Aperture mode versus Manual

[Ben Prusinski]

As a newbie to DSLR cameras, the folks at Backscatter advised me to shoot for a while in Aperture mode until I gain experience shooting with my Canon 5D Mark III rig. I have the strobes outward for wide angle and behind the dome to avoid reflections. So for wide angle, get close to a fish and use strobes but for F-stop maybe between 3-10? Any tips?

 

[Interceptor121]

Google 'depth of field'

 

[Blackwood]

f/3 (odd number, I'll call it 2.8) to f/10 is a *huge* range.

That's like saying "I'm going to Vegas, should I bring something between 1000 and 60000 dollars?"

Photography is equal parts technique and creativity. Selecting aperture and shutter speeds have both creative and technical implications. They each affect both the look and exposure of your image.

If you're going to shoot aperture priority, just start playing around and seeing what happens.

From an exposure standpoint, wider aperture (eg 2.8) => faster shutter speed; narrower aperture (eg 10) => slower shutter speed.

Interceptor mentioned Depth of Field (the total range of acceptably sharp focus). From a creative standpoint, wider aperture = lesser DOF; narrower aperture = greater DOF. If you're close - say a couple of feet - to a fish and shoot at f/2.8(or 3.3 or even "3" if your camera will set that) with an ultrawide lens, the DOF will be a couple of feet. Up at f/10 it's probably practically infinite.

Underwater, I suspect that shutter speed will trump aperture creatively. An intentionally narrow or wide Depth of Field won't mean much under motion blur. Perhaps shutter priority would do you better. That said, I always suggest manual - it's the best way to learn. But if you're aren't comfortable with that and don't want to blow an expensive dive vacation sure, use the semi auto modes.

It behooves anyone not shooting automatic modes to memorize the common f numbers and shutter speeds. Whole values for f-stop are 0.7 (though no such lenses have been made in a long time as far as I know), 1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32 and so on. If you are good with patterns you'll see that each value is sqrt(2) times the previous. Going from 1.4 to 2 reduces the area of the lens iris by a factor of two; it lets in half as much light. Going from 16 to 8 increases the area of the lens iris by a factor of 4; it lets in four times as much light. Cameras will often allow 1/2 (such as 3.3 between 2.8 and 4) and 1/3 stops (such as 3.2 and 3.5 between 2.8 and 4). I largely ignore them - just memorize the whole values.

Along with those go the shutter speeds. There's no sqareroot in there, so it's easier to think of. If a shutter is open for 1/125 of a second, it lets in twice as much light as one open for 1/250 of a second, and half as much as 1/60 (ish) of a second. 1/125, 1/250, 1/500, 1/1000, 1/2000, 1/4000, 1/8000 etc. (if it's like my 5D2 and indeed most DSLRs, the fastest shutter your camera will do is probably 1/8000; the slowest without an external control is probably 30 seconds). And like aperture, there are values in between.

So combine those two things. If you are shooting at 1/125, f/16 (with ASA/ISO ~100, this is common for a clear sunny day topside) and notice that it's exhibiting motion blur, increase the shutter speed. Going to 1/250 will stop the motion better, however it will cut the exposure in half, so you have to go to f/11 to compensate (or you could double the sensitivity, but that's a topic for another day).

If you're shooting at 1/4000, f/2 and decide you want a narrower DOF, you could go to f/1.4. But that would double the exposure, so you'd have to go to 1/8000 to compensate (similar caveat about sensitivity).

I think I've gone overboard. Sorry if that's information overload.

 

[PatW]

There is a problem with any automatic mode. The mode will select the F stop for you. The F stop might be wide open resulting in a far too narrow depth of field for the photo you are trying to take. Also, if there is plenty of light, the apeture mode may stop down your lens so much as to cause a loss of resolution from diffraction (this is sensor size dependent). My camera, a DSLR, loses some resolution with any F stop over 8. Now, there are times, especially in shooting with a macro lens, where stopping the lens down more is vital even if I lose some resolution.

With a wide angle lens, you might do better just shooting with a F 8 or so and varying your ISO to correct for the lighting conditions.

 

[Blackwood]

camera, a DSLR, loses some resolution with any F stop over 8. .

I've always wondered if the worries about stopped-down diffraction effects are overblown.

Ansel Adams, Edward Weston, Imogen Cunningham, etc all shot narrow apertures (in fact they and some others formed a club called Group f.64), and I've never seen criticism about aperture diffraction associated with their work.

Have you actually noticed a degradation of quality when stopping down past 8?

 

[00wabbit]

There is a known issue with the aperture controls in the 5dMarkIII. I suggest you send it to me for an evaluation. I will ship it back to you at the end of the dive season.

Welcome to the long road of learning.

 

[Interceptor121]

I am amazed that the op got a DSLR and does not feel comfortable using manual controls
DSLR have large sensors and using the appropriate settings makes a huge difference to the outcomes unlike compacts where there is always depth of field and in the worst case you get soft colours
I think you could start with a good book I recommend martin edge guide as it covers DSLR equipment and the rest in a complete but simple fashion

 

[fisheater]

I am amazed that the op got a DSLR and does not feel comfortable using manual controls
DSLR have large sensors and using the appropriate settings makes a huge difference to the outcomes unlike compacts where there is always depth of field and in the worst case you get soft colours
I think you could start with a good book I recommend martin edge guide as it covers DSLR equipment and the rest in a complete but simple fashion

+1 for the Martin Edge book, Underwater Photographer (4th Ed.)

Just finished reading it. It covers the theory, the mechanics and the thought processes of underwater photography. It's excellent and inspiring.


Sent from my iPad using Tapatalk HD

 

[JahJahwarrior]

I don’t see why there is any concern with getting an SLR and not knowing how to use it yet.

Lets compare it to car driving, where we can assume that those under 15 cannot drive, once at 15 you can get a learners permit, and you have to use the learners permit for a year before you can get your license. And, there are sets of rules you must follow in order to not only survive, but to keep your car without scratches and to not get a traffic ticket.

You don’t expect someone who is 10 years old to know how to drive, do you? No, they can’t drive yet. A 10 year old probably has a bike, though, and is around cars. So, they learn some of the rules of the road. They see their parent get at ticket or maybe a friend gets in a crash, but they don’t drive themselves. At 15, they apply for a learners permit and are allowed to drive, but there are some extra rules they follow such as a special curfew, and I know some areas require them to have a special shaped license or put a sign on their car that they are on a learners permit. They can still get a ticket, though. Finally after a year they become a licensed driver with less restrictions but many of the same rules of the road to continue following.

Someone without a camera still learns some of the basic rules by being around photographers. They might learn to clean orings before closing the housing, and to charge the batteries, and bring a card reader. They see that you have to not get task loaded with a camera, or else you can run out of air, or do something else to hurt yourself underwater. But, they don’t shoot photos themselves.

Then, they get a point and shoot. Maybe they don’t have a strobe, so they shoot mostly in shallow water, macro stuff with a handheld light, or silhouettes against the surface. They have to start following many of the rules of photography, such as not flooding their housing, or getting distracted and losing their buddy. But, we all understand if they violate some simple rules of the road, such as forgetting who has the right of way at a 4 way stop—maybe they get a lot of photos out of focus, underexposed, etc.

After some time, they feel ready to try out an SLR, but even then, they are new. They get a nice car, but they stick to local driving, and don’t drive late at night, or eat while driving. They get where they need to go, using some automatic modes, as they try out new things, such as controlling multiple strobes, that they didn’t do with their “learners permit.”

Of course, the analogy is not perfect—some people are happy with a point and shoot and get amazing pictures. Others skip the point and shoot and get an SLR and do fine. It’s just an attempt to point out that you can’t expect someone to know how to use features they’ve never had before, and it’s ok to start out with automatic modes.

On the rig I use, it’s a hassle to adjust both shutter speed and aperture in manual mode, so I’ll often use aperture priority. When the shots aren’t what I want, I set the aperture to what I’d like then jump to manual where I can adjust shutter speed easily. Aperture priority has gotten me some great shots.

At the end of the day, I have never once asked a photographer what model of camera, what size sensor, what lens, what strobes, what housing, and what mode he or she captured an amazing picture with, then changed my opinion of the art. A great picture is a great picture, regardless of those things. I might ask because I want to know how I can take similar pictures, but I don’t scoff because someone got a picture I’m jealous of in aperture priority instead of manual mode.

The most helpful thing to understand how manual mode works is to shoot in it, a lot! Practice on land to save yourself time underwater. I do find it helpful to identify what you have to press to change this or that, and find out where those things are on your housing. I’ve found some things just aren’t easy to do with only two hands on an Ikelite housing. And, some features I don’t use often, I find myself struggling to remember underwater. Once you identify something you couldn’t figure out underwater, practice it for a while on land to build that memory.

Also, make sure the histogram is turned on! The flashing background helps make it obvious when you guess wrong on exposure, and I’m a big fan of making it easy to catch mistakes.

 

[Blackwood]

I don’t see why there is any concern with getting an SLR and not knowing how to use it yet..

Agreed, I was perplexed by that comment. My first camera was an SLR (albeit not digital).


Also agree regarding the histogram. It's perhaps the single greatest learning tool available in digital cameras.

... Once you learn how to read it. Too bad so many google results will turn up Expose To The Right tutorials (getting the best signal to noise ratio is all well and good, but confuses the issue for someone just getting started).