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Tuesday, August 26, 2014

Optical test



Moving on with the tests on my latest lens the Samyang 500 mm f/6.3, here is a very objective comparison to give an idea of the level of magnification and optical performance this cheap lens is capable of.

Saturday, August 23, 2014

Traveling



Satisfaction with the 500mm reflex lens increases as I explore its potential in different situations. This time I took a number of shots holding it by hand during an afternoon next to the Lisbon international airport main runway. It was quite a challenge because of the moving targets, the lens being a pain to focus, and the fact that the camera was being held by hand. But the results seem to tell the rest...















To finish this topic full circle, here is a bit of cruise ship spotting, from the comfort of my balcony. These photos and videos were taken with a tripod and the 2x teleconverter added, resulting in a focal length of 1000 mm:






Wednesday, August 20, 2014

World Photography Day

Coincidentally, after having purchased an exotic lens for my camera and some days of wait for the F-Mount adapter, yesterday during the World Photography Day, I finally managed to test the lens. Aware of the shortcomings of this lens, still I was very pleased with the results, which I must say, open doors to different types of photographic work.

The lens is a Samyang 500mm f/6.3 mirror prime:

Saturday, June 14, 2014

Reflashing a quad ESC to BLHELI firmware in an attempt to solve pancake motor cogging issues


Ever since I've switched motors and ESC's on my "primary" quadcopter, I have been running on problems keeping it reliable. Every now and then it would crash, once because of a motor connection that got broken, and other times in a unpredictable manner without  a cause that I could identify.

Saturday, May 31, 2014

Teardown of a laser printer



In this age of mass consumption  and programmed obsolescence, it is not surprising that a few years after you shell out money for a printer, the availability of its consumables starts to decrease, followed by an increase of the associated price.

Thursday, May 29, 2014

Gimbal finally onboard

After a long wait and a hassle with a chinese seller, finally I could but together the gimbal, flash the board with Brugi (Martinez) and do some tuning and testing.

While a first flight have not yet been done, manual handling with rough attitude change movements shows that the gimbal seems to respond pretty well and no vibration could be perceived in the video at 1080p.


Wednesday, April 2, 2014

Custom made BEC

BEC's, which is short for Battery Eliminator Circuit is a fancy RC hobby term for a DC-DC converter that steps down the voltage to a given value used for example by servos and control electronics such as radio gear and flight controllers.

In the market there are two main types, most of which convert from a higher voltage to 5-6 Volts DC. These can either be of the linear type, or switching mode. The first is the simplest, where a simple linear regulator is used to drop the voltage to a constant value at the output. These tend to be very low noise steady sources of voltage, but have the disadvantage of being quite inefficient, getting worse the higher the input-output voltage differential. A considerable amount of energy is wasted in the form of heat.