Wednesday, April 29, 2015

A glimpse at Astrophotography

After a long hiatus, I'm going to post about a very different technique.  One of the things I really enjoy doing is astrophotography.   I've been doing some very basic astrophotography until recently.   I'll talk a little bit about my techniques to try to see if there is much interest in this topic.  If so, I'll dive in a little deeper in later posts.

My initial shots were taken with ordinary gear.   I started with a wide angle lens and focused on trying to get shots of the Milky Way.  Given I don't live too far from a major city (Chicago) I didn't have much of a chance around here.   It was only on vacations when I found darker skies that I could capture the amazing glow and details of our own galaxy.

10mm f/4.5 ISO 6400 30 second exposure

The key to shots of the Milky Way include the following:
Dark/Clear skies
Wide and fast lens
higher ISO 
solid/steady camera (tripod)

It's pretty fascinating to think you're looking in toward the center of our galaxy.  

I also started to learn about new photo techniques like photo stacking.   Despite not having a good telescope or a motorized mount, I was able to get decent (for a beginner) shots of another galaxy, Andromeda.   This helped to build my interest in astrophotography.   To think I was able to capture details with an ordinary camera lens of an object that is 2.5 million light years away was amazing to me.
This is the result of 16 images stacked using Deep Sky Stacker.  I used a 200mm f/2.8 lens.

I also started to take images using my DSLR and a telescope (an 8" reflector).   This time I was targeting planets.  I was able to get images of Jupiter, Saturn, Venus, and Mars.   The images weren't stellar, but it was still pretty cool to be able to see details on these planets.   I was also learning a new technique using video rather than still images.   I used a software tool called Registax to stack images from video clips.   

Another exciting event that I was able to capture using my DSLR attached to my telescope was the Venus Transit.  I had to stack multiple filters and minimize the opening on my telescope to just 1" in order to block the light (I don't recommend this.  It's best to use a specialized solar filter.)


Although the quality isn't great and I cracked a filter in the process, which is why you see the odd lines in the image, I was happy to be able to not only see this, but to get photos of it.   This even won't happen again for over 100 years!


This past winter I upgraded my telescope and also purchased a specialized planetary imaging camera.  I badly wanted to improve my photographs of planets.   My new (used) telescope had a motorized equatorial mount that would be able to keep the planet in view.   Previously I "chased" the planets across the sky.   Also with the new camera and its very small sensor, I was able to get far more magnification and hence far more detail.   To my pleasant surprise, I was quickly able to produce images like this:

This image shows not only nice details of Jupiter, but also shows its moon Io as it creates a shadow on the surface of the planet.   This image also was the result of running video through Registax.   My next goal is to replace the image above where I have Saturn, Jupiter, Mars, and Venus with brand new images of this higher quality.

Hope you enjoyed this quick glimpse of Astrophotography.  I'd be happy to share more on the details of how it's done if you'd like.





Saturday, January 31, 2015

The basics of using a flash with your photography (part 2)

Last week our post focused on the different types of flash units available from the built-in or pop-up flash to an external shoe mounted flash.   We also talked about direct flash and a very little about bounce flash.

Bounce Flash

This week I want to spend more on bounce flash.   My preference is to use bounce flash whenever possible.   As you probably already guessed is that bounce flash simply means you are bouncing the flash beam off of some other object rather than a direct flash which is pointed right at your subject.   That being said, you need to have an object like a wall, ceiling, reflector, etc in order to bounce or reflect your flash toward your subject.  

Why bouncing a flash is typically more effective than direct flash is that it creates a larger light source.   Confusing?   Basically when you face a flash unit directly at your subject the light source is very small.  This creates a much more focused beam of light, which is why you get harsher light and strong shadows.   When you bounce the flash off of an object the light disburses (spreads out) so that the light beams approach your subject from a much wider angle of view.   This is a much softer light and more even light which gives you a much more pleasant look.   Shadows are reduced.  The colors tend to appear more naturally.  

I'd like to point out that I use words like typically, tend to, mostly, and the like due to the variability of all the elements that can influence your photography.   Above I said the colors tend to appear more naturally.   One of the influencers of this is the color of the object you are using to reflect the light from your flash.   If it is a white wall, as an example, you'll have little influence on the light color.  However, if you bounce of a red wall you'll have a red cast to the light source which will alter the colors in your photograph.  

Another benefit of bouncing flash off an object is you can control the direction of light and thus the shadows on your subject.
93mm  f/8  ISO 400   1/200 second exposure

In the above picture I bounce my flash off a wall to my left.   This created nice highlights on one side of my daughter's face which added to the feel of the image.  A straight on flash would have been too harsh and would have not created as nice of an image.   Note that this photo was taken in a basement and the wall is a dark tan color.

93mm f/3.5  ISO 400  1/60 second exposure

In the above picture I used a wall behind me to create a nice even and soft light source.   The light from the flash did not create any harsh shadows and my son's skin tones are very natural.   You have to laugh at his use of my youngest daughter's chew toy (yes it was washed immediately after this shot.)  Too funny.


The two example provided were taken with a flash that is capable of rotating and pivoting.  This is important to understand.   Some entry-level flash units can only pivot up and down.   They do provide benefits over the pop-up flash units, but don't have the flexibility found in the units that can also rotate.    I personally really like being able to bounce a flash of a wall behind me.


Ok, we get that bounce flash is really nice to use, but what happens if I don't have an object, like a wall or ceiling, available?   There are times when you need to use direct flash.   There are times where you want to use direct flash.  

One of the best ways to use direct flash is for "fill-flash."  Fill flash is a way to fill in the shadows of your subject with a slight bit of light from a flash unit.   Another use is when you have a strong back light where without a flash your subject is very underexposed; such as the example below:

44mm  f/4  ISO 800  1/640 second exposure

44mm  f/4  ISO 800 1/250 second exposure - flash used

You can see how I was able to use the flash to fill in the shadow (in this case, my subject was fully underexposed) with the use of direct flash.  Also note, my shutter speed decreased to 1/250 second.  I did not do this despite using Manual settings.   The reason for this is my camera has a flash sync limit of 1/250 second.   Most cameras have a flash sync range from 1/180 to 1/250 second.  

The fill flash example also comes into play outdoors.   I'm sure we've all tried to take a photo of an individual or group on a sunny day.   We end up having the people facing the sun to make sure they are properly lit.   What happens?   Everyone is squinting and their eyes are watering and you just can get a good shot.   What you should do in these cases is have the back behind the subject(s) and use direct flash to fill in the shadows.   The people in the photo will appreciate it and the picture will turn out much better.








Friday, January 23, 2015

The Basics of using a Flash with your Photography (Part 1)

So far all of our discussions have be around using your cameras without any lighting aids... or flash.   Although my personal preference is to use available light, there are benefits to using flash.   One thing I want to point out, this discussion will NOT cover studio strobes.   In the studio, strobes are a fundamental tool with tons of technique and science involved.   What I plan to cover are on-camera flash; the flash built into your camera and hot shoe flash units.   We'll also talk about triggering flashes remotely.

Built-in Flash (pop-up)

Let's start with your built-in flash.   These devices get a bad rap mostly because how they are typically used.   When we buy a nice "fancy" DSLR, it is easy to be intimidated by its power and all its settings.  So the first thing we do is shoot in Auto mode.   This works, and you see the improvements over your previous point-and-shoot camera.   You notice how much more responsive the DSLR is in comparison.  When you press the shutter release, it responds immediately.  The photos seem to have more "pop" and general sharpness seems better.   However, you may also notice that you still get more shots than you expected that are a little too harsh, or you still get that red-eye effect.   You may notice that some of your shots are too dark, despite using the flash.   These are the things I want to talk about as some of the shortcomings of the built-in flash.   That being said, I will also talk about the positive attributes of the built-in flash and how to use it to aid your photography.


External Flash (Hot-shoe)

The next category of flash is an external flash, one that sits in your hot-shoe on your camera.   Typically, they can also be triggered remotely, when not seated in the hot-shoe.   There are a large variety of external flash units.   The variation between them is usually based on their power output, and their ability to pivot and swivel.   This later feature is very important when it comes to bouncing flash off of walls or ceilings, rather than pointing them directly at your subject.  Don't worry, we will discuss bouncing flash a little later.

Since external flash units ride higher than the built-in flash they are less susceptible to causing red-eye.   Don't get me wrong, they can cause red-eye, but that occurs less as the height of the flash increases.




This is the Canon Speedlite 430 EX II.  This is facing straight at the subject.  Notice how high the flash is compared to the lens.  This flash can both pivot (up and down), but also swivel or rotate 180 degrees.


This is the Nikon Speedlight SB-400.  This is closer to entry-level external flashes.  Notice that although higher than a built-in flash, it is closer to the lens than the Canon shown above.  This flash can pivot (up and down) only.  Still very nice to bounce a flash off a ceiling which is often far better than a flash directly pointed at a subject.


Finally, here is the build-in (pop-up) flash on a Canon DSLR.  Since it is on the camera, the flash is close to the lens, which is why they often cause red-eye effects.   Also, notice the size compared to the others.  The output from this flash is less and more pinpoint than the other two.  It is also in a fixed position, whereas both the external flashes have capabilities for moving the direction of the flash.


Now that we understand the different types of flashes available (there are more, but these are very common.)   Let's see how the output varies.


Direct Flash

In this first set of examples, we are going to use direct flash.  This means that the flash output is pointing directly at our subject.   After we cover direct flash and bounce flash, I'll talk about why or when each one comes into play.   If you only have the built-in flash to rely on, you'll want to learn how to use it most effectively.  In the first examples I've taken two extremely basic portrait shots.  Both are with the same camera; both using Auto; one with the built-in flash, and the other with an external flash.   There are some subtle differences between the two shots.

Pop-up flash used

External flash used

As you can see, in these examples the differences are subtle.   The most noticeable is the general light quality.   The external flash produces a more natural skin tone whereas the pop-up flash is a little more harsh.  Due to the positioning of the external flash, the shadow under the model's chin is slightly more pronounced.  Although it's very hard to see here, there is a slight red tint in the model's pupils with the pop-up flash.  It is barely worth correcting in this example.    These two examples are from close up.   The next two examples are from slightly farther away.  They will illustrate some of the challenges of using direct flash, and using Auto with flash for both pop-up and external flash units.

External flash from approx 10'

Pop-up flash from approx 10'

With both of these examples you can see the less than desirable output form direct flash.  Both cause very harsh shadows as seen directly behind the subject.  They also create a strong vignetting effect.

Now I will show a comparison when taking the same shot, but this time I am bouncing the flash off of a wall behind me.
External flash "bounced" of wall

As you can see this is significantly different than what the previous examples.   The harsh shadows are gone.  The color is much more natural and the vignetting is also gone.   This is where external flashes really show their benefit.   

There are absolutely times when direct flash comes into play and must be used.  I'll get into that in the next post, however, the general rule when shooting indoors is that a bounce flash will provide better results than direct flash.




Saturday, January 17, 2015

Time for some practice - Aperture Priority Mode

The best way to let all this information sink in is to practice.   Previously we did some quick tests using aperture priority and shutter speed to see how they work together.   We froze the ISO, and we changed the aperture to see how the shutter speed adjusted.

This time let's practice for a longer period of time.   For this practice, the only thing I would like you to set is your camera to aperture priority.   Use ISO accordingly.   Try to take all sorts of photos and pay close attention to how your camera reacts based on the lighting conditions.   Use your aperture setting to control the depth of field of your shots.   Also, use your aperture setting to allow as much light in as possible, when needed.   Refer back to previous posts to refresh your memory as you shoot.


To give you a few ideas on what to try to shoot:

Portraits:  Family or friends posing for you.  (hint: if you have ample light, try shooting at f/8 to get good sharpness and sufficient DoF.)   Try to use some natural light coming through a window.  Play with shadows on your subject.

Action shots:   Capture things in motion and try to freeze the action.   (hint: Open up your aperture and increase your ISO to get shutter speed high enough to stop the action.)

Long Exposures:  Perhaps some passing cars, to capture the streaking lights.  Remember, you'll need a solid surface or a tripod for this.

Pets:  Try some creative shots with your pets (if you have them.)   Try to get close and fill the frame with their faces.  Focus on the eyes.


Have fun with this and use it to learn more about your camera.   Make sure when you download your photos to may attention to the EXIF info... Aperture, Shutter Speed, ISO and focal length.   Try to get it to really reinforce what you've learned.

Below are some examples of the types of shots I'm recommending you try.   Get creative and have lots of fun.

55mm  f/4  ISO 400  1/80 second exposure

24mm  f/8  ISO 100  1/80 second exposure

400mm  f/5.6  ISO 100  1/800 second exposure

135mm  f/20  ISO 100  1/13 second exposure

10mm  f/13  ISO 800  2.5 second exposure


18mm  f/5  ISO 6400  1/18 second exposure









Wednesday, January 14, 2015

Learning about Lenses

Today I'm changing it up a little bit.   As one reader mentioned, I've talked about the exposure triangle, but on the pictures I post, I also mentioned the focal length, but I really haven't talked about what it means.

Your lens or lenses are critical to your overall photography capability.   In fact, your lens purchases are probably more critical than your camera body purchase(s).   That may sound funny, but the truth is your lenses will outlast your camera bodies.  They also provide you with all the flexibility in what you photograph.  There are two main types of lenses: Zoom and Prime.   The one you are most likely familiar with is the zoom lens.   A zoom lens has a range of focal lengths whereas a prime has only one length.

So what is focal length?  

In the easiest term it is the distance a lens takes to bring a light rays into focus.   If you don't remember this after this point, don't worry.   What you do need to know is that the shorter focal lengths provide a wider angle of view and longer lengths provide a narrower point of view.   What this means is a wide angle lens shows more across the field of view.  However a telephoto lens (with a long focal lengths) acts like a telescope and allows you to "get close" to things that are further away.  

How is focal length measured?

Focal length is measured in millimeters.  You can typically find this listed on your lens.  Many common kit lenses are 18mm - 55mm zoom lenses.   Sometimes you may buy a second lens in your initial kit that might be 55mm - 200mm zoom lens.  Given the range of these two lenses, you have something at the wide angle side, 18mm, and something telephoto at 200mm.   To grasp the effect of this simply look into your viewfinder and zoom in and out with your lens.  When you see a wide field of view, you are at the lower end, and when you see things closer up you are at the telephoto end of the lens.

Typical ranges you see in most lenses are from 10mm (very wide) to 300mm.   That being said, you can buy lenses beyond 300mm.  In fact some ultra-expensive telephoto lenses go to 800mm.  You can also go wider than 10mm, but those are typically fish-eye lenses.

24mm  f/4  ISO 12800  1/320 second exposure

This is an example of a wider lens.  It is shot at 24mm in order to capture a wide field of view.  There were a number of balloons spread across a field all lighting up at the same time.

400mm  f/5.6  ISO 100  1/1000 second exposure

This is an example of a telephoto shot taken of two Herons from very far away.  In order to get the picture I needed to use a very long lens (400mm).   You can see how the longer focal length helps brings object closer in view (magnification effect.)

Prime Lenses

Now that we understand a little more about focal length (and a bit about zoom lenses), what about Prime lenses?

A prime lens has a fixed focal length.  A very common prime lens is a 50mm.   With a prime lens you cannot zoom in and out.  You may wonder why someone would want a prime lens...   There are two key benefits (typically) to prime lenses.   The first is that they tend to be optically better than zoom lenses.  Since there are fewer moving pieces of glass within the lens, they are more precise.  This means they tend to be sharper, often have better contrast, and less distortion.   The second is they are often faster lenses.  Faster???  This mean that their aperture value goes LOWER than you find in zoom lenses.   A very fast zoom lens goes to a maximum aperture of f/2.8.  A very fast prime might go down to f/1.4.   That's two full stops of additional light!!  (note: some do go even lower but those are pretty darn expensive!)

Although I mentioned a 50mm lens, and that's one I often recommend, there are many different primes available.   They start at the ultra wide and go to the super-telephoto.   For you sports fans, you see those huge white lenses on the sidelines of football games?  Those are super-telephoto prime lenses.  They are fast (f/2.8 or f/4) and long (300mm - 500mm).   And let me tell you, they are not cheap.  I know I personally have some lens envy with those. 

Specialty lenses

Above and beyond the zooms and telephotos I describe above, there are specialty lenses available too.   One of my favorites is a macro lens.  A macro lens allows you get get really close to objects so you can get ultra-closeups.   

100mm  f/11  ISO 320  1/100 (flash used)

The above photo was taken with a 100mm macro lens.  (You need to be EXTREMELY careful when photographing bees/wasps/hornets!)   I was literally only a few inches away from the wasp nest when I took this photo.  With these macro lenses you can see incredible details of small objects that you would not be able to see with the naked eye.

Another specialty lens is a tilt-shift lens.  These are quite unique in that the front element actually shifts allowing you to change the focal plane.   What's great with these lenses is you can use them to make normal objects look miniature.

The above picture is actually a full-size locomotive.  You can see how the tilt-shift effect makes the train look like a toy.  Pretty cool effect if you ask me.


You can see through these examples how your choice in lens can effect what types of photos you are able to take.   As you develop your skills you may also develop a desire to take certain types of photos.   For instance, if you like wildlife, you will likely want a longer lens so you can capture animals from a distance.  Or, if you like portraits, you will likely want a mid-range zoom like a 24-70mm lens, or perhaps a nice prime like a 50mm or 85mm.   If you like to photograph insects, flowers, snowflakes, or other small objects, then macro lens is a great choice.

One thing I would recommend is talk with other photographers in your area.  If you are shooting with the same body as they are, you might be able to borrow lenses to get a feel for what you like before you buy.   Lenses aren't cheap, but they are great investments for this hobby.



Sunday, January 11, 2015

Overcoming one of the common challenges of Photography - Camera Shake



Now that we are starting to form the foundation of our understanding of the exposure triangle, I want to start to address some of the common challenges you will face with your photography.  We will apply what we are learning to put the odds in our favor of getting the right shot even when conditions aren't perfect.  Let's face it, all too often we're trying to take photos when conditions are less than ideal: Poorly lit gymnasiums, indoors with limited light, outside at a night sporting event.

One thing we all need to keep in mind is we won't always be able to get the shot we want.  We will all shoot lots of throwaway photos.  There will be frustration.  You'll want to get something but it just won't work for you.   This happens to the best photographers out there so don't worry.   What we will want to do is leverage our equipment to its fullest and maximize our opportunities.

Let's start with one of the most common challenge:

Camera Shake -  This is one we cause ourselves.  As much as we try to hold the camera steady, sometimes it's just not enough.  The result is an image that lacks sharpness, it may even be downright blurry.   This is far more prevalent the longer the focal length of the lens.   For instance, a 50mm lens is pretty easy to hold steady an not have camera shake, but a 300mm is much more challenging.  Even the slightest tremble will cause your image to lose sharpness.   The good news is that many of the newer lenses have built in technology which will help you maintain steadiness.   For instance, Canon has Image Stabilization and Nikon has Vibration Reduction.  Sigma has Optical Stabilization.  Some cameras have stabilization built into the bodies.

That being said, what if you don't have stabilization?  Also, stabilization isn't perfect.  Even with stabilization you need to do certain things to help ensure you're minimizing the risk of camera shake.

How do we minimize the chance of camera shake?  We talked before about freezing action.  If you recall we used fast shutter speeds to freeze action.   Well eliminating camera shake is essentially just like freezing action.   The difference here is the "action" is our natural tendency to move slightly (or shake) when trying to hold our cameras steady.

The first solution, and perhaps the most obvious, is to use a tripod, a monopod, or some other means to stabilize your camera.  This could be placing it on a hard/supportive surface like a table or counter. This solution takes us out of the equation so we won't be the cause of the vibration.   There will be times when this is the only right solution.  You simply won't be able to hand hold a long exposure shot.

The next solution involves you utilizing the exposure triangle.  At low focal lengths, we can combat this with only slight adjustments to shutter speed.  Many of the starter lenses you purchase in kits fall in this category.   They are typically 18 - 50mm or so.  With these you can fairly easily hand hold the camera at a shutter speed around 1/60 of a second.  With good technique and builtin camera or lens stabilization you might be able to dip down a little further to 1/30 of a second.   Below that and it gets more challenging.    As the lens gets longer, you often need significantly faster shutter speeds, in fact you'll often here that you need to equal the length of the lens.   For instance, if you're shooting at 200mm, you may need to shoot at 1/200 second (once again depending on if you have vibration control in your camera or lens.)  Although this will further add confusion, many of you are likely using crop sensor cameras.  This should be taken into account as well.  It means that the actual focal length is actually greater than the lens rating.   We'll discuss this in a later post.

The take away is that as you increase the focal length you'll need to increase your shutter speed if you are hand holding your camera.    How do we increase our shutter speed (while keeping a proper exposure?)    We can open up our aperture by going to a lower value, for example from f/8 down to f/4.   And we can also increase our ISO setting to allow for a faster shutter speed.

Let's look at some examples to see what this looks like.   I took all three shots handheld using the same bracing technique.  You can see the effects of a faster shutter speed on the sharpness of the image.   The three images are cropped to accentuate the impact.

100mm  f/4  ISO 400  1/25 second exposure

100mm  f/4  ISO 800  1/50 second exposure

100mm f/4  ISO 1600  1/100 second exposure

You can see from the first example that 1/25 second exposure is way too slow for a clear handheld shot.   The letters are very blurry despite me doing my best to keep still.

The second example is definitely better, but there is still some blurriness to the image, especially when compared to the third image where I match the shutter speed to the focal length:  100mm focal length and 1/100 second shutter speed.














Friday, January 9, 2015

Aperture + Shutter Speed + ISO : Putting the triangle together




Now that we've discussed the three primary elements that make up exposure: aperture, shutter speed, and ISO, it's time to put them together.   I've put together three tables that will help link them to give proper exposure.   For each table we are looking at FULL STOPS just to keep the math fairly simple. Remember, look back at previous posts if need be, how light is affected as we move up or down a stop in each of the elements.  For example, moving aperture value from 4 to 5.6 decreases the amount of light let through to the sensor by 1/2.   Then with ISO, moving from 200 to 400 increases the sensitivity of the sensor by 2x.   With shutter speed, the longer the shutter is left open, the more light (photons) are allowed to hit the sensor.

Let's look at the tables.   In this first table we have a fixed ISO value at 200.   For each row you can assume the amount of light is the same.   Therefore as we increase our aperture our shutter speed has to slow down (remain open longer) in order to maintain the same exposure.   

Let's say we wanted to achieve the fasted shutter speed, given the fixed ISO, we would need to open up our aperture to it's widest point; in this case it's f/4.


In our next table we are going to have a fixed aperture, at f/4.  Once again assume the the amount of light will be the same for each row.   As we decrease our shutter speed we will also be able to decrease our ISO.

In a real world type example, let's say that we wanted to freeze action in a dimly lit room, or outside on a cloudy day.   We would want to have our aperture open to its widest point, at f/4, but then we need to increase our shutter speed to an action freezing speed, at 1/1000.  In this example we would bump our ISO way up to 3200.  

Is the math starting to make sense?   We are doubling values or cutting them in half based on the combination of elements.

In our final table we will shift to a fixed ISO value.   For this example we are using a pretty fast shutter speed at 1/1000 second.  As we mentioned above and in previous posts, this is used to help freeze action.  Once again we are assuming the same amount of light for each row.   In this case, we can shoot with aperture f/4 and ISO 200 to get a good exposure.   But, as we learned before f/4 will give us a shallow depth of field.   What if we still wanted to freeze action, but also wanted a deeper depth of field?   We could close our aperture to f/11 and increase our ISO to 1600 and achieve the same exposure.


I hope this is starting to make sense.  If not, don't worry, it will.   Refer to previous posts to try to solidify what you are learning, but more importantly, try these out on your own camera.    As we move forward I'll give you more things to try and continue to expand on these concepts.   I want to make sure you are comfortable with these fundamental concepts.   Then we can start to get more creative and look at composition and even some basic editing techniques.

To close out this post, I'll share a photo I took recently.  Given I'm up north, we have some pretty cold weather.  I also enjoy macro photography so I took advantage of a recent snowfall to capture individual snowflakes.   Hope you enjoy them.











Tuesday, January 6, 2015

What is ISO? (Part 2)

In the last post I spent a bit of time discussing noise associated with higher ISOs.  Noise for most "normal" ISO values, between 100 and 3200, on most new digital cameras is essentially a non-issue.   Some might balk at that statement, but hopefully as we progress with this Blog, you'll understand why to ME it is a non-issue.  

The first thing I am considering is that most of us are non-professional photographers.   That being said, I would assume that most of our photographs won't be printed.  And, if we do print them, chances are we won't print above 13x19.   I know some of you will go out and get poster size prints from time to time, and that's great.   In fact, we should set a goal to capture that image that deserves to be printed on a poster.    In any case, the reason I am talking about viewing our photos on computers or iPads or smart phones, or even making relatively small prints, is due to the fact that when viewed on these smaller form factors, the noise is even less visible.  

The takeaway here is I want you to use your camera's high-ISO capability to its fullest.   That being said, I do want you to know a common 'rule' with respect to ISO.   It is:  Shoot at the lowest ISO possible.      That probably feels very contradictory.   Don't worry, this will make sense as we move along with this Blog.

I want to start with some scenarios that should be relatively common across most of us.  I am only going to discuss ISO values  (we'll bring in aperture and shutter speed values later):


The first scenario is a very bright day (in this example there is also snow on the ground to further light our image.)   In this case you can use a very low ISO value like 100 or 200.



In this next scenario, we are taking things in the opposite direction.  This time you're in an auditorium with only stage lighting.  Dim stage lighting at best.   In this case you will need to push your camera much further and use a very high setting like 6400 or even 12,800 if you have it.


This next scene is still indoors, but this time you have some focused, but dim lighting coming from a birthday candle.   Since the lighting is so dim you'll need to use a high ISO to capture it, in this case 3200 ISO did the trick.


In this final scenario, we are finding something in the middle.   Our subject is indoors, but is sitting next to a large window with decent light coming in.   For this shot, an ISO of 800 was used.


As you can see, ISO plays a key role in your photography.   For bright scenes you will be able to use very low ISO values, but as the amount of available light decreases, you'll need to increase your ISO to make sure your sensor is capture enough of the light.   Please note, I did not use a flash in any of these photos.   

In the next post, I'll start to bring the triangle together and see how all three components are used in relation to each other.  


Sunday, January 4, 2015

What is ISO? (part 1)

Hopefully you've had a chance to test out shutter speed and aperture with your own camera and began to see how they work together.   Now I'd like to add the third item that makes up the photography triangle, ISO.

Simply put, ISO is a measurement of how sensitive your camera's sensor is to light.   This exists with film as well.  For those who did shoot film, you probably remember 100 speed, 200 speed, and 400 speed film.   You could, typically through specialty shops, buy 800 or even 1600 speed film.   One of the large advantages of today's digital cameras is that they extend way beyond these values.   And they shoot fairly cleanly at high ISO values.   We'll get to what all this means.

In the last post we talked about stops.  We said that f/4 to f/5.6 is considered one stop.   Well ISO also follows stops.  Most cameras start at either 100 or 200 ISO, then they stop up from there.   Just as with Aperture, there are fractional stops, but for now we'll just look at FULL stops.   Here is a list of full stops:

100  200  400  800  1600  3200  6400  12800  25600  (we'll stop here, but some cameras now go a few stops higher than this.)

Just like aperture, each stop up is twice as sensitive as the previous level.  So ISO 200 is twice as sensitive as ISO 100.   And ISO 1600 is twice as sensitive as ISO 800 and so on.   I bet you can guess what this will mean when we see how this works with aperture or shutter speed... more math.

There is a very important thing to understand when it comes to ISO.   As you increase your ISO, you also introduce more noise.   Noise??  Noise can be similar to film grain.   It is basically imperfections in the image caused by the sensor.  At lower ISO levels, this may be very unnoticeable.  At very high levels it may cause undesirable images.  

Let's take a look at two images.  One was shot at ISO 100 and the other at ISO 3200.  Both were shot in RAW and the only adjustment made was to crop the images so you can see the noise better.  (Make sure you click on the images to see them full size)

82mm  f/4  ISO 100  8 second exposure

82mm  f/4  ISO 3200  1/4 exposure

Pay close attention to the background of the image.   In the first photo at ISO 100 the background is clean without any noticeable grain (noise.)  In the second photo at ISO 3200 the background displays a good amount of grain (noise.)     One thing here is that since this is a DSLR, noise isn't too terrible.   For giggles, I took the same shot with a point and shoot camera.   In this example the ISO is ONLY 400.  


You can clearly see how noisy this image is with all the grain and even false color (green & red blotches.)  You can also see what looks like hot pixels.   This is not uncommon for point and shoot cameras (or smart phones) which use very small sensors.  

Ok, now we know what noise looks like and we know that as you increase ISO the amount of noise will increase.   As you might have known, there is a way to control the noise in your images.   Cameras have built in noise reduction software that will have an impact on your outputted images.   You can also use software on your computer, like Lightroom, to reduce the noise in your photos.   One drawback to noise reduction is that it will 'soften' your image.  You will lose sharpness in your photos.   As you can imaging, the higher ISO, the more noise reduction applied (also longer shots require more noise reduction) and hence you are likely to lose more sharpness.   

In the next post, we'll take a look at how we use ISO along with aperture and/or shutter speed to get the images we want given the lighting conditions we are facing.   



Thursday, January 1, 2015

Time for some practice - Shutter Speed & Aperture relationship

To help solidify our understanding of how aperture and shutter speed work together,  I'd like to suggest that you take some time to do a quick experiment.  For this experiment I need you to identify a subject to photograph.   It should be something fixed (doesn't move) so it isn't a variable in the equation.   It should also have good lighting.   I also recommend that you either use a tripod, or place your camera on something solid, like a table.   Once again, we want to eliminate extra variables from our shots.

On your camera, please select an ISO value other than AUTO.   I know we haven't really discussed ISO, so my recommendation for this is to select an ISO of 200 if you are in a VERY bright room or an ISO of 1600 if you are in a room that doesn't have a ton of light.

Next, set your camera to Aperture Priority.   On my Canon is the "Av" on the mode dial.  On my Nikon it's the "A"on the mode dial.   You may need to look at your camera's manual if you're unsure how to set your camera to Aperture Priority.  (Side note:  I use this setting probably 80% of the time for my photography)

Now pick the widest aperture setting that your lens will shoot.  Most kit lenses start at f/4.  Some of you may be able to go even lower than that, like f/2.8 or if you're really lucky f/1.8 or f/1.4.   If you're one of the lucky ones to have a very fast lens like a 50mm f/1.8, set your aperture at f/2.0.  (fast lens? what is he talking about?  Sorry, I'll get to that later.)

Ok, you should now have a "still life" subject to shoot, using a stable platform (tripod or table.)   Your camera should be on Aperture Priority, using a fixed ISO of 200 or 1600 depending on how well lit your room is.   And finally you should have your aperture set to it's lowest setting possible based on the lens you're using (but not lower than f/2.0).  

Summary of our experiment:

Subject - Fixed
Aperture - Variable; we will change this manually starting with the lowest value we can based on lens
Shutter Speed -  Variable;  your camera's light meter will adjust this  (light meter??)
ISO - Fixed at either 200 or 1600

A light meter is a sophisticated measuring device in your camera which will assist you to get the proper exposure.  We'll probably have a full blog post dedicated to this topic.   In this experiment, the light meter is going to help make sure the shutter speed is properly set to ensure a correctly exposed image is captured.

My setup:

Subject:  My daughter's unicorns set up on a fireplace mantle
Aperture: I'm using a 50mm f/1.4 lens so I will start at f/2
Camera set to Av
ISO: 1600.... I'm shooting in a basement with two overhead bulbs (normal 60w light bulbs)

Ok... Let's start shooting:

50mm  f/2  ISO 1600  1/200 exposure

This first image is set at f/2 which is a very large aperture opening.   Since I started with such a large aperture the DoF is very thin.   I'm focused on the larger unicorn which is only a couple inches behind the other two.  You can see that the front two unicorns are blurry due to the shallow Depth of Field.

Given these settings the light meter used a shutter speed of 1/200 seconds to get a properly exposed image.

50mm  f/2.8  ISO 1600  1/100 exposure

In this second image, I have closed down the aperture to f/2.8.   Remember that f/2.8 allows in half as much light as f/2.0.   Since that's the case, the light meter chose a 1/100 second shutter speed to get the right exposure.   This is what we talked about in the last post...   1/2 the light coming in due to the aperture means we have to double (2x) the time the shutter is open.

The DoF has changed too.   The front two unicorns are slightly sharper due to the smaller aperture.  They're not sharp yet since f/2.8 still produces a pretty shallow DoF.

50mm  f/4  ISO 1600  1/50 exposure

To continue the experiment, I adjusted the aperture to f/4.  Remember this is the only thing we are changing on our own.   Once again f/4 allows 1/2 the light in as f/2.8 did therefore the meter adjusted the shutter speed down to 1/50 second.  This keep the shutter open 2x as long as it did when we had the aperture set to f/2.8.

As a result of the smaller aperture, the DoF continues to get deeper (slightly.)

50mm  f/5.6  ISO 1600  1/25 exposure

In this final image I've stopped down (a phase used when decreasing the aperture) to f/5.6.   Since this is the next full stop (f/4 to f/5.6 is one stop), the aperture is letting in 1/2 the light.  Our brilliant light meter has adjusted the shutter speed to keep it open 2x as long at 1/25 seconds.  Pretty cool.  The math is easy when the light meter is doing the work for us.

Depth of field has once again gotten a little deeper and those front two unicorns are a little sharper.  To have them fully sharp (given how close they are to the lens) I would have needed to go to an aperture of f/11.


Hopefully this is starting to make a little sense.  In all honesty, it will likely take time and practice before you feel really comfortable with these concepts.  The key is... don't give up!!


I threw in a few new terms/phrases that I want to discuss in a little more detail:  Stop & Stopped Down 

Everything we've talked about with regard to aperture have been related to full stops or f-stops.  Although our cameras are capable of fractional stops, I'm going to avoid using anything but your standard stops during our discussions.   These are full f-stops:

f/2  -  f/2.8  -  f/4  -  f/5.6  -  f/8  -  f/11 -  f/16  - f/22    

Each movement to the right (f/2 to f/2.8 for example) is a full stop and means that the aperture lets in 1/2 the amount of light.   Each movement to the left (f/11 to f/8 for example) is a full stop and means that the aperture lets in 2x the amount of light.   You'll hear photographers say Stop-Up or Stop-Down and that means they are adjusting their aperture.