Don't confuse contrast with quality of light

One more time with feeling!

We are coming to the end of my 10-week intro to studio lighting class and I still see confusion between light quality (determined by the size of the light) and contrast (determined by the environment).

Basically, contrast is the depth/darkness/density of the shadows. It is controlled by the environment. If there is a lot of light bouncing around off of the walls, ceiling, floor, or other nearby surfaces the shadows open up. Adding a diffuser to your light spreads the light out to bounce off all those objects to lower the contrast. The bigger and darker the environment you are photographing in, the more contrast you will have. Narrow beam reflectors and grids can be used to control spill (the opposite of adding diffusion) and maintain or increase contrast when working in smaller spaces with light color walls, ceiling, etc. Please, do not add diffusion material in front of your grids!

Quality of light is the transition from highlight to shadow. It is controlled by the size of the light. The larger the light is as seen by the subject, the softer the light is as the light hits the subject from many angles and provides its own fill light. Yes, it lightens the shadows, but the main thing is that it does away with the abrupt edge that you get from a smaller/harder light. 

Adding a diffuser such as a scrim or a shower curtain some distance in front of a small light source turns it into a larger source, making the light softer. But diffusion right on the light (which doesn't change the size of the light) will not change the quality of the light. While the shadow is less dark, it still maintains a hard edge if the light source is small.

Some pictures to help explain…

Black Friday 2018

**This post contains affiliate links and I will be compensated if you make a purchase after clicking on my links. 


Interfit USA

It is that time of year again. I will be listing photography related sales for the holiday season here and will update this post as I find new additions.

First up is Interfit with a great sale. Big discounts on their modifiers and on some of their lights. You probably know that I am a big fan of Interfit and use many of their products in my day to day photography. In addition to the sale prices you can get an additional 10% discount using the code CORNICELLO10 at checkout. http://bit.ly/jc_interfit


Think Tank Photo

Next we have Think Tank offering 50% off of their Advantage Plus roller bag for three days only. On Friday, November 23 use this link to get an additional free gift and free shipping. The Airport Advantage Plus rolling camera bag is designed specifically for traveling photographers. By it complying with international carry-on size and weight requirements, you can keep your most valuable gear safe and near you when flying. http://bit.ly/jcthink

There’s More…

In addition to this sale, Think Tank is offering more items on sale at 40% through December 2nd, including Think Tank’s Spectral shoulder bags, UltraLight backpacks, Signature shoulder bags, Sidepath backpack, and Multi-Mount holsters. The UltraLight backpacks are the lightest weight photo backpacks on the market. The Signature shoulder series are designed for wedding and other event photographers who seek a more elegant and discreet shoulder bag.


One more time. With Cubes!

Cue the Cubes!

diffusion-cubes.jpg

Again??? Well, yes. I do these blog posts for myself as much as for my readers. They are my public notebook of lighting tests and experiments.

Here we have three exciting and vibrant still life studies in gray. All three photos were made with the Interfit Deep Zoom Reflector on their Badger Unleashed strobe head. The image on the right was with the bare reflector. In the middle I added the included diffusion sock, and on the left I added an additional layer of diffusion (double-diffused as some might say). I have identified three places in the images to look at and compare.

At point one I want you to look at the primary shadow of the gray cube onto the white cube (scroll down to the bottom of the post for larger versions of the cube photos). With the open reflector there are actually multiple overlapping shadows. The open reflector is not even across. There are multiple light sources: the flash tube, the glass dome, the walls of the reflector. Each is slightly different in brightness and casts its own shadow. Adding a diffuser homogenizes the light into one large source and eliminates the hot spot. You can see this in these photos of the face of the reflector.

 Bare reflector, single layer of diffusion, and double layer of diffusion

Bare reflector, single layer of diffusion, and double layer of diffusion

Looking closely at the cubes you should still be able to see that there is a primary hard edged shadow at point One and that doesn’t change between the three photos because the overall size of the light has not changed. Remember, for a light to be softer with more gradual shadows the light has to come in from many directions. Once you have added a diffuser it won’t matter how many extra layers you add, it will not make the light any softer. The diffusion will alter the contrast of the scene as it spreads the light out in a wider pattern allowing it to bounce off of items in the environment such as the floor, walls, ceiling, etc. filling in the shadows and making them less dense. Less dense = less contrast. But the shadow edge, the quality, does not change.

Point Two is similar. The open reflector shadow is deeper. Adding the diffusion evens out the light from the reflector and fills in some of the shadow. But again the primary shadow edge is about equal.

Point Three is the most dramatic difference where the diffuser made the light larger and able to wrap around the side of the black cube to provide more illumination so you can see the back of the table top.

What I really want to concentrate on are the differences between the images with single and double diffusion. Or is differences the wrong word as they are actually very similar, almost identical in appearance. The main difference being that I had to open up the aperture a stop to maintain the proper exposure.

I hope this helps show that adding more and more layers of diffusion will not soften the shadows in your photographs. That comes from making the light larger. Multiple layers of diffusion require more light output or allow you to cut down the amount of light if you cannot power it down or don’t want to change your f/stop.

Click on each of the photos below for a larger version.

Open Reflector

 Single Diffuser

Single Diffuser

 Double Diffuser

Double Diffuser

Diffusion yet again

I just can’t stop…

In my last post I mentioned that adding diffusion at the same size as the light source will not soften the light (change the shadow edge transition), but will change the contrast. Adding an additional layer (or more) will still maintain the same light quality, but spread it out a little bit more and also lose a lot of power.

That got me to wondering just how much light is bouncing around the room to add to lower the contrast and fill in those shadows. Obviously in a very large studio with black floor, walls, and ceilings there will be nothing to bounce off of. Similarly if working out doors in an open field there will be no extra fill. But I am working in a modestly sized room with an 8-foot white ceiling, a light natural wood floor, and white walls.

Time for another test!

 The Interfit Deep Zoom Reflector

The Interfit Deep Zoom Reflector

Here are three images made with the Interfit Deep Zoom reflector. The first image is with the “bare” reflector. Next is with the included diffusion “sock” and the third image has a sheet of diffusion material added to the front of the modifier for “double-diffusion.” I kept the camera settings at ISO 100, SS 1/160 sec., and F/9 so that the ambient light effect on the image would remain the same. I raised the power of the flash in each image to compensate for the diffusers and to maintain the same flash exposure.

Click to enlarge

Here you can see that the shadow edge changes slightly from bare reflector to diffused reflector as the light is homogenized from multiple sources (flash tube, glass dome, reflector) all contributing their own shadows to one source (the diffusion material). And you can see that the shadows open up a little bit and the background gets a little bit brighter. Comparing the second image (single diffuser) to the third (double-diffuser) note that the shadow edge that determines the light quality is exactly the same. The diffusion is the same size as the light. If the light size doesn’t change the quality of light doesn’t change. What changes here is how much power you need from your lights to compensate for the light loss from the multiple diffusers. Again, don’t confuse contrast with quality (hard or soft) of light.

Now go out and light up your world!

John



Diffusion Confusion (take 4!)

Diffusion will be my epitaph

So I lied last time. It is more than once a year that I find myself writing about diffusion. But i still see so much misunderstanding about this topic. This time I will try to be short and sweet.

Diffusion scatters light. Diffusion can come from passing light through a translucent material (such as a white shower curtain, or a scrim, or diffusion material from the camera/cinema store) or by bouncing the light off of a mat surface (a painted wall, a sheet of foamcore, a sheet of art board, etc.). Here I will be concentrating on shining the light through translucent material placed right on the light source (or the metal dish reflector on the light source).

As I said, diffusion scatters the light. But it doesn’t soften the light. Diffusion possibly lowers the contrast as it scatters the light that will then bounce of of nearby surfaces like the floor, walls, and ceiling. This will cause the shadows to be filled in or lighter in density. But the shadow edge transition won’t change if the size of the light source doesn’t change. Don’t confuse contrast with hardness (quality). In a small studio space this is more apparent than in a large space (in the large space the light has to travel farther to a surface to bounce off of to come back and fill in the shadows).

How many layers of diffusion did you use???

It pains me when I read someone saying the put 3 or 4 or 5 (or more!) layers of diffusion over their light to soften it. All they actually did was lower the output of the light, causing them to either have to use a more powerful light, go to a higher ISO, or work at a wider aperture than they might have wanted to. But the one thing they did not do is change the shadow transition to make the light softer. To make the light softer would require using a diffuser that is much larger than the light source. If the diffuser and the light are the same size the light quality remains the same. The time to use double diffusion is if your diffusion material is rather thin and you can see the hot center spot of a light pointed through the material. (NOTE: This is separate from the concept of a softbox or octabox that has an inner and outer diffuser. In that case the inner diffuser’s job is to spread out the light from the strobe to completely illuminate the larger front panel diffuser and is not the same thing as double diffusing the front of the softbox or octa.)

7-inch reflector without and with diffusion

The opposite of diffusion is to narrow the light with some sort of baffle. This could be a snoot, a set of barn doors, or a honeycomb grid. I want to talk about grids here for one big reason. I often see photographers mixing a grid with a diffuser by putting the diffuser between the grid and the subject. I am not sure what they are trying to accomplish with that other than again losing a lot of light (2 stops or more in my testing). And they also lose the effect of the grid. If you feel you need a diffuser with a grid, you need to place the diffusing material between the flash tube and the grid, not in front of the grid. See the Deep Zoom Reflector examples photos later in the article.

First, let’s go to the standard 7-inch reflector that is common to most strobe systems. In the accompanying photos (click on the photo to see a larger version) I have used the 7-inch on its own, then with one layer of diffusion clipped on, and then with two layers of diffusion clipped on. There are a few things to notice. First is the large shadow on the background. Without diffusion there are actually multiple shadows with distinct edges. This comes from the combination of the flash tube itself, the reflector behind the flash tube, and the dish reflector around the flash tube each putting out a little bit different amount of light from their different sizes. When we add diffusion the light is homogenized or evened out so the shadow on the wall is more even. Then look at the shadow of the nose and the highlight on the tip of the nose. By adding the diffusion (one layer, two layers, or a dozen layers) we do not see any changes to these from one photo to the next. The edge of the shadow is still the same hardness and the highlight is still the same brightness in relation to the overall exposure. As noted above the density of the shadow might be a little brighter from light bouncing around the room, but that doesn’t affect the edge quality of that subject. If we want to lessen the brightness of the highlight on the nose one solution is to bring the light in closer, which will make the light bigger and cause it to fall off quicker (See! Everything in photography is interdependent and full of trade-offs). As a specular reflection the brightness will actually stay the same while getting larger, but the exposure on the rest of the face will also get brighter and we will power down the strobe to compensate for that which will then also bring down the brightness of the hot spot.

7-inch reflector bare, with a grid, and with a grid + diffusion

Now let’s look at combining a grid with diffusion. Three examples again this time. The first is with the same one we saw with 7-inch dish in the above examples. Then the 10-degree grid is added which limits the spread of the light for a more dramatic look and deeper shadows because there is less light bouncing around the rest of the room. This is the look I suspect that everyone is looking for with the grids. But then some people put a diffuser over grid. And look what happens when the diffusion material is placed over the grid—the diffusion material does its job (scattering the light into a wider pattern) and completely obliterates the effect from the use of the grid. Take a look at the diagram at the bottom of this post. And that is at the cost of two or more stops of light (translating into using more battery power if you are using a portable battery powered system). If you do feel the need to diffuse the light when using a grid you need to place the diffusion between the flash tube and the grid, not in front of the grid (yes, I am repeating myself for emphasis). We will take a look at how that works in the next set of examples below.

Diffusion scatters light

Baffles restrict light

Don’t confuse light contrast with light quality

Deep Zoom Reflector examples

One more example, this time with the Deep Zoom 11-inch reflector kit from Interfit. The Deep Zoom kit comes with a set of three grids (10-, 20-, and 30-degree) and a diffusion sock. Six examples this time. First we see the Deep Zoom by itself providing a nice crisp look. Adding the diffusion sock lowers the contrast, but retains the same shadow edge quality. Next I put on the 10-degree grid providing a more dramatic look with falloff of light across the background and a bit more contrast. Then I tried the grid with the diffusion sock over the grid and POOF there goes the grid effect that you spent good money on to purchase the grids. The next thing to try was with the sock behind the grid, between the flash tube and the grid. We get the drama back, but with a bit less contrast. So, while we’re at it, what happens wit with the sock behind the grid and a sheet of diffusion material in front of the grid. Again we can see that by adding diffusion in front of the grid we are negating the effect of the grid.

In all six examples we need to take a look at and compare the transition edge of the nose shadow. By now I hope that you don’t really need to look at it to know that it is going to be the same because the size of the light didn’t change between photographs.

So, to recap…

Diffusion scatters light in all directions and makes it cover a wider area. As the light is scattered and some is absorbed by the diffusion material you will lose some power.

Diffusion material can be specific products like those from Lee and Rosco. Or it can be a sheet of tracing paper or a bedsheet or a frosted shower curtain. Here I am assuming that the diffusion is dense enough that you won’t see a hot spot from a light shining through it. This is usually called a full-stop diffuser. Your diffusion material should be neutral in color, but often isn’t. That white shower curtain might contain brighteners that make it cause the light to be more blue, or it might have yellowed with age. Be prepared to have to do some color compensation when processing your raw files.

The opposite of a diffuser is a baffle (though I am befuddled as to why some softbox manufacturers and photographers call their scrims and the inner diffuser on their softboxes baffles). Baffles restrict the flow of light. Common examples are snoots, barn doors, and grids. Grids maintain the shadow edge while restricting the coverage of the light. Hard grids are available for use with metal reflectors like the 7-inch, the Deep Zoom, and beauty dishes. They are rigid with a honeycomb pattern of openings and snap onto the front of the reflector. They usually come in densities from 5-degrees to 40-degrees. The lower the number the narrower the light coming out of them. Soft fabric grids are available for most softboxes and octa boxes. They are usually around 40-degrees and allow you to have a large directional soft light.

Don’t confuse contrast (the difference between the light and dark areas of your image) with quality of light (how quickly the shadows transition from dark to light). While thinking about that, also do not confuse brightness with harshness. Moving a light in closer makes it brighter, but also softer as it becomes bigger in relation to the subject (or as seen by the subject). The exception to this is when using hard grids. Because the light rays are restricted by the honeycomb only the center rays from the light going through the grid will reach the subject, making the light appear smaller as it is brought in closer.

 Expanding on this illustration from a  previous blog post

Expanding on this illustration from a previous blog post

Well, thanks again for indulging me and reading through my thoughts on studio lighting. Now go out and make some photographs! Until next time…

Cheers!
John Cornicello



The Interfit Line of Studio Flash Units

High quality, good customer service, reasonable prices

 The Honey Badger and the Badger Unleashed

The Honey Badger and the Badger Unleashed

This blog contains affiliate links. If you purchase items directly from Interfit Photographic USA using my discount code, cornicello10, I will be compensated for the referral.

I was first introduced to the Interfit line of lighting gear at WPPI in 2017. I visited their booth to find out more about the LED panels they were distributing at the time. I was impressed with the people I met and came away from the meeting more interested in their studio strobes, which I hadn’t been very familiar with before. I kept in contact with Interfit over the next few months and signed on as one of their Creative Pros in June of 2017.

Along with the quality of their products, I was impressed that they have US-based operations in California and Georgia and that I was able to meet their staff not only at large shows like WPPI, but also at regional events. Their CEO and lead engineer both attended Glazer’s Camera PhotoFest in Seattle, for example. While I have not had a reason to contact their customer service department, I have heard a number of good stories from satisfied customers.

I started my relationship with a pair of S1 strobes. In August of 2017 Interfit released their Honey Badger line of strobes. I added those to my studio along with some of their modifiers. In early 2018 they introduced a line called Studio Essentials that included a 200Ws Value Flash head and an LED monolight. Their latest release is the Badger Unleashed battery powered strobe heads. 

Here is an overview of each of their studio strobe offerings.

FLASH HEADS

 Interfit S1 battery or A/C powered strobe

Interfit S1 battery or A/C powered strobe

 clean, clear, easy to use controls on the Interfit S1

clean, clear, easy to use controls on the Interfit S1

S1 - Interfit’s most powerful strobe at 500 watt-seconds. It uses S-mount accessories (as do all of their strobes). It has a built-in handle to help adjust the angle of the light on a light stand. It is battery-powered with the option of plugging it into an a/c wall socket. Controls on the back are clearly labeled and easy to use. This flash offers high speed sync (HSS) and TTL exposure control when used with their dedicated Canon, Nikon, or Sony remote triggers (the receiver is built into the strobe head). The S1 uses IGBT technology to offer very short flash durations at the lower end of the power range. The modeling lamp is a 10-watt LED, which is equivalent to around a 60-watt incandescent bulb. The low wattage helps make the battery last longer. There is a glass diffuser dome covering the flash tube and modeling lamp for protection and for even light spread inside of the light modifiers you use with the flash.


 Interfit Honey Badger studio strobe

Interfit Honey Badger studio strobe

 Control panel on the Honey Badger

Control panel on the Honey Badger

Honey Badger - The bright yellow strobe offers 320 watt-seconds of power and has a 60-watt daylight color balanced LED modeling lamp that is as bright as a 300-watt incandescent lamp. As it is an LED, it does not get hot, so no burnt fingers changing modifiers as you would with other strobes with incandescent modeling lamps. In addition to the standard S-mount for modifiers, the Honey Badger also accepts pop-up modifiers and comes standard with a 24-inch square softbox. This strobe is all manual and has a very fast recycle time. It is compatible with the dedicated remotes and the generic remote that works with just about any camera with a hot shoe. Controls are clearly marked and easy to use. A radio trigger receiver is built in. There is a glass diffuser dome covering the flash tube and modeling lamp for protection and for even light spread inside of the light modifiers you use with the flash. The Honey Badger is my go-to light for most studio situations.


 Interfit Badger Unleashed battery powered studio and location strobe

Interfit Badger Unleashed battery powered studio and location strobe

 Control panel on the Badger Unleashed

Control panel on the Badger Unleashed

Badger Unleashed - This is the new cousin of the Honey Badger, though it is also a mini-S1. It is 250 watt-seconds (which is only one stop less than the S1, or power level 9 out of 10) with a 15-watt LED modeling lamp. Like the Honey Badger, it offers S-Mount and pop-up modifier compatibility. The Badger Unleashed is IGBT controlled and offers high speed sync (HSS) and TTL automatic exposure control with the dedicated remotes for Canon, Nikon, and Sony. It also works in manual mode with the generic remote trigger. The Badger Unleashed has a short flash duration to help freeze motion and recycle time is 1.5 seconds at full power. This light can power down to 1 watt-second for those times you want to work wide open with your fast lenses or just need a little kiss of light to augment your scene. The battery is rated for over 400 full power flashes per charge and recharge time is around 90 minutes. Extra batteries are available, too. There is a glass diffuser dome covering the flash tube and modeling lamp for protection and for even light spread inside of the light modifiers you use with the flash.

The new battery-powered Badger Unleashed from Interfit Photographic is now available. I took one out for its first spin this evening. Check it out here.

 Interfit Studio Essentials Value Flash

Interfit Studio Essentials Value Flash

 Control panel on the back of the Studio Essentials Value Flash

Control panel on the back of the Studio Essentials Value Flash

Studio Essentials Value Flash - This is a compact and light weight “starter” flash with 200 watt-seconds of power. It has a built-in radio receiver that works with the $20 remote trigger. There are kits available, including the $300 two-light softbox kit which I use to light the Egg Chair as part of my Chair Series photos. This includes 2 strobe heads, two 20x28-inch softboxes, two light stands, a remote trigger, and a carrying case. A similar two-light kit with umbrellas (but no carry case) is only $200. These lights use a 75-watt incandescent modeling lamp and there is a built-in handle to help adjust angles. Operation is all manual with an easy to use control panel on the back of the strobe heads. Recycle time is 2 seconds at full power. Power can be dialed back 5 stops to 12.5 watt-seconds in 1/10th stop increments. Modifiers attach via the built-in S-mount. A very good value for $99.99!


Accessories

The new Nomad portable battery pack is a sine wave inverter with two A/C outlets and a USB charger port. Additional batteries are also available for the Badger Unleashed and S1 lights.

Interfit-nomad-1.jpg
Interfit-nomad-2

MODIFIERS

Another thing that endeared me to Interfit is their collection of high quality and reasonably priced light modifiers, most of which come with a fabric grid included. Here is a list of the modifiers I use regularly. Scroll down for some example photographs.


Example Photographs

 Interfit Badger Unleashed with Deep Zoom reflector and 10-degree grid

Interfit Badger Unleashed with Deep Zoom reflector and 10-degree grid

 Interfit Badger Unleashed with Deep Zoom reflector and diffusion sock

Interfit Badger Unleashed with Deep Zoom reflector and diffusion sock

 Interfit Badger Unleashed with 12x36-inch strip box

Interfit Badger Unleashed with 12x36-inch strip box

 Interfit Honey Badger with 48-inch deep parabolic softbox

Interfit Honey Badger with 48-inch deep parabolic softbox

 Interfit S1 with 28-inch folding beauty dish

Interfit S1 with 28-inch folding beauty dish

 Honey Badger with 24x36-inch softbox

Honey Badger with 24x36-inch softbox

 Interfit Studio Essentials Value Flash (two) with 20x28-inch softbox

Interfit Studio Essentials Value Flash (two) with 20x28-inch softbox

 Interfit Honey Badger with 65-inch silver parabolic umbrella and diffusion sock

Interfit Honey Badger with 65-inch silver parabolic umbrella and diffusion sock

 Badger Unleashed with 7-inch dish reflector

Badger Unleashed with 7-inch dish reflector

 Interfit Studio Essentials Value Flash (two) with 20x28-inch softbox

Interfit Studio Essentials Value Flash (two) with 20x28-inch softbox

 Honey Badger with 24-inch pop-up softbox

Honey Badger with 24-inch pop-up softbox

 Honey Badger with 24-inch pop-up softbox

Honey Badger with 24-inch pop-up softbox

 Interfit Badger Unleashed (two) with 36x48-inch softbox from camera left and 12x36-inch strip box at camera position for fill

Interfit Badger Unleashed (two) with 36x48-inch softbox from camera left and 12x36-inch strip box at camera position for fill

 Honey Badger with 36x48-inch softbox as the background

Honey Badger with 36x48-inch softbox as the background

There you have it! Since getting into the Interfit line of studio lighting I have been able to retire my Dyna-lite, Speedotron, and Einstein flashes. Let me know if you might be interested in purchasing a Speedotron Force 5 monolight or Speedotron 202VF heads locally in Seattle.

Remember that you can get a 10% discount on any products purchased directly from Interfit USA using the code “cornicello10” at checkout.

Thanks!
John Cornicello











Perspective (yet again!)

One word…, “DISTANCE”

Here we go again! Let’s start with the lesson drilled in my my college photography professor, Ed Sculley:

 
Pick the camera to subject distance that gives the perspective you want, then select the focal length lens to fill the frame appropriately
— Ed Sculley
 

Wise words! They harken back to a favorite Ansel Adams quote:

 
A good photograph is knowing where to stand
— Ansel Adams
 

For this post I define perspective as the relationship between the elements in a photograph. In a portrait that would be the size of the nose compared to the eyes compared to the ears, compared to the background. In an outdoor scene it might be the tree in the front yard compared to the house compared to the mountains in the distance.

Let’s start with the portrait. All too often I see articles claiming to show how lenses affect the look of a face. You’ve seen them, too. They show a photo made with a short wide angle lens where the face narrow with a big nose and then a series of photos with longer lenses where the face is flatter and flatter as the lenses get longer and longer. But what they don’t tell you is that not only did they change the lenses, but they also moved the camera. And moving the camera is what caused the changes in the looks. The lens just determines what is in the frame at the various distances.

Think of changing lenses as cropping your image in camera. All lenses show the same perspective at the same camera to subject distance. By putting on a longer lens you are magnifying the central area of the frame. If you don’t move the camera everything in the photo scales equally—the perspective remains the same. Let’s imagine a scene where you have a person in front of a window. with a tree outside. If you switch from a 50mm lens to a 100mm lens everything in the scene (the person, the window and the tree) all become twice as large in the frame, but their sizes relative to each other remain the same. If, on the other hand, you move the camera closer a more natural change occurs. The person in the front gets larger while the elements in the background appear smaller. The act of moving in might require us to change to a shorter lens to fit everything in the frame. But it isn’t the changing of the lens that altered the perspective, the move did that. The lens just determined what would fit into the frame.

 Start with our view of our subject by a window with a tree outside as seen with a normal lens.

Start with our view of our subject by a window with a tree outside as seen with a normal lens.

 Leaving the camera in the same position, a longer lens magnifies everything in the scene equally. But the relationship between objects remains the same.

Leaving the camera in the same position, a longer lens magnifies everything in the scene equally. But the relationship between objects remains the same.

 If instead of changing lenses we move the camera closer the subject in front gets larger while the background elements appear smaller. The size relationships all change.

If instead of changing lenses we move the camera closer the subject in front gets larger while the background elements appear smaller. The size relationships all change.

 
The closer the camera is to your subject the smaller the background elements will appear
— John Cornicello
 

As you move back away from your subject the objects in the background get larger in relation to the size of the subject—compressing the scene. Longer lenses force you to move back, leading one to think that it is the lens that is doing the compression. In reality it was moving back that compressed the scene. The longer lens magnified the subject to fill the frame better.

This is why you cannot “zoom with your feet.” Cinematographers tend to use prime lenses and move the camera (dolly in or out) to change the size relations in the frame. A zoom tempts you to keep the camera in one position and zoom to change size. But this is an unnatural look. In our 3-D world perspective changes as we move closer to and further from the objects around us. In a moving image a zoom instead of a dolly move just doesn’t quite look or feel right.

Don’t take this to mean I am against zoom lenses. Quite the opposite. I think they are very useful, especially in still photography, if used correctly. With a zoom lens you can position your camera exactly where you want it and then fine tune the framing to avoid or limit the cropping that you would need to do in post-processing.

And I do encourage you to move your feet. Step to the left or the right. Take a step in or back. Get down on the ground or up on a ladder. These all give you a different perspective. And you can do this with a prime lens or a zoom lens.

This all started a few days ago when my wife showed me this “great demonstration of lenses” in an Instagram post. I felt bad that I had to tell her it was all wrong. So I quickly made these crude illustrations to clarify things. The video on the left shows photos made with the same 16mm lens at various distances and resized to show how the drawing of the face is affected by the camera to subject distance. In the video on the right the camera remained stationary while the lenses were changed to show that the lens doesn’t alter the drawing of the face.

Here are side-by-side comparisons to help get the point across. The images in the first set were all made with a 24mm lens at different camera to subject distances and resized to maintain the same head size.

 24mm lens at various distances

24mm lens at various distances

This images in this next set were all taken from the same distance with different focal length lenses and resized to maintain the same head size.

 Different lenses from the same distance show the same perspective

Different lenses from the same distance show the same perspective

One more example to show that telephoto compression is a fallacy. Here we have a scene from a railroad station in Kyoto, Japan photographed with four different focal lengths from 18mm to 400mm. As you can see, the area of the scene that is common to all four images (in the magenta box) is exactly the same. The longer lens just isolates the central area, but the perspective is the same as in the wide angle photo. If you were able to enlarge the 18mm photo to match the size of the 400mm photo the quality would be terrible, but the compression (perspective) would be the same.

For more entertainment, please visit my post about the Incredible Shrinking Space Needle.

Well, enough early morning rambling for now. I hope you got something useful out of this.

Until next time, Cheers!
John
(Oh, yeah, please buy my book! THANKS!)

Learning to use your light meter

You are smarter than your light meter!

Just about every modern camera has a light meter built in. Plus digital cameras have a screen on the back where you can check your exposures and/or histogram. Do you really need an external meter, too?

The answer is a definite “Maybe.”

But before we try to answer that, let’s go through the basics of how a light meter works, the options available, and how to use the meter. We will look at both the meter in your camera and at external (usually hand-held) meters. And now there is a new meter that wirelessly connects to your mobile phone.

Light meters are color blind and unable to think. They make bit assumptions. They don’t always get things right. You have to do a lot of the work for them. Their readings are open to interpretation. You area much smarter than your meter, especially the one in your camera. Most cameras offer a few different metering modes. For most people the “evauative” or “matrix” mode can handle most situations. In this mode the camera meter reads different segments of the scene and quickly compares them to scenes programmed into the camera to try to make the best guess as to what you might be pointing your camera at. For general every day photography you should probably be using this mode. They usually also offer a center-weighted average and a partial metering pattern that only reads the center of the frame. Higher end cameras may also add a “spot” metering mode that reads an even tighter area. How big a spot varies by camera. For example, the Canon 5D Mkiii has a 1.5% area coverage, the Canon 6D Mkii uses a larger 3.2% area for its spot meter. It is the spot meter that I want to concentrate on here.

The meter in your camera basically assumes that everything you point it at is a medium tone of gray. And it wants to suggest an exposure setting that renders your subject a medium tone of gray. Luckily, many scenes that we photograph have a wide range of tones from darks to highlights that when averaged together are a mid-tone of gray. Whether that gray is 18% or 13% or 12.75% is an argument for another day. For now let’s just accept that average scenes average out to a gray tone that our meters are looking for.This averaging out is what makes the meter work. But it is also what makes us have to think about it and sometimes override what the meter tells us to do.

Let’s take some extreme examples—the proverbial polar bear in a snow storm and the black cat in a coal mine. If we relied on our in-camera meters both of these photos would be a mid-tone gray with a wildly overexposed gray cat and an underexposed gray polar bear. I am writing this at 7am in my PJs, so instead of going out to find the cat or the polar bear (or the coal mine or the snow storm) I am going to simulate the situations using a target with wide black, gray, and white stripes. Using the spot metering mode in my camera I metered each stripe separately (shown by the red targets) and made three photographs with the meter readings. I also made one more image using a hand-held incident meter, which I will get to later.

spot-meter-test.jpg

In the upper left I placed took the spot meter reading off of the gray stripe and all three stripes fall into line of black, gray, and white. In the upper right I made a spot meter reading of the black stripe (our black cat in the coal mine) and you can see that the meter made its expected assumption that the scene would average out to gray and by following along with the camera settings, that is just what we got. The black stripe turned gray and the white stripe overexposed. In the lower left I took the meter reading off of the white stripe (our polar bear) and the meter again assumed it was gray and turned the white patch to a muddy gray. The lower right shows a hand-held incident meter which reads the light falling onto the subject instead of the light reflected from the subject. More about that in the section below on flash meters.

This is where things can go wildly wrong if you don’t know what you are doing with the spot meter. Most of my photos are of people, so let’s look at what might happen in these situations. Caucasian skin tones are usually about twice as bright as the average gray (maybe 36% reflective as opposed to 18%). Darker skin tones might range from 18% reflectance down to 6% or so. If you point your spot meter at the different skin tones you will get very different readings that will lead to incorrect exposures with the caucasian skin being underexposed and darker skins being correctly exposed or overexposed. If you use the spot meter in your camera or if you use a hand-held spot meter you need to think things through more than when you use a matrix or center weighted mode and be ready to use your exposure compensation dial on your camera or work in manual exposure mode to get things just where you want them. Let’s look at some examples of where a spot meter can lead us if we blindly follow it.

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Here we have a still life set with objects of different brightness. From left to right we have a Color Checker Passport, a white index card, a Kodak gray card, a black card, a Gnomicello*, and a set of gray patches. In the upper left I made made a spot meter reading off of the gray card, giving a good overall exposure. Upper right has the spot reading made off of the black card, leading to an extreme over exposure of the scene. Lower left has the spot reading on the white index card, and the expected under exposure of the scene. Lower right is the exposure suggested by the evaluative meter mode in the camera. I actually think that the evaluative meter did the best in this series. The spot meter is not always our friend.

Extending this outside the studio, where should you point your spot meter? Point it at the white clouds and you get an underexposure. Point it at deep green foliage, get overexposure. You need to figure out something in the scene that you want to have render at a medium gray and point the spot meter only at that element, then lock in the exposure and recompose to make the photo. Bottom line, I think that spot meters have their place for photographers working with film and following the Zone System to control the tonal range of individual images. For the rest of us spot meters are useful if you want to figure out the contrast range of a scene, but you still have to work out the proper exposure overall.

For kicks, let’s compare the evaluative meter reading with the center weighted mode.

scene-meter.jpg

I think you can make a case for either exposure here. This all, of course, assuming that the monitor you are viewing this on is calibrated and set to a decently low brightness setting of around 100 cd/m2. Most monitors are set much too bright from the factory (for gaming or for watching movies), so make sure your calibrator has an option to set brightness levels.

Flash Exposures

hand-held-meter.jpg

This is all well and good for photography lit by continuous light sources like the sun, incandescent lights, LED lights, etc. What happens when you need to figure out the exposure for studio flash units that are not TTL** compatible? The meter in your camera has no concept of flash, so you need to rely on an external meter. Typically these have been hand-held devices such as the one shown here, my trusty old Sekonic L-358 (that is no longer in production). There is also a new meter, the Illuminati Meter (which I have not yet had a chance to try), that can be placed in the scene and connects with your mobile phone so you don’t have to hold it in your hand.

These meters can either be connected to your flash via a sync cable, a wireless transmitter, or they can be set to wait for a flash of light to trigger the reading. As noted, these meters are placed in the scene to read the light that is reaching them, the “incident” light. This provides a more accurate reading because it only reads the light falling on the subject and is not swayed by the brightness or reflectance of the subject or anything else in the scene. You set the ISO and shutter speed on the meter to match that on your camera, fire off the flash, and the meter tells you the aperture (F/stop) to set the lens to. For the most accurate readings the dome of the meter should be pointed at the main light illuminating the scene.

Some hand-held meters can also be set to read reflective light and/or be used as a spot meter, but then you run into the same issues that you have with your in-camera meters. And you don’t have the computer “smarts” of Evaluative or Matrix metering in the hand-held meter.

Color meters

The Illuminati Meter mentioned above and another relatively new device, the Lumu meter (iPhone only at this time and also which I have not had the opportunity to work with yet) extend the function of the meter by adding in a color meter mode. Normally color meters cost around $1,000 and only do their one thing. Having this available in a light meter costing around $300 - $500 is a big deal for those who need critical control over color.

Back to the beginning

So, back to the question of “do I need an external, hand-held light meter?” The answer remains a definite “maybe.” It depends on how you work, what type of lighting you use, how comfortable and sure you are about the display on the back of your camera, how much you know about reading the histogram on the camera, and on and on. I have friends like Tony Corbell and Matthew Jordan Smith or take multiple meter readings of every scene and friends like Joel Grimes who never touches a meter. The photographer makes the image, not the tools.

Wishing you good exposures!
John Cornicello

* Gnomicello is a birthday gift I received from artist Mike Oncley a few years ago.

** TTL means Through The Lens. Some camera and dedicated flash combinations offer a metering mode where the flash fires twice. Once at low power just before the shutter opens letting the camera meter read the flash and then again with the shutter open to make the exposure.