PWM-dimming of RGB LEDs

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Here I have tested a single individual lamp, of a single brand and type. From the ubiquity of identical or very similar lamps sold under different brand names by numerous sellers in eBay and Aliexpress, this seems to be a “typical” or popular type. The intention is for it to serve as an example of one specific technology for adjustment of the light output of LED lamps. This is not a comparative review. Continue reading PWM-dimming of RGB LEDs


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Photographing insects: lenses

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Last week I was asked about what objective I use when photographing live insects in the field. I do not always use the same objective, so I will describe the two I most frequently use. Neither do I use what would be the most suitable or state-of-the-art optics. Continue reading Photographing insects: lenses


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Dimming of LEDs

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If you are interested in photography, and take photographs under illumination from LEDs, you need to be aware of how the dimming of LED lamps works. LEDs are becoming very popular, and dimmers are quite frequently used to adjust the light level. This applies to households, offices, commercial spaces, and the now ubiquitous special LED lamps sold for studio and on location video and photography. Continue reading Dimming of LEDs


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Fluorescence of glass filters

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Until very recently I was not aware that optical glass filters can fluoresce when exposed to ultraviolet radiation. In this short post I use two filters from Heliopan that I own as examples of this. However, many other filters, and even the glass elements in some camera lenses can also fluoresce. Continue reading Fluorescence of glass filters


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AC line frequency and shutter speed

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The light output of many types of lamps varies at twice the frequency of mains AC line frequency. Alternating power follows a sinusoidal shape, alternating between positive and negative half cycles. This causes the doubling of the frequency, for each half cycle in the power supply there is pulse in the light output. Continue reading AC line frequency and shutter speed


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Macro extension tubes (lens mount)

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This is the third of three instalments on the comparison of three sets of macro extension tubes for MFT cameras: Macro extension tubes (description)Macro extension tubes (glare), and Macro extension tubes (lens mount). Continue reading Macro extension tubes (lens mount)


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Macro extension tubes (glare)

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This is the second of three instalments on the comparison of three sets of macro extension tubes for MFT cameras: Macro extension tubes (description)Macro extension tubes (glare), and Macro extension tubes (lens mount). Continue reading Macro extension tubes (glare)


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Macro extension tubes (description)

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This is the first of three instalments on the comparison of three sets of macro extension tubes for MFT cameras: Macro extension tubes (description)Macro extension tubes (glare), and Macro extension tubes (lens mount). Continue reading Macro extension tubes (description)


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Commlite products: how I wasted my money

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Disclaimer: Although both products I bought have serious design flaws I have tested only one copy of each, bought in June 2017. The design may have been corrected by the time you read this post.

Recently I wasted my money in buying two products branded Commlite. They are more expensive than equivalent products from other Chinese brands sold through eBay. The packaging is very nice, and includes a printed manual and warranty card, and the products themselves look well finished and of better quality than the usual cheap Chinese photography accessories. But there is a catch, the two accessories I bought have gross design flaws. Continue reading Commlite products: how I wasted my money


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