Apr 162011
 

Looking at some pictures my friend Wen shot at Olivia’s birthday party, indoors at a gymnastics-themed place, I realized that I should have opted for a higher minimum shutter speed – even if it came at the cost of having a higher ISO setting, and thus more noise, in the pictures.  After all, you can add some noise reduction after the fact, but there’s no blur reduction!  However, this made me realize that despite the existence of a large number of shooting modes, none of them actually does what I want.

Basically, every Nikon DSLR (and many film SLRs before it; same story for other brands) has the same core set of shooting modes that you can choose from:

D7000 shooting mode dial; picture by PowerShot S90

Almost regardless of which camera you pick in the line-up, you’ll essentially get the equivalent of the dial you see above:

  • Professional-oriented bodies – the D300, D700, and D3 models and variants – only give you the M/A/S/P  shooting modes.  These modes are the ones that it really makes sense to use anyways once you get the hang of things; more on this below.
  • The D7000 pictured above adds a couple of programmable user  modes (U1/U2), an Auto mode where the camera picks everything, a useless flash-off mode (just push down the pop up flash or turn off the attached flash!), and access to scene modes (with pre-defined settings for portraits, landscapes, etc).
  • The D90, D5100/5000, D3100/3000, and other cameras even back to my film-based F75 have the same M/A/S/P options, Auto, plus individual icons for selecting different scene types directly from the mode dial.

So basically, you always get M/A/S/P, and depending on what model you have, you might also get some automatic modes which are probably not why you decided to buy a DSLR anyways (but can be handy for learning).  The above is Nikon’s terminology, but Canon and other manufacturers all basically seem to take the same approach.  Each of the M/A/S/P modes (and most scene modes) control how aperture and shutter speed are chosen when taking pictures.

If you’re not familiar with how these affect what your pictures look like, it’s well worth understanding.  I can’t do the topic justice here, but I’ll provide a one-liner for each anyways.  Aperture controls how “open” your lens is – the wider the aperture (lower f-stop number), the more light it lets in, but the less depth of field you have (not as much will be in focus).  Shutter speed controls how long the sensor takes a picture for; longer (slower) shutter speeds let in more light, but if the object you’re taking a picture of moves during this time, you’ll get a blurry shot.  It’s all a trade-off – you generally want more light and it’s a question of what you’re willing to pay for it.

With that in mind, the M/A/S/P modes are very simple to understand:

  • M – Manual.  You set both aperture and shutter speed to what you want.  Set them wrong, and your pictures will be too dark or blown out.
  • A – Aperture Priority.  You set aperture, and the camera picks the matching shutter speed to get the right exposure (brightness).
  • S – Shutter Priority.  You set the shutter speed, and the camera picks the aperture.
  • P – Program Auto.  You set neither, the camera chooses for you – but allows you to adjust between options that allow an equal amount of light.  For instance, 1/200th @ f/4.0 is equivalent to 1/100th @ f/5.6, in terms of how bright your picture will be.

I usually use Aperture Priority, because aperture usually has the most impact on what you pictures look like.  Sometimes you want everything sharp, sometimes you deliberately want the background to be blurry to focus on the subject.  Many lenses aren’t quite as good wide open, but you get less light if you use a smaller aperture. Indeed, the difference between an inexpensive lens and a ridiculously expensive one – unless you look really close – is often in how wide an aperture is supported.  Stop down to f/8.0, and many lenses are hard to tell apart.

By contrast, shutter speed matters but only really makes a difference in one of three scenarios:

  • If you are holding your camera in your hand (usually the case, especially for non-photographers like me), then a slower shutter speed increases the chance of a blurry picture because YOUR hands are shaking.  The rule of thumb here seems to be to shoot at a shutter speed that’s the inverse of your effective focal length.  So if you’re zoomed to 100mm, then use a shutter speed of at least 1/100th. Technologies like vibration reduction [VR] (called image stabilization [IS] on Canon) minimize the effect of camera shake and allow you to get away with longer shutter speeds without inducing blur.  You almost never want camera shake in your pictures.  For this reason, there’s a minimum shutter speed you typically want.
  • If you are taking pictures of a fast moving object, like your kid playing sports, your kid jumping around in a gym, or your kid just being your kid, and you want to freeze the action, you may need an even higher minimum shutter speed.  Much depends on how fast things are moving, but 1/200th to 1/500th of a second is around what you may need.  Getting this fast is a challenge indoors in low light, though.
  • If you want deliberate blur, you may want a lower shutter speed.  Non-photographers will rarely use this, but often in pictures where there’s flowing water, you’ll see this done on purpose.  Sometimes, some amount of blur of this kind is also desirable to highlight motion.

Okay, so the above is a bad explanation of photography basics that was much longer than intended, though necessary to make the point I opened with. The problem that I see is that each of the M/A/S/P shooting modes is a legacy from the days when shutter and aperture were the only things you could adjust. Every digital camera, even the one in the iPhone, now gives you at least one if not two added options:

  • ISO – this controls the sensitivity (gain) of the sensor in your camera.  It used to be impossible to change this in the film days, except by changing the roll of film in your camera, which few people did at least until they finished the roll.  Now, it’s as easy as changing anything else.  ISO is also the easiest choice to make – higher ISO means more noise (grain) in your images, so you always want the lowest ISO necessary for the aperture & shutter speed you’re using.
  • Flash output – the camera can actually control how much power to use when activating the flash, which is pretty handy both for not blinding your subject, not draining your batteries faster than necessary, and getting the picture you want.  How this happens is a whole other complex topic, which we can skip for now.

So, with all that in mind, here’s how I wish my camera worked:

  • First I pick the aperture I want, knowing that wider apertures means more light, less depth-of-field (i.e. blurry backgrounds), and perhaps less sharpness (depending on the lens), with narrower apertures doing the opposite.
  • Then I pick the minimum shutter speed I want (unless I want to blur some flowing water, in which case I will just want to set the shutter speed to a fixed value). This the faster of:
    • The camera shake minimum speed, which in turn is determined by the focal length (longer focal lengths = higher required shutter speed), whether or not the lens has VR (and how good it is), and how steady the camera users hands are.
    • The subject movement speed, which can vary from totally still, to a speeding race car, all the way up to the average movement speed of your kids.  (Relative to the camera, the kids indeed can move faster than a racecar!)
  • Then I want the minimum ISO necessary to get the right exposure given the above.

This seems pretty logical (to me, anyways!).  Flash complicates this otherwise simple formula, and the way the D7000 handles this is one of my few complaints about the camera, but that’s a topic for another day.

Can the camera work this way?  No.  Despite all those shooting modes and lots of menu options, it actually can’t.  There are two options that come close, and both depend on a feature that exists on Nikon cameras and most others called Auto-ISO, which automatically raises ISO if shutter speed falls below a specific value that you can set. The two options, both of which have their own failings, are as follows:

  • Use Aperture Priority mode, with Auto-ISO on, and the minimum shutter speed set to whatever you need.  This mostly works,  it’s how I have my camera configured by default, and it’s how I take most non-flash pictures.  What doesn’t work?  Ergonomics.  While you can normally change shutter speed with one touch by rotating the rear command dial (which is easily accessible), you can’t change the auto ISO minimum shutter speed this way.  The latter has to be changed via a deeply nested set of menus.  Even if you assign one of very few programmable buttons to take you directly to this menu option (as I do), you still need to navigate through things on the back LCD and scroll through all available shutter speeds to find the one you want.  Did you zoom in or out?  Different required shutter speed.  Did your kid switch from the balance beam to the trampoline – or did they stop for a second allowing a portrait shot?  Vastly different shutter speed requirements.  It’s just impossible to use the menus to adequately adjust for this on the fly.  At Olivia’s birthday, I stuck with a default of 1/100th – 1/125th for most shots as it was impossible to switch shot-by-shot, but this was more than necessary for some and not nearly fast enough for others.
  • Use Manual mode, with Auto-ISO on.  In manual mode, the minimum shutter speed you set for Auto-ISO doesn’t do anything, so shutter will be whatever you tell the camera to use, and you can set the shutter speed via the rear command dial (which means you can adjust very quickly without menus).  What’s the problem?  Now you’re setting the absolute shutter speed, not the minimum shutter speed.  Since Auto-ISO can’t go lower than the base ISO of your camera (ISO 100 in the case of the D7000), very bad things happen once you get to base ISO – any additional light means your picture will be overexposed and blown out, potentially quite severely so.  But ironically, you want the lowest possible ISO for the best image quality – so if it is bright enough for you to get to base ISO in at least some shots, you are constantly trying to adjust your shutter speed for the lowest speed that is both higher than your minimum requirements and doesn’t cause overexposure.  This is near impossible, and you will lose pictures if you try (at least I did, in dynamic situations).

What I’m asking for is actually trivial to implement – in Aperture Priority mode with Auto-ISO enabled, allow the rear command dial (which sets shutter speed in manual mode) to set the minimum Auto-ISO shutter speed (and show this in the viewfinder).  Sadly, I have no friends or family who work at Nikon, so they’ll never see this, and even if they did, updating firmware is sadly not Nikon’s thing.  If the firmware was open source, I’d add this myself, but unfortunately it isn’t.

If I wasn’t just tweaking the current interface, then this whole mess of M/A/S/P + ISO vs. Auto-ISO + aperture/shutter settings could be simplified much further:

  • One setting for aperture, which can be a specific value like f/2.8, f/5.6, or AUTO.
  • One setting for shutter speed, which can be any valid shutter speed or AUTO, plus a qualifier of whether the shutter speed is a fixed value or a minimum requirement.
  • One setting for ISO, which can be a specific value like ISO 100, ISO 400, or AUTO.  I’d probably just replace the mode dial with this.

The above would take fewer controls and less menu items than exist now, and is essentially about just treating ISO as an adjustment like any other setting – which it has been, ever since digital cameras were introduced.  It’s kind of amazing that with so many knobs and options, the simple one I want isn’t somewhere to be found amongst them!  Just as amazing is that even compact camera designers, like Canon with my PowerShot S90, has the same idea about how things should be (Av = A and Tv = S in Canon’s terminology):

 

Canon PowerShot S90 mode dial, shot by D7000

Well, here’s to hoping that some future iteration of cameras simplifies things down and just does what seems to make the most sense, at least for how I use the camera!

 Posted by at 10:28 am

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