When not to use flash (flash basics 1)

This is the first post in a long series about flash photography, the series is starting with a few posts about how to use the camera’s built in flash and will continue to external flashes both on and off camera, I will publish the flash posts every few weeks between other topics because I don’t want to write just about flash for months.

I really like to use flash in my photos, it makes life easier and can give wonderful results with just a little bit of expertise and just a little bit of equipment – but flash is not useful in every situation, there are a few areas a flash is ineffective or downright harmful – so I’m starting this series with some situations you should never use flash in.

When your subject is not very close

This is probably the most common flash mistake people make,

Every flash has a maximum range, those ranges (especially for the camera’s built in flash) are very short, anything outside that range is not illuminated by the flash at all – here is a picture of my point and shoot camera firing the flash in the dark:

It’s easy to see that the light is very bright on the right close to the camera but drops off very fast and by the time we get to the left side of the image it’s very dim.

For that camera, according to the manual, the flash is only effective up to 3 meter (9.8 feet) so anything farther is effectively in complete darkness. My DSLR has a more powerful flash that can reach up to 5 meters (16.4 feet), still not much.

This means that if your subject is out of the flash’s range it’s not illuminated by the flash at all – in the past this would have resulted in a black frame but the modern camera compensate by taking the exact same picture you would have gotten with the flash completely off (except it fires your flash in full power and drains the batteries in the process).

If you are photographing a sporting event or a show and you are not in the first row all your flash is doing is bothering the other viewers and draining your batteries – turn it off.

If you are photographing landscape than this is silly, the mountain in the distance is so outside the flash’s range that all it’s doing is draining your batteries and making you look silly – turn it off.

Photographing through glass, fences,  nets, cages, etc.

Any time that you have something between you and the subject there is a chance that something will reflect the flash, let’s show an example:

I’ve positioned my lovely point and shoot on a tripod behind some bars, the camera lens is positioned between two bars and the camera is focused on a small tree in the distance.

And here is a picture without flash, the white thing on the right is a piece of furniture that is standing right next to the tree, on the left side you can see a dark out of focus part of one of the bars.

Turn on the flash and we get this:

First, the dark, out of focus, barely noticeable bar became the brightest and most prominent item in the photo – and as if this isn’t bad enough the light reflected of it totally washes out all the colors in the picture.

Now, let’s close the glass window and take a shoot trough the glass:

Yes, what you see it the light from the flash reflected in the window, everything else is gone.

Anything that is remotely reflective

For your enjoyment, from left to right, an iPhone, a closed laptop and a cake in the oven – all with a big ugly bright burst of light reflecting from the flash:

Another painful effect that you can’t see at this small size is that the light is reflected by every scratch, dirt or fingerprint on the reflective surface – so whatever you are photographing should be completely and totally clean.

This also applies to photographing people who wear glasses – there will be a whole post on photographing people with glasses in the future.

People

Direct flash, especially at close range, is a very unflattering light – it makes the face look flat and highlights every little bit of sweat, also, often in the dark the camera will use too much flash and make the skin look very white, sometime even bright.

And let’s not get started about red eye.

No example pictures here – I don’t want to make people who let me use their pictures look bad on my blog.

So, we shouldn’t use flash?

Flash is wonderful, I love flash (really) – but like any tool it has it’s limitations.

And of course, there are things we can do to overcome those limitations:

To increase the flash range you need… a more powerful flash – but every flash has a range (even the big studio ones) and if your subject is out of range turn the flash off.

To minimize reflections you need to find an angle that reflects the flash’s light away from your camera, there will be a whole post about it soon.

And just to finish on a more positive note I’ll tell you the next flash post will be about things you can do with your camera’s built in flash.

Getting everything in focus–the hyper focal distance

In last week’s post we talked about the factors that effect depth of field and how to use them to increase and decrease it (let’s face it, mostly decrease, everyone just loves to blur the background those days).

But some times you want to get everything in focus, a typical example is when you are taking a picture of a person in a nice landscape and want both the mountains in the background and the family member in the foreground to be in focus (and even if you don’t take vacation snapshots it’s still common to have some object close to the camera in landscape photos because it makes the photo more interesting).

When faced with such a challenge you can focus on the foreground subject and blur the background, you can focus on the background and blur the subject, you can use the techniques we discussed in the last post to increase depth of field (use a wider lens, stop down the aperture, get farther from the foreground subject) – or you can learn about a useful concept called “hyperfocal distance”.

What is hyperfocal distance and why should I care?

The diagram below shows what happens when you focus close to the camera, the red triangle is the point of focus and the yellow bar is the distance range that is in sharp focus – when you’re focusing close to the camera the in-focus are is small and relatively symmetric (the sharp area before the focus point is the same size as the sharp are after the focus point).

As you focus farther from the camera your in focus area grows, but the area behind the focus point grows more than the area in front of the focus point, in the next diagram you can see that focusing on the person leaves a wide (but not wide enough) are in focus behind the person.

As you focus even farther the are behind the focus point continues to grow until it reaches infinity – that is everything behind the focus point is in focus – that exact focusing distance is called hyperfocal distance.

When focusing to the hyperfocal distance (or behind) the area of sharp focus starts at exactly half the distance between the camera and the point of focus and never ends (everything from halfway to the focus point and farther will be in focus).

In the diagram below you can see that by focusing to the hyperfocal distance you can get both the person and background in focus – by focusing a bit behind the person.

How do I know what the hyperfocal distance is?

The hyperfocal distance is effected by all the factors that effect depth of field:

  • Focal length – wider lenses (smaller focal length) makes the hyperfocal distance closer.
  • Aperture – smaller aperture (larger f number) makes the hyperfocal distance closer.
  • Distance – well, we are trying to calculate the distance.
  • Circle of confusion – Smaller sensor makes the hyperfocal distance closer.

Like depth of field there are many on-line calculators as well as calculators for every smartphone platform (actually, most depth of field calculators also tell you the hyperfocal distance).

How can I focus to the hyperfocal distance?

If you have a lens with a distance scale you are in luck, after you get the distance from a calculator switch the lens to manual focus and turn the focus ring until you see you are focused just behind the hyper focal distance using the distance scale.

If you don’t have a distance scale you need to find something that is approximately at the correct distance from you and use that to focus.

Quick Tip: focus a little behind the hyperfocal distance because if you accidently focus a little closer the background will be blurred.

Real life example:

I wanted to take a picture where both the subject near the camera and the background are in focus, I started my depth of field calculator app and entered a focal length of 35mm (my favorite focal length) and an aperture of f/8 (for a nice middle of the road aperture) – The calculator tells me the hyper focal distance is 8.20 meter (or ~27 feet).

Armed with this information I went out to a park just across the street from where I live and took this picture I call “dog looking at path” (if you want to buy prints just e-mail me):

In this picture I used the lamp posts to focus, since the posts are more-or-less evenly spaced they give us a nice way to measure distance – I know the post behind the dog is more than 8.2 meter away so I focus on it, I know the post the dog is tied to is about half way between the post I’m focusing on and the post I’m standing next to (it’s out of frame) so by making sure the post near me is in front of me I know the dog is more than half way between me and the focus point.

If I focus on something that is farther than the hyperfocal distance than everything farther than halfway between me and the focus point will be in focus – so that means both the dog and the background.

To prove the point I took 3 pictures, one focused on the dog, one on the background and one on that second lamp post,

Here are 100% crops from those pictures:

The left part is from the picture focused on the dog, the dog ear is sharp but the background is blurred.

The center is focused on the background, the background is sharp but the dog is soft (look at the darker area of the ear that is so clear in the other pictures).

And finally on the right, the right picture is focused using hyperfocal distance and you can clearly see both the dog and the background are in focus.

That’s it for today, hope that helps the next time you want to photograph something close while keeping something far away in the distance sharp.

Blurring the background–even with a point and shoot or cell phone camera

In this post we’ll talk about controlling the “depth of field” the parts of the picture that is in sharp focus and the parts that are blurred – and I will show examples taken with a point and shoot camera and with my iPhone.

When the camera is focused on an object that object and everything at the same distance from the camera is in sharp focus, there is a range before and after that object that is also sharp and everything outside that range is blurred (more blurred the farther it is from the focused object).

The sharp range can be small (that’s what’s called a “shallow depth of field”) causing the background and objects close to the camera to be very blurry or it can be large (usually called wide or deep depth of field) up to the point everything is in focus and nothing is blurred at all.

There are just 4 factors that control the depth of field (that’s actual physics, backed up by math and formulas) and with most cameras we can control 3 of them, and they are:

Focal Length (How zoomed in you are)

Note that this only works with real optical zoom that is created by moving pieces of glass inside the camera not with digital zoom, so this works all but the cheapest point and shoot cameras but not on most cell phones.

To show the effect I’ve took my lovely Canon 550D with the 18-135 lens and shoot two pictures without moving, one fully zoomed in at 135mm and the other at 32mm (not fully zoomed out at 18mm because that would show you too much of the mess in my garden on the sides of that nice fence ).

You can clearly see that the background is much more blurred in the zoomed in image (you can also see the ridicules construction I used to position the bear, but that’s another subject), but what would happen if I did the same experiment with a point and shoot camera? let’s try, I took my old Fuji S700 (a relatively high end point and shoot from 2007, maybe earlier) and shot the same pictures again, one fully zoomed in at 63mm and one zoomed out at 13mm.

Because the very different sensor size between DSLR and point and shoot the “zoomed-in-ness” at the same focal length is very different, the physical focal length in the point and shoot is much smaller (that’s one of the reasons point and shoots can’t get as shallow a depth of field as DSLRs).

 

 

 

Again, we clearly see the difference in background blur, juts to make it easier to see here is a small part of the upper left corner of all four pictures:

 

The top left is the DSLR zoomed in clearly showing the blurred pattern, the top right is the point and shoot zoomed in it’s so blurred it’s almost a solid color (some of the blur is caused by the lowest quality lens of the smaller camera, if you don’t look in the corner you can see the blurred pattern very clearly), the bottom left is the DSLR zoomed out and the bottom right is the point and shoot zoomed out (the difference in color is simply because the DSLR got a wider area in the picture and caught a piece of the fence that is under a roof while the entire point and shoot image is in direct sunlight).

The focal length have such a big effect on depth of field that at wider focal length (lower number, zoomed out) it’s completely impossible to blur the background, even with a good camera and lens.

One thing that is painfully obvious is that changing the focal length seriously changes the entire composition of the picture and not just the background blurriness – and this brings us to:

Aperture Value (Size of the hole in the lens)

The aperture value is the only option that changes the depth of field without otherwise changing the composition, this is easy to use in cameras that support this, just switch the camera to A or Av mode and set a lower number for smaller depth of field and an higher number for a larger depth of field (if you want to know what those numbers mean look at my previous post understanding f numbers).

But remember all 4 factors always effect depth of field, you can open the aperture wide open (smallest number) but if you are zoomed all the way out you still won’t get a shallow depth of field, especially with point and shoot cameras you have to set the aperture value and zoom in (and get close, we’ll talk about that below) to get a nice shallow depth of field.

To demonstrate I’ve used the Canon 50mm f/1.8 lens on the 550D (because that lens opens all the way to 1.8 it’s easier t o see the difference) the first image the aperture value is set to f/11 to get an extremely wide depth of field:

And in the second picture  I’ve gone all the way to f/1.8 for extremely shallow depth of field (if you look closely you will see that while the bear’s nose is very sharp the ears are blurry).

The aperture value also effects other things in the image (see my previous post on aperture) mostly the amount of light coming into the camera and so the required shutter speed but also how light sources look.

This is all good and nice on higher end cameras but I did mention this is also possible with the iPhone that has a fixed focal length and a fixed aperture – so this brings us to the third factor that is always under your control no matter what kind of camera you have:

Distance to subject

Simply put the closer you are the smaller the depth of field, here are two pictures to demonstrate: in the first, we are near our bear of a model

and than a picture with the same camera settings but from farther away:

For smaller cameras you may have to be very close to get the effect (for the iPhone 3GS, it’s just a few inches), just be aware there’s a something called “minimum focusing distance” – this is, unsurprisingly, the minimum distance  the lens can focus to, everything closer will be out of focus, in point and shoots turning your camera macro mode (icon of a flower) may help, here’s a picture from my iPhone (this time using a toy monkey as a model, with an extra cluttered background – just to make a point):

You can only see the eye because this is how close you have to be to get a shallow depth of field with an iPhone.

Now, depth of field is one thing where a nicer camera really makes a difference, just compare the previous picture – that is the shallowest depth of field I could get with the iPhone and I had to place the iPhone so it was almost touching the monkey to get the shallowest depth of field.

I can easily get much shallower depth of field with my entry level DSLR and lens (Canon 550D with 18-135 at 135mm, wide open at a non-impressive f/5.6, minimum focusing distance):

Or with the cheapest lens Canon make (50mm f/1.8 II wide open at f/1.8, minimum focusing distance)

The difference in depth of field is very obvious, the difference in colors is also obvious – and a large part of it is due to the difference in lighting – the iPhone 3GS doesn’t have any flash at all while the DLSR used an external flash bounced on the ceiling.

Circle of confusion

Circle of confusion is 3 things: 1. the coolest name ever for a technical concept. 2. not important because we can’t control it. 3. A way to describe how out of focus something has to be before we consider it blurry (that is, how big the blur have to be before we notice it).

Circle of confusion is determined by the physical size and resolution of the camera’s sensor and is only important to you if you want to calculate the depth of fields manually or create your own depth of field calculator (or in other words, not at all to most people). 

Using this in practice

Depth of field is one area where a good camera and lens makes a huge difference, with a camera with a larger sensor (like all DSLRs) and a “fast lens” (a lens that can reach lower aperture values) controlling depth of field is easy, just set the aperture and you’re set, for point and shoots you mostly have to work with focal length and distance.

Focal length and subject distance really effect the composition of your image, you can’t just dial them in to set the depth of field – they also interfere with each other, if you want to reduce depth of field by zooming in you have to step back to get the same image and that increases the depth of field due to the change in distance to subject.

If you do want to get a shallow depth of field with a point and shoot try to use all the factors, zoom all the way in, set the camera to A or Av mode (if it has one) and set the lowest number the camera let you and get as close as possible to you subject.

If you have a DSLR you probably want a depth of field calculator so you know what to set in order to keep your entire subject in focus while blurring the background, there are many free ones on the internet and there’s also many free apps for every smartphone so you can carry one with you.

Next week I’ll write about the opposite problem, how to get a widest possible depth of fields (for example, so both the person next to you can the mountain in the background are both sharp).

What to know how to photograph something?

Is there a picture you want to take but just can’t? leave a comment and I’ll do the research and teach you how to take it.

Want tips for photographing animals? mirrors? jewelry? home interiors? or maybe you want to learn how to create reflections in water? use flash better?

Whatever your question, as long as it’s photography related, leave a comment on this post and I’ll find the answer for you.