Category: Photography

Godox AD200 flash for UV, VIS and IR photography

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[Updated 2019-07-18] Godox sells a medium-power flash called AD200 with interchangeable heads and several accessories like light modifiers and remote wireless triggers with TTL exposure metering and high speed synchronization capabilities. This gives a lot of flexibility in its use. After a few separate purchases I now own the AD200 and the H200, H200J and H200R heads, an Xpro-O TTL Wireless Flash Trigger, and several light modifiers, all of them …

Digital UVA-photography with M43 equipment

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How far can we go, with off-the-shelf equipment One question which I have been pondering for some time is: do I need to have a digital camera converted to full-spectrum for UVA photography? and are there any modern objectives that are good accidental UVA-objectives? This is not a question of cost alone. Although a converted camera can be used for VIS photography, obtaining good colour reproduction requires effort. A suitable …

Oversized lens hoods and windows

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I read during the 1970’s, most likely in a photography magazine, about the use of collapsible rubber lens hoods to take photographs through windows. They do work, specially if one manages to find a stiff enough one that will not collapse instantly at the first bump in the road or in the flight. Hama branded rubber lens hoods did work well for this purpose 45 years ago and those currently …

Most neutral density filters are not neutral

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[Updated 2019-07-17] A neutral density (ND) filter is a “grey” filter, a filter that transmits equal fractions of the incident radiation at all wavelengths. A perfectly neutral filter over a broad range of wavelengths is an idealized concept, and one very difficult to implement in practice. There are different approaches to making filters approximating colour neutrality. We here compare the spectral transmittance of of ND filters of three different types …

Capture One to the rescue

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Rescuing a technically “bad photograph” is not that difficult nowadays. This photograph was taken against all odds… through the double glassing of a dirty window on a train racing at high speed through the landscape. To make things even worse the sun was shining on the window I took the photograph through and the glass was slightly tinted green. The result out of camera was a low contrast raw image …

How small a spectrometer can be made?

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[I will update this post after testing the sensor] In a recent post I described a miniature two-channel UV-A sensor with digital interface. Here I will describe a miniature and low cost spectrometer, type AS7265X from ams. It does not used a grating as monochromator, but instead each of the 18 channels has a different interference filter deposited directly on the silicon chip. The FWHM is 20 nm, and the …

How small can a UV-B plus UV-A sensor be made?

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[updated 2019-02-13] [I will update this post again after testing the sensor] Rather recently Vishay announced a miniature sensor under the name VEML6075 with two channels nominally centred at 365 and 330 nm. The peak width at half maximum is 20 nm. So, in practice it is a sensor measuring two regions within the UV-A band with the tail of one of the two channels extending into the UV-B. It …

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