Here are three examples of time lapse videos captured in the absence of visible light. Two videos were captured under ultraviolet-A (UVA) illumination and one under infra-red (IR) illumination.
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 the surface is smooth. The ribbed surface frequently used avoids specular reflections, so controlling “stars” and similar artefacts but not so much the loss of contrast due to diffuse reflection. Continue reading Black anodised aluminium in IR
Depth of field is the depth region that looks in focus in a photograph of a three-dimensional object or arrangement of objects. Consequently, we discuss here how and why DOF is not absolute. Continue reading Depth of Field (DOF)
An on-going Kickstarter campaign offers sophisticated pinholes for digital cameras in an assortment of different lens mounts. I ordered mine, as I am interested in ultraviolet photography and pinholes, in spite of their many limitations, allow radiation of any wavelength through. Pinholes are simply very small holes in a thin plate.
When travelling by train, bus or aeroplane we frequently see views that would make great photographs. In this post I display a selection of pictures I have taken through windows while travelling in Finland between May and October 2017. I also explain some tricks-of-the-trade that hide or attenuate the effects of the optical imperfections of windows. Continue reading Photographs through windows
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 other words exposure bracketing followed by digital processing to merge the images. If you do not know what is the meaning of bracketing in photography please first read my earlier post on the subject. Continue reading High dynamic range
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
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
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
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