Matrix metering is the most advanced of the metering options on a Nikon camera, be it a DSLR or a ML camera. It divides the scene into multiple zones and evaluates the light intensity and contrast in each zone. The system considers the brightness and contrast levels in each zone to evaluate the overall exposure. Subject recognition may also be used to determine the most important zones as well as the zone that has the focus point. The system has developed over the years and hence the system is not static but had improved from one model to the next.
Nikon Matrix Metering can work with non-CPU lenses, but with some limitations. Non-CPU lenses do not transmit lens information (e.g., focal length, maximum aperture) to the camera, which can impact the metering system’s accuracy. Therefore the Nikon camera – when shooting with a non-CPU lens – will typically default to center-weighted or spot metering mode, instead of Matrix metering.
There can be many reasons why you want to control your exposure manually – the scene may contain a lot of bright or dark that confuses the automated metering system, you are shooting with flashes in manual mode or you just want to control the exposure because you like this way of working. Whatever the reason, there is a way to secure correct exposure using a grey card (18%) and the histogram in the camera.
Right in the middle
One of my flashes came with a grey card in credit card size. Actually it came with 3 cards, one white, one black and one grey. You only need the grey one, but just for the fun of it, I will use all 3 in the following.
The grey card to the left, the black card top and the white card right. The fact that the white card appears a bit grey would indicate that this image is slightly underexposed.
The grey card returns light in such a way that if your exposure is correct, then the grey card will produce a peak in the histogram right in the middle of the diagram. The histogram shows the distribution of light in the scene, with completely black areas to the left, completely white to the right and everything in between somewhere in the middle. The height of the graph shows the number of pixels in relation to the entire scene. So if you have a very dark scene, then the histogram is “lefty”, i.e. it looks like a mountain appears in the left side of the histogram whereas the right side is more flatland.
The simple idea is now that you take a test image of the scene, study the histogram and if it is off center, then you adjust the camera settings to make the grey card appear in the middle. If you are in Live View on your DSLR or have a mirrorless camera, you can actually see the histogram update real time as you adjust the camera settings, and hence no need to do a test shot unless you want to.
You adjust the camera settings meaning ISO, Aperture and Shutter speed. If shooting in manual mode is new to you, you can follow the link and see how it is done on a Nikon D750. The principles are much the same across different camera brands, and I think you can get the gist of it by reading the post in the link.
In the example above, you can see the 3 cards on a whit table and top right the histogram. Yes, it is a bit small, but you can see that there are 3 peaks – one the the very left originating from the black card, then the peak in the middle from the grey card and then the wider peak to the right, that is a combination of the white card AND the table behind the cards. This table is also white, but not as bright as the card. So the rightmost peak is also wider than the other two, as it is a combination of the table and the white card that span across a wider range.
In this example the grey card peak is not in the middle, but to slightly to the left, which is a sign of underexposure. Had it been to the right – then overexposure. So in this case the camera settings needs to be adjusted to let in more light, say leaving the shutter open for longer time or opening up the aperture. After the adjustment, a new test shot is needed to see if the desired effect has set in. If not, then redo until the grey peak is right in the middle.
So this is really all there is to it. Given that the ambient light does not change or the flash settings remain constant, you can now shoot a series of images without worrying about the exposure settings on your camera. I find this super useful for product shoots and indoor portrait shoots.
So I got a question on YouTube related to nightclub photography and how that can be achieved. In order to answer, I will start with the human eye, which has a dynamic range of 21 stops! Even the best cameras ever made can keep up with this performance – for example the acclaimed Nikon D700 “only” has a dynamic range of 13.9 stops according to DXOmark, whereas the very best modern cameras manage to go to 15 stops.
The dynamic range is the ability to distinguish between light intensity in the darkest of the dark and the brightest of the bright at the same time. The fact that it is at the same time is important. You can always underexpose an mage to make sure you preserve the details in the brightest of bright areas. And the other way around, you can always preserve the details in the darkest areas by overexposing the image. But the challenge is to do both at the same time.
A nightclub with both neon lights (super bright), disco light (bright and moving fast) and also dark areas (could be the dancing floor itself or the side of the bar) has an extremely high dynamic range. It is very similar to shooting the moon at night – you both have something very bright and something very dark at the same time. It is like shooting a 100 watts light bulb in a dark room at night.
Metering
Your metering system is likely to very confused if you shoot at a nightclub, especially if you meter with an average method. 95% of the frame is likely to be pitch black, whereas the remaining 5% is super bright. My guess is that your camera, unless you try spot metering or go to manual exposure, will over expose the image to compensate for the dominating dark. Try to experiment with different metering modes or manual exposure to get the exposure as you want it. You can also give exposure compensation a try.
ISO or not
A camera that can go to crazy high ISO values will not help you. Setting ISO high enables you to capture images where there is little light, buy when doing so, the parts where there is light will be over exposed. In other words, you will loose details in the bright areas. Here I ignore the issues related to high ISO such as grain and noise, the point is that even if you can live with these issues, it will not help you much.
Fast lens
A fast lens has the same features as high ISO, but without the grain and the noise. It will take in more light and enable you to shoot at faster shutter speeds all things being equal, but you will have the same issue as with ISO, that it will only push your histogram to the right and you need it to be extended in both sides.
HDR
High Dynamic Range or HDR you probably know from your smartphone. It offers the HDR feature without telling you what it does – it is an integral service that just presents you with the result. But behind the scenes the smartphones takes a series of images, typically some over exposed and others over exposed, and combine them into one picture selecting the correct exposed parts from the different pictures into one. You can do HDR with your DSLR and combine the images in post processing, and this will certainly work. The problem is just that your subject has to stand still while this happens. And disco lights have a tendency not to obey to this wish.
Loosing details
One of my favorite photographers is Sean Tucker. If you study his work, you will see that he often and deliberately looses details in the dark. His motto is to “preserve your highlights”, i.e. preserve the details in the highlights and let the different shades of grey be one big black surface without any detail.
You can loose details in both ends of the spectrum. Which “end” you choose is up to you. I would imagine that loosing details in a neon light would not matter much, suggesting that you should expose for the dark parts, i.e. over exposing to preserve details in the darker parts. But this is of course entirely up to you and what you want to express.
EV is an abbreviation for exposure value. It is a way to express exposure in one number, i.e. the combination of shutter speed, aperture and ISO. To be quite honest, I doubt that many use EV’s today, as most rely on the exposure meter in their cameras, possibly in combination with the histograms.
But you can study EV as a way to understand exposure better. For example, if you shoot at f/4 and 1/125th, you are at EV 11, but if you open up the aperture to f/5.6 and maintain the shutter speed, you are now at EV 12. This is referred to as going one stop up. So walking up and down the EV scale is referred to as stops of light. The light is doubled or halved for each stop. This gives you a “settings independent” way of talking about exposure, and you can say go one stop up in aperture and one down in shutter speed and arrive at the same EV. So shooting at f/4 and 1/125th gives the same EV as shooting at f/5.6 and 1/60th. I half the light that comes though the lens (f/4 -> f/5.6) but double the exposure time (1/120th -> 1/60th). Both are EV 11.
For simplicity I have kept the ISO out of the description above, but it is the same logic: doubling of halving the ISO is the same as going one stop up or down in exposure. So the ISO scale is: 100 – 200 – 400 – 800 – 1600 etc. Many cameras allow you to select ISO values more granularly than full stops, and that can be handy, but remember to double/half to make a full stop difference.
Another area where EV is useful is when it comes to the spec list for a camera. The cameras dynamic range is expressed as an EV. For example the Nikon D750 over at DxOMark is listed as having a dynamic range of 14.5 EV’s, whereas the Nikon D810/D850 has 14.8 EV’s. Higher is better, as it enables you in one shot to span across more difference in light in the scene, without blowing out the highlights or loosing details in the shadows. So if dynamic range is important for your kind of shooting, then the EV for a camera you consider buying could prove an important part of your decision making.
Back in the days of film, dual exposure was when you shot two images but without advancing the film between the two shots. The film would then be exposed two times and the resulting image was a combination of the two exposures.
These days most digital cameras offers dual (or several) exposures as an option available via the menu system in the camera. My Nikon Z50 for example has “multiple exposure” as an option in the photo shooting menu, just to give an example. In the image below I have shot the little toy cow two times moving the camera a bit downwards between the two shots. Not exactly a price winning image, but I think it works to illustrate how double exposure works:
With advanced post processing software like Photoshop, it is possible to combine the images long after they are shot, and this gives even more options for creative use of combining two or several images into one.
Only your creativity sets a limit for what you can use dual exposure for. It often creates images that clearly depicts a scene or a subject that you would not find in the real world. So the result can be e.g. dreamlike, surreal or just strange. In the example below I have put the cow from above into a glass bottle by shooting the cow first and the bottle afterwards.
I hope this gave you an appetite for trying out double exposure yourself. Only your imagination and creativity is the limit! Best of luck!
Going up one stop means you double the amount of light that hits your sensor or film. Going down one stop means you half the amount of light.
You can go up and down in stops in the 3 dimension you know from the exposure triangle:
Shutter speed: If you double the time the shutter is open, then you go up one stop. If you change the shutter speed from 1/100th of a second to 1/50th, is the same as going up one stop. You let in more light because the sensor is exposed for a longer time.
ISO: If you half the ISO setting, it is the same as going down one stop. Say you are shooting at ISO 1600, then reducing to ISO 800 is the same as going down one stop. Increasing to ISO 3200 is going one stop up.
Aperture: If you change the aperture from f/1.4 to f/2, then you are going up one stop. Same if you go from f/2 to f/2.8. When you walk up and down the aperture scale in hole stops, you walk in steps of 1.41 (the square root of 2). This is not as easy to remember as the linear relationship for shutter speed or the doubling when it comes to ISO, but you will quickly get used to it.
What is the point? It is to give you a common language for changes to the exposure, irrespective of which dimension in the exposure triangle is changed. So to maintain status quo, you can go one stop up in shutter speed and one down in say ISO, and get the same result as before. This is a smart way to have a common language to changes to exposure, without knowing what the specific camera settings are.
A high key image is one that in its tonal range is dominated by lighter mid tones and white highlights.
In this product shoot there is a very bright white desktop to set the scene, and on top of it most subjects are very bright as well. The Notebook and the coffee, together with the pen, are in stark contrast to the otherwise high key image.
This happens naturally if you a shooting where there is lots of light and/or bright surfaces to reflect the light. Or it can be achieved by over-exposing the image or post processing it in post to achieve the same effect.
High-key image example
If you study the histogram of a high-key image, you will see that it “tilts” very much to the right, with almost no blacks or shadows. The few black tones that you do see however, stand out so much more because of the “light” impression of the image overall.
In the example above you can see that the seagull and the black sails of the boat stand out, whereas the rest of the image is highlights or whites. This helps the subjects “pop”, i.e. they stand out because the contrast to the rest of the image is so significant.
High-key images have a light and positive feel to them, quite contrary to low-key images that in all aspects are the exact opposite.
A low key image – lots of blacks and shadows, but not many whites or highlights.
A short post about what exposure compensation is and how you use it.
When your camera calculates the correct exposure in the automated or semi-automated exposure modes, the camera sets the shutter speed and aperture to achieve a technically correct exposed picture.
Exposure compensation is simply that you ask the camera – on top of the calculated exposure – to deviate from that exposure as per the exposure compensation settings. So if you dial in a exposure compensation of say -1 stop, then the resulting image will be slightly under exposed.
Dials
The exposure compensation dial in the Fuji X-T20 ranging from 3 stops over exposed to 3 stops under exposed and all in between in 1/3rd stops
The image above shows the Fuji X-T20 exposure compensation dial where you simply turn the dial to the desired compensation. A more traditional implementation is a little push button on top of the camera with a +/- sign. When you hold down this button and at the same time turn the command dial, you can set the exposure compensation value. The top LCD will typically show you the values while you push the +/- button.
The exposure compensation button on the Nikon D4. The Nikon D700, D750 and Z50 has exactly the same implementation.
Use
You can use this a as a creative tool, where you systematically over or underexpose your images (low key and high key) to achieve a creative effect. Or you can use this to compensate for the automated exposure when you know your camera will get it wrong – for example shooting portraits in the snow, where your camera will have a tendency to under expose in attempt factor in all the white in the frame.
If you shoot in RAW format, then a lot of tweaking to the exposure can be done in post processing as the RAW format give a lot of headroom for adjusting the exposure. However, many prefer to get the exposure right “in camera” to simplify their workflow and save time.
An ND-filter or a neutral density filter is like a pair of sunglasses that you put in front of your lens. The purpose it to reduce the amount of light that hits the sensor, just like you want to protect your eyes from the strong light on a sunny day.
A variable ND-filter sitting on my beloved Nikkor 16-35 mm lens.
The point with an ND filter is to allow you to keep the shutter open for longer time without clipping the highlights in your picture or in other words simply avoid that you over expos your picture.
Why would you then want to keep the shutter open for a long time? Take a look at the picture below. It is taken over several seconds. The stones of course do not move, while the waves of the sea are reduced to pure silk. Moving parts become blurred, stationary items stay sharp. That is one effect you can get with an ND filter. You can also shoot waterfalls, harbors, etc. with this technique and get similar results.
Long exposure. The stones stay put, the waves of the water are reduced to pure silk…
Another application is simply that there is so much light that even when you shoot at the fastest shutter speed your camera offers and base ISO, you still get too much light. Then an ND filter – like sunglasses – comes in handy to reduce the amount of light.
You can also use the long shutter opening to move the camera instead, and this is what is done in intentional camera movement where you move the camera to create a blurry effect.
ND filters come in variable and fixed ones. I prefer the variable, because I can then turn the ring to reduced effect (ND8), so I can actually see what I am shooting and then once focused, return the ND filter strength to full throttle (ND2000) and get the most out of the filter. If you have a filter with a fixed value, you typically find you have to take it off the lens in order to focus, and the re-mount to take the picture. The variable filter saves you a bit of work.
The light reduction your ND filter yields is typically measured in ND values – if you look at the picture of my ND filter above, you can see it ranges from ND8 to ND2000. That is a reduction of 3 stops to 11 stops. That is a lot! You may be able to get by with less than that.
ND filters are not cheap, and you want to get a good one. The “neutral” in ND is to be taken very literally – you don’t want the ND filter to change the color or toning of the light. It should really stay neutral. Cheap filters unfortunately often has this un-wanted side effect. Make sure you get a filter with good reviews – it is quite expensive, yes, but you will not enjoy a filter that alters the colors. Believe me – been there, seen it, done that. Not to be repeated.
I think of the shutter as a curtain in the theater that comes up, exposes the show for a little while and drops again. For how long the curtain is up defines the speed of the shutter.
Others use the eyes and the eye lid as an analogy to the shutter speed: closed eyes, open them – take in the view – and close again. The duration of your eyes open is the shutter speed.
The longer the shutter speed the more light will hit the sensor. A fast shutter speed is great if you want to avoid camera shake (you move the camera while the shutter is open) or motion blur (the subject moves while the shutter is open).
The shutter speed dial sits just to the left of the red shutter release button on the Fuji XT20. As you can see the camera is in “A” mode where the shutter speed is chosen automatically. Below the “A” you can select 1/4000th down to 1/1, then timer release and bulk.
Shutter speed is expressed in fractions of a second, so a shutter speed of 250 is 1/250th of a second. The fastest of cameras can go to 1/4000th or 1/8000th of a second. That is fast! On the other end of the scale you can have the shutter open for several seconds, even minutes, when photographing in extreme low light like astrophotography.
Back in the day all shutters were mechanical, and if it was not for the mirror flickering in your DSLR, you probably could hear some mechanics working in there. There actually is a little black curtain moving when you hit the shutter. Most modern cameras can both work with the mechanical shutter and the electronic shutter – the electronic shutter being the new kid on the block. The electronic shutter works by switching the sensor on and off. This happens super fast of course! It simply switches on the sensor and allow light to hit it, and then off again to allow the camera to read the sensor values.
Thank you for reading this far! Comments and questions more than welcome!
