Last Week We saw about the basic controls Shutter speed, Aperture, ISO how it will affect the exposure.
Actually Shutter speed and aperture will affect image in two ways. Let see about shutter speed how it affects the image this week.
Shutter Mechanism: There are two types of shutter(mechanical and electronic) in digital cameras, we saw this last week. But in Mechanical itself there two types of mechanism. What we see in our 35mm format cameras are curtain shutter. Medium format cameras use two types. Some uses curtain shutter, and some uses leaf shutter
Knowing about this may not be required, but there are advantages and disadvantages with both hence I need to cover both but not in very detail.
The centre grey coloured blinds is the shutter. It will be two split upper and lower. First lower will go down and upper will follow. Based the shutter speed you define the gap between the two and time the upper to start follow the lower.
In some other brand cameras this will be like right to left or left to right. But those are also called curtain shutter In practical the lower curtain is called the first curtain and upper curtain is called second curtain. This is not very important at this stage, but if you use flash this will help to understand few settings clearly.
Maximum speed of curtain shutter is 1/8000 secs. And maximum number of frames a curtain shutter can shoot is 16 FPS (Canon 1DX mark III) is the maximum in current market. But this value is not solely depend on shutter mechanism. Processing capacity, AF speed, etc. will also be considered. It will be a balance between these features If you use flash you should know about X-sync or sync speed of any camera you use. For canon and Nikon cameras it is either 1/200 secs or 1/250 secs. In electronic shutter Sony A1 has sync speed about 1/400 secs(electronic shutter). This we will cover in detail when we discuss about flash.
Leaf shutter mechanism in closed position and open position
In some medium format cameras they use leaf shutter mechanism. The maximum shutter speed of leaf shutter is up to 1/500 secs. But they can sync to flash at all speed till 1/500 secs. Electronic shutter:- We have discussed about this last week.
Advantages of electronic shutter are,
1.You can have very high shutter speed up to 1/64000 secs(depends on camera model). In current market all 35mm mirrorless has electronic rolling shutter.
2. Recent flag ship cameras can shoot 30 FPS with electronic shutter.
Disadvantages of electronic shutter are,
If the electronic shutter is rolling shutter then there will be distortion in image of any fast moving object you shoot. Even in recent flag ship cameras this issue is there. Electronic global shutter is ultimate solution for this, OEMs are working towards to get that tech in to prosumer and consumer cameras. At present Global shutter sensors are used in some high end cinema cameras. Google for “rolling shutter effect” you will get images and videos you can easily identify it by yourself.
To say in simple words - Rolling shutter and global shutter are defined by how the data is read from the sensor. If rolling shutter it will be line by line. Global shutter all pixels at one time
Modes to control Shutter speed:-
Every DSLR or Mirrorless or bridge camera will have full manual mode and semi automatic modes and full automatic modes. We will discuss about full manual mode and semi automatic modes. First we will see semi automatic mode. Shutter priority mode and aperture priority modes are the semi automatic modes available in any of above mentioned camera.
In shutter priority mode, (In mode dial :- Tv in Canon and S in Nikon) you have to set the shutter speed based on your desired output. For that shutter speed and given ISO camera will set the aperture automatically to obtain the proper exposure considering the metering mode used.
If you kept shutter speed above 1/1000secs you can freeze the motion, like in sports images. if you keep shutter speed below one second you can get milky water fall and light painting. but for normal shooting at slow shutter speed, you should be careful about camera shake and motion blur.
Camera shake is due to camera in motion. Motion blur is due to subject in motion. Motion blur can be used creatively(Sample images attached at end of document)
But camera shake must be avoided.
So to avoid camera shake, 1. Keep shutter speed slightly higher than your focal distance( if you shoot at 70mm keep shutter speed more than 1/70sec), if you are using lens or body without image stabilisation
2. Use lens or camera equipped with image stabilisation(IS in canon, VR in Nikon, OS in sigma, VC in tamron). All highend mirrorless bodies are equipped with IBIS(in body image stabilisation), hence for those bodies you can use lenses without image stabilisation. Check the capability of image stabilisation unit either in lens or in body to know how many stops you can lower your shutter than the required shutter speed for any scene to avoid camera shake.
3. If you have time, space and gear use tripod. Most situations monopod will solve this issue, but for very low shutter speed tripod is the best.
If you are shooting moving subject at very low shutter speed, you will get motion blur. In this case you have to increase the shutter speed no other choice(with flash it will be a different story)
There is a saying in photography “grainy image is better than blurry image”
What it means-
If you don’t find any solution to avoid camera shake, just boost the ISO beyond safe limit to get the shot without blur. As a event shooter, I know the value of this. At the spur of a moment you will not have any options other than to boost ISO. But don’t keep it as standard practise for all situations.
Sample situation to use shutter priority mode:
If you are using a fast lens like canon 50mm F/1.2 lens. And you are moving in to variable lighting conditions to shoot moving subjects(without flash). In this situation your target is to get images without motion blur. You priority is shutter speed, set your camera shutter speed to the required level, ISO to the maximum tolerable limit(beyond which it will affect the image quality) and camera will vary the aperture for every exposure based the different lighting conditions. In these situations many shooters will tend to use auto ISO. You can use it if you can set the range of Auto ISO(to be within the safe limit). Pro bodies will have this feature(not sure about entry level bodies). Without the limit if you use auto ISO it will affect the image quality(unpredictable at times) It need not be a fast lens like above mentioned, you can use any lens at this condition. But using fast lens is advisible to get considerable shutter speed at decent ISO.
Fast lens – lens with wide open apertures are called fast lenses, since they will provide good shutter speed at very low lighting conditions
In Manual Mode, Shooter has to set all three parameters shutter speed, Aperture and ISO. With my experience most beginners will shoot in manual mode with auto ISO. As I explained above, you should know the sensor capability and the tolerable limit. To set these three parameters, there is no standard settings. It depends on available light(flash not included for this discussion, If flash included it will be very different story for this manual mode as well as shutter priority mode) and your final desired output. If you are about shoot a group of people dancing you have to keep shutter speed high and adjust the other setting to achieve the proper exposure. If you are shooting group of people standing in four rows and posing to you as in any wedding venue. Your priority is depth of field and clarity of the face. So shutter speed can be minimal in the safe range to avoid camera shake. Aperture(f-number) need to be high to get sufficient depth of field(will cover this in next topic “aperture”), and ISO need to as low as possible.