MIDOPT filters

For those interested in photography “beyond the visible”, some of the filters available from Midwest Optical Technologies Inc. under the MIDOPT brand name should be very interesting. They are distributed in European countries by Stemmer AG. Both companies are specialised in the supply of machine vision equipment. What adds additional interest is that filters are supplied in very many different sizes (from M13.25 all the way to M105, mounted and …

Black anodised aluminium in IR

Many cheap extension tubes, lens adapters and lens hoods are made of aluminium and have a black anodised finish: are they always better than plastic ones? As it was revealed by the macro extension tubes comparison internal reflections can be a problem in visible light and lead to glare and low contrast. These problems are caused by a relatively small amount of visible light reflected by anodised aluminium, specially if …

High dynamic range

High dynamic range (HDR) is used to refer to photographs which have captured a broader range of luminosity values than what is usual. In most contexts it implies a higher dynamic range than a digital camera sensor can detect between saturation and its noise floor. How can this be achieved? By combining several images so that different parts of the scene come for images taken with different exposure settings. In …

PWM-dimming of RGB LEDs

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 …

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