UV Photography

Exploring light wavelengths beyond what our eyes can see constitutes an interesting domain, because in a scientific perspective it can reveal characteristics of the imaged objects, that our eyes and/or visible light based cameras cannot see.

For example UV photography can reveal the story of our skin. Solar UV burns leave scars that are practically invisible to the naked eye, but through long wave ultraviolet these are clearly distinguishable from untouched skin (for example see http://www.huffingtonpost.com/2012/06/22/cara-phillips-ultraviolet-beauties_n_1606131.html)

While not having specialized gear for UV photography I decided to give it a try with a UV power LED that I had laying around:

Custom Camera for Image Stacking

On the expectation of obtaining different and better astronomical images I have taken the oportunity to build custom gear for that purpose. The camera itself is an analog Sony CCD HAD 700 TVL based on the Effio chipset. I had it in my quadcopter, and decided to transplant it to this application. It has excelent low light sensitivity (indeed it outperforms the human eye in that respect!), being an interesting candidate for astrophotography.

My task was to adapt an aluminium enclosure to contain the camera sensor and the control keypad:

Listening to Digital Radio Mondiale

The versatility of the Software Defined Radio doesn't seem to have boundaries. While exploring the HF bands, I tried to decode the occasionally received signal from Vatican Radio (http://en.radiovaticana.va/), which as of this writing was the only station I could identify as sometimes transmitting in DRM.

SDR - going higher in the wavelengths

While a 22 - 1400 MHz band coverage is pretty cool (given the price of the hardware), there is still more beyond (and below) these bands. In particular LF, MF and HF bands are interesting for a number of reasons:

Again with the SDR (Software Defined Radio) craze

After I bought my first RTL-SDR dongle (regarding which I made this post covering APT satellite (weather) image reception: http://creationfactory.blogspot.pt/2013/03/receiving-weather-satellite-images-with.html ), it's been sitting on the bench without much use. More recently I found extra stuff that could be interesting to take a look at, such as ADS-B reception (decoding commercial aircraft transponder signals) and less earthly things such as a doing some radio-astronomy, which includes for example trying to detect the 1420 MHz hydrogen line RF signal emitted from within our galaxy (it's a very exact frequency almost as accurate as our atomic clocks).

http://www.rtl-sdr.com/low-cost-hydrogen-line-telescope-using-rtl-sdr/

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.

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:

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:

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.

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.

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.

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.

2nd quadcopter practically RTF...

Other than having the recently ordered flight control board (Multiwii SE) mounted and configured, everything else was completed today with the addition of the custom made landing gear:

Brushless gimbal almost complete

With the arrival of the Mobius action camera, which is a Full HD (1920x1080 @ 30 Hz) little animal (very nice video quality for the price), my aerial filming addition to my #1 quadcopter is almost complete. The only missing element is the gimbal controller board, which I have ordered through ebay, but my mistake (or not) the seller have sent the MPU6050 instead (which I had at the same time ordered from a different seller). Result: I have two MPU6050 gimbal sensors and no gimbal controller. As such a dispute is being solved, and the seller decided to (supposedly) ship me the controller board. Otherwise I will escalate to ebay, get refunded, and the seller downgraded (or banned, who knows..).