So let's dive in and start with a picture that is deceptively simple looking but needed a firm grasp on the exposure triangle to keep the image steady, and the background a pleasing blue.
One of the benefits of dedicated underwater photo trips is the freedom to dive at certain dive sites, whenever you'd like. And here myself and my friend, my model for the dive, and one of our guides Adel, planned to get up at before first light, to enjoy the wreck to ourselves, but also to get some shots, just not possible when the light is higher in the sky.
As this is at the propellor and at the deepest part of this dive, this was shot within five minutes of our descent into the darkness, and just before 6am.
By the time we reached the prop, the background had lightened a bit, but would have still resulted in a black background had I chosen the mythical 'go to' settings that some advocate to newbies.
And even on this day itself when I came up from the dive some people about to get in asked me for some 'go to' settings, and I did my best, but if you read the last blog I talk about why this is useless in most circumstances underwater.
Especially in this case as the sun had moved a lot higher in the sky since we got in, and was still moving of course, as you'll know at either end of the day the light changes a lot very quickly.
So me even having a stab at a guess for them would be really no help, and so why it's best for everyone to learn the 'exposure triangle' as it really is the key to photographic understanding and freedom.
How we see this picture here below is how I experienced the scene, and I wanted to replicate this in my shot.
This experiencing the image in our minds eye is often where we can slip up.
Because what 'we' see and what the 'camera' sees is usually at great odds, especially in low light, either at dusk or dawn, or inside caverns or wrecks.
This is because our brains, eyes and optic nerves are actually adjusting and adapting to the situation. And as our night vision kicks in like this, we get a very distorted impression of what is happening in front of us, and to the uninitiated this causes a lot of confusion, as unhelpfully, at least in these cases, the camera LCD screen. will also be serving up a much brighter image than what is actually there.
This is because technology has come on in leaps and bounds, and cameras are able to see in the dark a bit like us, but only for the purpose of viewing, and not for the taking at least not without a big quality hit.
To give us this nice bright image the camera has to raise the noise (graininess) levels a huge amount, and whilst this image on the screen looks ok a few inches across, it really isn't up to the closer scrutiny of a computer screen or a print.
What is important to you in the shot?
In the shot above, my main priority was having a blue background to my liking, and I knew that I needed to drop the shutter speed in favour of raising the ISO to achieve this.
Because I knew that in this particular case the combo of aperture, shutter speed, ISO and flash output would deliver the result I needed.
This only comes when you've grasped the basics of the exposure triangle and applied it to the shot you're trying to get.
If there was a school of fish moving around in the picture, I'd have to make a choice, and in the first blog there was exactly such a situation, with my friend Adel in the background, taken a few minutes after the picture above actually.
In the end as I wanted a similar blue background, I used the movement of the fish as part of the shot. And so I had to set the camera to second curtain flash synchronisation, this meant that, whilst you can see that the fish are blurry, they have been frozen with the flash too, but the blur is behind and not in front of the fish which would have looked less logical.
And they have caused this blur, because they have moved this far in the duration of a 1/15 second.
But me (my camera), Adel and the rest of the scene haven't moved in that time.
I'll do a separate blog about deliberately using this effect and in greater detail about second curtain synch in another blog at some point.
If I'd wanted to have no secondary blur in the picture from the fish movement. I'd have had to pick a higher shutter speed, at least a 1/125 second in this case, which means I would have either had to have a much darker background, or I would have had to raise the ISO to 800/1600, and suffered a drop in quality.
I'd also have needed to lower the flash output to compensate too, assuming I kept the aperture at f5.6.
In the next shot, my priorities and the situation was different, for a very specific couple of reasons.
What on earth is dynamic range? I'm sure a lot of you already know, but there'll be an equal amount scratching their heads at this term.
Dynamic range is the range of light to dark in your scene, from the brightest white to the darkest dark, and your cameras ability to record it.
And cameras have got better at this as time has progressed, but they can't hold a candle to an average human being and our ability to see a much bigger range of brightnesses even than the very best camera sensors out there.
It's another very geeky subject so by all means give it a Google, but suffice to say you don't need to be an expert to get what effect it can have on your pictures. All you need to be aware of its that it's happening, and it has an influence on your shots. especially in extreme light variations like in a cave or inside a wreck.
In the side by side shot below I've tried to show you what the actual image I took on the day looked like when I reviewed it on my camera screen.
You see, camera sensors have never been that good at recording the very bright highlights in a scene, and left to their own devices, and shooting in auto has usually meant that the bright areas of the shots have been what we call blown out, or clipped. This is seen as an ugly white blob or patch, where the brightest bits are, and the detail goes completely.
So my advice in these types of shot, is to expose so that the highlights are kept with detail in them, this will mean that the rest of the picture will look very dark, and you sometimes won't be able to see any detail at all in the dark areas on your camera screen.
Camera sensors are better able to record these darker areas though, and there will still be some data in these parts of the shot that will look completely black on screen
So you'll need a leap of faith here, and what youre doing is effectively hugely underexposing to keep the bright areas recorded. Which for shots like this is our priority.
This is a two part solution to the problem, as to get these types of shots you'll need to process your pictures, a great reason to shoot RAW in the first place, and to learn how to edit.
You can push modern cameras quite far, as seen in the above example, so you can now achieve a lot with much less than you needed even a few years back.
Phil talked about the pocket rocket, the mighty Canon G9Xmk2 in his last blog, which combines a 1” sensor, huge by traditional compact standards, all in a small form factor, easy to house and use underwater.
Also relatively inexpensive by comparison to it’s peers, and a huge jump in technology from the previous generation of compact cameras.
Then we’ve got the increasingly popular ‘mirrorless’ cameras with ranges from Olympus, Panasonic and Sony.
These have given us cameras with sensors the same size as in DSLR’s so indistinguishable from a quality standpoint.
And again of course for us photographers that take our cameras underwater, these cameras are much smaller and easier to house, less expensive too.
And what I've used to illustrate these most recent blogs.
This tech isn’t going away, and the big camera manufacturers are now onboard, with Nikon having just announced the Z7, it’s very first full frame mirrorless camera, and Canon can’t be far behind, as Sony have been producing full frame mirrorless cameras for a while now, and they’re taken very seriously within professional circles.
This all filters down to more domestically orientated kit, and every generation sees big quality improvements, so we’re very lucky right now to reap these rewards with pocketable kit that delivers results unthinkable only a few years back.
The upshot of all this is that you’re able to produce pictures on cheaper smaller kit in conditions that you can barely see in, and not just show them off to your friends but use them commercially and in a professional context too.
If you want more specific advice or have a suggestion for a blog subject feel free to get in touch, details on how to do this are on our contact page. Do the same if you'd like a quote for equipment or to book on one of our courses or workshops (dates are on our Events page). Anyone with an interest in photography is welcome to join the Alphamarine Photography Q and A