Focus: Depth of Field

Focus: Depth of Field


So I mentioned Depth of Field (DoF) earlier in Part I, on exposure using aperture.  Changing your aperture settings of your lens changes the depth of field in your photos.  Now, what is depth of field?  It is the width of area in your photo that is in focus.  The larger your aperture (or smaller the aperture number) the smaller DoF you have.  So I demonstrated this using my portrait shot of my friend at f/1.4 (wide open/large aperture) with my 50mm f/1.4:

Portrait - 50mm f/1.4 D

So, I mentioned that the area of focus is just on her eye that is closest to the camera.  That is a very small or "shallow" DoF.  Another example of this would be some of my hand held macro work.  I need to use a wide open aperture to allow the most amount of light in to allow myself to have a fast enough shutter speed to not have any blur.  Some of my macro photos demonstrate a very small DoF which happens when you shoot macro photos with a wide open aperture.  This example of the dragonfly demonstrates just how small of a DoF we are talking:

Dragonfly - 105mm Macro VR

The depth of field in this photo is roughly the width of this dragonfly's head.  And when you look into the background it is completely blurred out.  This blurred out background is call bokeh.  Bokeh is not so much a cool hip trait for dragonfly portraits but more so for people portraits.  The photo above has very nice creamy bokeh.  The bokeh or out of focus background allows portraits to pop out a little more.


In landscape photography, as I also mentioned in Part I, needs a small aperture (or large aperture value) to create a large DoF so everything in the landscape is in focus.  Here is an example:

Boardwalk - 17-55mm

This photo just demonstrates that the depth of field is good because you can still make out the grass in the background and the boards going off into the distance.  In landscape photos you want the most detail you can get usually.  However in this photo the background isn't completely sharp because I focused more on the foreground because I wanted that area of the photo to be sharpest.  This was so that you looked at the bottom of the boardwalk first because it was sharpest, and then were led to the top of the photo.  The boardwalk gave your eyes a path, literally through the photo.  So you don't always have to follow photography rules especially if you have a game plan with what you are doing.

Depth of Field can be changed by Tilt-Shift lenses.  These flatten the DoF a little so that the DoF is more horizontal than just vertical.  This allows landscapes to have more detail because the DoF is flatter to the horizontal axis.  I personally have not used a TS lens so I have no examples and the photos would just look like a very sharp landscape photos from the foreground to background.  

Other manipulation of optics or in post-processing can blur the photo more to make the aperture effect on the DoF different.  Lensbaby lenses alter the effects of the DoF to blur areas of the photo while keeping certain areas of the photo in focus.  Again I have not tried one of these lenses so I am not an expert witness but that is the gist I have gotten from seeing the photos from those lenses.

So DoF can be a factor that makes or breaks a photo.  But just like most rules in photography, they can get tossed out the window from time to time.  It's art, who cares.  I am sure you can find an audience to like your photos even if you don't do the normal things with DoF.  But more often than not, DoF is a good thing to pay attention to since it is a large-ish part of photos.  

And with that I will wrap up my focus on DoF, I hope that helps and again if you have any questions or things you would want me to cover on my blog, do not be afraid to send me off a e-mail @ tomhouston7@gmail.com.

Focus: ISO. My Take On The "Exposure Triangle" Part III

Focus: ISO.  My Take On The "Exposure Triangle" Part III


So, first I will recap.  Part I covered aperture and how it effects exposure as well as shutter speed in part II. Now in Part III I will cover the third and final part of the triangle, ISO.  Once I am done with ISO, I will put them all together.


Now last but not least, ISO.  To be honest I have no idea what ISO stands for but do not fear, I know what it does.  So ISO is from the film days (not that they are gone but..) where ISO was the sensitivity or "speed" of the film.  So different film had different sensitivity to light which means different film would be better for different lighting situations.  ISO numbers that are low (100, 200) are not very sensitive to light so they would be used for a bright sunny day because it would take a lot of light to effect the film.  ISO speeds of 1600 and around there are very sensitive to light, so they would be good for dark situations because it does not take a lot of light to effect the film.


Now I am guessing for most of you reading this post are probably using a digital camera, so how does this effect you?  Well it is the same thing but a little more artificial since digital cameras have a sensor, not film. So ISO for the digital age is the same but you don't need to buy different film for different light now.  You can just go into your settings and turn up or down your ISO which increases and decreases the sensitivity to light.


So if you have your camera's ISO on 200, it will allow you to take well exposed photos during bright sunny days.  If you use ISO that is high like 1000-1600, you will have a very sensitive camera sensor that will be good for very dark situations.


Now before I put these all together... how does ISO effect you photos?  Just like aperture and shutter speed, ISO also has an effect on your photos.  Depending on your camera/film, the higher you crank your ISO, the more grain there is into your photos.  This grain is called "noise" because you can see all the pixels and it usually makes your photos not turn out so well.  To demonstrate noise I will bust out a old photo from a Weatherthans (Amazing band by the way) concert I was at when I had my old Point and Shoot camera:

The Weakerthans - Noisy Image Exmaple - P&S

So yes, that is a bad photo.  But I am posting it to demonstrate grain.  You can see all the pixels and it just isn't a great photo because of it.  This is what happens when there is not enough light so what my camera did was it automatically cranked up the ISO.  It was high enough that the photo had a lot of noise.  But it was a good concert!

Digital cameras these days are getting better and better at having minimal noise at higher ISO's.  My Nikon D90 is decent, but the D700 is known very well to be one of the best cameras in low light.  The new D3s can "shoot in the dark" or whatever the slogan was.  But they can, they can pick up light without noise from the environment that your naked eye would be hard pressed to see.  So depending on how current your camera's sensor is and the quality of it, you can have noise in your photos near ISO 1000 to 6400 haha, or never if you have a D3s.  But I am guessing if you have a D3s, you may not need to take advice from myself but if you are, I am honoured. 

So with ISO and noise, you just have to take photos at different ISO's and figure out what ISO your camera starts getting grainy.  I will quickly go over how it can be used.  So you increase your ISO if you need to keep your shutter speed and aperture fixed (or is you are already as wide as your lens can get).  So if it is dark and you need a fast shutter speed to capture action but also need a large DoF with a small aperture, then you are left with ISO to change to get a well exposed photo.  If you use a fast shutter speed and need a large DoF in a dark situation, you need to have a higher ISO to have a properly exposed photo usually.

So if you are doing star trails, or long exposure photography, having a low ISO is what to do so that your sensor is not sensitive to light which allows you to have longer shutter speeds.  If your shutter needs to be open to for a long time, you do not want your sensor to be sensitive to light or else it will look like you are being summoned to heaven again.  Also having some grain in your photos and some good post-processing (editing after) you can get a photo that looks like it was film.  This can be a desired look for some.  

Now to put it all together.  As I covered with the concert example, ISO can be used to brighten or darken a photo if you cannot use aperture of shutter speed.  So these three things are used to get the proper exposure of a photo.  So if your photos are too bright or too dark, these three things can help you depending on how you want your photo to look.  Personally I always leave my ISO at 200.  That is the lowest ISO my camera can do.  This allows me to not have any noise in any of my photos.  I rarely up my ISO because I do not want to risk noise in my photos.  But as I mentioned, if I cannot change my aperture or shutter speed more to get the right exposure, I will play with my ISO.

So depending on what you want to control in your photo, you use ISO, aperture or shutter speed to compensate for proper exposure to get the look you want in your photos.  I can't tell you how to have your camera settings for everything shot because each camera has different sensors and each lens has different apertures and every shot is different.  What I can tell you is to keep those three things in your head as you shoot.  If you are always practicing those things and actively thinking about how to control the light you will probably get better at taking photos.  

I hope my take on the exposure triangle helped in some way.  Sure you can read all of the basic foundation information for photography but you can't stop there.  You have to go out and practice.  Sometimes you only have a small amount of time to capture a great shot and you have to know your stuff to get the photo.  Sure sometimes you can take a couple of test shots before you get the one you are looking for but usually life goes easier if you can get it right the first or second time.  Saves you from taking a bunch of photos you know you are going to have to delete later.  Anywho, practice, practice and practice is what I am trying to say.

Hope that helps!  I will keep thinking up more helpful things to blog about.  I decided for me to help you better I will open up my e-mail for questions and ideas.  So you can e-mail me at tomhouston7@gmail.com if you have any questions for me on photography or an idea you want me to write a post about.  I will start checking that e-mail now to see if anyone has any questions or ideas they want me to cover.  Please don't hesitate to ask questions.  I was always asking questions on gear and photography knowledge and I still am to this day asking other photographers questions.  So thank you again for reading and I hope to hear from people now with photography questions, I hope I can help!

Thanks again,

Tom

P.S. Just made videos for understanding the exposure triangle and here is the one on ISO: http://youtu.be/h0V4SqBi6HU

Focus: Shutter Speed. My Take On The "Exposure Triangle" Part II

Focus: Shutter Speed. My Take On The "Exposure Triangle" Part II


Part I covered aperture which I decided to cover first.  If you did not read it, you can click here to read the post.  I would recommend covering aperture first since this post will build on that knowledge a little.


Shutter speed is the duration it takes to open and close the mechanism that allows the light to hit the film or sensor of the camera.  It is the click as you take your photo.  Shutter speed allows you to control again how much light you can let it just like aperture does just in a different way.  


Slow shutter speeds keep the shutter open a longer amount of time which allows more light to pass through to the sensor/film to create a brighter image.  Having a fast shutter speed opens and closes the shutter quickly creating less time for the light to come through the lens to hit the sensor/film.  So both aperture and shutter speed control how much light hits the sensor however they both do this in different ways.  Just like aperture, shutter speed has other effects on your photos than just controlling the amount of light that is let in.  Aperture had an effect on the out of focus areas of the photo or bokeh as well as the Depth of Field (DoF) of the photo.  Shutter speed has it's own effects.  


However before I go into the effects of shutter speed I will discuss how it effects your photos if you are not using it for creativity purposes.  Shutter speed is something that can negatively effect your photos beyond having them too bright or too dark.  Using a slow shutter speed allows the camera to capture the movement of the camera which in most cases is from your hands shaking a little.  This results in blurry photos and lights streaking around in the photo.  Using a fast shutter speed ensures that the photo is captured quick enough that there isn't enough time to have any camera shake effect the photo.  Usually in most cases between opening up your aperture and slowing your shutter speed you can get decent photos if you do not have a lot of light.  There can be a couple of reasons you need to have a slow shutter speed.  If you cannot open your aperture wider due to the lens or you want a certain aperture for a desired DoF then you have to play with the shutter speed to get the right exposure. If your aperture limitations cause your shutter speed to be too slow for a hand held shot then you will get blurred photos.  This can sometimes be fixed with a tripod if the subject of the photo is stationary, or now with some newer lenses there is the ability to decrease the effect of camera shake.  


Using a tripod as a fix for slower shutter speeds is helpful if you are doing landscapes since usually there is not a lot of movement and therefore having a 2 second shutter speed wont result in a photo that looks like abstract art.  You are in a tough spot if you need to have a slower shutter speed and have your subject moving around.  For me this is what I run into at concerts.  Lighting is terrible and the singers are moving around.  Here is where it is very useful to have a large aperture on your lens.  


From the example from the concert, you may have noticed that a faster shutter speed "freezes" movement in a photo better than a slower one.  So with a fast shutter speed, you can capture something moving in a still photo and not have it blurry.  However if you are photographing something moving with a slow shutter speed you get motion blur.  The problem here is that sometimes you want motion blur and sometimes you don't.  Having your camera setup on a tripod you can get motion blur of cool things like stars or water which both can have very cool effects.  However if you are again taking photos of a concert and use a slow shutter speed as someone is strumming a guitar, you just get a semi sharp portrait with a very blurry hand/arm which looks kinda weird most of the time.  


Before I go into the cool effects that shutter speed can have I am going to lastly go over how your lens can help.  So we went over aperture already, but some newer lenses have the ability to shake opposite to your hand to allow for slower shutter speeds without camera shake effecting the photo.  Different camera/lens companies call this technology different things.  Nikon calls it VR for Vibration Reduction, Canon calls it IS for Image Stabilization and Sigma calls it OS for Optical Stabilization.  Personally I am a Nikon user so I only know how well Nikon's VR works but I am sure they all are basically the same.


VR is very useful and I only have it in one of my lenses.  I have it in my 105mm Macro lens.  Most people think that it shouldn't be in a macro lens but it is outrageously useful.  I rarely use it with a tripod as I should for marco work.  However I have managed to capture some very good marco photos (I think but you can make that call so I tossed one of my hand held macros at the end of the post) without a tripod and just taking photos hand held.  Shutter speed along with VR help do this as well as sunny days and steady hands.  I have heard photographers speak and write about the new 70-200mm VR II Nikkor lens and it's amazing ability to get shots with slow shutter speeds.  It is a useful technology that definitely helps photographers get tougher shots in low light that were almost impossible before.  


Now for how you can use shutter speed to help you.  You can use a fast shutter speed to capture actions or movement.  I think my best example of this would be in this photograph:

Humming Bird - BC - 18-105mm VR

So with a fast shutter speed I was able to capture a photo of a hummingbird with it's wings not blurry.  That is impressive since their wings beat at 60-90 beats per second or so.  Slow shutter speeds can get nice night shots with stars as well as motion blur like this photo:

Queen Charlotte Islands - 18-105mm VR

I took this photo with a semi-slow shutter speed in a car while it was moving.  This slow shutter speed allowed me to capture the movement of the car.  To be honest I accidentally took this photo, but I liked it a lot so I kept it.  


To sum this up, shutter speed is the duration of time that the shutter allows light to pass through to the sensor/film which dictates the amount of light that is let in for the photo.  So now aperture along with shutter speed control the amount of light that is let to the sensor/film.  Together they can be used in combination to allow you to get the look you want in you photo be it a large or small DoF to motion blur or freezing action.  


Next I will go over the last thing responsible for the brightness or darkness (exposure) of your photos, ISO.  So that will be Part III.  Since ISO won't take as long as shutter speed and aperture, I will tie them all together in Part III.  


Again, if you have any questions to make anything clearer please do not hesitate.  Hope this helps.  And always remember to practice!


As I said with the macro shots and the aid of VR, here is a hand held macro shot:

Frog - 105mm Macro VR

P.S. I've now made videos on my youtube channel about the exposure triangle so here is the one on shutter speed:  http://youtu.be/z1VNrU6PofI

Focus: Aperture. My Take On The "Exposure Triangle" Part I

Focus: My Take On The "Exposure Triangle" Part I


I cracked and decided to write posts on aperture, shutter speed and ISO.  I finished the reviews of my gear so I decided to move on and try to pass on more knowledge.  I am not an expert on exposure but I will share what I know.


First I will start with aperture however it is hard for me to explain these components separately since sometimes they are link together at times.  So aperture is the diameter of the lens diaphragm that is responsible for controlling how much enters to the film/sensor.  My best way to explain it is, the aperture of the lens is like the pupil of an eye.  So in low light or dark situations, the aperture can to be opened up to allow more light to enter just like a pupil dilates to allow more light to enter the eye.  And vice versa, in bright situations, the aperture closes to decrease the amount of light so the photo is not blown out.  The pupil also constricts in bright situations so you don't burn your eyes.  Aperture allows the photographer to control how much light the lens lets in which can brighten or darken the whole photo.


So now it gets a tad bit confusing.  Sorry, there is no way around it.  The lens, not the camera, is responsible for the aperture.  The camera can control the aperture of the lens but it is the lens that dictates the range of apertures available to you.  So on a lens, the aperture value is denoted by the f-value.  So the value is written as "f/__."  So for example, my 50mm has an aperture value of f/1.4.  So now the confusing part.  The smaller the f-value number, the larger the diameter of the diaphragm.  So f/1.4 can open up larger than a f/2.8, and an aperture of f/2.8 can open up wider than a f/4 etc.  I will go into aperture values and what is good at the end but first I will cover what these numbers are used for and how aperture affects photos.


The f-stops are in numerical values so that you can determine how much you are increasing or decreasing the light by.  So one stop of light difference, is if you go from f/2.8 to f/4.  So what that means is if I change my aperture from f/4 to f/2.8, I am letting in twice as much light through my lens.  It is just math and calculations on figuring out the numbers and how many whole/half/third of a stop difference there is between values.  I wont go into the math of it cause I find it boring and I never think of that in my head ever while I am taking photos.  To get by and use your aperture of your lens(es) well, you just need to understand how it works and the smaller the number, the large the diameter and vice versa.  It is go to know the approximate differences of the apertures so you roughly know how much more light you are letting in or keeping out.  However I have never taken a photo and said "man, I need to triple the amount of light being let in.  I need to change my aperture from f/2.8 to f/8."  I just know "okay, my photo is dark (or underexposed) so I need to let in more light so that means I have to increase the diameter of my lens," and therefore go to a lower f-value to achieve that.  And the opposite to a photo that is too bright where I have parts of the photo blown out or over exposed.


Now, I think it is important to briefly go over what other effects aperture has on photos other than just increasing and decreasing light.  The aperture selected also dictates the amount of area in the photo that is in focus which is called Depth of Field (DoF).  So, what on Earth does that mean?  Good question.  The Depth of Field or DoF is the width of the area of focus in the photo.  So I will use my photos to explain.  A small DoF would have a very little amount of the photo in focus.  Here is a portrait I took that has a very small or shallow DoF:

Portrait - 50mm f/1.4 D

So as you can see, the background is out of focus, her shoulder is not really in focus but just a thin sliver of the photo is sharp/in focus, which is in the same plane as the eye closest to the camera.  You can also tell this by looking at the hair laying on the front side of her shoulder.  If you look carefully, the hair goes from in focus to out of focus very quickly because the DoF, or the width of the area in focus is very small.  This time, the numbers line up... the smaller the aperture, the smaller the DoF.  So that shot above was shot at f/1.4, so the DoF was extremely small.  This is good for portraits for multiple reasons but one of them being is that you are focusing on the model and not any of the trees or the road in the background.  Also most of the face is out of focus which makes the skin look nicer and just makes portraits overall more flattering. 

While a small aperture value has a small DoF, a large aperture has a large DoF.  Example:

Cape Forchu, NS - 17-55mm

This photo was shot at f/11 which has a large DoF which is more suited for landscape photography because you want to have everything you can in the photo in focus.  The photo has the foreground of rocks that are in focus, to the lighthouse in the background.  If this was shot at f/2.8 which is the largest diameter the 17-55mm can go to, the foreground would be fuzzy if I focused on the lighthouse.  That isn't really wanted for landscape photography.  Well, I sure didn't desire it in this photo.  For myself personally I try to have my landscapes all in focus because I want my landscapes to look exactly like it was when I saw them.

Different aperture values have different uses.  Sometimes you have to use a wide open aperture (the smallest number your lens can do) to let in the most light if it is in a dark room for instance.  Sometimes on a bright sunny day you have to close your diaphragm right down so your photo doesn't look like you are being summoned to heaven (completely white everywhere or blown out).  The larger the minimum aperture, the more versatile the lens is because you have the option to gather a lot of light if you need to.  However which a larger diameter diaphragm, comes a larger diameter glass and larger pieces of glass makes a larger price tag.  

Lenses and apertures.  Kit lenses usually have a variable aperture.  This means the aperture has a range depending on the focal length of the lens.  My kit lens was the AF-S DX NIKKOR 18-105mm f/3.5-5.6G ED VR.  Important part of the name for this post's purpose is 18-105mm f/3.5-5.6.  So at 18mm, so the widest angle of view, the lens could have an aperture of f/3.5 and up.  At 105mm, the lens could have an aperture of f/5.6 and up.  This means, as you zoom out from 18mm to 105mm, the lens needs to have a smaller diaphragm to make the optics work.  So as you zoom out, you lose some ability to let in as much light.  This for a lot of normal scenarios is manageable, however there are some cases where you do not want your aperture to change on you if you zoom.  So fixed aperture lenses are in my opinion and I believe almost everyone else's, are best.  Currently I have all fixed aperture lenses which means I can keep my lens at whatever aperture I want and zoom in or out and have it stay at the value I picked.  For an example I will use my example from the portrait above to help pull some of this together hopefully.  I wanted a shallow DoF in that portrait, so I set my lens to f/1.4, the widest the diaphragm in that lens can go.  If it was a zoom lens, and I decided to zoom in, and the aperture would changed then I would have a completely different look than the one I wanted.  More of the photo would be in focus which may not be flattering, and more of the background would be in focus which would make it more distracting.  Another example would be in a dark room which was actually the reason I bought a 50mm f/1.8 D.  I was at a dinner and didn't want to use a flash because it is a little obnoxious to do in a restaurant.  My kit lens couldn't let in enough light so all my photos were blurry and the colours were off because the shutter was open too long.  So that is another occasion to "need" a larger aperture or fixed aperture.  

Smaller apertures allow for the backgrounds of photos to be more out of focus which makes them less distracting and allows for some photos to just look better.  This is called "bokeh" which people pronounce as "bo-kay" or "bo-kah."  I don't know what is the right way to say since people say it differently.  I will cover that in another post since this one is already long enough.  So stay posted for my take on bokeh later.

So to sum up a little:

Aperture is the size of the diaphragm of the lens which dictates the amount of light that is let in as well as the DoF.  Which is like the pupil of an eye dilating and constricting depending on the light conditions.  And the Dof (Depth of Field) is the amount of area of the photo that is in focus which is controlled by the aperture.  The aperture is donated as f-values like f/2.8 which is fairly large diameter to f/16 or f/22 which is a very small hole.  So the smaller the number, the larger the diameter and vice versa.  Then for DoF, it is the smaller the f-value, the smaller the DoF and vice versa.  Fixed apertures that are small numbers usually are best because they can allow you to let a lot of light in compared to larger apertures.  Variable aperture lenses that have a variable range depending on the focal length of the zoom range make it more difficult to harness the light needed for photos sometimes especially indoors.  

The larger the aperture, the more light that you have access to which allows you to have a faster shutter speed.  I managed to keep shutter speed mostly separate from aperture which is nice because it makes it simpler that way but shutter speed will be the topic of Part II.

I hope that is simple and easy to understand.  Personally when I was getting a handle on all of these things I read multiple articles on the same topic so that I could build a strong understanding of it.  Also I went out and practiced shooting a lot which helps to have the "hands on" part of learning as well.  So if some of this is confusing or written poorly I am sorry but ask any of your questions in the comment section or read other sites on aperture and things will hopefully become clearer.  And don't forget to try it for yourself!

Here is a link to a video I made for my Youtube Channel on this topic.