Natural light photography underwater

by  on  in Scuba diving

Flash, Forrest, flash!

Many starting photographers conclude there is not much light underwater and start flashing. Many using one flash, more luxury divers use two flashes to prevent shadows. Lazy photographers close the diaphragm and blast out a hell of flash light, having always sharp photos due to the large depth of field and not having to worry about white balance. This however, has some drawbacks:

  • Flashing casts shadows
  • Flashing illuminates dust between camera and object, if flashes direction is not set properly
  • Many fish flash back by reflecting your flash
  • Backgrounds become dark, making the image flat

 

OLYMPUS DIGITAL CAMERA

Flashing casts shadows

 

OLYMPUS DIGITAL CAMERA

Backgrounds appear dark

 

Light comes natural

Photographing using natural light has advantages, when done properly:

  • Light underwater is diffused by the water, even in sunny conditions giving nice and smooth illuminated objects
  • You can use the color of the water to get the real underwater experience
  • Dust becomes less annoying
  • You capture much more of the environment, since everything is illuminated, not just your subject
OLYMPUS DIGITAL CAMERA

Naturally illuminated pike

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Open Sesamy: Port-knocking using just one port

by  on  in Tech&Science

Port knocking is a mechanism to provide additional security to firewalling. Port knocking is normally used in firewalls. A target port needed for a particular service (e.g. SecureShell, SSH) is normally closed and the service is unreachable. Only by ‘knocking’ on a number of ports in a particular order opens the target port. Knocking means: sending a TCP or UDP packet to the port. Though the knock ports are closed and won’t respond, the firewall notices the knocks. To the outside world the firewall appears totally closed. Portscans fail. Only when the proper sequence of ports is knocked the target port opens and the service is reachable for a few seconds. During this time-span the service can be reached.

There are a large number of port knock implementation. See for an overview: portknocking.org. Open Sesamy differs from other mechanism because only one port for knocking is needed. It may even be the target port. It is implemented using Linux iptables. This is another difference: most port knocking algorithms are implemented as scripts scrutenising the log files. Using iptables the packet filtering is exploited as present in the Linux kernel or modules.

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Photographing the Milky Way

by  on  in Photography

NK2_20120813-4494

At some dark parts on this globe we have a beautiful view on the milky way. It shows as a lighted band on the nightly sky. It is possible to capture it on camera. The fun part is: The camera can see more than the naked eye.

It requires a SLR on tripod and a bit of technical knowledge. This shows how easy it is. Hardest part is probably to find dark night sky, real dark night sky.

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Showcase

by  on  in Photography

More info on https://www.studioblueplanet.net.

Solar Power

by  on  in Projects
 
 

The gauges present the actual production at my home: left the Photo-Voltaic (PV) System, right the MicroCHP production. More information on the project site.





Star Trails

by  on  in Photography

NK2_20110327-7387-95S

ISO200, 12mm, F/5.0, this photo has an effective exposure time of 90 minutes

The trick is not to expose one image very long, but to combine multiple photos into one image. The image above consists of 9 photos that were exposed for 10 minutes each (1.5 hour total).

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