We received a few great questions from the first Q&A post on photography and wanted to share them in their own post. Due to the technical nature of the questions and answers it just didn’t seem right to leave them there as the worlds longest comment. The questions pertain to the main camera settings such as ISO, Shutter Speed, Aperture, Manual Mode, etc. I will do my best to an answer and explain these concepts in normal language. I hope this will benefit a bunch of the readers out there. For the rest of you, flag this post and come back to it when (or if) you want to learn how to start driving your camera.
Reader Question 1:
I truly appreciate this information. I own a DSLR but do not know enough about it. I find that I use the program mode with an external flash. I get some great pictures, but I feel like most of that is pure luck. I would like to know more about ISO. What is it exactly?
Thank you!
My Response:
Great question. ISO is simply a measure of the camera’s sensitivity to light. You will see it in your settings in a numerical format (ISO 100, 200, 400, 800, 1600, etc). The larger the number, the higher the sensitivity. It does come with a catch, though. Light sensitivity comes at the expense of image quality, known as noise. Our own eyes even have the same limitation. We can see in a dark room, but at a much lower quality. So the trick is finding out what your camera is capable of while still maintaining sufficient image quality. I’ll give you a hint, it isn’t the highest number on your camera, it is usually at least half of that. So if your camera has a max setting of ISO 3200, chances are your image quality will really start to suffer after ISO 800. Better ISO quality is the main reason I would advocate buying a new camera, it is that big of a deal.
ISO makes up one-third of what is known as the exposure triangle, with the other two variables being shutter speed and aperture. Now you get to choose how automated this process is. In Auto ISO and program mode, the camera makes all three of those decisions for you. With Auto ISO still on you can choose Aperture priority mode or shutter priority mode to take control of one of those variables. Turn off Auto ISO and you are now in control of 2 of 3 variables. Go to Manual and you now control all three.
Does that answer your question? Any other questions?
Reader Question #2:
Yes. Your information regarding ISO was very good. I was wondering if you could explain more about the exposure triangle and what it means to control shutter speed and aperture. I find that when I shoot in manual mode, it is trial and error (mainly error) to get the picture looking the way I would like.
Thanks!
Response:
Okay. Find a quiet place to sit down and read. You may have to read this a few times, and even come back to it after a few weeks(months/years) of practice. This will be a long read folks. As was writing I kept finding more terms or concepts that I felt needed to be explained.
Camera Terminology
ISO: As discussed above, ISO is the sensitivity of the sensor (or film) to light. Your lowest ISO setting tends to give you the “best” quality image. As the ISO increases (the sensitivity of the sensor/film) it comes at the cost of digital noise in the file. In the film it shows as a more pronounced film grain. ISO works in inverse proportion to Aperture and shutter speed.
Shutter Speed: The length of time the shutter is open and exposing the digital sensor (or film, if using a film camera) to light. The slower the speed, the more light comes in, the faster the speed the less light comes in. Slower shutter speeds can produce a blurring effect. Faster shutter speeds freeze motion. Shutter speed works in inverse proportion to Aperture and ISO
Aperture: Aperture is the size of the opening in your lens that light comes through on its way to the sensor. The bigger the opening, the more light that comes through, the smaller the hole the less light. The numbering scheme for an aperture “f-stop” is seemingly backwards in that the smaller numbers correspond to the larger opening, and vice versa. A small aperture has the effect of keeping more of the image in focus. Whereas with a wide open aperture only a portion of the image is in sharp focus, the rest drops off dramatically. This effect can be quite pleasant when done with portraits of people or things.
Depth of Field: The amount of sharpness in an image away from the main point of focus. Your eyes and camera have something in common, they can only focus on one thing at a time. Go look outside into the distance. Every looks sharp, right? That is an example of deep depth of focus(field). Now lets say there is an object 10 feet from you, and another 15 feet away. When you focus on the first object, you can still some sharpness in the second, but not the same amount as the first. This is an example of somewhere in the middle. Now focus on a book right in front of you. As you maintain focus on the book, anything in the background behind the book disappears into a consistent blur. That is an example of shallow depth of field.
Inverse Proportion: If you increase one element another must compensate with an equal and opposite decrease. In a camera you have three floating variables; shutter speed, aperture and ISO. If one of those variables increases, either one or both of the remaining two must decrease by the same amount to maintain the balance. It is like a three-sided teeter-totter. The only difference is that not all three of the variables need to move at a time, only if you want them to.
Camera Meter: A visual display that shows how your camera reads the image. It is shown in a scale with the center of the scale being the ideal exposure.
Exposure Compensation: The amount that you alter from the camera’s “ideal” exposure. Most every camera has exposure compensation control. In manual mode you can control it directly. Cameras can be fooled by areas in and image that are extremely dark or bright. Why do most photos taken on a snowy day look so grey? The camera underexposed the bright white snow, and will continue to do so unless you compensate for that. In the home, a bright window will dominate the scene and underexposed the image.
Camera Modes
AUTO ISO: This not a direct camera function, but it does affect how the other modes operate. If you turn on Auto ISO it will adjust the ISO for you in all of the camera modes.
Auto: The camera makes the choice of at least the shutter speed and aperture and usually the ISO as well. Result? Pretty good most of the time for average situations, not so great in the house. Great when you need to take a shot quickly and don’t want to or don’t have time to figure it out. Drawbacks? AUTO isn’t even like training wheels, its more like riding a tricycle. It has its place for a short time but then you should outgrow it.
Program: The camera has a bunch of modes that it has pre programmed for you. It changes all the variables depending on program. You can also override the settings if you so desire. This is a bit more like training wheels. Using this forces you to think about what you are shooting before you do so.
Shutter Priority: In this mode you pick the shutter speed and the camera chooses the aperture. This has two main uses. The first is entirely creative. Choose a shutter speed for a desired effect. Kids playing sports = fast shutter speed. Make a waterfall, waves on the beach, etc look nice and smooth = slow shutter speed. The second reason is more practical. Every lens has a minimum shutter speed that you need to use to produce a sharp photo. It used to be easy to figure out in the days of 35mm film cameras, your minimum shutter speed would be 1/focal length of lens (a 50mm lens would need 1/50th of a second shutter speed at minimum. Now digital sensors come in several different sizes so the calculation is more difficult. The safe bet is now to use the calculation 1/1.5 x focal length of lens. All blurry images are a result of too slow of a shutter speed.
Aperture Priority: Here you pick the aperture, and the camera picks the appropriate shutter speed. I use this mode a good amount. Shooting in the home, or landscapes, or with people, aperture is the most important variable because of the effect is has on depth of field. Since controlling sharpness and focus depth change the mood of the kinds of photos I described, get familiar with aperture priority mode.
Manual: In manual mode you control both the aperture and shutter speed. You are driving the car; no cruise control. Here you will be using the camera meter to guide you to what the camera determines to be the correct exposure. From there you can adjust up and down to find the exposure that you like. You are in complete control here.
A good working knowledge of the terms and concepts described above is important, but not essential to making good images with a camera. I would rather have vision and be ridiculously creative than to know all this stuff but not be able to use it to make a photo that actually means something. For truly great images you need a balance of both. You need to know how the camera works in enough detail that you can make the creative and technical decisions necessary to get the image you want. Everyone’s knowledge threshold is different, so don’t judge yourself by someone else’s ruler. Judge yourself by your images turning out the way you want them to. If they still aren’t where you want them to be then it is time to learn a little more and push yourself out of your comfort zone a little bit, or a lot. One word of advise though, don’t try this kind of learning when you are in a hurry. Take some time to try, and be okay with getting it wrong a few times before you get it right. My own journey has seen many failures, many frustrating times spent trying to understand a concept, many times questioning my own intelligence. Yet I am stronger for it. The day that you say you know it all is the first day that you are in serious trouble. Me, I enjoy the lifetime of learning. How about you?
Yeah! Very valuable stuff here. I feel that I can start exploring my camera and kind of know what I am doing.
I have so many other questions, but need to just focus (pun intended) on one. Can you please explain focus and perspective? I have some great shots of my children, for example, but I can see everything around them in the picture and have to edit out or blur the edges to have the focus on what I want. This is time consuming and never really looks right no matter how hard I try . This could also be due to my lack of knowledge about editing software, but it sure would be nice to get the picture the way I want it to look when I take the picture instead of editing afterward.
Thanks!
There are a few possible reasons here, and most likely a combination of a few. The first could be the maximum aperture (f-stop) of your lens. Most kit lenses start at around f4. If you zoom the lens in you usually end up somewhere around f5.6 Those really nice portraits of kids where everything is nicely blurred behind them are typically taken using an aperture of between f1.4 and f2.8. At f4 – f5.6 you get into the in between regions between a nicely blurred and everything sharp. Choose the largest (smallest number) of an aperture that you have. Eventually you may want to start looking for specific lenses that have wider maximum apertures. That is the great thing about buying a DSLR; you invest in a camera system. A system you can keep changing as you learn or as your tastes change.
The next possible reason has more to do with perspective. The wider the lens, the more perspective it gains. As you zoom the lens in, your perspective starts to narrow. They say the human eye has a similar perspective to a 50mm lens (about 35 on most small sensor DSLR’s). Anything less than that is deemed a wide angle, and anything more that that is called a telephoto. To produce the kind of shots you are looking for you want to shoot in the telephoto range. That’s not to say that you can’t shoot portraits with a wide angle; you can shoot things however you want. An interesting thing happens when you change the perspective of the lens. The depth of field given to you by the aperture of the lens will change. An aperture of f5.6 with a wide angle perspective will put almost everything into sharp focus(*), that same aperture of f5.6 on a telephoto setting will be much different. My favourite perspective to shoot portraits with is between 85mm and 200mm, or about 55 – 150 on most small sensor DSLR’s.
The other possible reason relates to the (*) in the above comment; focus. Where you have selected your focus and how far away the other elements are in your image will surely affect the look. The closer the main element is to the lens, the more dramatically the focus will fall off behind them. Take a look at the macaroon photos from a few weeks ago. I shot those with a 90mm close up lens. I was about 30cm(12″) away from my main point of focus. From there the focus fell off VERY quickly. That is an extreme example, but shows the point I am making.
With those shots you are trying to take of your kids, try a few things. First pick a lens that will give you a moderate telephoto effect AND give you the largest possible aperture. Most camera kits come with two lenses. One that is wide to mild telephoto, usually 18-55mm (f4-5.6). The second lens is usually something in the 55-200mm(f4-5.6) variety. Now move between 55mm to 100mm on the lens and find the look you like. NOW position your kids and yourself in a way that the closest thing in the background is at least 15feet away, or as further. This will give you the effects you are looking for. The big key here is getting a lot of physical separation between your subject and the background (for this desired effect).
As far as your comment about editing, I agree. Having started out shooting film you had to get everything right without getting a chance to preview it. There was digital editing, but is was costly so I never did it. That meant if you wanted an image to look a certain way the ONLY way to do that was to do it RIGHT in the camera the first time. The beauty of digital is the ability to experiment and learn with such a quick feedback loop. The downside is quite frankly, laziness. Never has it been easier to experiment and learn how cameras work, but it seems like the knowledge level is going backwards. Keep asking questions, keep trying, keep learning!
Thank you Darryl for your knowledge and encouragement. I will put all of this into practice now.
I will contact you with any more questions I have.