Photographing ghosts

Today I have an extra scary photo tip for you – how to photograph ghosts.

The trick is actually simple, we will take a simple, everyday and solid object or person that will play our ghost – we will take our photo and remove the “ghost” from the scene in the middle of the exposure so it leaves a ghostly semi-transparent image in the final picture.

There are just a few simple tricks you need to know.

First, the background, you need your background to have lots of detail that will show trough the ghost, a solid color background or a background with very little details will just not create the ghost effect.

Also, the background has to be a very different color than the ghost, if the background and ghost are of similar color the background will “fill” the ghost and make it look solid.

The second thing you need is a long exposure, I use 10 seconds because if we use a shorter shutter speed it’s difficult to time the rem0oval of the ghost and if we use longer shutter speed it makes it to likely something that shouldn’t move will move and ruin the shot – especially if there are people in the shot.

Obviously for 10 seconds you will need  a tripod or some other way to steady our camera, a remote shutter release will also help because it will let you take the shot without touching (and moving) the camera.

Even more obviously, you don’t want flash (flash will “freeze” the scene and make the ghost solid but blurry instead of transparent), normal indoor room light will probably be just fine.

You can switch the camera to S or Tv mode, set the shutter speed and let the camera choose the aperture or use manual mode and set everything yourself.

You will want a small aperture, on a DSLR probably around f/11, so the background will be in sharp focus and show trough the ghost, luckily with such a long shutter speed you will need a small aperture to prevent over exposure – you may want to set your ISO to a low value to prevent the aperture from being too small.

Now that everything is ready, get everything and everyone (including the ghost) into the right pose and start your exposure, at some point during the long exposure quickly remove the ghost (or, if the ghost is a person get him/her to run out of the frame).

From my experiment you should remove the ghost about 70% into the exposure (that is,  at second 7 out of a 10 seconds exposure), this will create an image that is solid enough to be clearly visible but transparent enough to see the background trough it.

That’s it for today, happy ghost shooting.

Understanding camera modes

All DSLRs and a lot of smaller cameras have a mode dial on the top, the cameras that don’t have a physical dial always have a mode menu somewhere – in this post I’ll quickly cover all those modes, what they are for and when you should use them – I’ll also comment on what modes to use when learning photography.

There are a lot of cameras out and they don’t all have the same modes (and they have different names for the same modes), so, if you see a mode on your camera that isn’t on the list just leave a comment and I’ll update the list – and if you see a mode on the list that isn’t on your camera that’s ok, not all camera’s support all modes.

So, here are the modes in order of automatic-ness starting from the most automatic:

Full auto/ full auto with no flash – In this mode the camera does all the work, modern cameras are actually very good but they don’t know what you are photographing and they don’t know how you want the picture to come out – so the camera will try to make all the safe average boring choices and this is likely to result in a safe average boring photo.

This is a good mode for “safety shots”, photos you take just to make sure you have something if the picture you planned to take doesn’t come out right.

If you see a once in a lifetime event getting a few pictures on auto mode just to make sure you got it is a good idea – and while you’re learning taking an auto shot in additional to a non-auto shot is smart because you are likely to get some badly exposed photos until you learn to use your camera’s other modes.

For learning I recommend using this mode only for safety shots, you are not learning anything while in this mode.

Scene modes (portrait, landscape, etc.), CA, A-DEP – Those are automatic modes where you tell the camera what you are photographing, those are likely to result in a better picture than full auto mode because the camera can make a more intelligent choice about what settings to use.

Those are good modes for people who are not interested in photography and don’t want to learn about aperture, shutter speed and the likes.

For learning I recommend not using those modes at all because, like full auto mode, you are not learning anything while using those modes.

Program (P) mode – In this mode you can use all the camera’s option but not set the aperture and shutter speed directly.

For learning I recommend using P mode for a little while to get a good feeling of selecting the correct ISO to and using the other camera’s features and then moving to A/Av or S/Tv modes.

Aperture Priority (A or Av) mode – In this mode you set the aperture and let the camera choose the shutter speed, in this mode the camera does not make decision for you because for each aperture value you set there is just one possible shutter speed.

This is a good mode for non-action shoots because it let you control the depth of field directly, with exposure compensation and exposure lock you can also override the camera’s light meter when the camera gets the exposure wrong – but you should consider switching to M mode if the camera gets the exposure wrong.

Note that on Canon DSLRs in Av and Tv modes the flash is used as a fill flash only, so if you want to use fill flash just switch to Av or Tv mode, on the other hand if you want the flash to be the main light source you should use either M or P mode, on Nikon the flash is the main light source in P,A and S modes and to use fill flash you should use M mode.

For learning this is a very good mode to use most of the time.

Shutter Priority (S or Tv) mode – In this mode you set the shutter speed and let the camera chose the aperture value.

This is a good mode for photographing moving objects because it let you easily choose a fast shutter speed to freeze motion or slow shutter speed to create some motion blur.

Everything I wrote about aperture priority mode also applies to shutter priority mode.

Manual (M) mode – This is a mode that let you set everything manually, it is very useful in a wide verity of situations (I’ll write about those in future posts) and is easier to use than people think.

For learning getting comfortable with manual mode is extremely important.

Bulb (B) mode – This is a mode where the shutter remains open for as long as you press the shutter, in cameras that don’t have a dedicated B mode you can usually use M mode and set the shutter speed to “bulb” to get the same results.

Movie mode – Used for shooting video, obviously.

 

Those are the camera modes, and as I said in the beginning, if you can’t find a mode your camera has on the list just leave a comment below.

Controlling Light Falloff

In this post we will see how to control “light falloff” – the difference in light intensity between the areas of the photo who are closer to the light source and the area who are a bit farther away – this will let you create dramatic lighting (for example, cause one side of the face of fall into darkness) or more even lighting that is very flattering in portraits and essential for product photography.

Basically, this is very simple, the intensity of light drops has the subjects gets farther from the light source (no surprises there) but the drop is not even – the light drops off very quickly near the light source but very slowly farther away.

This is because the light falls off according to something called “the inverse square law” – here’s a picture of a wall lit by a flash to demonstrate the effect:

If you look at the area between the rightmost blue line and the center blue line you can clearly see that on the right is much brighter than the center – actually it’s about 4 times brighter (or 2 stops), now look at the area between the center and leftmost blue lines, this area overs approximately the same distance but the lighting difference is much harder to see – I’ve measured it and the center is twice as bright as the left (1 stop).

If we also look at the red ranges around the blue line we can see that in that tiny distance around the rightmost blue line we lost 20% of the light intensity, at the same distance around the center line we lost only 10% of the light and at the leftmost line the light is the same for the entire range.

So what does it mean in practice? let’s take a “one of a kind” toy from Ikea and photograph it with the flash to camera right just out of frame:

We see the left side of the face is completely dark and so is the background, let’s take the exact same picture but move the flash about 2 meters (6 feet) back (and raise the flash power to compensate for the change in distance):

Now the face is well lit because the relative distance between the parts of the face is now small compered to the distance from the flash, also, the background is no longer black (because the distance between light and  to background is no longer much longer than distance from light to subject).

If you remember in previous posts we used this effect to make the background black by placing the flash very close to the subject and to make the background white by placing the flash near the background.

Now, there’s just one more thing, while the light drops in intensity between light source and subject it does not lose power between subject and camera, to show this I’ve taken two more pictures of the same toy, both pictures are taken with the same camera settings (f/8, 1/200 sec, ISO 400, 135mm) and the flash at the same position with the same power settings, the first picture is from the closest distance that fits the subject in frame:

The second picture is from another room, the farthest I could get inside my home:

And here is the first picture and a crop of the same area from the second picture, the colors are a bit different because I forgot to turn auto light balance off but the brightness is absolutely the same:

Hope you enjoyed this post, and that this will help you better control the lighting in your photos.

Using light to show or hide texture

Sometimes you want to show the texture of what you are photographing, for example, you may want to exaggerate the texture of wooden or paper items to make them look more authentic, other times you want to hide texture (and make skin look smother).

Today we’ll see how you can control just how much texture we will see in the images.

Our first test subject is a printout of the dinosaur from the white background post a while back printed on cheap office paper.

For this experiment I’ve set the camera in manual mode, ISO 100, f/8, 1/200, at those settings all the light we see is coming from the flash (without flash the picture is completely black), the camera is on a tripod looking almost strait down at the printed paper that is on a small table.

In the first picture the flash is on the camera pointed directly at the paper and in minimum power (because the white paper reflects a lot of light back at the camera) and we get this:

In the second picture, with the same camera settings and the same flash at the same distance from the subject and still pointed directly at the paper – but this time located to camera left at the same height as the paper and in maximum power (because this time most of the light crosses from left to right without hitting the paper) and we get this:

The picture is too dark so we open the aperture and raise the ISO and get this:

We can clearly see the difference in the paper’s texture between the first and third picture (the second picture is here to prove that the difference was caused by moving the light and not by changing the camera settings).

Now, I’ve chosen those two extreme positions To make the difference obvious in real life, you rarely light your subject directly from the side and, unless you don’t have a choice, you also rarely want the light to come from the camera, in most cases you should choose something in the middle.

Why does this happen? when the light source is close to the camera and the light hits a textured surface all the surface is more or less evenly lit – making the surface look flat.

On the other hand, when the light is coming from the side it only lights one side of each little ridge that makes up the texture – transforming the surface into a series of lighter and darker patches and bringing out the texture.

This is why people say the light from on-camera flash is “flat” it makes 3D object seem flatter and reduces the feeling of depth is the image.

That’s it for today, see you next week.

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.

Macro photography with no macro equipment

Most point and shoot cameras have a macro mode (flower symbol) that let you take extreme close-up pictures of small things, when you move up to interchangeable lens cameras you need special macro lenses to get those pictures – but there is actually one cheap way to take extreme macro pictures without any special equipment.

Take the lens off the camera and hold it backwards – normally your lens take a light from a big area and shrinks it down to the the size of the sensor, if you simply hold the lens backwards in from of the camera you get the opposite effect – the lens take  a picture of something very small and enlarges it on the sensor.

Here is a picture of the setup, flash pointing at the ceiling (we’ll talk about this in a moment) and the my hand is holding my 18-135mm zoom, fully extended at 135mm backwards, I actually shot the pictures for this post hand-held, in this picture the camera is on a tripod because I have one hand holding the lens and the other hand taking the picture with my cellphone.

Now, you need to be careful, the lens is not attached to the camera and you don’t want to drop it, also, you are using it not in the way it’s designed to be used – be very careful and if you damage your equipment don’t blame me.

You may have to enable some setting on the camera so it takes a picture without a lens attached, also, because the lens isn’t attached to the camera there’s no auto focus or aperture control.

The depth of field you get from this setup is extremely shallow and you focus by moving the camera forward and backwards until your subject is in focus, I recommend trying the live view focusing trick wrote about last week.

The aperture control is very brand specific, on Canon when the lens isn’t attached the aperture is wide open – making the already too thin depth of field even thinner – but there’s an easy trick you can use to stop down the lens on Canon cameras (this should also work with other brands where the aperture control is electronic) – attach the lens, set the aperture and press the depth of field preview button (locate right behind the lens on the lower left, right below the lens release button) – now, with the camera on and the DOF preview button still pressed detach the lens – the aperture blades will remain in the same position.

On Nikon when the lens isn’t attached it’s stopped down all the way – good for DOF but making us need a lot of light and can make the picture soft due to diffraction (if you don’t know what  diffraction is that’s ok, but I’m not going to explain it now because it’s not the topic of this post), for Nikon (and other brands where the aperture connection is mechanical) there’s a little lever on the back of the camera you can push to open the aperture (at your own risk, I don’t own a Nikon and never tried it myself).

Marco photography needs lots of light, for those pictures I’ve used my flash on camera pointed at the ceiling – not to soften the light (with the flash head physically larger than the subject I expect the light to be soft anyway) but because at that distance the lens would have cast a shadow on the subject if I used direct flash.

So, let’s see what do we get, first, this is the setup, I’ve put the pencil there to show scale, it’s not there in the macro pictures (also, the picture was edited to remove a barcode that was visible on the corner of the paper, the edits are nowhere near the flowers).

Here’s the yellow flower in the middle with a reversed 50mm F/1.8 lens, stopped down to F/8 using the DOF preview trick (click to enlarge):

And the same flower with the 18-135mm at 135mm wide open at F/5.6:

We can clearly see that longer focal length means more magnification.

We can also see that the depth of field is painfully shallow – so take lot’s of photos, a tiny camera movement will move your focus and the more pictures you take the better chance you have to get one where the focus is just right.

After you take a few reversed lens macro pictures if you discover you like it you can buy a cheap “macro lens reversal ring” that let you mount your lens backwards without having to hold it in your hand, here’s one that fits Canon DSLRs and the Canon 50mm F/1.8 for less than $7 on Amazon (at the time I wrote this) and such rings for other lenses for Canon, Nikon and all brands (also on Amazon), make sure you get one that fit’s your camera and the filter thread size of your lens.

The next step up in macro photography is extension tubes –  if you want me buy a set and write about them click any of the links in the previous paragraph and buy something on Amazon.

Understanding f Numbers

In photography the size of the aperture is measured in f numbers, a lot of people just learning photography find f numbers confusing, this starts with them being backwards (smaller aperture = larger number) and continues with the fact that to double the amount of light you multiply the number by 1.4.

The aperture has a huge impart on the photo you make, so being confused about it is not a good thing.

Basically it’s rather simple, an aperture of f/2 (for example) means the width of the hole in the lens is the focal length divided by 2 (and f/8 is divided by 8, f/2.8 is divided by 2.8, etc.) so if you have a 50mm lens at f/2 the width of the hole in the lens is 25mm – it’s even written as a math equation.

Now the reason for the numbers being backwards is obvious, dividing by larger numbers give smaller sizes.

The reason for multiplying by 1.4 now also becomes simple – you just take the formula for the area of a circle and you get that to make the area twice as large you have to increase the diameter by the square root of 2 (or approximately 1.414) – I’ll skip the math, you can easily check this for yourself if you want.

Now the only question left is – why do we specify the aperture size in relative terms? and to answer that I took a few pictures, both pictures were taken with the Canon EFS 18-135 f/3.5-5.6 IS using the same camera settings (ISO 100 f/7.1 1/160sec) from the same location – the only thing that changed between pictures was the focal length (I zoomed in and out) – the first picture was taken at 18mm and the second at 135mm:

And for you convenience I’ve cropped the 18mm photo to show the same area as the 135mm photo:

Apart from the effect of the focal length on depth of field (that’s the topic of a different future post) both images look the same, if you look closely at the middle flower you will see the same colors and the same exposure in both pictures.

But the diameter of the hole in the lens is 18/7.1 = 2.5mm for the first picture and 135/7.1 = 19mm for the second – a 7x difference! and yet they both let the same amount of light into the camera – and that’s why we measure aperture in f numbers – if we used the size of the aperture the exposure would have changed radically when zooming in or out.

And, as a side note, it’s now also easy to see why cheaper lenses have variable max aperture – the same size hole has different f numbers at different focal lengths, and making a lens that can open up at the same ratio at both ends for a large zoom range requires a very big lens (or a tiny aperture at the wide end).