Photography – Page 2 – Photo rumblings and whispers

UVIR-cut filters

Pedro J. Aphalo 2020-06-11 2020-06-17Equipment, Photography, Techniques 0

Filters can block radiation either by reflection or absorption. Absorptive filters are usually made of glass containing various metal ions while cheaper plastic filters tend to be coloured with organic dyes. There is a third type of absorptive filter, which are rare nowadays that consist of a coloured gelatine layer in-between two glass sheets. Most high-quality absorptive filters sold for photographic use are made of solid glass and absorptive. In the case of square filters plastic is more common than for smaller circular filters. The current perfected version of the gelatine-between glass filters is Tiffen’s “core technology”. With absorptive filters…

A time lapse video assembled in ImageJ

Pedro J. Aphalo 2019-08-21 2019-08-21Landscape, Photography, Techniques 0

Steps used to create video Use time-lapse setting in camera to take a series of 300 photographs, one every 10 seconds. Set auto-exposure lock. Set camera on a tripod. Import the 300 images into Capture One (version 12.1). Edit the first image including correction for perspective and cropping. Select the 300 images, copy the edits from the first photograph to the remaining 299. Export the 300 photographs JPEG, setting long edge maximum length at 1600 pix. Read the 300 images into ImageJ (version 1.52p) using “File > Import > Image sequence”. Export the video from ImageJ using “File > Save…

Godox AD200 flash for UV, VIS and IR photography

Pedro J. Aphalo 2019-07-14 2019-07-18Equipment, Mehods, Photography, Techniques 0

[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 branded Godox. (The same flash and accessories are also available under other brand names.)

Digital UVA-photography with M43 equipment

Pedro J. Aphalo 2019-07-14 2019-07-14Equipment, Photography, Techniques 0

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 filter is used on the objective to replace the one removed from the image sensor unit during conversion. As it is not possible to find a perfect match to the…

Oversized lens hoods and windows

Pedro J. Aphalo 2019-07-13 2019-07-14Equipment, Photography, Techniques 0

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 available from Hama also do work well. The problem is that given their size one has little room for deviations from pointing straight into the window as vignetting quickly becomes…

Most neutral density filters are not neutral

Pedro J. Aphalo 2019-05-11 2019-07-18Equipment, Mehods, Photography 0

[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 available for use on camera lenses and explain why the use of some of them can introduce strong colour casts in the photographs we take with them.

Capture One to the rescue

Pedro J. Aphalo 2019-03-04 2019-05-03Photography, Techniques 0

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 that looked like a sure discard… but was it?

How small a spectrometer can be made?

Pedro J. Aphalo 2019-02-13 2019-02-13Equipment, Photography 0

[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 wavelength range from 410 nm to 940 nm. The spectrometer consists in three separate sensor units working together. The interface is digital, and temperature compensation and analogue to digital conversion…