Experiment: Ghost Self Portraits

It all started with the latest eveready ultima advertisement. Long exposures, Animations through lighting streaks etc. etc. I also had good discussion on it, on one of my orkut community. So I was inspired to perspire (literally!) to try my hand on some long exposure photography.

While returning home from my gym, stopped by a stationary store, bought those china-made torchlight pens and a couple of black card-paper. I thought of rolling that black paper in cone like formation to further sharpen the light source. Also rolled a white paper inside black paper so the intensity doesn't reduce! Now was a time for some petty but headache giving problems. To make lighting streaks either the camera or the light source should move. Yesterday, I had created some very much acceptable lighting streaks with my CPU's green and red light, by moving my camera. (I didn't find the process worthy enough to write a blogpost!)



So flatly was not interested in again doing that. I better go to sleep than randomly moving my camera with it's shutter open every night. I will get bored soon and why to be up all night, doing boring stuff! And it is already past midnight. So the remaining option is of moving the light source.

If I move the light source, who will click?

If I use timer, how it is going to focus in all darkness?

If I prefocus it at the light source somehow, how can I move it randomly?Yeah, prefocusing at around desired distance was an option but my small little kit lens does not have a distance scale...

Hello, I know that I have written nothing yet in relation with the name of this post. But this was the process of how did I do, what did I do. (?) Here, Minimum focusing distance of 0.25m/0.8ft came to rescue me. If I have not told earlier, I have Canon 400D and EFS 18-55 F3.5-5.6 IS lens. From here a simple procedure followed. I paid some attention to details ;) but you need not if you follow my procedure!

1. Put your camera on tripod or any other firm place, where it has no chance for moving unnecessarily. (I put mine on a stool! and kept soft cotton cloth under the lens for support. )


2. Stand around 1 feet away from camera, properly posing yourself/your face. Press the shutter half way down. (My hand could easily reach there, with those torchlight pens acting as extensions!) Or better use a remote control!


3. Once you have your camera focused, switch it MF and hit the lights off.


4. I should have told this before. As I am posing in front of camera, I cant really use the bulb mode. So the standard setting used was 30 seconds exposure at F 11.


5. Now before stretching your hand to click the shutter, see if your posing just where you focused. Adjust those lights as you want. Look for some catchlight in eyes. (Special tip: You can actually see your face illuminated in the lens!)


6. Once done all this, take a deep breath, press the shutter (finally!). Breathe out, be still and switch on torchlights, as per determined before.

I have used two torchlight pens and was around a feet away in total darkness. Actual exposure around 15-20 seconds served the purpose. Then I switched off torchlights. And I think, even in total darkness, being steady in front of camera is necessary and so I did. No matter how much precautions you take, how much you try to be steady, the motion blur does get introduced in the image. May be thats why I called them ghost self portraits after I saw the first result! After four photos, total timing of that scorching torchlight into my eyes was around 1.5-2 minutes and so an eyesore. You should have seen me then; I was crying with only one eye!

Enough! I uploaded those photos on my PC. Did basic editing of some curves and contrast. And yeah to save my lazy soul from white balancing difficulties, turned them to B&W! Except the last one, which I did a bit pop art style... with too much colours and saturation not to worry about white balancing again!!

And sat down write up this blogpost immediately...

Digital Image Sensors and the Human Eye- A Basic Comparison

As we all know, image sensors are very integral part of any digital camera infrastructure. They capture images. There are two technologies available, namely, CMOS and CCD. None of them has a considerable advantage over the other. These sensors basically work like converters of incident light into appropriate electronic signal. This electronic signal is then analyzed and compressed into file formats, before finally getting written on card. All this is done so fast that, 100s of such processes would complete by the time I write these sentences about them!

But my main concern here is not about image sensors, but about a basic comparison between them and our eyes. Because they are the only way to see everything. After a little bit of research (just googling everything!), I came to know that the procedure is much different than that of CCD or CMOS digital image sensors and films too. Our eye, such a good machine it is, works not only as a image sensor, but as a powerful focusing system with a wide range of apertures with a self cleaning mechanism that does not obstruct sight. Anatomically, our eye is a hollow ball, which regulates light from one end and senses and signals them to brain from the other side. Pupils work as diaphragm to control the amount of light entering eyes. They can expand from half mm to 8 mm that is a huge 16 fold expansion.

Slightly going away from the topic, do a small but funny experiment on yourself. It is no harm. Take a torch, or any handy small light source. Stand as near as you can to a mirror. Switch the torch on, and point it towards your eye, in a way that it does not obstruct your view in the mirror. Keep switching on and off the light source to see yourself, your eye adjusting to the light, by fast expansion/contraction of pupil. Being in complete darkness is advisable. So the point here is, depending on how much light there is, the iris, by contraction or dilation, decides and arrives at proper exposure.

In optical terms, the anatomical pupil is the eye's aperture and the iris is the aperture stop. The light then goes through the lens. Just like the lens of a camera, the lens of the eye focuses the light. After the exposure and focusing is taken care off, we gradually proceed to our color vision. Our eye is a perfect and interrelated system of about 40 individual subsystems, including the retina, pupil, iris, cornea, lens and optic nerve. For instance, the retina has approximately 137 million special cells that respond to light and send messages to the brain. About 130 million of these cells look like rods and handle the black and white vision. The other seven million are cone shaped and allow us to see in color. So these rod and cone shaped cells can be termed as a biological equivalent of digital image sensors.

How do they process colors? Why don't we need white balance? So let us get it this way. In the first place, our eyes don't know colors. Because, there is no other way round to distinguish them. What our eyes simply do is responding to different wavelengths. Roughly, wavelength spectrum from 380 nm to 740 nm is detectable by normal human eye. The color sensing cone cells are categorized in three ranges of wavelengths within the above said range, that they sense.

1. Long- Long wavelength sensing cone cells have their peak wavelength near 564–580 nm.

2. Medium- Medium wavelength sensing cone cells have their peak wavelength near 534–545 nm.

3. Short- Short wavelength sensing cone cells have their peak wavelength near 420–440 nm.

The processing here, then can be well explained in comparison with photoshop. In photoshop, every shade of any color can be described by a combination of RGB. From the ratios arising by their values standing between 0-255, we can see the respective colors in the same dialog box! Similarly, our brain gets input by three types of cells, long, medium and short. And by adding them up, our brain can derive a colour. For the purpose of kind information for my readers, these wavelength categories do not necessarily describe RGB! A table showing respective color's wavelength range is as below.

Color	Wavelength Interval
Red	~ 700–630 nm
Orange	~ 630–590 nm
Yellow	~ 590–560 nm
Green	~ 560–490 nm
Blue	~ 490–450 nm
Violet	~ 450–400 nm

So the exact color/wavelength seen can be calculated mathematically (may be!) by doing weighted average of wavelength reported by each n every cone cell.

After getting to know about the color(wavelength) sensing system of the eye, lets have a overall view of it's functions. Here, I would prefer to make just statements.

• Our eye is just a light sensing system, which with a proper exposure, partly assists the brain in recognizing colors.

• Our brain distinguishes between the the ambient light and the light emitted/reflected by an object. For e.g. once known my car is red, it will not look magenta in lesser light or orange in yellow ambience.

• Lesser the light, lesser our capacity to differentiate colours. So as we go in complete darkness, we just differentiate in dark and bright, or black and white.

• Brain just analyses and calculates sensed wavelengths, and its a concern of linguistic sciences that how was a specific wavelength or specific range of wavelength given a name?

On this note, I sign off from this post. There is no new topic wondering in my brain right now. But I am sure to come up with one.