Flüssiger Sauerstoff fließt an einem Magneten vorbei.
How fast is the rotor of a Helicopter
Tuesday, 16.02.2010
With an exposure time of 1/100s and a roto diameter of 11m one estimates about 220m/s for the speed of the blade tips.
One often reads again that the blade tip of a helicopter reaches supersonic speed (over 340m /s). In hover, this is not the case for this helicopter. The helicopter, Eurocopter BK117-C1 has a rotor diameter of 11m. During the exposure time of 1/100s the tips moved about 2.2 meters. The rotor moves at approximately 220m /s and turns nearly 7 times per second.
Defraction limit using a digital camera
Tuesday, 24.11.2009
Die Auflösung eines Objektivs ist beubungsbegrenzt von der Blende abhängig.
Due to the diffraction limit the diameter of a pixel is d = 2.44 · ? · B, where F-number B and the wavelength ? determined. With a typical value of ? = 555nm we obtain d = B · 1.3?m. The typical pixel size of today's digital SLR cameras is about 5?m, so that we reached at f / 4, the theoretical limit. Digital Cameras have in some cases significantly smaller pixel sizes because they work with smaller image sensors.
Polarized light in nature
Wednesday, 14.10.2009
There is more polarized light than you think
The 20 regular readers are probably a little tired of the polarization, but the big difference between horizontally and vertically polarized light at a normal view I was not aware of. The sun was low, and about 90 degrees to the left of the view direction. The sunlight is therefore scattered in the mist by approximately 90 degrees. In this case, the polarization can only be perpendicular to the direction of incidence and outgoing beam. Therefore in the picture it is almost vertically. Both images were taken with the same aperture and shutter speed. To get an idea of where polarized light appears in the picture, I have determined the difference with the GIMP. In the fine structures in the tree, the leaves probably did not stay exactly in the same place. The brightness at this positions are probably artifacts.
Here the difference between vertically and horizontally polarized light is shown
In landscape photography you should always have a polarizing filter it.
3D glasses contain a lot of physics
Thursday, 1.10.2009
Used in the wrong direction the 3D eyeglasses blocks linear polarized light of the LCD display.
Modern 3D eyeglasses consists of circular polarisation filters. These filters have on the one side a normal linear polarisation filter and on the other side a ?/4 plate. Therefore both glasses of the eyeglasses behave in linear polarized light LCD of the screen directly, if the side with the linear polarisation filter shows toward the screen. For a 3D effect the eyeglasses would not be suitable, since here each eye has to see another picture. In the next picture the eyeglasses held at the large horse produce circular polarized light, both glasses in different direction of rotation. The light of the lower eyeglass lens is blocked due to the front eyeglasses and let through that of the upper eyeglass lens.
The glasses for 3D cinema use circular polaized light.
Polarisation of a LCD display
Monday, 14.09.2009
Foto with polarisation filter
Foto of a LCD display using a polarisation filter. By putting a transparent paper on top of the screen, the polarisation is broken and the display can be seen. Parts without transparent paper are dark due to the polarisation filter.
