Reef Photography

[techdiver]

I know some of you have cameras, but maybe you can't get it to take a good photo of your reef. I will post a few tips for you guys to try.

I bet most of you have point and shoot cameras. You will want to use the "Macro Mode" for getting close shots of coral. If you do not have a macro mode, then try to use manual mode and experiment with it. When getting close in on your subject, you will probably find the manual focus to be your best friend so you can choose the exact focus point. Auto-focus isn't always that great for macro photography. Depth of field will be one of your greatest obstacles in close-up photography. Depth-of-field determines how much is in focus before and after your subject. When taking Macro shots with coral, the depth of field can often be so shallow that you can only get a small portion of the coral in sharp focus. You will battle with this in reef photography. I can address this more latter.

Coral shots will turn out best if you have the following:

-Tripod (this keeps your camera steady to help get tack sharp pictures)
-Macro Lens (macro mode for point-and-shoot cameras)
-Shutter release cable, or wireless remote (takes away camera shake when pressing the shutter release button)
-Lens pointed level with your subject, perpendicular to the glass (shooting at an angle distorts the subject)
-White balance set correctly (critical when shooting in JPEG format, not critical for those shooting in RAW as it is adjusted when processing)
-Adequate Depth of field (Get as much of your subject in focus as possible)
-Make sure your shot composition makes your subject stand out (you don't want a distracting background)


I'll post more information for those that are interested.

Take care,
TechDiver

[techdiver]

Aperture

Think of the aperture like the iris of the eye. In really bright light your iris closes down to try to compensate for this amount of light. If it is too much light then it is blinding and would be an example of overexposure. In a dark room your iris opens up to allow more light in. If you give your eyes time to adjust, you are able to view objects with very little light. If it is too dark you can't see which would be an example of underexposure. You want enough light so the film or sensor can see the details throughout the image.

The aperture on your camera is at the very end of the lens right before the mount. They are interlocking leaves that form an opening that can open and close just like an iris. The size of the opening is represented by f-stops. It may sound confusing, but the higher the f-stop number, the smaller the opening of the aperture. An f-stop is "the ratio of focal length to effective aperture diameter."

Depth of field refers to how much of your image is in focus. 1/3 of the depth is generally in front of the point of focus while the other 2/3rds is behind the point of focus. The higher the f-stop (smaller the aperture opening) the more depth of field you will have.

Portraits, for example, generally require a shallow depth of field. So you would use a smaller aperture (or f-stop) to have the subject in focus and blur the background. This is more pronounced when you zoom in on the subject.

Landscape photos usually require the opposite. You would set a very small aperture (high f-stop) to try to make everything in focus.

Also note that extreme open and closed apertures usually do not produce the best results. Each lens can have a sweet spot of a stop or two back from each extreme.

You guys can try taking shots of the same subject with various f-stops to see the difference. Just remember that you will be limited by the amount of light available, whether you are using a tripod for slower shutter speeds, what ISO setting you use, and if you have image stabilization.

Here are aperture settings that are a full increments:
f2, f2.8, f4, f5.6, f8, f11, f16, f22, f32

Try taking the same shot using 3 different apertures from above. You can accomplish this with Aperture Priority (Av), Program mode (P), or Manual mode.

Depth-of-Field Photo Comparisons

I am using a Canon XSI with stock lens hand held. You really need a tripod to get tack sharp pics with lower shutter speeds, but I currently do not have one. It may be a while since I am purchasing scuba gear, so bear with me here. The focal length settings I include simply reflects how far I am zoomed in.

Aperture f5.6 Shutter 1/100 ISO 1600 Focal length 46mm


Aperture f8 Shutter 1/50 ISO 1600 Focal length 46mm


Aperture f11 Shutter 1/25 ISO 1600 Focal length 46mm


Aperture f16 Shutter 1/13 ISO 1600 Focal length 46mm


Aperture f22 Shutter 1/6 ISO 1600 Focal length 46mm


Notice the shutter stays open longer as the depth of field increases. The last one gets enough depth of field to start bringing a paly into focus behind the main subject. FYI: These pics were not cropped. It is large enough that it wasn't necessary.

[dzones]

HEYYYYYY I know that coral!

and nice guide by the way

[techdiver]

Originally Posted by dzones

HEYYYYYY I know that coral!

You should definitely know that coral. It is doing well now and has gained some size and weight.

Originally Posted by dzones

and nice guide by the way

Thanks.

[dzones]

Well I am glad he is doing well. I know when you got him my imperator had done a number on him. He made a fine comeback i see.. Dr Marcus.

[SNAKEMANVET]

One of these days I will have a camera that can take pics like Marcus and Dave.Point and shoot doesn't compare.

[05grandprix]

Don't feel bad snake I don't have camera except on my cell :-(

[techdiver]

Exposure

There are 3 primary ways in which to control light. The settings you use can create totally different results.

1. Aperture - this controls depth-of-field (We'll go more into this later)
2. Shutter Speed - this controls the ability to stop motion or show it
3. ISO - the higher the number, the more sensitive it is to light

Underexposure: This happens when you do not get enough light to properly expose your image. It can be from using an f-stop too high (too small of an aperture opening or a shutter speed that is too fast.
There are certain circumstances that fool the metering in the camera that can cause this.

Overexposure: This happens when too much light hits the film or sensor. This can happen when you use to long a shutter speed or the aperture is opened too much (small f-stop setting). There are also circumstances that can fool the metering into this situation also.

There is a relationship between all 3 of these. If your camera's metering is correct and gives you the suggested settings of:
ISO 400 Shutter Speed 1/500th Aperture f8 then you can change one of the parameters as long as another parameter is changed to balance it back out. So you could change the Shutter Speed to 1/250th of a second (which is faster and lets less light through) as long as you change the Aperture to f5.6 (opens more to let more light in). You can also change the shutter to 1/250 leave the aperture at f8 but simply change ISO to 800.

Each ISO setting progression, Aperture full increment f-stop, and full increment Shutter Speed represents on stop difference. One stop is either a halving or doubling of light. Don't worry if it is confusing, we'll explain them more in detail and make it easier to understand.

[techdiver]

ISO

ISO is a measure of film (analog) or sensor (digital) sensitivity. Just like in the good old days when you had 100 / 200 / 400 speed film, the digital sensors in cameras today use the same method for denoting sensitivity. For those not familiar with the film speeds, the 100 speed film was more for outdoor as it takes more light or longer shutter times to develop. The 400 speed is much more sensative making it better for low light or fast shutter speeds.
The 200 was a compromise since you could not adjust ISO on the fly like today. You finished the roll of film and carefully choose the ISO roll based on your next shots. Today,ISO speeds up to 3200 are common.

The higher the ISO, the more noisy or grainy the photo becomes. There are settings on certain cameras and software that help with this, but your best resolution for enlargement comes from lower ISO. There is always a trade off in photography so you have to determine what your goals are.

Low ISO settings:
Generally you would use a low ISO setting if you have a stationary subject or one that is moving a little in very bright light.

Low ISO is usually used for shooting portraits indoors when using bright studio lights. You then have the option to enlarge this photograph to poster size.

High ISO settings:
Let's be honest. Most of your pictures will never be enlarged to poster size, so don't be scared off from higher ISO speeds. High ISO does start introducing noise or graininess the higher you go, but it allows you to capture things that would otherwise be impossible.

High ISO can be used for existing light photography (without a flash) and also allowing much faster shutter speeds. Use this setting along with holding the shutter open to capture fireworks or lightning. If it isn't very bright outside you can still crank up that ISO to freeze the swing of that little league batter.

You can use software to help clean up the noise from higher ISO settings when you process your files.

How to work ISO into your shutter and depth of field equation:

Just as aperture and shutter speeds work on moving a stop up or down, ISO also represents a stop of change as you progress up or down the scale.

Remember that a stop represents the halving or doubling of light.

Example of using ISO to your advantage:
Let's say that you are taking a shot of a coral that is moving and the tentacles come out blurry. If the part not moving is in focus, then you simply need a little faster shutter speed to stop the tentacle motion for a nice focused frozen frame. Here is how you would do it.

Beginning with ISO 400 Aperture f5.6 Shutter 1/60
Let's say your problem is that you are getting the blurring of the parts of the coral that are moving, but you are wide open at an aperture of f5.6. You could move up one ISO setting which would make the sensor more sensitive allowing you to adjust the speed one stop faster. Here is what you would end up with:
ISO 800 Aperture f5.6 Shutter 1/125 if that wasn't enough to freeze your image then:
ISO 1600 Aperture f5.6 Shutter 1/250

When one variable changes, another has to adjust to balance it out for proper exposure.

We could take the same beginning setting above and introduce a different issue:

Beginning with ISO 400 Aperture f5.6 Shutter 1/60 sec
Let's say in this example that the shutter is fast enough because it is a hard non-moving coral that is your subject, but you aren't getting depth of field to pull all of it in focus. You would then move to a higher ISO making the sensor more sensitive to light which allows you to close down your aperture for more depth. It moves one full stop like before. Move up one ISO and adjust the Aperture one full f-stop up (which is a smaller opening letting in less light). Here is the one ISO higher setting:
ISO 800 Aperture f8 Shutter 1/60 sec
If you need a little more depth then:
ISO 1600 Aperture f11 Shutter 1/60 sec

[Rendos]

Another tip.

*Clean your aquarium glass. Everything will show in your pictures.

[mr.badams]

Maybe i can get that dslr, im sure it takes great pics

[techdiver]

Originally Posted by mr.badams

Maybe i can get that dslr, im sure it takes great pics

Yes it will. It is actually a step up from my DSLR. I need to get mine out and start using it more.

[Cruezn]

Wow, nice write up. Thanks for the advice.

[techdiver]

Originally Posted by Cruezn

Wow, nice write up. Thanks for the advice.

Thanks.