Hobbies and their physics | INFJ Forum

Hobbies and their physics

wiredandwound

Community Member
Jul 16, 2019
608
1,694
598
MBTI
infj
Enneagram
Loyalist
I am an amiture radio, photography, and music hobbyist. I guess the main reason I like these types of hobbies is because of my interest in their inherent exploitation of energy - which I find fascinating. In fact, I find the discovery of the [why] more important than the actual employment of them.

I have always managed to keep some kind of musical outlet throughout most of my entire life. I've learned much of it - even attended the Berklee College of Music - and find that the composition and harmony I enjoyed the most. Performing is very enjoyable, but not as much as the exploration of it.

Music-Theory-and-Music-Composititon-Class-in-Bethesda.jpg


Radio I have always been interested in, but only began the hobbie after a certain age and means were achieved - for it is an absolutely frivolous endeavour.

images


Photography I only started the better part of a year ago. What intrigues me most is the mastery of Light and how the camera perceives it.

img_main01.jpg
 
Calibration of Light Sources for Photography

There is a lot of information that confuses many of us relating to exposure. As photographers, we are well aware of the Exposure Triangle consisting of Aperture, Shutter Speed, and ISO. But how do these relate to Artificial Light Sources, such as Speedlight’s and their Modifiers?

Artificial Light Sources are the best way to get the sharpest, clearest pictures. Many people do not find the time to explore how useful the mastery of light can be, or how much it can improve your photos through effects of deliberately contrasting light and shadows.

What is the Nature of Light Intensity?

Electro Magnetic Radiation [EMR] follows the Inverse Square Law. This means that the intensity of EMR decreases over distance logarithmically, by an order of half its power for every [√(2)]^n units of measure. A halving or doubling of light intensity in photography is called a “Stop”. This is referred to as Exposure Value [Ev], when speaking in relative measures:

i.e. ±(n) Stops Ev

The measurements for light intensity are determined by the powers of [√2].

[√2]^0 = 1; [√2]^1 = 1.4; [√2]^2 = 2; [√2]^3 = 2.8… and so on. What you may have noticed is that the [F Stop] values are the same as the distance values. This is because of the inverse square law that is intrinsic to EMR.

What is Meant by Calibration?

Calibration is often mistermed as “tuning up”. In Metrology, calibration just refers to the process of determining the deviation of a system to known standards. This is critical when learning about your equipment, since manufacturers, via their marketing teams, are inclined to “cheat”, when it comes to the performance of their products.

Calibration begins with determining a standard.

I like the approach from Beyond Photography. His method is called 888. What this means is that you are calibrating your light and camera systems to [F8] on the lens, [1/8 power] on the light source, and [8 ft.] from the light source to the subject (make sure that your camera is on its lowest ISO setting). 8’s are a great reference because they are typically midrange adjustments on your gear. These setting are now your “calibration standard”, native to your equipment. The outcome will be expressed in ±Ev, because this is a relative calibration.



The Process of Calibrating

The first thing that you will need is an [18% Grey Card]. This is a reference that is used by manufacturers to set the correct exposure readings for the camera’s metering system.

Use a tape measure, or string-scale (shown in the video) to set the distance of the Flash from the Grey Card to 8 ft., then set the power on the flash to 1/8. Set the aperture to F8 and ISO to its lowest setting. Make sure that the light is pointed directly at the Grey Card and is set to its shortest distance (widest beam), without any diffuser or modifiers.

Now take a picture, and make sure that you have the Histogram active on the playback screen. What you should see if all goes well, is a moderately thin line smack in the middle of your histogram. This is where your camera thinks perfect exposure is [±0 Ev]. If it is not in the middle, then you know that your gear must have a deviation from the standard. This is not a bad thing, because cameras and lights are all designed differently. All we are trying to achieve here is to know how your particular system works, so that you know how to adjust it correctly.

If your readings show that you are underexposed by 1 Stop, then you know that your light source is [-1 Ev]. What I do is label the light source with a [-1 Ev]. Now I know exactly where my system is in respect to a known standard.

The only choice that you have to make is to decide which settings to change in order to increase the [Ev] by 1. You could choose to open the aperture to F5.6, or increase the ISO by doubling it (i.e. 200 to 400). You can also increase the light source to 1/4 power, or move the light source closer to 5.6 ft. away from the subject. All of these separately will increase the Ev by 1 Stop.
 

Attachments

  • Photography_Forum.pdf
    82.5 KB · Views: 4
Last edited: