Depth-Of-Field explained

While the phrase depth of focus was historically used, and is sometimes still used, to mean depth of field, in modern times it is more often reserved for the image-side depth. Depth of field is a measurement of depth of acceptable sharpness in the object space, or subject space.

Depth of focus, however, is a measurement of how much distance exists behind the lens wherein the film or sensor plane will remain sharply in focus. It can be viewed as the flip side of depth of field, occurring on the opposite side of the lens.

Where depth of field often can be measured in macroscopic units such as meters and feet, depth of focus is typically measured in microscopic units such as fractions of a millimetre or thousandths of an inch.
The same factors that determine depth of field also determine depth of focus, but these factors can have different effects than they have in depth of field.

Both depth of field and depth of focus increase with smaller apertures. For distant subjects (beyond macro range), depth of focus is relatively insensitive to focal length and subject distance, for a fixed f-number. In the macro region, depth of focus increases with longer focal length or closer subject distance, while depth of field decreases.

Source: WikiPedia 

What are the laws in regard to shooting in public places?

It's the tripod that's the give-away. Tripods pose a potential liability issue for local councils when they are used in public places. Members of the general public might trip over them even though your know that it's unlikely. If you are shooting for a network it's best to make sure that you have releases from people who have identifiable  appearances in your footage.

General cutaways of other people, in the context of a sequence featuring someone who has signed up, are also within reasonable boundaries. Carry release forms with you. If in any doubt, ask individuals that you can recognise to sign a release . Here in Australia, common sense prevails.

This is not meant to be definitive advice on this matter. Check with a legal advisor if you have any doubt, especially if you might be showing incidental passersby in the context of some place or activity that they may not like to necessarily like to be associated with.

This is general advice only. Run this question by a solicitor for the most up to date rulings.

© 2013 Pieter de Vries ACS

Lighting a campfire scene

You will have to supplement the light coming from the campfire flames with artificial sources. The best lights to use for is are small battery poweredLED lights covered with orange gel (CTO) doubled over to increase the warmth – it will give it the LED's a nice warm firelight colour.

The idea is to make the glow from these lights appear to be a natural part of the scene and the easiest way to do this is to include a camp light lamp in the scene, placed to one side to side-light the people sitting around the campfire.

A kerosene lamp or battery fluorescent light can work and would not look out of place. By "side-lighting" your subjects, you create an unlit darker side to the faces of those sitting around the fire and this allows the light from the flames to "play" on this dark side of the face.

The output of a practical lamp is sometimes not enough, so you may need to hide a few battery lights to lift the level of what is already happening with the camp-light. Place your battery light just out of shot, and at an angle that makes it appear that it's the practical in-shot lamp that's doing all the work.

Finally, you could try to get some light happening behind the actors to separate them from the black hole in the background – headlights from a vehicle are great for this. The vehicle should be just out of shot and the headlights shining on to the back of the people or illuminating a tree in the immediate background.

If it’s a period story, using just campfire light, use your battery light again, but this time place it on the ground pointing up at the actor/s. Some orange gel (CTO) doubled up and placed over the light source will give it the warm firelight colour, and a little diffusion will help blend it in with the firelight. Make certain that the level of light is low so that you can still see some of the flames from the fire playing on the face. Keep the flames burning so have lots of wood standing by.

© 2013 Pieter de Vries ACS

Dedolights

I've used the same 12v/100w Dedolight kit for over twenty eight years. The transformer can simultaneously power four Dedolight heads equipped with 20W, 50W, 100W or mixed wattage lamps. Dedolights in this voltage are no longer available.
The 24 volt transformer has three outputs and this output is higher at 150w. The lower power consumption of the 12v/100w kit was good for working in places with dodgy power (Africa and Asia & Sth America) where there is often only a single output in a tiny home.

Certainly the output of the 24v/150w transformer is brighter than the older 12v/100w model and this aspect is better and more valuable at times, however I've found so many shoots where I want to run four lamps, and the 12v/100w version did that.

However, that is not a huge consideration, I'd prefer to go for the 24v/150w kit using a central transformer – you can put 12 volt lamps in the lamp heads to run from car batteries, gel cell packs or camera batteries etc. The DT24-1 in-line electronic/dimmable power supply also works with the 150w heads so you can purchase additional lamp heads as you go along.

© 2013 Pieter de Vries ACS

Sequences – the best approach

A common mistake is to limit your shooting to only one or two, often most convenient, camera angles.
This will limit your potential to create sequences of great visual impact. Video shooters who use limited camera angles find it much harder to edit sequences.

Shoot from various camera angles

A strong video sequence is cut together from shots recorded from varied angles using a range of lens sizes. Many films are about ordinary people doing ordinary things. It is your skill with the video camera that will add interest to an otherwise uneventful scene. It may seem obvious, but think about what it is that you want your audience to actually see.

You are there, immersed in the scene and there is often a lot going on. You should be sure that your audience too, is also left with this sense of place. Make the time to walk around before you start shooting.

Position yourself where you can include things that add depth to the frame, seeing right through to the background.

Distracting backgrounds
Be wary of distracting backgrounds. Higher or lower camera angles will help here. Your eyes can ignore distracting background clutter, but your video camera will show it in all its distracting detail.

Look for telephone poles, street signs and the trunks and branches of trees. While these are all a part of locations, HD video will show them in sharp focus making it hard to keep you audience interested in the more important parts of the composition. A small relocation of the camera to the right or left is often just enough to fix this because cannot easily fix the problem of distractions in the background in the edit room. 

Finding the best angles

There is really no such thing as the correct camera angle, but there is a best camera angle for any situation. If you are in a position where you want to record something or someone, a good place to start is at a position of about forty five degrees to one side of your subject. 

Use 45 degree angles

Positioning your camera at approximately forty-five degrees balances the frame and at the same time, puts you in the best position to cover further action. There is real dimension when you can see two sides of the subject. The perspective diminishes, giving an interesting and dynamic feel.

You can also see past this foreground subject to the background, giving your audience an idea of it’s location relative to the overall scene.
In sunshine, a shadow side is revealed and this unlit side increases contrast in the picture.
It is the same when you are working with people. Turn the person 45 degrees or move around to the right or left, so you see the front and side of the body.

An alternative is to shoot from front-on. However shooting front-on means you see only one plane and the result is a perfect passport photo – nothing more.

At a back yard garden party for example, this could include shooting from the back fence looking back to show everyone, with the house as the background instead of shooting in the opposite direction with just a fence as a background. Thinking in layers allows each camera position to reveal a little more about where you are. You could for example, pan slowly from the garden to reveal this scene – pans can be considered a kind of layer.

 
© 2013 Pieter de Vries ACS

The Low-Down on Low Angles

There are times when wider shots look flat and one dimensional.video cameras record impressive high resolution images however this clarity can also be a disadvantage.

In contrast to the telephoto lens, the wide-angle end of a zoom lens shows everything in the frame in sharp focus. Why is that?

  • Bright exterior scenes automatically use small iris/aperture settings eg. f8 to f11
  • Small iris settings in conjunction with wide-angles result in images with way too much depth-of-field – even specs of dust on the front glass of the lens are in focus
Why is this not so good?
  • HD images need soft focus foregrounds to neutralise a harsh video look
  • With everything in sharp focus, the viewer's attention cannot be directed to the best part of the composition – there is too much to to see
  • Sharp HD pictures do not always make arresting wide shots

Unless there is a strong foreground element, there are no layers to make the shot appealing. There is a way to fix this…

Enter low-angles

Low-angles work well in a number of ways. Firstly, they can help to include foregrounds relevant to the location, foregrounds that may not be noticed at eye level. Also they provide an strong visual perspective to add strength to what may otherwise be a very ordinary shot.

It is not hard to find objects to create immediate foreground and the result can be a scene with depth.

Use the fold-out LCD panel

That fold-out LCD screen on most camcorders is perfect for shooting low because they let you find the frame quickly and still monitor the shot without being uncomfortable.

Placing the camera on a small tripod or even resting on a camera bag introduces a refreshing perspective that can instantly transform the scene.

Visual impact

Low wide angle shots can have powerful impact and while not always appropriate, they offer a perspective that can exaggerate the feeling of size or power. A vehicle passing close by a camera placed low to to ground has a strong visual presence, especially when the camera is close as the vehicle passes. This is enhanced by the sound of the engine as the vehicle passes by.

© 2013 Pieter de Vries ACS

Lens Perspectives – the Field of View

It is a mix of shots that give the editor greatest creative control. Wide shots, close-ups, telephoto and mid-shots. In the assembly of clips below, the camera has been moved approximately one meter closer to the vehicle for each shot. The field-of-view remains roughly the same because the zoom lens is re-positioned to a wider angle to retain a similar field-of-view. 

The framed content of each shot is roughly the same in each take, however it is the change in perspective. While I would never wish for these shots to be cut together it's way the lens behaves in each shot that makes it interesting. This is known as lens perspective and there are great reasons to make them a part of your mix.

Note how the position of the vehicle remains relatively the same but you see more in the background as we get close and wide. Notice too how the proportions of the car are drawn out as the camera moves closer. The final two shots show the difference between telephoto and wide-angle.

Often when you are in the middle of a shoot, there is little time to appreciate the advantages of the different lens sizes. By sizes I mean wide shots, medium and telephoto shots. 

However, it is important to appreciate how lenses and their field-of-view work. It helps if you consider your zoom lens as being equivalent to having a whole bag of fixed focal length lenses – a 10mm, a 16mm, a 25mm or a 200mm or even a 1000mm lens.
Even if you are not intending to edit your own footage, shooting with a mixture of lens “sizes” will make footage viewed straight from the camera much more engaging.

Why different perspectives

In most sequences, there should be a combination of wide, medium and telephoto shots. A sequence made up of little more than wide angle shots taken from similar positions will result a series of jump-cuts which can look quite strange. It’s almost impossible to cut them together to form a engaging sequence.

On the other hand, a series of shots edited from a mix of wide angle, telephoto, tripod and handheld shots work brilliantly. Your sequences have the potential to affect the emotions of your audience if there is little awkwardness in the way different shots are put together in the timeline.

Telephoto: the long end of the zoom lens

At the telephoto end of the zoom, backgrounds appear bigger in dimension and at the same time, seem to draw in closer to the foreground subject. This happily results in a compressed look that works so well with digital video. The optical nature of the telephoto lens is that it takes the foreground and background and draws them together, and it is known as compressing the scene.

Shots look gutsy and the limited dynamic tonal range associated with digital video is minimised, as the amount of over-bright cloudy bright sky in the top of the frame is kept to a minimum. A similar wide angle view would feature lots of sky and if it’s a cracker of a day with a beautiful blue sky, this could be just right.

The impact of the tele lens is strong and at times graphic, and invites the potential to explore the scene with tasteful pans or tilts from one part of the scene to another.

Wide angle and close to the subject

For your audience there is a real sense of being right there, immersed in the scene. The wide angle perspective draws the subjects towards the lens and exaggerates size, almost to comical effect. Look around for something to include in the immediate foreground – a tree, a busy road or a garden feature. This will add depth to the frame and reveal more about the location. A good rule is to always seek out immediate foreground in wide angle shots.

Try an in-camera edit

Here’s an easy way to get fast coverage of a scene. Follow the action on the medium to telephoto end of the zoom range.
at a suitable time while still recording, snap zoom out quickly to a wide shot and reframe (you will edit out the actual zoom later}
by crash-zooming out to a wide shot, you should be able to match the action as only a short interval of time will have elapsed during the re-framing.

This technique works just as well if you choose to start with a wide angle shot and crash zoom out to a matching close-up. You are actually making the edits in camera while you shoot.

It is perfect for the situations where you have little control over what is happening and it keeps the sequence fresh and importantly, editable.
The skill of the cinematographer is to work with these different perspectives in a creative way; to either hide visual distractions over which you have no control, or add some dimension to something that is a little ordinary. 

© 2013 Pieter de Vries ACS

Panning to reveal

If you have set up to record a scenic landscape, there are a few tips to keep in mind.
Firstly, check to see if there’s a place in the scene that you could pan from – another part of the scene that could deliver a nice camera move. Pans like this will give you a valuable option in the edit room

You don’t have to use this pan, but you will have a choice and at the same time, gain extended screen time for narration.

Here are two examples. As the shot begins in the trees the shot is only revealed at the last minute.
In addition, you will have the option to dissolve from one location to the next.

Putting it into practice
  1. Make sure that you are balanced and standing in a clear space between the tripod legs
  2. Set your framing, exposure and focus for the end point.
  3. Ensure that you are standing balanced for this end point position
  4. Without changing the position of your feet, just shift you body balance as you pan the camera to the start point
  5. Hit the record button and record a static shot of this starting scene for at least ten seconds
  6. When you are ready, ease the tripod head away from that scene and pan the camera to the end point.
  7. Slow the pan as you reach the end point
  8. Allow the camera to continue recording in this end static position for at least ten seconds to give you another editing option. 
Panning speeds

The speed of the pan should be slow enough for the viewer to take in detail in the scene. To get it right, take in the details yourself as you pan. These in-shot transitions are important for those times when you need to do something a little more interesting. The flow of your story can be created at this shooting stage and so it's best to remember that not everything can be fixed on the computer.

Moving objects

The secret to making smooth professional pans with moving subjects is to be aware of the location of the object relative to the frame as you pan.

The distance between the left edge of the frame and the front or of the object is the space to watch. Make sure that your panning movement keeps pace with the pace of the object – keep that distance fixed. Here are two examples.

It is easy on the eye to watch this jet ski powering through the surf if the ski is “locked” in the same lateral part of the frame during the pan. It looks awkward if the subject drifts in the shot and if you are shooting in Progressive Mode, it’s even more important.

Telephoto – pan and reveal

Here is a way to get beautifully smooth pans using the telephoto lens

  1. Compose the shot then lock the up & down movement of the fluid tripod head (the tilt). Leave the pan lever unlocked.
  2. Instead of using the pan/tilt handle, grip both hands around the collar of the fluid head and use this as a fulcrum to pan the camera.
  3. Using the centre of the tripod as the fulcrum point takes out any bumps making a panning move that is close to perfect. 
  4. You will be able to bring the pan to a nice smooth finish, despite the high magnification of the image. 

© 2013 Pieter de Vries ACS

Shooting in bright sunlight

Getting good results shooting outdoors on a bright day is a challenge. Video just looks better when you don’t have to work in the glare of the sun. You’ll need some basic sun controlling tools to make it work or your scene could end up looking like Funniest Home Videos.

Shoot your wide shots early in the morning and from a position where the sun is lighting the scene from one side; side light will get the precious light and shadow happening.

You may end up shooting medium/dialogue shots and close-up/dialogue shots in the middle of the day. This is not too bad as you can use an overhead diffusion panel to shoot the closer shots. You’ll also need reflectors; some means of evening up the deep shadow areas. Use the white side to bounce light into backlit faces.

As mentioned, part of your sun controlling tools should be an overhead shade cloth and some means of suspending it over the actor/subject for close-ups and medium shots where there’s harsh full sunlight falling on faces. A overhead silk that allows most of the sunlight through (half stop or full stop) is best, otherwise it looks like your actors are performing in an unseen mystery poolside pergola!

Make sure that the backgrounds are not too bright. A small left or right shift of your camera to a position where there are trees behind for example is often enough to give you the best overall balance in this situation.

Use a small overhead diffusion panel

A 6 foot X 6 foot scrim/silk or very light sail cloth clipped into a frame is the ideal tool. You can then use reflectors to bounce light into the faces with a direct solid kick off the sun to continue that sunny feel. Late afternoon or early morning light is very flattering, and using this direct front light is the way to go, so don’t be afraid to shoot without reflectors and scrims at this time.

White balance your camera from time to time and if you choose to continue shooting when the odd cloud rolls over, make sure that you balance to that quality of light. I do a manual white balance in full sun (“B” position) and a balance in cloud cover (“A” position) and switch between the two as needed – The Z1 has this feature. This will help to disguise the impact of totally different light colour and totally different light characteristics.

Finally, try to position the camera further back from the subject and shoot your close-ups on the telephoto end of the zoom and use the built-in ND filters to get you an aperture of around f5.6. This will give you some nice focus fall off behind and in general, be more flattering, especially if your have the light falling on your subject under control.

I hope for an overcast day when I have to shoot outside. In the filtered and indirect soft light video still looks vibrant and in some cases more colourful than in full sun, and the evenness of this light makes it easier to get through the shots. Wide shots do look better in sunlight, you just have to reign-in the harshness of the sun by trying some of the ideas suggested. As a last thing, make sure the sun doesn’t hit the front glass of lens. There is no need to highlight every particle of perfectly focus dust sitting on the front lens element.
© 2021 Pieter de Vries ACS

How to deal with a fluorescent-lit office spaces

These are always tricky lighting situations and the best approach is to keep it simple. I would suggest using a fluorescent light, a Lowel CaseLite or a Kino Flo Deva to provide the fill to even out the “toppy” overhead light from the existing flouros. A single light on a stand should not be too disruptive.

To add some punch to the sequence, shoot using the tele end of the zoom lens shots to bring the depth and the scope of the room into the sequence and rely on your light to take care of the close-up shots. The long telephoto shots will deliver the business of the room which surely is what the client would prefer. It's important to cut as much light from the LCD computer screens as you can, so a black cutter on a lighting stand may be helpful. This may not work as your impact will be bigger and it may impede the operation of the office. To get a nicer balance, turn down the brightness of the computer LCD screens. With LCD screens you will not have to deal with roll bar issues .

Tracking shots will do justice to the sequence and the office. The repetitive set-up of many office cubicles and work stations is appealing so don't attempt to light these shots.

It's best to not over complicate however a gentle fill from a flourescent light may be needed. Use your fill light at a low output setting or move it away from the subject to find the right balance. Daylight tubes should be fitted in this situation.

If a light on a lighting stand is not practical then a Lite-Panel LED battery operated camera light is the next step. The dimmer on the panel will allow you to set just enough fill to clean up the toppiness from the overhead house lights. Check first that you have a reasonable colour match with the existing lights. Add a sheet of Rosco Half Plus Green to the Lite Panel or the CaseLight add green in order match the green colour cast in the overheads; make it everything greenish – remove this overall cast in your NLE and the colour will look quite normal again. Some testing would be good if you have the time.

In summary, use gentle light fill for faces and use your flouro to back-light mouse and keyboard shots. Rely on long lens to create busy foregrounds, and dolly shots: a Wally Dolly or even someone pushing you on a rolling office chair.

Frame faces with the computer screens breaking up the frame. Half face – half back of the screen and organise lots of stuff hopefully moving through the foreground.

© 2013 Pieter de Vries ACS