Category: Learning photography

Post about learning photography, such as exposure, composition and colors. You can also find reviews of books about photography.

What is hyperfocal distance?

The hyped distance…

Although the name sounds very advanced and almost like something from a galaxy far far away, it is really very simple: to make the most of your dept-of-field (DOF).

Notice the “distance” in the term “hyperfocal distance” – it is all about the distance between your camera and the focus point. When you focus at the hyperfocal distance, everything between that point and to infinity is in focus. Or I should say, appears to be in focus. There is a lot of technical details here that I omit, but I want to give you a drivers license to shooting at the hyperfocal distance – not turn you into an engineer.

Your depth-of-field (DOF) is an interval before and after the focus point where things appear to be in focus. I normally think about it so that 1/3 of the depth-of-field (DOF) lies before the focus point, and 2/3rds lies after the focus point. This is not very accurate, but a good operational way to think about it. So when your focus point is so that the far end of the DOF just reaches infinity, then there is also a good part before the focus point that is in focus. If your hyperfocal distance for example is 10 meters away, then the space between the focus point and halfway back to you also appears to be in focus. In other words, only what is between you and 5 meters out will be out of focus. From 5 meters out and to infinity is in focus.

Calculations are not necessary

So should you calculate the (DOF)? You can if you want to, but what I do is to focus to infinity with manual focus, and then pull the focus point back towards me until infinity becomes out of focus, and then revert just a little bit until infinity becomes sharp again, and then I have the focus point hyper focal distance. If you have a mirrorless camera with focus peak highlights, this is a brilliant illustration of how your focus plane and the (DOF) works you can find the hyper focal distance using the method I just described, but supported by the focus peaking highlights.

Learning from old lenses…

On old lenses, there was markings showing the (DOF). The black dot just above the blue “11” shows that the lens is at f/11 aperture . The same blue color as the “11” is used for the (DOF) markings on the zoom ring. You can see that to the left, the blue mark is at infinity, and to the right the other blue mark is between 3 and 5, i.e. around 4, the precision is not that great. The focus point is between 5 meters and infinity (the tilted 8 to the left just above the black dot). The blue mark to the left is the far end of the (DOF) whereas the blue mark to the right is the near end of the (DOF).

DOF indicator on the Nikkor 50mm f/1.2
DOF indicator on the Nikkor 50mm f/1.2

Is the lens at the hyper focal distance? Yes, it is as the far end of the DOF touches infinity. Had I focused closer, then infinity would be out of focus (which every portrait photographer knows), had I focused further away, I would have wasted DOF beyond infinity.

The distance is not linear

Also notice the distance scale: You can see it (in meters) top right is at 1.2 meters, then 1.5, 2, 3, 5 and infinity! So it is almost is if the distance “explodes” when you get beyond 5 meters, i.e. a very small turn on the focus ring gives a big jump in the distance. That is why it is vital that you get the far end of the DOF to touch infinity, because you then work with the part of the distance scale where you cover a lot of ground!

DOF calculator

If you put the above example into a DOF calculator (credit: Photopills) then you will get a hyperfocal distance of 7.42 meters, DOF near limit to the half of that and the DOF far limit to infinity. In this example we have got the most out of the DOF and only the distance from the camera and 3.7 meters out is out of focus.

DOF calculator from Photopills
DOF calculator from Photopills

Notice that the DOF depends on several factors, such as the sensor size, the aperture you shoot at, the focal length of your lens, distance to the subject etc. But no matter what DOF you are working with, the hyperfocal distance is the focus distance where you make the most of what you got.

Related reading

What is manual focus in photography?

What is the focal plane in photography?

 

How to do ICM (Intentional Camera Movement) ?

Normally you would expect a skilled photographer to deliver clean, well exposed images, but with intentional camera movement (ICM) the aim is to make the images look a bit more abstract by introducing a deliberate camera movement while the shutter is open.

There really are no rules when it comes to ICM and you can develop your own style and expression. The classic way of doing it however is to move the camera along lines in the subject, so that you emphasize these and blur details. For example, in a wood with tall trees you would move the camera up/down in a vertical movement, whereas a landscape image with a horizon, you want the movements to follow the horizon left to right or the other way round. You can also move the camera more freestyle, for example try to follow a wave as it comes to shore. The possibilities are infinite and you can really develop your own style and expression. In the example below I have moved the camera in circles to get the effect.

The way to do ICM is to make sure your shutter is open for say 1/2 to 2.0 seconds. You may want to go down to 1/10th or up to 5 seconds, but start with 1/2 to 2.0 second just to get you going.

You can do this by putting your camera in shutter priority mode and simply ask the camera to leave the shutter open as you see fit. The camera most likely will put the camera in base ISO (say 100) and minimize the aperture to whatever the lens allows, say f/22, but you may find that this will not do and the picture is over exposed. This could happen if your are shooting a sunset or a bright scene. In such cases an ND filter is needed. An ND filter is basically a pair of sunglasses you put in front of your lens to minimize the amount of light that gets through. I use a variable ND filter that takes between 3 and 11 (!) stops of light out of the equation.

Don’t be discouraged if you come home with a lot of images that are no good. This is only natural, also for experienced photographers. You may find that out of 2-300 images, there are only a few if any that works. Keep going and eventually you will succeed! Best of luck!

Video link

Can you learn photography just by watching YouTube videos?

The answer is yes. However, there are a few things to be aware of, that can help your way into photography using YouTube as a teacher.

YouTube is a great pool of information about many things, also photography, but there is no guidance as how to use YouTube if you want to learn photography. In this blog post I share a few lessons learned from my own journey learning photography from scratch using YouTube. With a few awareness points, you can learn photography via YouTube both faster and more efficiently than what I did.

Know yourself

We all learn in different ways. Some like to read text, others to see pictures, yet others like practical exercises and hands-on experience. We learn in many different ways, and good school systems acknowledge this and make sure to cover different ways of learning.

YouTube obviously is a very visually oriented teacher, and only you know if this is a good way of learning in your case. If for example you know that your preferred way of taking in information is say via reading, you may want to vary the videos with blogs or other sources of information that presents the material in a different way. Many of the larger YouTube channels about photography also have a homepage with material and books available, often at a price, but it may be a good investment considering the time you may save .

Create your own structure

YouTube videos are often very specific. They compete with other videos about your attention, and to win that competition it is good to seek out a spot where others are not, and that tends to drive the content to be more and more specific. So overview and structure and helicopter view is not what you will find in the typical YouTube video. And it is difficult to know when you have covered all relevant ground to cover the basics of photography.

When you attend school there typically is a curriculum for the upcoming term. That tells you what you need to study, gives structure and also scopes what the final exam will be about. When you study on your own, you have to develop your own curriculum, otherwise you will be lost in the sea of information in the YouTube universe, and although you are making good progress, you lack some good yardsticks to measure your progress.

One way to make some structure is to narrow your searches for videos according to what type of photography has your interest. I know this is difficult when you are new to photography, but give it a shot still:
– Landscape photography
– Street photography
– Portrait photography
– Event photography (weddings etc)
– Product photography
– Abstract photography
– Architecture photography
– Wildlife photography, and so on…

Another dimension you can use bring some structure to your curriculum is to take the table of content from the manual of your camera! Yes, I know, this makes you want run away! But I am not asking you to read the manual (although it can be a good teacher), but just use the TOC as a guidance for your reading plan.

A third option is – yes I know it is old fashioned – to  buy a book about the basics of photography. Joel Sartore has written a book that I find relatively easy to read: Photo Basics, published on National Geographic. Once you have read that book, you have a very good overview of the basics of photography and the TOC can be used to your YouTube searches to further deepen your knowledge.

Remember practice, practice and practice

It is tempting to binge watch YouTube videos in one long stream, and I did that as well. But remember to take a pause, to let the information sink in and for you to digest the information.

Secondly, it is important that you apply theory to practice and test what you have learned in real life. You think you know it when you understand it, but the practical appliance brings new dimensions to your knowledge and understanding. So don’t skip the “exercises” – apply what you have learned, and learn even more!

When you grow…

When you have been using YouTube for a while, you will find two things: (1) there are some YouTubers you like more than others and (2) suddenly you are thinking to yourself: I know this already! Both cases is a good sign that you have grown as a photographer and that you have learned a lot!

The few YouTubers that I enjoy may not be the same as those you have found or will find, but I share them anyhow to give you some search terms in case you are interested:

  • Jamie Windsor (very good perspective on things)
  • James Popsys (entertaining + you learn a lot)
  • Tony and Chelsea Northrup (basics and reviews)
  • Sean Tucker (street)
  • Steve Perry (wildlife)
  • Daniel Norton (flash especially)
  • Tech Gear Talk (reviews)
  • Omar Gonzales (Fuji + entertainment!)

These may not work for you, but then you will find others that do work for you.

Finally…

There will be good days and bad days. There will be days when you think “I shall never learn this!” – but don’t despair. Take a break. Go shoot some pictures instead, or do something else you enjoy.

Your brain needs time to relax and re-organize all the information you are feeding it, so see your down time as productive time in terms of processing and archiving all the useful information you are taking in.

With this, I wish you all the best on your journey to learn photography!

What is hard light vs soft light?

If you heard that soft light is better than hard light, it is likely that statement came from a portrait photographer. Soft light is in general perceived as giving a more flattering look, where the light wraps gently around the subject.

But what is soft light? Soft light is light where the transition from bright to dark happens gradually, i.e. there is a lot of mid tones in the transition zones. Take a look at this pencil that I placed in my window space on an overcast day:

On a cloudy day, the sunlight is made into a massive light source as the light is spread across the vast area of clouds. In other words, the light source is huge! Notice the shadow at the tip of the pen? It is hardly there. You see a shadow where the pen rests upon the AirPod charging case, but the rest of the shadow is one big zone of tones of grey.

Now look at the next example, where I placed the pen under a reading lamp. A light source much smaller than the light from the clouds:

Suddenly you can now clearly see the shadow of the tip of the pen. If you look carefully, there still is a bit of grey zones where the white from the case transitions into the dark of the shade, but it happens much more abruptly than in the former example. The reading lamp as light source is simply much smaller.

Finally, the most harsh and brutal hard light I could think of: a flash held some distance from the subject with no diffusion at all! The bare bone flash activated here – you can see the flash light reflected in the yellow of the pen:

Notice the reflection of the flashlight on the pen.

In this final example, the transition from light case to shadow from the pen happens almost from one pixel to the next. Okay, maybe not so suddenly, but I hope the difference is clear.

It all comes down to the size of the light source, relative to the size of the subject. The bigger the light source, the softer the light.

So what should you use? As you may have guessed, my annoying answer is: it depends. Yes, for portrait photography you probably want to show the more flattering side of your subject and use flattering light. But hard light works fine as an artistic expression or to simulate a sunny day with no clouds at high noon. So use the softness of the light as a tool in your toolbox and use it deliberately, instead of just saying “soft light is the only light that works”.

Related reading

What is fill light in photography?

Does low light photography make any sense?

Using full frame glass on cropped sensors – what happens?

One of the things I love about Nikon is the vast amount of cheap vintage glass that is out there on e-bay, plus their backwards compatibility – all the way back to 1950 or thereabout. Than means that most of the Nikon glass that they have produced since back then, can be used on a modern Nikon camera. And if you don’t like Nikon camera bodies, you can buy an adapter to fit the glass on the camera body of your preference.

Back in the film days full frame (FF) was the standard, as it was 35 mm film and not a digital sensor that sat in the cameras. That changed during the 1980’s and later, so that most cameras today have a digital image sensor. And for starters the digital sensor had the same size as the negative on a film – approximately 35 mm. What also changed was the amount of available sensor sizes. The so called APS-C and other reduced formats were introduced, along with new lenses. The advantage being that it was possible make lighter and cheaper glass, as the light would have to cover a smaller sensor. Although being smaller, the APS-C sensors could easily cram say 24 MP into the sensor despite the reduced size and hence a new fan base was created – people who do not want to carry heavy glass but on the other hand do not like the idea of reducing the resolution of the sensor.

Nikon made the APS-C cameras so that they used the same mount – the so called F-mount. That means that you can mount glass designed for APS-C on a full frame camera, and the other way around: mount full frame (FF) glass on a APS-C camera. It is the latter case I want to explore in this post, to see what happens.

In the best of worlds I would have shot the test shots with two Nikon cameras, say the D700 (full frame) and the D7500 (APS-C) or the D5600 (APS-C), but I lost my D7500 in a salt water accident and I have sold my D5600 to finance new gear, so I simply do not have a Nikon APS-C camera anymore. Luckily, I do have a Fuji X-T3 camera, which has an APS-C sensor size. And with an adaptor from K&F concept, I can mount the full frame lens on the Fuji camera:

Fuji X-T3 with a K&F adaptor to allow the Nikkor 24mm f/2.8 to be mounted

The disadvantage is that I now have to focus manually, and that the camera cannot control the aperture so I have to set the aperture on the lens itself. Further, the EXIF information that I get with the picture does not show the aperture anymore, as the lens and the camera cannot “talk” to each other – it is a dumb adapter. But for the purpose of this test, it is no big issue.

I am testing here with a wide lens, the Nikon 24mm f/2.8, and first I want to show you the picture taken on the Nikon D700 full frame body. The subject here is a little clay figure and I have put some items on the table to give some sense of the depth in the picture:

Nikon 24mm f/2.8 at ISO 400 f/2.8 – full frame sensor
Nikon 24mm f/2.8 at ISO 400 f/2.8 – cropped sensor

The second picture is taken on the Fuji X-T3 using the same lens with the adapter shown previously. As you can see, it seems like the little figure on the table has moved much closer and the frame is much less wide. For example, you cannot see the door to the right anymore and the stands to the right are almost gone.

This is known as the crop factor. When you use full frame glass on an APS-C sensor, then the picture is cropped because the sensor only uses the center part of the light from the glass.

The crop factor is typically 1.5 (for Cannon I believe it is closer to 1.6), and shooting with a 24 mm FF lens on an APS-C sensor as I have here, is the equivalent of shooting with a 36mm lens on a FF sensor. That explains why the frame is less wide and the subject appears closer.

Some say the crop factor is also to be applied to the aperture, so that the 24 mm f/2.8 is actually a 36 mm f/4. Below I have the two shots next to each other in Lightroom, where I have zoomed in on the FF version to the right, so that the clay figure has roughly same size. And then I have put some small lights that I normally use to test bokeh, to see if the full frame version would yield more background blur than the APS-C one. As far as I can tell, they are very similar:

The reason could be that f/2.8 and f/4 are both very wide apertures where the level of background blur does not change much, but from this test alone, I cannot conclude that you need to apply the crop factor also to the aperture to achieve equivalence.

Thank you for reading this far! Please don’t hesitate to leave a comment below or click the like button!

What is Live View on a DSLR?

The evolution of cameras

Ever since the film days, SLR (Single lens reflect) cameras were built with a mirror behind the lens, that sends the light from the lens up into a pentaprism, that passes the light on to the viewfinder for the photographer to see. When the shutter is pressed, the mirror flicks up, exposing the film or the sensor behind it and the content captured will be the same as what the photographer could see in the viewfinder. During this process, the viewfinder turns black as the mirror blocks the light.

The traditional travel of light in a SLR/DSLR: Through the lens, hits mirror, sent upwards in the pentaprism and finally through the viewfinder to the photographers eye.

With the introduction of Digital SLRs, the film was replaced by a sensor that not only can read the light in a fraction of a second, but actually can do so constantly, which opens up for shooting movies. Further, many DSLRs today are equipped with a large screen on the back to present menus and options for configuring the camera, plus previewing the pictures.

Live view combines the sensor and the LCD on the back of the camera, so that the camera continuously shows on the screen what the sensor receives. As the mirror, when it is down, blocks the light from the sensor, the DSLR will – when it is put in live view mode – flick the mirror away to allow the light continuously to flow to the sensor:

Live view mode. Rear screen shows what the sensor receives.

The camera will – subject to the processing capacity – try to make what is viewed on the screen as close to real time view as possible, but for older cameras you will notice a lag or a bit of delay in what is shown in the rear screen.

Rear screen on the Nikon D700.

Some cameras allow you to flip the screen upwards or downwards, and some are even fully articulating, allowing you to swing the screen 180 degrees around to be viewed from the front of the camera. Many vloggers use this feature to view themselves when recording video. The rear screen on the older Nikon D700 depicted above is fixed and cannot be moved at all.

So what is the point?

So other than this now being technically possible, what is the point with Live View, if any? I think there are several:

First of all, sometimes the optical viewfinder is hard to use, for example when you try to shoot in a very low or a very high angle. You may want to shoot over a crowd at a concert, or shoot very low to get a certain angle of view. In those cases it can be difficult to put your eye to the viewfinder, unless you either have brought along a ladder an/or want to crawl on the ground. Especially if your camera has a tilt screen, then you will love this feature, but even with a fixed screen the Live View is a big help.

Second, the fact that the rear screen is a processed version of what hits the sensor, it is possible to combine what the sensor sees with various electronic overlays like a large virtual horizon indicator. I use that a lot to secure that my landscape pictures are level. Another example is focus peak indicators, where the screen shows which parts of the picture is in focus – it can be in the shape of say red colored dots. This is a great aid in obtaining focus when shooting with a lens without autofocus. A third example is to show picture in picture, i.e. the normal picture and then a smaller frame inside the picture where a zoomed in version of the picture is shown, again to aid focus.

Third, maybe a variation of the second, is that you can zoom in on the picture in the rear screen. Again this feature is super useful if you shoot with a manual focus lens and want to zoom in to make sure you have nailed focus.

A fourth benefit of Live View is that the camera typically does not use the dedicated focus system, but instead used the sensor and a bit of processing power to obtain focus. As many elder cameras have the focus points only in the center of the frame, you cannot obtain focus say in the corners. With Live View this limitation is gone and for single point focus you can use all of the frame to select your focus point. Especially macro photography shooters with elder cameras use this feature a lot.

Finally, when shooting into the sun, the light that you see on the rear screen is a processed version of reality and I doubt that the LCD screen is so powerful that it can blindfold you. When shooting into the sun using the optical viewfinder, I often find that I am blindfolded temporarily when staring straight into the sun. So I often turn to Live View in those cases.  Notice that many camera manufacturers warn against shooting into the sun, both in Live View and using the optical viewfinder, so please consult the manual for your camera beforehand.

Any downsides?

The rear screen requires power to operate, and a lot more than the optical viewfinder where that part of the process is purely mechanical. So you will find that your batteries will be eaten faster than when shooting using the optical viewfinder.

For elder cameras, you may find that live view is sloooow. Very slow. It takes ages from you hit the shutter to the picture is done. On my Nikon D700 for example, the focus part alone takes several seconds (when in Tripod mode), where it for later models (the D750 for example) is much better.

And finally sunshine is not your friend if you shoot outside on a sunny day. It is like watching TV outside. It can be difficult to see the screen.

Thank you

Thank you for reading this far. Comments, questions and suggestions are more than welcome!

 

Credits

Illustrations used:

User: Kolossos – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=925806

http://orig01.deviantart.net/6d63/f/2009/019/a/1/eye_in_profile_by_evaldaz.jpg

 

What is TTL in flash photography?

TTL means through the lens. Your flash will fire 2 times, once to measure how much light reaches the camera at a given standard flash power, and a second time when the picture is taken.

It uses the first flash fire to understand how much light is needed to expose the picture correct, and then boosts or reduces the amount of light in the second round.

It is a super convenient (automated) way to get the flash light right without any manual measurements with a light meter, or trial-and-error with a manual setup of your flash.

The big disadvantage of TTL is that your camera and your flash has to be able to talk to each other. The simple way to do this is to have the flash on camera, but if you want it to be off camera, you need to establish radio communication between the flash and your camera, which typically involves a flash trigger and a flash with radio receiver, so they can communicate with each other.

Another disadvantage is that the light your flash yields varies across a series of shots, as the camera may make different readings per shot due to slight variations in say available light. This can be a bit of a headache if you want to do consistent post processing of a large number of images, as you will have to adjust the exposure for each picture individually.

 

What is the focal plane in photography?

In this short blog I will give a non-scientific layman terms explanation of how I see the focal plane in photography. You can find more technical and advanced explanations out there, but this one focuses on what you need to know to make use of the focal plane.

A big umbrella

The focal plane is the plane where your lens and camera in combination has your subject in focus. So when you zoom in and out, different things will appear sharp in your viewfinder. If you take a picture of a person, you risk that the eyes are out of focus if you focus on the ears or the nose. Eyes are super important in portrait photography, and hence all portrait photographers and advanced auto focus systems make sure to zoom in on and detect the eyes. It is less of a problem if the nose or ear is slightly blurred or out of focus.

You can think of the focal plane as one big virtual umbrella that you push back and forth as you turn the focus ring on your lens. Exactly where the fabric from the umbrella touches the subject, the subject will be sharp.

In the picture below, you can see the glasses that I have put in focus are almost the only thing in focus. Both before and after the glasses, everything is out of focus:

Only one focal plane

It is important to understand that there is only one focal plane. No matter how advanced a camera you have and how much intelligence there is in the auto focus system of your camera, the physics and mechanics do not change. There is only one focal plane. You can only push one “umbrella” back and forth. You can do this with auto focus or manual focus, but there is only one.

I say this because when you see or read some of the camera manufacturers adds for the latest and greatest in auto focus technology, you get the impression that the intelligent systems have overcome all focus and sharpness issues. They have not, because they cannot fundamentally change the fact that only one plane can be in focus at a time.

There is some good news…

The good news – and what has saved me a lot of times – is that a little before and some after the focal plane, there is an additional area where the subject appears to be sharp. This is known as the depth of field. Good news is that you can increase (or decrease) the depth of field if you change the aperture. A small aperture (large f-stop number) gives large depth of field. In other words, there is some room for slack if you have a small aperture (large f-stop number like f/16) .

There is no such thing as a free lunch in photography. So the price for a small aperture is that it lets in very little light, which means you need to bump up either the ISO or leave the shutter open for a longer time or both. This introduces the risk of camera shake and subject blur, meaning your pictures will appear not-so-sharp anyway. So you have to strike a balance, find a compromise. General advice is hard to give in this regard, but try to start out with a middle-of-the-road aperture (say f/5.6) and work your way up or down until you find a good compromise.

Depth of field is also depends on your distance to the subject, so the closer you are to your subject, the more shallow the depth of field will be in absolute terms. This is what causes a lot of headache for for example flower photographers. This is where focus stacking comes into play, but that is the subject for a different blog.

Questions and comments

Thank you for reading this far. I hope you found this blog useful. Questions and comments (and likes!) are more than welcome!

 

What is the holy trinity of lenses in photography?

In photography the notion of a holy trinity of lenses refers to a set zoom of lenses that cover the full range of focal lengths, going from the ultra wide 10 mm to the long 200 mm. This is typically achieved by 3 lenses that cover each their area:

  • Extremely wide – 10-24 mm
  • Standard zoom – 24-70 mm
  • Long zoom – 70-200 mm
  • (and some also have the 200-500 mm, good for wildlife and sports photography)

The beauty of this lineup is that you do not need any other lenses!

The holy trinity of lenses illustrated

The series of lenses is illustrated in the graphics above. Notice that all the above refers to full frame equivalents, so if you are shooting on a cropped sensor, you need to apply the cropping factor to get to the right values (1.5 for DX or APS-C lenses), but the idea is the same: to have a few lenses to cover the full range of focal lenghts.

Not all photographers like zoom lenses, and there are several reasons for this, one being that they are expensive compared to prime lenses, another that their weight can be significant, especially in the long end of the scale and then some argue that prime lenses with fixed focal lengths are more sharp than zoom lenses. Those who agree to these arguments typically cover the focal range with prime lenses to achieve the same end.

As you can see in the graphics above, the angle of view changes as you move up through the focal range, starting at a whopping 130 degrees and a lens of 10 mm (far left), ending at 5 degrees or less at a super long lens (far right). Here the photographer working with primes will have to change lenses each time a new focal length is needed, and as the prime lens only cover a point on the scale illustrated above, you may risk that the prime lenses in your bag does not make the desired focal length available. In such cases a prime lens that typically is too short is used and the frame is afterwards cropped in post processing. Some also “zoom with their feet”, but you have to remember here that the angle of view does not change, no matter how much you zoom this way, so you will not get the same result (due to compression) as you did would with a zoom lens.

Questions and comments

Thank you for reading this far. I hope you found this blog useful. Questions and comments (and likes!) are more than welcome!

What is light falloff in photography?

The inverse square law…

You may have heard of the inverse square law and seen some posts and videos going through the technical aspects of the inverse square law. I will try to stay clear of the technical aspects here, and simply say that light falloff is the fact that the intensity of the light drops fast, as you move your light source away from your subject.

Quite counter intuitively, the light falloff does not happen in a linear way, rather it drops like a stone! In the beginning that is. So if you move your flash from 1 foot away from you subject to 2 feet away, the intensity of the light has dropped not by 50% but by 75%! So by doubling the distance, you only get a quarter of the light on your subject. This is what the inverse square law is all about: the non linear relationship between light intensity and distance. You can maybe see it in the picture below, where I have taken a LED light and put it close to a white wall:

Good news is that the curve flattens quickly, so 3 feet away the light has dropped to 11% of the original light, 4 feet away it is 6 % and so on. So if you are very far away from your light source, moving one foot closer or further away means very little.

The intensity of the light drops dramatically as distance to the light source increases.

In the example above, had there been a 4th cup, it would get only 6%! If you draw a curve of the intensity of the light as a function of distance, you will get what I call a hockey stick curve – it drops a lot as distance increases only to flatten the more the distance is increased. 

If you photograph a group of people and light them up using a flash, the ones standing in the rear will get a lot less light than the ones standing in the front, if you have the flash (or modifier) close to the front row. The solution is to move the flash further away from the subject to make the relative drop in light less. The price you pay is that your flash will need to work harder and that the light is less soft.  

You can use the light falloff to produce a grey or black background, even if you have a white backdrop. Just make sure the distance between your subject and the backdrop is sufficient, then the light falloff will take care of “dimming” the backdrop to grey or even black! See the examples below, where the only thing changed is the increased distance between subject and the backdrop:

Here some light is still reflected from the backdrop. But not much, hence the grey color.
 
Here the background is black due to light falloff. But IRL the backdrop is pure white!
Using a flash and the effect of light falloff, I was able to make these withered leaves stand out on a dark background. If you are thinking that it did not look like this IRL, then you are absolutely right!

Related reading

What is hard light vs soft light?

What is flash exposure compensation?