Now that Santa/Ctuthlu/Flying Spaghetti Monster has given out all their presents it’s time to have a look at why all your DSLR-xmas photos are turning out crap while your smartphone pics are decent…and what to do to avoid this issue. Furthermore, I’d like to bring up a comment from a friend of mine who just got a DSLR and is now hoping she can take great shots from the far-end of the stadium of the next Madonna concert, because the last batch taken with her phone were crap. (I’ll get onto this a bit later in the post).
I’m making a few assumptions in this article, and please note that if you don’t understand the terms below then do read on because what I’m on about does apply to you.
Assumptions:
- You’ve got a DX-sensor camera. (this doesn’t refer to the brand and indeed as long as you have a DSLR, it matters little which company made it for the purposes of this 101).
- On a sidenote, it matters little if you have an entry-level DSLR or a bit better, e.g. Nikon D3300 vs D5x00 or whatever Canon makes nowadays, because the sensors are largely the same for our purposes and that’s what matters
- You have kit lens, usually a 18-55 and maybe a 55-200 or 55-300, or something along those lines.
So let’s get started. I’ve touched upon this in a previous post but the one key tricks about photography that users need to understand is that from a technical POV the act of taking a photo means light particles hitting the sensor (film on old cameras). In order to take a photo that’s just about not too bright or dark the camera needs to apply settings that allow just about enough light to hit the sensor. This can be achieved through 2+1 ways:
- modify the shutter speed
- modify the aperture
- +1: modify the amount of noise you allow
If this makes little sense then think of a water bucket that is being fed through a pipe. Shutter speed means how long you have the pipe open for, aperture means how large your pipe is (larger pipe = more water / unit of time), and noise is…well that doesn’t particularly apply in case of water but think of how much sand in your water you find acceptable. [the more sand you’re willing to take the less water you need to fill the bucket].
There are options on your camera that control each of the three settings I just mentioned: you can set the camera to S-mode where you have to specify the shutter speed (and the camera will figure the rest), A-mode where you need to specify the aperture (and the camera will figure the rest), and the ISO sets the noise level. Most beginners set the camera to automatic, and then get surprised that the photos are poor. This comes down largely to two reasons:
- The camera isn’t omniscient, it doesn’t always get things right (this is where you come in the question/picture [pun indented])
- Depending on a number of things the camera usually attempts to balance between what it thinks is too dark and what it thinks is possible to hand-hold. You will therefore more often than not find that your camera will, in auto mode try to force slow shutter speeds hoping your subjects are stationary. The reason fro this is that the camera tries to enforce the rule of reciprocals – detailed below but that only works in well-lit conditions.
- Your lens are crap (little to do about this but it’s useful if you understand why).
A quick answer as to why your phone takes better photos than your DSLR does is because the lens on your phone are better for specific purposes. The lens you got with your DSLR are almost always zoom lens, and your phone’s camera’s lens are almost always fixed. Fixed lenses are de facto better at taking photos in dark conditions because the amount of material that has gone into their construction needs to make sure they’re great at doing a decent job on one zoom ‘range’, whereas zoom lenses…well they have a zoom so it needs to function okay over a variety of focus lengths. It’s a bit like expecting the Terminator to be a great baby-sitter and cook as well –> it won’t be great, but it may be okay — its main purpose will still be terminating people.
Explaining the previous thought in a more technical way, the aperture of a fixed lens is better, it’s like having a bigger pipe for your water bucket. Looking at your phone or DSLR’s lens, the f value signals the aperture. The closer to 0 the better- usually you won’t get closer than 2.0ish at least not unless you buy prime lens. In photography we talk about stops when it comes to the aperture and the rough idea is that for each stop, the lens lets through half of the available light than before. 2.8 is letting through roughly half of the light than 2.0. Below is an overview of generally accepted stops. A jump between each of them will result half (or double) the amount of light hitting the sensor. (kudos)
| f/N |
0.5 |
0.7 |
1.0 |
1.4 |
2 |
2.8 |
4 |
5.6 |
8 |
11 |
16 |
22 |
32 |
You may take the mental note/comment that an iPhone’s lens is a lot smaller than your DSLR’s lens but that’s largely because the sensor in the two cameras as differently sized as well. We can project the sensor & lens sizes to be similar for the sake of calculations – this will be referred to 35mm equivalent sensor size (because old film cameras and professional DSLRs have a ~35mm film/sensor size). Now, an iPhone 5S has an aperture value of f2.2 and a 35mm equivalent of ~28mm – newer models are roughly similar. So your phone is roundabout 28mm/f2.2. The kit lens that comes with a new Nikon (or Canon) is a 18-55 lens coming in at 28mm/f4 (kudos).
If you think about the idea that taking a photo == light particles hitting the sensors, then it’s easy to understand that although a dimly lit room may be enough for the human eye to see things, it’s still a lot less bright than even a cloudy day outside. This is a lot worse for the camera that is a lot less lenient in terms of darkness than your eyes. When you can still see things, the sensor is likely to be struggling big time.
The reason why your phone does decent pictures and your camera doesn’t is because you have a fair number of stops between 2.2 and 4.0 to go. You need to understand that to go from 2.2 -> 2.8 -> 4.0 will roughly mean that your camera is getting ~0.25x the light your phone is getting. The funny thing is, there’s very little you can do about this aside from buying more expensive lens (there are ~28mm f1.4 lens around but they will cost a lot more than your camera’s body).
Now what can be done to make better photos…one thing is that you can use the flash. That results in more light.
The other thing is that you can set your camera to S-mode and specify a shutter speed. As a rule of thumb, on a professional camera (not yours that is) a reciprocal value of the lens’ length can be hand-held without motion blur (subject to no jumping kids!). This would mean that on a pro body you can hand-hold a 28mm lens for 1/28th of a second. In reality because the sensor is smaller in your camera you need to multiply this value by 1.5 (sorry – and actually it’s 1.6 for Canon but let’s keep things simple) – so you can theoretically hand-hold a 28mm lens for about 1/42th of a second, which isn’t a valid setting so you’ll need to attempt 1/50th. The problem with that setting is that you’ll find that unless Santa also got you a pack of high-powered LED lights it’s going to be a bloody dark picture.
Here’s where to noise comes in. If you don’t know what photograpic noise is then think of the grain you see on a dark photo. The more grain = the more noise. Noise in simplified terms allows to substitute the need for more light while sacrificing quality. There’s a direct correlation between the noise (ISO level) setting and how much light you’ll need to produce a non-dark photo. Double the noise and you’ll need half the shutter speed at constant aperture to produce the same photo. Since your camera’s sensor is physically larger (in terms of sq mms rather mpixels) than your phone’s sensor you can allow for a higher noise-level before getting terrible photos. Noise level can be either manually set on a DSLR or the camera can decide what’s the best. My personal experience is that levels up to ~ISO3200 may be acceptable on a camera. 1600 should be okay.
Summing up so far, how to take decent xmas pics on a kit-lens? [18-55]: set your camera to S-mode, calculate your lens length * 1.5 and experiment with ISO. Also tell the kids and pet bunnies not to jump around.
Having read this far if you feel you’ve lost the will to live, you may stop, else read on. Many of the newer lenses have a VR or IS mode (same thing). This is image stabilisation or whatever other names the marketers came up for it. It does what it says on the label and you can check if you have VR/IS lenses by looking at them, if you do it should say somewhere on the lens. The key point is that VR allows you to eliminate some of the motion-blur caused by shaky hands (but not by jumping kids) and still allow for a steady photo. Once again depending on what marketers claim you can gain up to 4 stops of magic by using VR lenses. In human terms this means that using the previous example of 28mm @f4.0 = 1/50th exposure, you can theoretically take decent photos with 1/50 * 2 * 2 * 2 *2 = 1/800th of a second with a modern VR lens. There are plentiful reviews to read about whether a certain lens can do 4 stops or not but in general a 2 or 3-stop advantage is credible without further research – you need to read more on the topic or more rather experiment you get the idea anyway. So if you got a VR/IS lens you can try something more brave, or lower the ISO value and get a quality improvement-tradeoff, up to you.
I did want to get back to my friend’s question/comment about doing photos from faraway at an indoors concert and “will that work?” – well probably not is the answer – but it’s worth a try. She was specifically pondering on getting a DX body with a kit lens plus a 55-300mm f/4.5-5.6 VR lens. This means on the 300mm end your lens can do f/5.6 .
Using the calculations outlined above you need to multiply the 300 by 1.5 crop factor = 450mm. In theory, not counting for the VR you’ll therefore need a 1/450th (in reality 1/500th as the prior isn’t a valid selection) shutter speed to take a non-blurry photo. Concerts are rather a hit-or miss as they are really dark places, but the singer is quite well lit. I won’t go into calculations over how far you need to be to cover whatever part of the visual field @450mm but the point is that on a concert that’s dark and your subject jumps around constantly there’s almost no way you’ll get a decent shot at 1/500th of a second.
So what can be done: if you don’t have a VR lens then you’re doomed. It won’t work.
But…a realistic 3-stop VR reduces your shutter speed needs by 500/2/2 = 1/125th. That will mean that at 1/125th of a second you should not get blurry photos subject to zillions of other things. The problem is that concerts are dark, so you’ll need a lot more light than that because you’ll likely end up with dark photos. Sadly this is up to experimentation but for sake of calculations we can assume that if on a decently lit day (which is not a concert) you need ISO100 @ 1/125 @ f4.0 to do a good photo then you’ll need 4 stops worse than that, which will be ISO100-200-400-800 for your equivalent photo at 1/125 @ f4.0. The problem you’ll have is that 1/125th of a second may still be blurry because your subject isn’t stationary at all. You can do quick and simple estimates here: assuming constant f value, 1/125@ISO800 produces the same amount of light as 1/250@ISO1600 and 1/500@ISO3200 [do attempt but you may not like the outcome].
You get the gist. There’s magic that can be done on day one with a DSLR if you understand how the photo comes to existence from a technical point of view. There’s a lot more to this, RAW photography, lights, primes, whatevers, but this should set you on course.
Any Cs or Qs shout. Shares welcome.
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