This is just a mid-point

Stem readers, I would like to hear about your opinions. I have been writing for a while now. Just to remember you, I wanted to start by explaining the basic concepts of photography, as what does ISO, shutter speed and aperture means.

I believe there are tons of explanations on how to use a camera, most notable, due to fact that digital cameras are used in the same manner. But for now I wish to know something about you. From now on I will start to explain more darkroom oriented topics. And I am asking you:

• What do you expect?
• What would you like to learn?
• Do you have any idea in mind?

After this I will give you a little resume of what topics I am going to be explaining the next weeks:

• How to make a darkroom.
• Types of chemicals for developing, developer, stop bath, fixer, hypo solution, photo-flo.
• How to choose an enlarger. Enlarger accessories.

With time, I hope to have enough money to buy color chemicals and explain them. (Except E-6 process, I will explain why).

(Sorry if this post does not contain explanations, or something like that…)

About the film picker and developing tanks

This is the last video I have posted on Youtube, I explain a bit of the film picker and developing tanks.

Equivalent lectures

I hope, my stem readers, that you have practiced how to read the expose meters on your cameras. If you still have some doubts, please be confident enough to send me a comment.

When you master how to read the values, now you are prepared to make equivalent lectures. This means, that you are able to change shutter speed or ƒ numbers to accommodate your needs or the end result you wish, without changing the quantity of light that is going to get into the film. Maybe by now, you are going to be able to have an idea if you know what each light step means.

This is going to be a little bit more practical than before. First of all, lets imagine that a friend of us has a hand expose meter, and he (or she) measures the light on his face, and the displays says: s 1/250 @ ƒ 4.0. In this case we want to blow away the background, in other words, make it unfocused. How do we do that? Easy one! We just open the lens aperture, in this case we are going all the way to ƒ 2.0. If we write an scale:

ƒ numbers   1.4   2.0   2.8   4.0   5.6   8.0   11   16   22

Speed   15   30   60   125   250   500   1000   2000

Note: I did not write the 1/ of the speed

Each number is a step, in which I am going to let pass the double or the half of light, so if we are in ƒ 4.0 and we want to go to ƒ 2.0, how many steps are we moving? Just two steps, but in this moment we let enter four times the amount of light to make a perfect exposure, so what do we do now? We have speed in the other hand and as we are not worried about its effect, we are going to move it the same number of steps until it compensates the light we let pass with the aperture, this means we are going to move the speed to 1/1000, as it let passes four times less light than before, and so our new lecture is going to be 1/1000 @ ƒ 2.0 and we assure a shallow depth of field as we wanted to do the portrait of our friend.

This also applies to the case in which you are more concerned about the speed, for example not letting it go below 1/30. For example, we are in a place where the Sun is about to set, the shadows are very long and dark, but we found that some places where the lights still passes trough is interesting, we make a lecture with our camera, and it says: 1/8 @ ƒ 8.0, and also we do not bring any tripod, and there is not a table at sight. 

ƒ numbers   1.4   2.0   2.8   4.0   5.6   8.0   11   16   22

Speed   8  15   30   60   125   250   500   1000   2000

Note: I did not write the 1/ of the speed

We want to be safe about shutter speed, so we want to shot at 1/60, so from 1/8 to 1/60 are three steps, in which we will not let pass much light at all, like about 8 times, so what do we do next, is compensate with the ƒ number, the same number of steps, so we let pass more light to it, from ƒ 8.0 we head to ƒ 2.8, and this way we end letting pass the same amount of light as the original reading.

The next pair of images exemplifies the Equivalent lectures.

1" @ ƒ 8.0

1/15 @ ƒ 2.0

Contrast seems a little bit different on each… but as you can observe, both have similar amounts of light on them, the only difference is how I wanted to move DoF, so only the little turtle was in focus. As you can notice both values moved five steps, if I just moved one without compensating the speed that would be blank image.

And now… what?

We have discussed about film sensibility, shutter speed and aperture, all of which will have a different effect on how our image will be. But now, if we are using light and we are using all those parameters, for whichever reason, how do we know how many light is the right amount. Well, said in greater words, ISO is going to be the one who decides, but photographers will not talk about lumens or luxes (units for measuring light) but instead of that, they will explain everything with shutter speeds and aperture values. If you are a digital photographer in the making, do not use ISO Auto, as this will not let you advance. Film photographers, well, ISO can not be changed in the whole thing, so do not worry about that.

But before we continue on, we need to know how we measure our source material, light. So there are essentially two ways for doing so. Incident or reflected, one is more accurate than the other, but in the other hand the other is more practical. Lets go in parts.

Incident light

As far as mankind knows, light travels trough space but it tends to dissipate, and we can see this phenomena in just any lamp, as we put it higher it will draw a bigger circle but its "power" to illuminate will diminish, this happens because light travels in any directions, and sum to that the fact that there is also air, that has particles floating in it. Where are we going with this, that depending on how far the light source is, the intensity of it will be different. In the case of natural light, the Sun, it is a little bit irrelevant, but with artificial sources this is the most important consideration. 

In this case of light metering, what you are going to buy is a hand expose meter, the most basic of this devices will have a light sensitive zone. Older models, had the look of an old voltmeter, as they used selenium, an compound that exposed to light will generate a voltage, so depending on the quantity of light the voltage will vary.

Many of this expose meters, you just set the dial in which the green and the red lines were one over the other, and then read the combination below. As you can see, it has a speed and an aperture scales, so when you made both were aligned, you were able to choose, ƒ 8 @ 1/60 (using the image as reference) but you also get something called, equivalent measures, we will discuss that later.

Most modern light meters are digital now, and most of them have at least three basic functions, ambient light, flash and flash with cord. The ambient light, well, may seem obvious but is when we are going to meter, continuous sources of light, like the sun or light bulbs. The other two functions will depend, in one, the device, will be waiting for the flash to fire and then measure, and the one with the cord, the apparatus is connected directly to the flashes and send the signal so it fires them.

In both, analogue or digital, we need to face the light sensitive part to the light source. As we are using a device solely to meter, this is why is the most accurate way of getting the exposure value, aperture and speed, on one ISO sensibility.

The downside of all of this, is that you have to buy an extra, that the cheapest are between $150-$200 USD, new, as always you can go to flea markets, swap meets, and so and maybe have luck and find one in great conditions. But do not fear my fellow readers, since a long time camera manufactures had come with a nice solution.

Reflective light

Last method worked by recieving light directly from the source, this one will work differently, and works just like our eyes do. We see because light is reflected from the objects, white light contains all the colors within it, we see the colors of things because they absorb the other colors and reflects the color they are. Inspired on this way of metering light, cameras from the 70's and on, were manufactured with an expose meter integrated with them. Some were like a crystal thing with bubbles attached to the camera, but other were more advance and the term TTL became famous, this means Trough The Lens, this meant that the light that passed trough the lens made the measure. This kind of metering was so accepted, because the expose meter was showed in the viewfinder, mostly in SLR's, so the photographer has a fast glimpse if it need more or less light for his/her shot.

Depending on how old and brand the camera is, the expose meter is displayed in different ways, some are very simple while others are quite trouble some. The most commons are like this:

In this case of expose meters, there is a needle, a plus a minus sign, and the middle mark, if the moving needle is charge to the minus, it means that your original settings are not letting enough light to pass, just compensate with speed or aperture letting more light pass (just move one, do not move the two freely), do this until, the needle stays very close the the middle mark. Doing so, we are going to have a well exposed photo, if the needle is in the less zone this means that our photograph is going to be underexposed, meaning that we let pass less amount of light that the one needed. This will lead to dark pictures with textureless darks and grey whites. In the other hand, leant to the plus side, we will end with an overexposed image, this will make that our blacks will not be blacks and our whites will not have textures. But as a safety for each photo it is better to be slightly overexpose, doing so we are going to force to the negative to receive information, that latter will be visible in the print.

There are other kinds of displays, there is one just with the plus, the minus and a dot. In this case each sing will shine, and when the dot shines the exposure is right. But there are some that are not as easy to get, there are some without lesses and pluses, some Minoltas used to have some like this:

In this case of exposure meters the needle in function of the aperture selected will move to the most suitable speed, at the beginning is a little bit confusing, but it all depends when both, speed meets the aperture, in this kind of expose meters, at the start, is hard to tell when is over or under exposed.

Newer expose meters are more like a ruler, with a mid-point, less or plus, but showed in steps, and some in half or thirds of a step. Canon and Nikon have something like this:

But this way of metering is not fool proof, it will depend highly on the lens mounted, how big is the metering zone inside the camera, or in modern cameras, how many metering dots has and the most important of all, it uses reflected light and not everything reflects the same amount of light, a white cup compared to a black one, the light one reflects more light than the darker one, and so we could end with a failed metering. In the next to images this is going to be demonstrated.

When you meter over something bright, like the white cup, the camera thinks is overexposed, and tells you that you need less light, resulting in an underexposed image, also se how white became gray.

When you meter over something dark, the camera thinks the image is underexposed, and tells you to let more light to pass, this will result on an overexposed image, see how whites start to lose details, and also textures.

But do not fear, there are ways to achieve the right measure, and is not with any fancy stuff, is even a little bit old in fact. All the cameras' expose meters are calibrated to something called Grey at 16% or medium gray. So if the camera is expecting to see this gray, why not to use something that has this reflectance, here is when the Grey Card comes to hand, this cards can be found in any photographic supply store, it is also wide used in digital photography (not precisely to measure but for Withe Balance). They come as just a cardboard card with a gray side or be more sophisticated like a cube, that also has white, black and shiny things, more oriented to digital photography.

This image was metered using a grey card, see how balanced are the whites compared to the blacks, and compared to the last to images, is the one where Beatles could be read clearly, but without losing textures.

The grey card was just showed, and compare it with the previous image, in which we do not need to show it to have a nice photograph.

To use the Grey Card we only need to put it in front of the lens, parallel to the lens front face and adjust speed or aperture so the meter is in the center, well expose, zone. Then we proceed to take the card of the sight of the lens and proceed to take the photograph. If we do not have a grey card at hand, our body has a part that reflects almost the same amount of light than a grey card, and is the palm of our hand, so we could put our hand in front of the lens, adjust the exposure so the meter stays in the zero zone, take the hand out of the zone and take our pic.

The last part of the exposure triangle: ƒ numbers.

Last week’s post was all about shutter speeds, and if we remember what was all about, it explained how shutter speed affects how moving objects may or not may be seen, stilled or blurry. 

This post is going to be the finale of the triangle exposure, next week I am going to be explaining how to mesure light, so we will be able to know how much light our photograph is going to need.

Before shutter speeds existed, the ƒ numbers were already invented. The photograph camera as an imitation of the human eye, and the knowledge about stenopeic (from greek, stretch opening). But the human eye has something called iris, which, controls the pass through light just by altering the area of light that is passing through, but the eye is capable of maintaining most of the things focused thanks to the ability of having a focal length, while in the stenopeic camera, the little opening is the focal length itself. So adding arrangements of crystals, we are forcing the camera to be able to work almost like the human eye. Also cameras were able to have more sophisticated crystal arrangements, and with it different focal lengths without the need to change the size of the camera. And with it, the lenses gained the ability to have and iris, but in photography are more often called diaphragm or ƒ numbers.

The ƒ numbers are defined by the area formed by the iris, this means the area of light that is going to pass trough and so, also the go by double the area or the half of area, but defining this is not like the ones in time or ISO values. The ƒ number is defined as:

ƒ = √(2ⁿ)_0≤n<∞

Square root of two power of n, in which, n  is equal and greater than cero and less than infinity.

So in this case n is the number that is going to go in increments of 1, starting from zero. Doing this so, is going to give us approximate numbers to the ƒ numbers. The most common are:

ƒ 1.4

ƒ 2.0

ƒ 2.8

ƒ 4.0

ƒ 5.6

ƒ 8.0

ƒ 11

ƒ 16

ƒ 22

ƒ 32

ƒ 64

ƒ 90.5

ƒ 128

From top to below the quantity of light that is passing trough is the half, so ƒ 1.4 lets pass more light than ƒ 2.0. And just like the last article mentions it, they had become with half steps or third steps. Like ƒ 1.8 is half step of ƒ 1.4 and ƒ 2.0.

The second most important of ƒ numbers is the Depth of Field (DoF)

Just like the shutter speed, the ƒ number will modify the end result of a photograph, but in this case the difference is about the sharpness of what the lens is going to see. And that is called the depth of field. The DoF, to abbreviate, is the distance in front of the lens that is going to be sharp, this distance will be around the the focused object, this will apply in front and behind it.

This happens because wider openings will let pass "irregular" light, that is going to make that light coming from places outer the DoF, be projected in the film as blurry or diffused, as we go closing the opening, this will force light to pass more concentrated trough the lens, something like a stenopeic camera, and increases de DoF, making most of things defined.

This diagram shows how the DoF go in front and behind the focused subject.

The next images are going to illustrate how DoF changes, depending on how wide or closed the diaphragm is.

ƒ 1.8

ƒ 2.8

ƒ 4.0

ƒ 5.6

ƒ 8.0

ƒ 11

ƒ 16

As you can appreciate, as the aperture goes smaller the quantity of sharp objects increase, at ƒ 1.8 only the elephant is focused, but everything behind and in front of it is "unfocused", above ƒ 11 the Crystal Frog and the Golden Cat became sharp enough, but if you put attention to the background, the line behind is kind of blurry, maybe the next aperture value will define it.

In more serious photos, controlling the DoF will force the viewer to concentrate in only one thing, as you can see in the first images, even if the Golden Cat shines in the background, your attention concentrates on the Elephant, so mastering this technique for portraits is quite a rule, so your subject will be over all the things.

In the other hand if we try to do a landscape or we want to see the most details on everything we are going to focus on smaller apertures, preferable above ƒ 5.6, as in the example, almost all the toys are seen clearly.

There are other ways to have shallow DoF, but that depends highly in the focal length, and will be discussed on other entry.

The second part of the Triangle Exposure

Last entry was focused on ISO, what it meant and what considerations you should take. This time, I am going to explain about Shutter Speeds or in other words how much time we will expose the film.

In the history of photography Shutter Speed became after the aperture, but I think is easier to understand. Before standardized shutter speeds,  the photographer just put off a lens cap and wait a little time to just cover it again, something that today stenopeic photographers still do. As manufacturing technics advanced, and different ISO sensibilities became much wider, different shutter speeds appeared. Like many concepts in photography, shutter speed was determined by dobles and halfs. So if we take for instance, one thousand of a second the starting point, the double of light we need is: (1/1000)/2 (one thousand of a second divided by two) will equals 1/500. And so on.

1/1000

1/500

1/250

1/125

As long for this seems very straight forward, due the fact that 125/2 will equals 62.5, makes very specific to do mechanisms, they went to the easiest nearest value 1/60.

If you make the division:

1/62.5 = 0.016

1/60 = 0.01666667

so, its the same…

1/60

1/30

1/15

1/8

1/4

1/2

1"

Most old cameras will have a dial with this values, but those, will be without the "1/" and only show the denominator of the division, so you will see 1000, 250, 30, etc.  In later models, the ones with digital displays, will have medium values, for example: one between 1/60 and 1/30, 1/45. These are called half stops, and digital cameras will have thirds of a stop. Also this electronic cameras will have longer times programed, from 1 second (1") all the way to 30". Some old cameras will have different colored numbers. The most commons are:

• 60 Synchronization speed
• 30 or under, shutter speeds too low that are not recommended to shot the camera unless you use a tripod or other stable elements (like a table).
• In some cases only 1 comes in a different color, representing is 1 second

Most SLR, because not all (like the Canon T50) will have a B on the dial. This B means Bulb, this mode or selectable speed is a speed chosen by the photographer, more like the old days, and is used for longer exposures, longer that the slowest time that the camera let. The shutter will be open as long as the shutter button is pressed. But as mentioned with speeds slower than 30, you are going to need extra help, from a tripod, or something else that could keep the camera fixed. In the case of the B, is also recommended the use of a shutter release cord. Older cameras will have more standardized accessories, while electronic ones, in most of the cases, will only accept first party cords. The cord will have a block system, in which there is no need to be continuously pressing the shutter, just to remember when to release it.

As for some mechanical cameras, and all semi-automatic, you could choose freely the speed. In old cameras, some lenses had an A, mostly in green, in the aperture selection ring, and in the electronic cameras, there is a mode called Tv (Canon and Minolta) or just S in Nikon. So by now you are not going to worry about selecting the right aperture value. The next week topic.

There are two major effects created by the shutter speed, blur or still.

Blur

It is said, and it is true, that the whole Universe is in motion, but depending on which point of view we have chosen, things may be moving or may be still. Most of the times people think photography is just a moment captured, although, a photo is able to record the succession of moments in just one shot, it can illustrate trajectories.  This effect is going to give a sense of motion, and it is not very hard to achieve.

The only consideration we have to think about is the velocity of the object we try to photograph. For example: we see a juggler and he is doing some fancy stuff with his toys, we could try to have a sharp still image of his face but not of his toys. In this case his toys are moving way more faster than the juggler, he is standing still and just his hands are moving. The slowest speed in which I am able to shot without a tripod, is 1/30. So if he is standing still, and just moving his hands, the end result may be of some blur on his hands and his toys, while his face may seem still. If I would go with slower speeds, if I had the tripod, I could be in risk of making everything blurry, even the juggler. 

But in shiny conditions, if you are able to do it with sunlight, very long exposures will tend to "erase" the blur, as the original object you tried to blur is no longer in front of the camera, and the objects behind it will start to show in the image. The only sure blur that will last long enough, are when at night, you do it with objects that emit light, like cars or county fair rides, they last because the background is dark, and it takes more time to be exposed.

Still

For many years of advertisements, the still has been the selling point for cameras, even nowadays, in which there are cell phones with very sensitive sensors… Just as in school, the opposite of blur is the still, in which everything that may be in motion will appear frozen in time, that magic moment in which many sport photographers rely on.

Remembering the Juggler and his toys, in this case we want to have everything still, so we are going to go the opposite way in the shutter speed scale, as his toys may be moving in quite a fashionable way, we will try to set it to 1/250, the blink of the shutter may be fast enough to just see the toys just that 0.004 of a second, not letting expose the trajectory.

The next two images are little examples of a blur and a still, it was made with a digital camera, just for didactic proposes.

This image was shot 1/45, you can clearly see how pages overlap above them.

This one was shot with 1/125, maybe it does not see very obvious, but all the pages look like if the were still.

I leave you with the video tutorial in which I show you how shutter speed is controlled by the camera, and how to select it on a semi-automatic camera.

Some examples of different ISO sensibilities

Last time I just explained different ISO sensibilities but I did not give some examples to exemplify what I wrote.

All of the next examples are 8x10 enlargements I made.

This one was shot with Ilford HP5 at 400 ISO, as you can appreciate grain is not so visible, but not invisible. It can handle good detail.

This film was Ilford Delta 400, shot at 400 ISO. Compared with the HP5 grain is smaller and holds better details. This film can emulate the feeling of a 100 ISO film.

This last image was shot with Delta 3200, at 3200, at first glance grain is visible, but as was developed with Ilford Micrphen, grain does not explode, and gives a nice texture to the image, even a warm one. But some details become diffuse 

Sorry if I did not published a 100 ISO photograph, I was not able to find one.