Getting To Know Your Digital Camera

[alexander]

More and more lately i've come across people that while they seem to like taking pictures, have no clue about some of the most basic ideas behind photography, and are amazed at some of the simplest techniques used with their cameras to achieve results they never thought they can have.

 

This is all partly due to the oversimplification of the camera, as the designers make cameras simpler and simpler to use, a lot of people rely on the safety of the "Auto" setting to take every picture, basically bypassing the art of photography and taking (most of the time, those typical, white out, hard shadows, red eye, dark, blurry pictures) we see in nearly every family album. The thing is, you really don't have to be a professional photographer to take great shots, all you need is to gain a little understanding of the concepts, get to know your camera, per say, and move off the auto setting, to take, fewer, but better quality shots, more interesting shots, and achieve effects that you thought were only possible to do with Photoshop, or only a professional photographer can take...

 

So, let's get to know your camera a little bit. There are many digital cameras out there, they range in price from 30 to 60000 dollars, and ranging in sizes from cameras built into phones, to cameras that take 2 hands and a tripod to operate. From under 1 to over 60 megapixel, from built in tiny lens and digital zoom to DSLRs. Let's define the range of cameras i am going to discuss here, I am talking about cameras that generally have a little optical zoom (thus they generally have a little slide out lens), usually starting with the size of about a deck of cards, ones that generally have a little wheel on top or back that allow you to select modes of operation and ofcourse this is applicable to DSLRs as this is really a stripped down basics of mostly any digital camera.

 

Pixels:

 

Ok, so let's first discuss the megapixels, what they are, and how they should effect your choice of a camera. I find that a lot of people, when talking about cameras, range how good those cameras are merely by how many megapixels it has (really an incorrect use of that term, but we'll get to that). So what is a megapixel? Well first we drop the metric prefix mega, and strip the word to "pixel", a pixel is the smallest item of information of an image, it is a dot, a colored dot that makes up the image. I say the smallest item of information because you can not "split" a pixel to get more information, contrary to what you may see on CSI... So a lot of those different colored pixels in a square array make up a picture. Your screen, if it's set to 1280x1024 shows you a mesh 1280 pixels wide by 1024 pixels high, the total amount of pixels on that screen is 1,310,720 divided by 1024 its 1280 kilopixels or 1.25 megapixels. Megapixels indicate the level of detail your digital camera sensor can capture. A digital camera sensor is a special device that is comprized of cells, each cell, when hit with light (photons), produces a tiny electric current, that is read and interpreted by the camera's processor into a color value. Thus each cell corresponds to a pixel on the screen.

 

So then what is the difference between a 5 and a 7 megapixel camera? The size of the final image, a 5 megapixel camera can take a picture in 2584x1936 where a 7 megapixel camera takes a picture in 3056x2288. Big difference? Not really, consider how you are going to view this picture... say you print both pictures, what would the size of pictures have to be for one to start noticing the grain? This is different when printing with different purposes in mind. For example printing at 300 dpi, you get an ultra high resolution photo that shows no pixelation at even the closest distance of about 8.6" x 6.5", normal photo print is around 100-150 dpi, at arms length a photography professor wont be able to tell the difference between a 150 and 300 dpi print, plus most people tend to view larger prints from longer distances, so printing at 300 as a home photo is rarely needed (though that already produces a fair-size photo), at 150 dpi you can print photos 17.2"x12.9", which is a fair sized print for any wall, or at 100 dpi 25.8" x 19.4" poster can be produced, similarly a 7mp camera will produce a normal 150 dpi picture of 20.4"x15.3", not a hell of a big difference, considering that nobody would be able to tell the difference between the 150 dpi 20.4"x15.3"@7mp and 100 dpi 25.8"x19.4"@5mp posters.

 

So what is the conclusion here? You dont need the top notch cameras to get nice-sized prints, most people for their home will rarely if ever need to exceede 5mp. More is not a mean to say better here, a person who knows a little about their 5mp and can come up with creative shots will have a better family album then a person who uses his 7mp as a point and shoot on full auto all the time...

 

Zoom:

 

What is the difference between optical and digital zoom, and is my camera better if it can do 16x digital zoom then a camera that can do only 4x digital, but also 4x optical?

 

What is optical zoom? Optical zoom is the zoom that can be provided by moving lens pieces, simplest way to think about is this, take a magnifying glass and put it really close to the subject, you dont see a lot of magnification, now move your lens away from the subject, which effectively magnifies that subject through the glass. Like the magnifying glass, all lenses have limist to magnification, and every time you magnify (or zoom) you do two things, you narrow your field of view, and you also decrease the amount of light that is hitting the sensor, and where you can't see this too much on a sunny day, in the darker conditions, your exposure (which i will discuss in a bit) will, however differ.

 

What is digital zoom? Digital zoom is an excuse of the camera makers for not creating proper optics, so to give you an illusion of zoom, they crop the data off the sensor, and decrease your final resolution. Yes it is THAT cheap of an idea, and hence why no DSLR that i know of has that so-called functionality. In all reality, the difference between taking a shot at 0 zoom and at 4x zoom is the same as if you took that shot in 0x and cropped it to the size of the 4x zoom photo you just took.

 

So what zoom do you want to use? Optical... If you cant get a good shot with that, get closer to the subject. If that is not a possibility, still refrain from using digital zoom, just take it at maximum optical and then crop to your liking, you get more data and thus more photo to play with to crop it differently for whatever need you may have...

 

How should optical zoom effect your choice of a camera? Simple, its like selecting what lens you will use most of the time on your SLR. On a standard camera, 35mm zoom is about what a human eye sees, all the X(times) zooms are a derivative of that, 2x zoom means that you are shooting at 70mm zoom on an slr, divide by 1.5 to get the value for DSLR. So a 4x optical zoom on a standard digital camera equates to a 35-140mm lens, or about a 24-90mm DSLR lens which, quite honestly will cover most of the range of shots that i would take. I have a 14-70 lens i use all the time, and there have only been very, very few occasions when i wanted more/less. So 4x optical zoom is about ideal for most people's uses.

 

So what actually matters:

 

What actually matters on the camera are things that most people don't look into. The sensitivity of the sensor, the color reproduction, the grip on the camera and the position of the controls and most of all, the ability to manually adjust the most settings that you can possibly get away with. Ideally you want that wheel to have a M (manual) setting.

 

Another thing to look at, perhaps, if you are thinking about getting more into getting great shots, if your camera has a standard hotshoe adapter for flashes and flash syncing. This depends on what it is you want to do, but you can have your own home microstudio with an off camera flash system for as little as about a thousand dollars.

 

For someone getting into more advanced photography, but only very recreationally, looking for a point and shoot, i would recommend the Cannon Powershot G series, you can pick up a G10 for under 500 bucks, and it has nearly everything an advanced home shooter is going to want, from full manual control to a hotshoe, raw mode, iso up to 1600, actually 3200 in a special shooting mode, 5x wide angle optical zoom, image stabilization, this is basically all and more then most people need, but that would be my point and shoot camera of choice...

 

Never the less, lets discuss some digital photography terms, this applies to most cameras, even some of the cheapest cameras, i have been able to find ways to adjust some of these, so while maybe you cant adjust all the settings and thus terms we'll discuss here, some is still better then none.

 

Terms:

 

4 of the mainest terms in photography:

 

Apperture:

Apperture is an adjustable opening through which the light passes to the lens. You open and close the apperture to set it to settings anywhere between 1.4 or less to 22 (22 is usually the highest). Contrary to standard logic, the smaller the number, the wider the apperture is open. Each stop decreases exactly half the light of the previous stop. This controls the amount of light hitting the sensor, this also controls the depth of field you will get. This is the F-value or F-number also referred to "F-stop" or just "stop". Standard values are 1.4 2 2.8 4 5.6 8 11 16 22, these are powers of [math]\sqrt{2}=1.414[/math]

 

This is how photographers measure light actually, in stops, and generally, photographers not married to a light meter will measure light relatively to ambient (which is light that is already there), but i will explain that concept in a separate section, for now, apperture is the amount of light that the lens passes through to the sensor

 

ISO:

ISO, in the traditional sense is how sensitive your film is to light. ISO can range from 50 or less to over 6400, the higher the value, the more sensitive to light the film was. Similarly with digital cameras the sensor will be more or less sensitive to light that it's presented at different ISOs (rather ISO equivalents). Unlike on a film camera you can change your iso for every picture you take, which is an advantage, but beware, higher sensitivity to light does not come free. The higher ISO's will allow you to take pictures at decent shutter speeds (i will discuss in the next section) in low light conditions, the trade-off is something called ISO noise, the higher your iso, the more prone to getting noise (grain, its noticeable). Unlike most old school photographers i dont believe in choosing the lowest ISO all the time, i think that ISO, like all other settings, is something that one should adjust for the situation, i will discuss this in the ballancing section and in techniques.

 

Shutter Speed:

Shutter speed is the last of the three major parts to any photo, shutter speed is the length of time in which the sensor is exposed to light. It varies from 1/8000's of a second or less to hours. Something to remember here, physical shutters generally stop at about 1/600's of a second, because of the physical restrictions (shutter is 2 plates that slide across, one opens up the openning allowing the light to fall in, the second closes the openning, thus preventing the light from coming in and also evenly exposing the sensor. The super high shutter speeds are acieved by opening the physical shutter and cutting the power of the digital sensor at some point. Most point and shoots will not have this, so you are basically confined to shutter speeds of down to 1/600 of a sec (and that is fast).

 

Exposure:

Combine the three of the above terms and you have exposure, the total amount of light that is allowed to fall on the photosensitive material. It is a combination of all of the above factors combined. Note, there is no "right" or "wrong" exposure, every situation you will have a different exposure, no such thing as too dark, or too light, shots can get more meaning by bleaching out the background, others can look totally awesome by only showing a part of the whole picture that was well-lit; this is something that you as photographers will get to define.

 

There are more terms in photography, composition, selection, lighting terms, etc, but these 4 are your most foundation pieces, knowing them, knowing how they relate to one another, and nowing what changing one will do to your final product is what involved photography, something i want those who have read this far, is all about in its core.

 

Another term before we get finished with this section.

 

White balance:

This refers to what your camera, or your photo, defines to be the white color. Your eye sees a lot of light as white, light coming from a tungsten light bulb, and daylight bulb, light in the shadow and out in the open sun-lit areas, to be of a similar color. But the camera sees those lights as different colors, thus to achieve the colors you are looking for may be a matter of adjusting the white balance. The adjustment changes the intensities of the color values of red, green and blue, and this influences everything in the picture, all the neutral colors to be perceived as they were, or perhaps as they were not (depending on what it is that you want to do). White ballance refers to adjusting color temperature, as different things produce different temperature light, it is also crucial to know which way and when to adjust your settings, though for what its worth, you can color correct in post processing... Temperature, at which the heated black-body radiator matches the color of the light source is that source's color temperature. All that means that when i say that the temperature of an incandescent tungsten-fillament light bulb is around 2700-3300K that means that if i was shooting a white sheet of paper lit by an incandescent light bulb, it would appear to be yellow/orange if i shot it at say a daylight white ballance (around 5000-5500K) the higher the temperature, the more from red to blue you are going to push. (I will discuss this in one of the techniques, whenever i get to those.

 

Controlling your light:

 

So now that you know what all the settings that your camera that control things are, how do you use them to control your picture?

 

First of all let's discuss ambient light, it is the light that is available in the environment. There will be different amounts of it depending on what and when you shoot, but you will nearly always have some ambient. When you take a shot on auto, your camera will attempt to interpret the amount and temperature of light, adjust its settings and take a picture that mathematically works out to have good average lighting over the picture. This is a good start for your shots, but use this as a sort of a light-measuring device. Some studio photographers are married to their light meters, but field guys will generally take some shots on auto, figure out their ambient exposure, and play off of that.

 

So how do we control light from the ambient?

 

One thing to remember here, shutter speeds and appertures have been fairly standardized, in such a way that dropping a stop of light (meaning raising your F-Stop by one value say from 11 to 16) and decreasing your shutter speed by one value (say from 1/80th to 1/60th) will produce the same overall exposure. Changing the sensitivity of the sensor (ISO) will allow you to change one of these values without affecting the other, and this may come in handy depending on what it is you are trying to do.

 

So now what does changing Apperture or shutter speed in relation to one another acoomplish?

 

The apperture controls the amount of light that hits the sensor, also it controls the focal length of the shot. Focal length is the depth of field that will appear to be in focus on the picture. Sometimes you want that to be very big, thus you will set your apperture to be higher, 22 will have mostly everything in focus from the foreground to the back. But that is not always the desired effect, sometimes you may want to blur the background to make the subject stand out. Consider taking pictures of your friends at a party, setting a really short focal length may produce a photo where only the subjects are in focus drawing attention to them in the picture. Alternatively when taking a group shot, you might want to have your apperture more closed (higher number) to make sure everyone is really in focus.

 

Shutter speed controls the freezing of your subject in motion. Above you can easily freeze a runner in motion at 1/100th or 1/300dth of a second. Keep in mind that in order to achieve the right exposure this may mean dropping the field of depth to get the right exposure.

 

With shutter speeds slower then 1/60th i would recommend to consider a tripod, as even hand shake will be visible as blur, but i will say that having a decent steady hand, and bracing against things, you can achieve good consistent results up to a 1/40th, this will just take some practice.

 

Its all this playing around that makes things in photos really pop out, you can freeze a flying bug, you can capture the motion of the water, you can paint your name in the dark and capture the spin of the earth. Understanding these and most of all playing with settings and knowing what you will achieve with changes is what photography is all about. You may spend days playing with things, and more time prepping up the shoot, but the result you get can truly awe your family and friends...

 

I will stop this part here. You will grasp the concepts above with techniques. Techniques are like tools in your photo arsenal. Every situation may require a different technique, one that you may know and have already used, or one that may have not, or you may have to come up with your own technique to achieve the results you want, bottom line, techniques are something you always have with you in your head, it is often another way to make a shot interesting or achieve an effect you desire. I will post those in separate posts as this is already getting to be very long, and my hands are getting cramped from typing. I hope you enjoy your intro, post if you are interested in learning some techique behind an effect you have seen somewhere (link to a photo would be nice) , if you have questions, or just interested in reading more.

 

 

Sources:

Wikipedia

Strobist

Digital Photography School

[freeztar]

Excellent breakdown Alexander!

 

In my experience, I've found the white balance adjustments to be the single greatest assets in my point-and-shoot experiences. Sure, most of this can be fixed in photoshop, but you want a good pic going in. Photoshop is not there to perform miracles. It can make a good pic outstanding, but it can't make a piece of turd anything other than a good turd. Having a digi camera that will allow such adjustments is very beneficial.

 

I'll probably get yelled at here, but I love the scene modes available on some dig cams (notably Olympus). They don't always work out quite right, but when they do you can get some really cool shots. The main benefit, in my experience, has been time. With analog SLRs, you can dial to different setting pretty quickly (on the fly). With the digital cams I've used, you have to dig through menus to get to the most useful settings, such as those described by Alexander above. This can ruin those "in the moment", or spontaneous, shots.

 

As a ageneral rule, if I'm at an event that starts in the day and ends in the night, I will typically use auto settings during the day and around dusk I will switch to a longer exposure and turn on the auto flash. Simply turning off the flash and setting the camera on a table or other flat, solid surface (with timer mode) has resulted in some really great group/scenery pictures.

 

Here's one I took recently of downtown Monterrey, Mexico at night with a long exposure. It's not a great picture, but it illustrates the point. The colors are very warm. Notice that blur is still introduced (likely from the table or low vibrations on the ground nearby [ie my feet]).

 

[alexander]

nobody will be yelled at here, and white ballance is beneficial, and i have two olympus cameras, can't say i have ever used the scene modes, but then again, oh wait, once i played with the macro mode in there. Anyways, here is the first effect i will discuss: how to capture motion.

 

So say you are out at a car or a bike event, really any kind of moving sport, and this works best with vehicle sports, be that a bycicle race or a drifting event, it produces motion blurs that give the picture the sensation of a moving object, rather than a stationary freeze-frame.

 

So how do we capture motion in a still? Setting your camera on auto on a sunny day will most likely get you a shutter speed of about 1/120th or higher at f11 or so, actually a maybe even faster with a higher ISO, so any shot you take of a moving vehicle will be rather frozen in time. To get the motion, you might want to bring your shutter up to about 1/60th of a second, and move the camera to try to keep the object that is moving still in the frame. On bicycles, cars, bikes, this motion blurs the background motion blurs the wheels, and freezes the main subject giving one a perception of a moving object :(.

 

if you need to bring down shutter speed, you need to firstly change your iso to something lower if you can, adjust your shutter and play your F till you get the exposure you are looking for.

 

Give you an example, i was shooting with my friend's camera this sunday at the lot, i had ambient at 1/200 at f8 on iso 320. To get my desired effect i sat the iso to 100, dropped the shutter to 1/60th and set it to f11 to properly expose the picture (which seemed overexposed on auto anyways) (once i find the pictures, i'll show you what i got out of it) but the effect was visible, and seemed to capture motion fairly well. I will actually probably make a post here on comparison shots of what standard all auto gives you, and what an effect you can achieve to attempt to capture motion :)

 

tomorrow i will discuss a slightly more aggressive adjustment, in order to light paint, express traffic on a road without showing cars and take pictures of fireworks...

[CraigD]

A very nice piece of writing, Alexander. The images of the collective digital world would be the better for people reading such explanations! :eek_big:

 

It puzzles me no end that no cameras I’ve yet seen has something like this included in their packaging, right before the “how to insert the battery/memory card” instructions – nor anywhere in their paper or electronic documentation. :dog:

 

One part strikes me as wrong:

Something to remember here, physical shutters generally stop at about 1/600's of a second, because of the physical restrictions (shutter is 2 plates that slide across, one opens up the openning allowing the light to fall in, the second closes the openning, thus preventing the light from coming in and also evenly exposing the sensor. The super high shutter speeds are acieved by opening the physical shutter and cutting the power of the digital sensor at some point. Most point and shoots will not have this, so you are basically confined to shutter speeds of down to 1/600 of a sec (and that is fast).

While I’ve not done a lot of disassembly of digital cameras, I’ve taken apart a few of the cheapest, and am certain they have no mechanical shutter. I’ve also listened carefully to my wife’s DMC-FZ series camera, a “bridge” model resembling a DSLR but with a non-removable lens, and with it’s shutter click speaker sound switched off, can hear no mechanical sound, so am failry sure it has no mechanical shutter, either.

 

Some other important practical camera features, gleaned mostly from my wife’s experience (she blogs a good bit about music events, taking hand-held pictures at them when possible):

• Digital image stabilization – near real-time processing of the image to correct blurring due to camera motion, at the expense of a bit of resolution – can be a great help in avoiding blurring with snapshot-quality photos, especially in low light. Panasonic’s Venus module – the one in all it’s Lumix models - seems better at this than several others I’ve tried, but I've not tried that many.
  
• Shot speed – the amount of time the camera needs between shots – can be a problem in some cameras. As late as 2007, I’ve seen some low-end Nikons that required several seconds between shots without flash.
  
• A “burst mode” feature, which allows 3-10 or so images to be captured in quick succession when the “take picture” button (“shutter button” for traditionalists ) is pressed and held – like a high-speed motorwinder on a film camera - can be very nice, as it allows you to "lead and follow" a shot, not have to hit it perfectly.
  
• Some museums and performance venues restrict photographs to “non-professional” cameras, which they commonly define as “no changeable lenses”, so a good bridge or snapshot camera can be a necessity, as a camera you’re not allowed to carry is of no use whatever
  

[freeztar]

One part strikes me as wrong:

 

While I’ve not done a lot of disassembly of digital cameras, I’ve taken apart a few of the cheapest, and am certain they have no mechanical shutter. I’ve also listened carefully to my wife’s DMC-FZ series camera, a “bridge” model resembling a DSLR but with a non-removable lens, and with it’s shutter click speaker sound switched off, can hear no mechanical sound, so am failry sure it has no mechanical shutter, either.

 

Your claim was interesting, so I decided to look it up. Every source I found claims that digital cameras do have shutters. Instead of their analog counterparts that rely on a mechanical shutter, digital cameras utilize an electronic shutter.

 

All cameras, be they film or digital, have a shutter. In film cameras and digital SLRs this is simply a mechanical barrier that prevents light from falling on the film or sensor until it is needed. Digital compact cameras usually have an electronic "shutter". When a picture is taken, the shutter is opened for a precisely measured amount of time allowing light to pass through. The duration of the exposure is set by the camera's light meter, and depends on the amount of available light and the aperture setting.

 

Most digital cameras will have a range of available settings from a few seconds to a few thousandths of a second. Some can go as high as 1/4000th of a second, some can time a shutter release as long as 30 seconds and many also have a feature called a ‘B' setting, in which the shutter stays open for as long as you hold the shutter release down. (The ‘B' is from bulb; very old cameras commonly used an air-bulb attachment as a remote shutter release.) It's worth noting however that some older digital cameras suffer from increased image noise on very long exposures. If your camera has adjustable noise reduction, set it to maximum for long exposure shots.

Digital Camera Tutorial: Shutter speed - TrustedReviews - TrustedReviews

 

Could it be, Craig, that you did not find or identify the shutter mechanism in the dig cams you disassembled? Or perhaps this is a myth of epic proportions?

 

Honestly, I've never considered the fact that a dig cam might not have a shutter. But now that I'm thinking about it, wouldn't this be easy enough to control on the CCD? Perhaps this is what they mean by electronic "shutter"?

[alexander]

I guess i was speaking more towards DSLRs, DSLR's use a mechanical shutters in the lens, but can also have a digital shutter, and will use either or depending on the shutter speed. (both of my cameras use mechanical mechanisms, but my E3 does switch to a digital and goes up to 1/6000)

 

Most DSLR's have at least a mechanical, or a combination of the two shutters, i think you get better results with an analog shutter, sensor all properly powered up before light hits it and all...

[CraigD]

Could it be, Craig, that you did not find or identify the shutter mechanism in the dig cams you disassembled? Or perhaps this is a myth of epic proportions?

 

Honestly, I've never considered the fact that a dig cam might not have a shutter. But now that I'm thinking about it, wouldn't this be easy enough to control on the CCD? Perhaps this is what they mean by electronic "shutter"?

I’ve done a bit of web browsing, and while not quite getting down to the level of actual parts specifications, am pretty sure that low price cameras, including the kind built into mobile phones and on keyring fobs, don’t have mechanical shutters. Instead, they’re purely electronic – when their button is pressed, they “drain” (the charge of each pixel of) their CCDs, then, when a timer reaches the fixed or calculated exposure time, convert each pixel’s charge to a (digital) number, process them into jpg format, and write the file to their internal memory (flash, I assume), or, if they have them, removable card.

 

As best I can tell, decent snapshot, midrange, and high-end digital cameras all have mechanical shutters. DSLR cameras, as their acronym suggests, also have a mirror that sends the lensed image through a viewfinder eyepiece, then “reflexively” retracts just before the shutter opens to expose the CCD, just like SLR film cameras. Some cameras, such as ones based on the recent “Micro 4/3" system”, keep the lenses, shutter, and CCD of a DSLR camera, but eliminate the mirror and optical viewfinder, instead keeping the shutter open and using the CCD – what the Micro 4/3 specification calls “live view”.

 

Because CCDs need to be drained in actual darkness to be as accurate as possible, these cameras produce lower quality images than ones with actual mechanical shutters.

 

Having looked at a picture of a disassembled Lumix camera, I’m pretty sure my wife’s DMC-FZ8 has a mechanical shutter, which I can’t hear because it’s too quiet, and sealed inside the camera body. My initial impression that it didn’t was, I think, wrong.

 

The best digital cameras, like the best film or plate cameras, have focal plane shutters, “curtains” that open vertically or horizontally to expose either the entire CCD, film frame, or place, or a partial strip of it that moves across the entire surface. For fast shutter speeds, it doesn’t matter much if each line of the surface isn’t exposed at precisely the same instant, allowing focal plane shutters to have effective exposure durations than the total time the shutter is moving.

 

The “digital shutter” alexander describes is, I think, accomplished by using the mechanical shutter to allow a good draining of the CCD pixels, then a computer-controlled timer to measure the charge of the CCD pixels before the mechanical shutter has actually blocked light from reaching them. Synchronizes with the movement of the shutter curtain, this can give very fast effective shutter speeds.

 

In short, the mechanical shutter isn’t used for timing, but to assure that the CCDs perform as accurately as possible.

 

Wandering into the realm of extreme photography, rapatronic cameras, which have been around since at least the 1940s, have shutters based on the Kerr effect that can achieve exposure times of around 1/100,000,000th sec. Even with extraordinarily sensitive photographic plates, they need very bright illumination, though as far as I know they’re used only to photograph nuclear explosions, which are plenty bright, so this isn’t a major problem. Since the Kerr effect is wavelength specific, single-shutter cameras based on it wouldn’t be much good for ordinary photography, as they’d “clip” significant parts of the visible spectrum. To take advantage of their super fast shutter speed, you’d also possibly need to use a nuclear bomb as a flash, so I wouldn’t be surprised if Kerr effect shutters aren’t on the consumer market anytime soon.

[alexander]

The digital shutter i am referring to works similar to the smaller digital cams, they drain the CCD, turn it off, then open up the shutter wide, control the time turn when its collecting light by turning on the CCD, turning off the CCD again and closing the shutter. As i said, mechanical shutters are not too too fast, so when you shoot above their working range, and my camera once again goes to 1/6000, it starts using digital timing at fully open shutter...

 

But yes i was about to say, that the quality of a picture will differ if you have a camera with a normal shutter, as the CCD would be less exposed to light, giving you both the ability to shoot old style, and drain the CCD before timing how long it stays on, giving you more true readings...

 

I will confirm, most handheld digital cams have a digital timer vs an actual shutter or a combination like in the higher end cameras.

 

Anyways, back on topic of photography, lets discuss another technique. Actually speaking of flash photography and shutter speeds, how once can get shutter speeds of 1/11000 or faster to photograph things like say, fast flapping insects in mid flight, to freeze them in motion and ofcourse properly expose

 

First of all what is a flash (well from now on i will call it a strobe, that would be more correct)? A strobe is a device that uses a pulse of electric power through a small xenon-filled tube to produce a flash of bright light to, for instance, help correctly expose the subject on the picture. Now, you can go extremely crazy with flashes, and they can be useful, but lets discuss what purpose a flash can take that most people don't think about.

 

So a strobe lights up an object, we dont need it during the day, right? Wrong actually, one of the more widely used purposes of a flash by the pros is to use it as a fill light. Everybody likes to see strong shadows, err, well actually, when you are taking a picture of a person outdoors, or even indoors, those are something you are trying to eliminate, harsh shadows can make the whole picture look bad, so to remedy this, one can use the flash (ballancing the power to fill in shaded areas, but not to make it obvious that you are using the flash). Course noone does this better then David Hobby, the godfather of the off camera flash world and a master light manipulator, as an example of such a fill, examine this photo ( ), or even better this one ( ), and guess how many strobes are lighting the subject...

 

Anyways, another use of the strobe is to freeze subjects. A standard flash, like an sb800, on 1/16th power will produce a flash of light lasting about 1/11,000th of a sec. This will properly expose the subject it is facing, fixating it in the shot at that instance. This ofcourse meaning that if you are shooting in dark conditions, at say 1/80th shutter speed, you still have around 274/22,000 of a second before your shutter closes

 

SB800 has a long tube (longer then some other flashes, certainly longer then anything built in), shorter tubes built into a point and shoot would likely produce a faster exposure speed at a low power target here is to get the flash to expose your subject right. Then, think of it as a frozen image, meaning that that area is already properly exposed, now you can play with camera shutter to achieve the right exposure for the background. (use F-stop to control depth of field then set shutter to correct background exposure (or one you are looking for))

 

This would be the ggist, the beginning stages of how to effectively use a flash, as long as you remember that it allows you to vary exposure between foreground and background, and that you can effectively use it in light and dark to fulfill different tasks, your journey into the world of manipulating light is getting more interesting.

 

Another way to use a flash to liven up the shots would be to take an ambient reading at dusk, power your flash to low power, drop ambient by 1 or 2 stops to still get a crisp subject, but a much more defined background (much more dramatic clouds, sun, colors, what have you)

[freeztar]

On the subject of strobes, can you (or someone) explain red eye reduction? How does it work and when should it be used?

 

I tend to not use it as it throws people off. A held smile waiting for the flash can drop once the flash starts strobing.

[Qfwfq]

On the subject of strobes, can you (or someone) explain red eye reduction? How does it work and when should it be used?

Very simple, the red eyes are due to the pupils being wide open cuz of the dim ambient lighting. There's definitely not enough time for the physiological adjustment to take place during the single flash (even less, before exposure starts) but the sequence of weaker flashes is calibrated so that typically folks eyes will have adjusted to a greater brightness. This makes the pupils tighter by the time exposure commences. Also, I find the weaker flashes less annoying and, obviously, the actual "real" flash isn't nearly as annoying since the pupils are tighter. I think it's better, so long as the subjects aren't misled by it; before shooting, tell'em to count the flashes.

 

If ya wanna know whether to use it then, before shooting, go squint into the folks' eyes to see how their pupils are...:hihi:

[freeztar]

Good answer, thanks.

 

But it raises another question, perhaps beyond the scope of this thread...

 

Why do dilated pupils cause "red eye"?

[alexander]

tomorrow, wait, already today, i will work on some shots for you guys with my moms point and shoot to show what the settings i was discussing do for your picture :)

 

for now Q, nice explanation, that is exactly why they do that. Generally this is not a large problem for the pros as they will work in well lit areas, but it can be, in which case, it is generally a matter of angle, if red eyes show up, you would reposition light, perhaps soften it, bounce it, and/or ask the subject to focus on another spot. Sometimes you have to reposition the camera too, but that is how pros will take care of red eye (like lens flares from glasses actually) (occasionally some PS work may be needed :)

[LaurieAG]

Hi Freeztar,

 

Why do dilated pupils cause "red eye"?

 

Good Question and a good example of how the image capture mechanism works in Digital and Film cameras compared with our own eyes.

 

Theory of color

 

At low light levels, cones cease to function. Cones respond to different wavelengths of light

 

There are red, green and blue cones that act as color receptors in the eye and the red cones are probably the last ones to cease functioning in low light. Other animals have different numbers of cones with many missing the red cones so they display a different color (or combination of colors) when their eyes are dilated and their images are captured.

[Qfwfq]

Generally this is not a large problem for the pros as they will work in well lit areas

Yup. certainly the flash is for impromptu photography, when lighting isn't taken car of better. The problem is of course when we want people to watch the lens so that they are looking at the viewer of the resulting photo, the flash being near the lens for practical reasons.

 

In any case the flash is only any use for very short ranges of a subject, like 3 or at the most 4 metres. You see so many people using it when it is totally out of place. It should only be used when both necessary and effective. I hardly use it and once I missed a good shot, when I could have exploited the very last one of the spool (back in prehistory) in my girl's little automatic compact. I always found it annoying because I had to remember to set it to no flash every time I switched it on; that time I forgot and I couldn't repeat! It was hopelessly underexposed.

[jab2]

Why do dilated pupils cause "red eye"?

Due to the many blood vessels in the retina, it will display a red colour when illuminated. If the iris is wide enough and the flash/lens axis is of very small angle and strong enough, one can actually see this red colour displayed as "red eyes" in a picture. This effect is not normally visible as normal illumination (sun, roof lighting etc) is never from a source that shines horizontally and would thus not reach the retina in the back of the eye. The one cure for “red eyes” is to force the iris to contract by giving a pre-flash, thus forcing an reflectance angle that is smaller than that between the flash and lens axis as described by Alexander. This however have the disadvantage that people react to the pre-flash and might have "lost" their “pose” by the time the exposure is made. A much better solution is to move the flash off-camera, (only possible with high end cameras) thus increasing the flash/lens angle outside the cone of reflection of the retina through the iris. This have an added advantage that the resulting photo will have much more depth and natural looks as the off-camera flash will cast slight oblique shadows due to the greater flash/lens angle. This is particularly true for faces. In normal on-camera flash one get a very flat looking photo as the flash do not cast visible shadows due to narrow angle.

[jab2]

Anyways, another use of the strobe is to freeze subjects. A standard flash, like an sb800, on 1/16th power will produce a flash of light lasting about 1/11,000th of a sec. This will properly expose the subject it is facing, fixating it in the shot at that instance. This ofcourse meaning that if you are shooting in dark conditions, at say 1/80th shutter speed, you still have around 274/22,000 of a second before your shutter closes

Much easier to describe than to do.

 

Back in the early 80's I bought Stephen Dalton's book: Caught in Motion: High Speed Nature Photography.

 

The book is a real treasure of information on using strobes to freeze motion in the natural world. It is full of diagrams on setup and has some really amazing photos.

 

Leopard frog diving I remember from the book as well as Swallow drinking. I also remember another unique photo of a swallow as it contorted itself mid-flight to squeeze through a rather narrow gap above a barndoor.

 

I only found Stephen's website while researching for this reply, but do not think it does his work justice at all, at least not from the experience I had reading that book. I'll have to dig it up again and enjoy it once more.

[alexander]

Yup. certainly the flash is for impromptu photography, when lighting isn't taken car of better. The problem is of course when we want people to watch the lens so that they are looking at the viewer of the resulting photo, the flash being near the lens for practical reasons.

 

In any case the flash is only any use for very short ranges of a subject, like 3 or at the most 4 metres. You see so many people using it when it is totally out of place. It should only be used when both necessary and effective. I hardly use it and once I missed a good shot, when I could have exploited the very last one of the spool (back in prehistory) in my girl's little automatic compact. I always found it annoying because I had to remember to set it to no flash every time I switched it on; that time I forgot and I couldn't repeat! :naughty: It was hopelessly underexposed.

Flash has a lot of uses, and can be used much farther away then 3-4 meters, it all depends what it is that you are shooting and how you are using flash. If you are speaking strictly about on camera flash, then yes, generally it is used close up, take that flash off camera and your flashes, while will likely be within 5 meters of the subject, will take on objectives that most sane people don't like to think about :eek_big:

 

for example this before-mentioned photo here: there are 3 flashes used to light up this photo (but you couldn't really tell now, could you :shrug: ), there is a strobe to the right, that looks soft, so probably with a soft box, probably at a fair power to light up the right side of the body, there is a strobe hidden behind him, knowing David, probably bare, set very low, to backlight the subject and separate him from the background. And there is a green-gelled strobe on the left of the photo, lighting the subject's right shoulder with some green light it looks...

 

I know it looks like your average photo, but there is a lot of thought put into it to make the light look natural, and yet light the subject just enough

 

Here are some of my fav shots of his, shots i used and still use to learn more about photo myself :umno:

 

 

 

Yes high speed is indeed easier said then done, you are absolutely right jab, infact that sound like something fun to do today, i'll attempt a high speed shot of something (i'll figure out what eventually :hihi: )