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With a few little tricks you can shoot really fun shots in really poor viz
 

Last week, we kicked off our new series talking about what most divers face regularly—visibility often sucks. We might dream of the Maldives, but our reality is a rough shore dive full of sand and surge, or maybe a local quarry full of cold, green water. None of this should matter though; you can still have a great photo dive in conditions that might politely be described as less than ideal.

In Part I of the series, we told you to get close to your subject. Brilliant, right? Oh, come on, we had to start somewhere! Okay, so you’ve decided to shoot macro or close-focus wide angle (CFWA). Now what? Well, this week, we will focus on things that can be done in your camera.

Lousy visibility means less light. How do you overcome this? Crappy conditions also have a habit of creating backgrounds that are just horrible. Have no fear though; there is an easy way to fight back. Here then are a couple more things to keep in mind when preparing your drysuit for that epic reservoir dive you are planning for next weekend.
 

To get good natural light shots you are going to need to crank up that ISO, especially in bad viz

Increase Your ISO

What is ISO? It stands for the International Organization for Standardization. Yeah, we know, it should be IOS. Either way, it is merely a measure of the sensitivity of your sensor to light. Lower numbers mean less sensitivity to light, and vice versa.

Probably the easiest thing to do to compensate for darker conditions, increasing your ISO can draw a scornful reaction from the peanut gallery. Not many years ago, when sensors were called film, there was an evident correlation between higher ISO and increased graininess in pictures. With the introduction of digital photography, the increase in grain, or rather noise, on an image with a high ISO often rendered an image unusable.
 

This was shot at about 130 feet and in poor viz, so a high ISO was essential
 

Well, things have changed. The little brains inside the latest-gen cameras have become very adept at handling higher ISOs without increasing noise too much. Some cameras are better than others, but the basic premise is still the same: You can shoot far higher ISOs now than you could just a few years ago.

The only way to figure out how high your camera can go is to try it. On your next dive, try shooting at 800, 1000, 1600, and 3200. If you can, you can go crazy and try 6400 or even 10,000, but those will probably suck even on great cameras. If you have a newer camera, you will probably come back very surprised by what you find. You’ll likely be able to shoot immaculate images at ISO 800 and possibly 1000. If you’ve got a higher-end camera, even 3200 will be very solid. This bump in ISO will give you a lot more room to play with your aperture and shutter speed, which is the next step.
 

The background to this 8-inch gun on the USS New York was hideous, but f/1.8 came to the rescue

Make Your F-stop Really Low

F-stop—the ratio of focal length to the diameter of the opening of your shutter—is just the numeric value that corresponds to the aperture setting. The smaller the number, the more light you let in, and the shallower the depth of field. Setting that f-stop as low as you can will allow you to shoot better in low-light situations.

By combining a high ISO and a low f-stop, you can shoot in much darker conditions. Well, that is ideal for when the visibility is something between pea soup and milkshake. It doesn’t matter if you are shooting macro or CFWA, the result is the same. When shopping for a lens, try and find one with a minimum f-stop of below 3. These are usually heavy pieces of pure optical glass awesomeness, and you can shoot some amazing shots with them. My preferred lens for wreck shots is an 8mm with a minimum f-stop of f/1.8.
 

An f/1.8 lens, plus a super-macro diopter, gives this shot a paper-thin depth of field
 

If you are new to photography, you can set this by using manual or aperture priority mode. (If you’re not sure, just use Google to find an endless number of how-to videos on your camera and how to set it.) The low f-stop will also allow you to add blur to the background, depending on where you place your shot and focus. Having a very shallow depth of field will enable you to tackle that other problem of hideous backgrounds: If the background is blurry, it looks cool and artsy, even though it may be a pile of cinderblocks!
 

The tight focus on this xeno crab gives a pleasant, blurry background. It was actually just rocks
 

Hopefully, you picked up an interesting nugget or two of wisdom from this week’s installment. Next week, we will get more into backgrounds and getting creative with your lighting.
 

Andrew is a diver, photographer, writer, and trophy husband. Oh, he is also the Editor of DPG! You can find him on all the usual social media stuff if you feel like harassing him.