Hi there, first I have to say that I changed plans a bit because I will sometimes not be able to stick with the topic to the exact same day every week. I found it especially impossible to write legal articles without my books at hand, for example when I'm travelling. So as this blog focuses on photography there will be some weeks where I post more articles with new photos and those related to cameras and techniques. I will try, though, to switch to society and law in other weeks therefor a bit more.

Today I want to talk about digital noise and why it is important to modern photography. First of all, what is digital noise? Digital noise appears in digital photos sometimes when there is not enough light available, mostly in dim situations or at night. You can easily spot it in a photo as colour blotches and grittiness, the images is not as clean as those photos taken in bright daylight.

Why is it that way? You can compare digital noise to the grain in film photography. The bigger the grain in film was, the more sensitive it was to light, so the dimmer the surrounding could be in which you were going to take a sharp photo in. In digital cameras the film is replaced by a digital sensor of different sizes, actually a silicon chip with millions of little pixels, themselves comparable to the grain in film. Film sensitivities are expressed in ISO values, that's the same in digital. The higher the number the more sensitive now the digital sensor. ISO values normally alter in doubling steps, f.e. shooting in daylight is perfectly fine with ISO 100 with every possible camera. ISO 200 f.e. is double the sensitivity of ISO 100, so you can shoot with half the available light or with double the shutter speeds. It's getting interesting when you need to change to settings of ISO 1600 and above, because then big DSLR have a clear edge in image noise. But are the pixels getting bigger, too, like the film grain with rising sensitivity? No, they stay the same size, the higher sensitivity is achieved by amplifying the signal the sensor reads out from each pixel that collects the light. Complicated? Well, it's actually quite simple. Compare it to an audio amplifier. When you had a really muted recording on a Compact Cassette you had to increase the volume of the amplifier, that way the noise was getting louder, too. With a digital sensor it's the same, when you have only very little light available and recorded by the sensor, it needs to be amplified a lot. That way all steps during digital image processing that add noise to the image get amplified as well, for example the noise from the circuitry of the sensor, from heat, base noise levels and more.

Put simple, the lower the light the noisier the image. What can you do about it? First, to be honest, noise has never really been a problem for me, in film more grain could even add some atmosphere to the image and I find myself delibirately adding grain afterwards to an image that was clean in the first place. People are different, though, and there are situations where noise is not desired, for example in the church when you shoot the wedding couple kissing. It's always great to bring back clean images from situations you wouldn't have thought they were possible. Still, it's always a question of personal acceptance. Higher sensitivities also allow for higher shutter speeds, needed to freeze people's motions. Shooting in a dark room without flash you need very high ISO values to retain fast enough shutter speeds to not get blurry images. Image stabilizers for example let you shoot stationary subjects with longer shutter speeds but they can't help when shooting people in dim light.

On the other hand it really depends on when you find noise in an image obtrusive. Women often don't care about things like noise and I have to agree, when you take a great photo its noise levels become secondary. Still, easy things to consider when chosing a camera and lens combination to shoot people in dim light are: The bigger the sensor the lower the noise levels, DSLRs have sensors sometimes 10 or 20 times larger than a normal point and shoot. I show you what I mean. The following images are taken with a premium compact, a Panasonic LX7, that has a bigger sensor than normal compacts (7,44mm vs. 6,17mm) and a DSLR, a Canon 5D Mark III with a sensor 21 times bigger (36mm). Both where shot at the same shutter speeds, aperture levels and a very high sensitivity of ISO 3200. The above image is from the point and shoot, the lower one from the DSLR ...

And here are the two at a pixel level ...

As you can see you get much cleaner images with a big camera. But you can also make great images with a small one, it lies in the eye of the beholder. To give you a perspective I will shoot the Canon with an ISO level of 25600, 8 times more sensitive to light, have a look how they compare now ...

Noise levels are quite comparable with the 5D being sharper because it got more pixels. Referring to noise this means you can shoot with the same shutter speed in light levels 8 times darker or you can shoot with 8 times the shutter speed in the same light levels, here a 1/400s with the LX7 and a 1/3200s with the 5D. Pretty cool, huh!?

Second very important thing to consider for noise free images are fast lenses. Most zoom lenses already start slow and get even slower when zooming in. By slow I mean the shutter speed needed to let in the same light to the sensor. Those zooms often start at an aperture value of f/4 and slow down to f/5.6. What does that mean? Well, I will talk about shutter speeds and apertures another time but imagine the aperture of a lens as the pupil in the human eye, the smaller the pupil the less light gets in or the lower the light the bigger the pupil gets. It's the same with lenses, different lenses have different maximum aperture values, slow zoom lenses being quite dark. When you shoot in dim light you need slow shutter speeds to compensate for the little light coming through the lens, thus you get blurrier images of people or you need to increase the ISO level and get noisier images. Take a fast prime lens and you get more light to hit the sensor, that way you can retain fast enough shutter speeds to freeze people's motions or/and need a lower ISO level and get less noisy images. For example when you zoom in your zoom lens to shoot a portrait your lens aperture becomes a quite small f/5.6 at 55mm. Take a 50mm prime lens, that only costs 120 €, you get an aperture value of f/1.8. That's over three times the aperture value compared to the zoom, means over 8 times more light comes through the lens, you may shoot in 8 times lower light levels with the same shutter speed or you can shoot with 8 times the shutter speed in the same light. This gives you the ability to shoot with lower ISO levels and still get faster shutter speeds to stop motion. For example, when you shoot your slow zoom at 55mm f/5.6 with ISO 3200 in a bar your shutter speed could be a slow 1/30s, too slow to freeze motion and also too slow to compensate for camera shake. If you put on your 50mm prime and shoot at f/1.8 you could alter shutter speed to a 1/80s, fast enough to freeze motion in portraits and fast enough to compensate for camera shake. And you can set the ISO down to 800 and still get the same bright images as with the zoom with much less noise in it. Cool, eh? So, if you don't like noise, buy a camera with a big sensor and a fast lens and you're set to shoot in dim light without flash.

Alright, now you should understand what digital noise means and what effect it has on your images.

See you next time

KIKI

Hey there! As I have have told you this blogsite will be focused on photography. I will host images from out of my life, work, travels and more. I will also be reviewing cameras and equipment, will write about what gear to use and why, which programs and plug-ins will get you the results you want faster and I will give a lot of tips regarding camera technics and what‘s important for a good picture. I will refer to my favorite sites of Ken Rockwell or imaging resource as well, that are specialized on testing cameras. My focus will be more from a photographers perspective. Some days of the week I will also write some articles about what‘s going on in the world regarding ethical and socio-political issues. I would also like to explain basic labour rights and Grundrechte (those articles will be in German) to you people that are not that familiar with law but as employees actually directly affected, maybe once a week and give some news on changes to labour laws and union developments and what that means for the normal employee ...

But today is a photo day and there‘s millions of things to be told when it comes to photography. But there‘s also some very simple things that you should always keep in mind. For example it‘s the photographer that takes the picture and not the camera. The most expensive camera will be totally wasted when you do not care about the most basic tasks that are necessary for a good photo. A great picture comes from a great vision and not a great camera. You can actually make winner shots even with a cellphone. So that‘s something to keep in mind.

More difficult things like „How to make a winner shot“ are to be discussed later on ;-). I will start with something basic that‘s also important to know when picking up a camera:

It‘s the focal length.

What does focal length mean? Focal length is indicated in millimeters on camera lenses, popular focal lengths are 50mm or 35mm, 24mm or 16mm for example. Those lenghts express the distance between the focus point (at which the beams of light come together in a single point and spread mirrored again from there on) and the recording medium, in digital cameras it‘s the sensor. The recording medium itself can have different sizes, the smaller it is, the smaller the focal length has to be accordingly to give the same field of view. Traditionally the focal lengths refer to the 35mm film format of classic cameras, the exposed part of the film was 35mm wide. Today 35mm equivalent cameras are those called fullframe, like Canon‘s or Nikon‘s Pro cameras for example. Their digital sensor is actually a tiny bit bigger, measuring 36mm.

If you now take a 50mm lens for example the focal length point is 50mm away from the image sensor. With a fullframe 36mm sensor you will get a so called normal field of view, pretty close to the human eye (actually I think the human eye field of view is somewhat wider, at least subjectively). The focal length point and both ends of the sensor shape a triangle. If you take a smaller sensor now, found in less expensive cameras or point&shoots, with the same focal length the angle in the triangle becomes smaller, resulting in a narrower field of view. You could actually draw the sensor on a paper as a line of say 36mm and draw the focal lenght point of your choice next to it with the according distance, in this case 50mm. If you extend the lines coming from both ends of the sensor beyond the focal length point you get the idea of what would actually be captured in the real world.

With a 24mm lens for example the distance between the focal length point and the sensor is roughly half of a 50mm lens, shaping a twice as wide angle in the triangle described above, thus you get a twice as wide field of view. Take an even smaller focal length and the field of view gets even wider.

To give you an idea of how different focal lengths look like I took a couple of photos from out of the window of our flat with various focal lengths, starting with an ultrawide 12mm, then 16mm and so on, have a look ...

The main cameras I use are Canon‘s 5D models which also have 36mm sensors. Lenses used with those bodys keep the same field of view they have originally been designed for. Apart from the technical aspects explained above the focal lengths or lenses you use have a very strong impact on the look of your images and it often depends what subject you are going to photograph which lens is best suited. If you shoot animals for example a very long zoom lens is needed to get very detailed shots.

On the other hand I once read a photographer say you get the best images with a wide lens and get as close as you can to the subject. Actually that‘s pretty much what I think everytime I look at really dramatic images. Because you get much more in the frame with a wide lens you can immediately see if a photo was taken with a long tele lens or a wideangle lens. To get people resonably sized into the frame you need to get very close bringing the recipient or viewer right into the scene. This makes photos with a wideangle lens so much more special and intimate or even spectacular. I always find images with long tele lenses a bit boring because it‘s obvious that the photographer has not been very close to the subject. When shooting a wedding for example for me it is very important to be as close as I can to the couple to bring back the most intimate and touching images of this special day.

Documentary often refers to 35mm lenses to be the best suited for this style of photography. I am using a 35mm lens a lot as well, also on weddings, my most used focal length, though, is probably 24mm. I love wide angles because it brings you right in the middle of the action. In very tight places I could imagine using 16mm or even 12mm more often, it happens, though, that a lot of my images are taken at 24mm. For artistic portraits I normally use a Canon 50 1.2, that gives you spectacular background blurs, but that‘s some topic for next time.

See, there‘s much to say about focal lengths ...

See ya later

KIKI