Why a camera's auto mode seldom produces good underwater pictures

In part four of my blog series about what makes a good underwater camera I talked about the advantage of having a full manual mode available that will allow you to change all the camera's settings. In this blog I'm going to take things the other way and explain why taking underwater images using the Auto mode puts the photographer at a disadvantage.

When starting out taking a camera underwater, you are adding an additional task load to your diving. Because of this it's best to get used to having the camera in your hands on the dive and learning to share your attention appropriately between your diving and your photography. Setting the camera to Auto and just taking snaps to start off with isn't necessarily a bad thing. 

But what you'll find is that often your pictures won't look as good as you'd like them to. This isn't something to worry about, it may be partly due to technique but a lot will be because of the camera being in Auto. 

People attending our workshops or speaking to us at the talks for clubs we do, will often show us images and ask for advice. We can very often tell when someone has been shooting on Auto, by the look of it. The picture will have a blue or green cast to it depending on where it was taken. The subject will usually be somewhat blurred and part or all of the picture may be too bright or too dark.

This happens because the camera is struggling to deal with the lighting conditions underwater. Without using Custom White Balance (either in camera or editing software), a coloured filter or a light source, images taken deeper than a few metres will appear blue or green because most cameras struggle to automatically adjust colour. Some cameras recently, in particular the GoPro 6 onwards have upped their game when it comes to Auto White Balance especially for video. But for stills these cameras lack a lot of other abilities and to most intents and purposes action cameras are often basically a camera permanently set to Auto.

The picture may be too bright or not bright enough, because in most cases the camera will calculate exposure based on what you point the camera at. If you aim the camera at something that is mainly dark you'll find the brighter areas around the subject will be overexposed and if you go for something bright you'll have darker areas underexposed. 

How the camera sets exposure is also why you may find that a lot of your images are a bit blurred. This is because to deal with the different light levels underwater the camera will adjust itself in something of a juggling act to let more or less light in when taking the image. If you are pointing your camera at say a dark coloured moray eel swaying slightly in its hole, in Auto the camera will do a combination of open the aperture wider, slow down the shutter speed and increase the ISO. For more on what these are see the blog about full manual mode I mentioned earlier.

A wider aperture gives you less depth of field in your shots. This basically means a narrower band of what you are pointing the camera at will be in focus. As I discussed in my last blog about shallow depth of field this can be used to good effect but it also makes it harder to get a small subject to be in focus. Slower shutter speed is more likely to show movement up in the picture as blurring, whether it is moving fish or the camera moving as you hold it. And higher ISO while making the camera more sensitive to light can make pictures appear more grainy as so-called noise appears in the image.

You’ll also find that if you turn your flash on the camera will choose settings based on including the flash light in its exposure calculations. This usually means that it will limit its shutter speed to no slower than 1/60sec and ISO will go low typically 100 or 200. Then the camera will try to balance the exposure by adjusting the flash output and the aperture. This may mean more consistent results than if you aren’t using flash because the settings won’t change quite so much between subjects.

Moving around the dial or along the menus from Auto you’ll usually find the Scene settings. These are a range of automatic modes that are somewhat optimised for a particular type of photography. Lots of cameras do have an underwater mode included, with a fish symbol denoting it. Sadly, most of these are only really useful for shallow water of no more than a few of metres where the mode will take out a bit of blue tinge from images. They do vary considerably from one camera to another. I would say that if you have one on your camera and you are taking it underwater for the first time, there’s no harm in giving the underwater mode a try. It will probably perform slightly better than the normal Auto.

But in the long run the more control over the settings of your camera you exercise the more predictable your results will be.

Once you are comfortable with having a camera with you move on to a mode that will let you exercise more control. Start with the Program or Program Auto mode, denoted by a P on your mode dial or menu. This will let you Custom White Balance, control exposure compensation and set ISO. Then move up through Aperture and Shutter Priority to eventually using Manual mode. You'll be surprised once you start using Manual how easy it really is.

If you want more specific advice or have a suggestion for a blog subject feel free to get in touch our email is info@alphamarinephoto.com. Do the same if you'd like any information about the workshops we run or the equipment we sell (Workshop dates are on our Events page). Anyone with an interest in photography is also welcome to join the Alphamarine Photography Q and A Facebook Group.

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