of obtaining a smoothed light. One possibility would be DC lighting, but it needs to be quiite bright. Another possibility might be flourescent lighting - but does phosphor coating on the tube provides some lighting persistance? Any views on feasibility of either (& how to achieve it) or any other suggestions would be most appreciated. TIA |
#2
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Removing 100hz pulsing from mains lighting
jim wrote:
The background is that I've been trying out a Canon Powershot digital camera on a tripod with the Canon Zoombrowser software that lets the camera be controlled from a computer via the USB. This works well but illuminating the subject (a ragbag of documents and old pictures) with desk lights using ordinary GLS lights gives a visible pulsing of light which can be seen in the monitor due to the 50Hz mains frequency. [which means 2 flashes per sec or 100Hz] This isn't ideal as it clashes with typical camera exposure speeds. SFAIUI professional copystand lighting is expensive, so looking for a method of obtaining a smoothed light. One possibility would be DC lighting, but it needs to be quiite bright. Another possibility might be flourescent lighting - but does phosphor coating on the tube provides some lighting persistance? Any views on feasibility of either (& how to achieve it) or any other suggestions would be most appreciated. TIA Fluorescent is much worse in this respect. I used to use a twin 8' fitting for photos, just picked suitable slowish exposure speeds. If you want to get rid of 100Hz for quicker shutter speeds, the simplest solution is high current filament lamps. High current means thick filament means lots of thermal inertia. So we're talking 500w halogen, or 12v 50w halogens. NT |
#3
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Removing 100hz pulsing from mains lighting
"jim" wrote in message ups.com... The background is that I've been trying out a Canon Powershot digital camera on a tripod with the Canon Zoombrowser software that lets the camera be controlled from a computer via the USB. This works well but illuminating the subject (a ragbag of documents and old pictures) with desk lights using ordinary GLS lights gives a visible pulsing of light which can be seen in the monitor due to the 50Hz mains frequency. [which means 2 flashes per sec or 100Hz] This isn't ideal as it clashes with typical camera exposure speeds. SFAIUI professional copystand lighting is expensive, so looking for a method of obtaining a smoothed light. One possibility would be DC lighting, but it needs to be quiite bright. Another possibility might be flourescent lighting - but does phosphor coating on the tube provides some lighting persistance? Any views on feasibility of either (& how to achieve it) or any other suggestions would be most appreciated. TIA Ordinary fluorescents are worse than incandescents. Have you tried low power fluorescents? They are switched electronically at high frequency and should avoid the problem. John |
#4
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Removing 100hz pulsing from mains lighting
jim wrote:
Another possibility might be flourescent lighting - but does phosphor coating on the tube provides some lighting persistance? If you go for lights with electronic ballasts then the fliker rate will be in the kHz rather than the 10s of Hz These are quite cheap, work nicely, and have a good colour temp: http://www.tlc-direct.co.uk/Main_Ind...ing/index.html -- Cheers, John. /================================================== ===============\ | Internode Ltd - http://www.internode.co.uk | |-----------------------------------------------------------------| | John Rumm - john(at)internode(dot)co(dot)uk | \================================================= ================/ |
#5
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Removing 100hz pulsing from mains lighting
In article . com,
jim wrote: The background is that I've been trying out a Canon Powershot digital camera on a tripod with the Canon Zoombrowser software that lets the camera be controlled from a computer via the USB. This works well but illuminating the subject (a ragbag of documents and old pictures) with desk lights using ordinary GLS lights gives a visible pulsing of light which can be seen in the monitor due to the 50Hz mains frequency. [which means 2 flashes per sec or 100Hz] This isn't ideal as it clashes with typical camera exposure speeds. I'd be surprised if what you're seeing is indeed the lights varying in intensity. It's more likely to be something to do with the monitor. -- *Never put off until tomorrow what you can avoid altogether * Dave Plowman London SW To e-mail, change noise into sound. |
#6
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Removing 100hz pulsing from mains lighting
Dave Plowman (News) wrote:
In article . com, jim wrote: The background is that I've been trying out a Canon Powershot digital camera on a tripod with the Canon Zoombrowser software that lets the camera be controlled from a computer via the USB. This works well but illuminating the subject (a ragbag of documents and old pictures) with desk lights using ordinary GLS lights gives a visible pulsing of light which can be seen in the monitor due to the 50Hz mains frequency. [which means 2 flashes per sec or 100Hz] This isn't ideal as it clashes with typical camera exposure speeds. I'd be surprised if what you're seeing is indeed the lights varying in intensity. It's more likely to be something to do with the monitor. I wouldn't. I have a tacho that works on ac components of light. Its unusable in artificial light. Even incandescent. Only way to use it is with a torch... I'd advise LV halogens fed of a regulated DC power supply. |
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