How do I control macro (and other) depth of field?

On a Flickr discussion the other day, someone asked what the best way was to control and improve the limited depth of field when shooting with a macro lens.

Pollen In case you’re not familiar with the term, macro photography is very close-up photography.  Technically, it’s photography where the size of the image on your sensor is at least as big as real life, but most people use the term more loosely.  I’m not interested in picking technical nits here, so I won’t be picky.

If you’ve ever done any macro photography, you know that getting your whole subject in focus can be tremendously challenging.  When you’re shooting macro, your depth of field is extremely tiny, often measured in millimeters or fractions of millimeters.  Just a little bit of movement from you or your subject and everything goes to out-of-focus hell in a windblown handbasket.  Even when you have a perfectly still subject and your camera rests firmly on a tripod, shooting your subject at the wrong angle will get you in trouble.  For an extreme example, check out the larger version of the grains of pollen on the left.  The camera was at a slightly different angle than the pollen, and you can see the changes in focus at the top and bottom of the photo.  (You can also see some excellent examples of sensor dust if you look closely at the top right and bottom left corners.)

Back to our question:  how do you control depth of field when you’re shooting macro?  My response on Flickr was that you do it in exactly the same ways that you do for any other shooting:

  • choose your aperture wisely
  • manage your camera-to-subject distance
  • choose your focal point wisely
  • when you can, use depth of field preview to check your image before you shoot

We should all understand the first one by now– choose your aperture wisely.  If you’re new to Stop Shooting Auto! and you aren’t completely familiar with aperture and how it works, you should go reread this lesson and the few that follow it.  In short, choosing a wide aperture (a low-numbered f-stop like f/4) will give you a very shallow depth of field.  Choosing a narrow aperture (a high-numbered f-stop like f/16) will get you much more depth of field.

Don’t forget that there’s an online depth of field calculator that you can use.  If you click around on that site you can also find a PC version, an iPhone version, a PalmOS version, and several other tasty tidbits.

People often overlook the camera-to-subject distance when they think about depth of field, but it’s a key parameter.  Try pulling up the DOF calculator and enter the following values:

Camera format:  Canon Digital Rebel, XT, XTi, XS, XSi
Focal length: 100mm
Selected f-stop: f/11
Subject distance:  30cm

Note that 30cm is right about one foot.  Click the calculate button, and you’ll see that your depth of field goes from about 29.9cm to 30.1cm, for a total of .26cm.  That’s about two and a half millimeters, which doesn’t leave much margin for error.

Leave everything the same, but change the subject distance to 60cm.  Now, your depth of field is from 59.4cm to 60.7cm, for a total of 1.29cm. That’s still not a whole lot, but it’s almost five times what you had when you were a foot away.  Try it at more normal focusing distances, like ten feet and twenty feet, and you’ll see that even there, doubling the distance between the camera and the subject gives you about a 4x increase in your depth of field.  In short, if you’re having trouble focusing, move back.

IMG_5835Choosing your focal point can make a huge difference when you’re working with limited depth of field.  It’s often true that your camera can do a better job of focusing than you can, but it can’t choose what to focus on.  If you really care about a certain part of the image being in perfect focus, your best bet is to put the lens into manual focus mode and do it yourself.  This will give you absolute control over where you’re focusing.

In this image, letting the camera focus might well have meant that it chose to focus on a deeper part of the spadix (the sticky-outy part for non-botanists), leaving the tip out of focus.  This might have been an interesting effect, but it wasn’t what I wanted.

Don’t forget the depth of field preview button on your camera.  If you have a shot lined up, and you want to see how much of it will be in focus, press the depth of field preview button.  The viewfinder will get darker, sometimes very dark, but if you have enough light on your subject you can probably squint and get a good idea of how much of the image is in focus.

If you just can’t get enough depth of field, there are a couple of things you can do.  First, you can add more light to the subject.  I often use desk lamps for macro work, since I can aim the light wherever I want it.  Flashes are always an option, though they can be challenging to use.  If you’re outdoors, get your subject out of the shadows, or use a white reflector (even a piece of paper will work) to reflect light onto the subject.

Putting your camera on a tripod will let you use a longer exposure, and therefore a smaller aperture.  This only works for subjects that are stationary, though– don’t try it with moving objects or you’ll wind up with a blur.

And finally, if your camera is parallel to your subject it will be easier to get the image in focus.  If your subject is at an angle to the front of the lens, move the subject and/or the camera to get a better angle.  Look up at the pollen photo for an excellent example of what happens when you get this wrong.

While depth of field issues make macro photographers pull their hair out (and then photograph the strands), it’s challenging in lots of other situations as well.  Learn to control it and you’ll have a powerful tool for taking better photos.

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Evolution of photographic maturity

I just finished packing my camera bag for a shoot, and as I chose gear I thought about how packing gear was an interesting reflection of a photographer’s maturity.

Novice photographers carry everything they own.  At first it’s easy, because they probably have one camera and one lens, and leaving either of those behind doesn’t make sense. Very quickly they add accessories, and those always go in the bag.  And then they get a second lens, and maybe a third, and they get a bigger camera bag to carry everything.  I confess that I have a behemoth camera backpack that I use fairly often.

After a while a photographer either accumulates too much equipment or comes to his senses (or both) and realizes that he doesn’t need every single piece of gear he owns with him every time he takes a picture.  Often this is caused by the sheer impossibility of carrying everything he owns, but it’s still an important growth step.  The photographer is now planning his shoot before he goes out, so that he can carry what he needs.  OK, often it’s so that he can leave behind what he’s sure he doesn’t need, but it’s still progress.

The third stage of maturity comes when the photographer packs carefully for a shoot, uses every major piece of gear he packed, and doesn’t wish for anything that he left behind.  This means that not only is he thinking about what he needs for the shoot, but he’s predicting correctly.

I’m about a 2.3 right now– I plan carefully, and sometimes get it right.

How about you?

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Would you like to write for Stop Shooting Auto?

Do you enjoy Stop Shooting Auto?  Is there a subject that you’d like to see discussed here?  Would you like to write about it?  If so, SSA! would love to hear from you.

I’m looking for a couple of guest bloggers to contribute occasional articles to the site.  Articles should fit with the general theme of the site, which is tutorials and lessons to help novice dSLR shooters use their cameras more effectively.  There’s no minimum requirement– you can write one article or several.

Sensor cleaning with a blower bulb You should be able to write clear, engaging articles that can be easily understood by and are relevant to beginning dSLR owners– think clear, simple explanations wtih very little technical jargon.  You should be able to use WordPress well enough to create and publish your articles, though I can help with that if necessary.   If your articles require sample photos or illustrations, you should also be able to provide these.  It goes without saying that you should own the rights to any content you contribute.

Legalish details: you will retain ownership of any material you contribute to the site, and will grant SSA a non-exclusive license to publish it in the blog.

SSA! is largely a labor of love on my part, and the tiny revenue stream that it generates doesn’t even cover expenses.  I can’t afford to pay for contributions, but I can offer the glory of seeing your name in pixels and the satisfaction of helping people become better photographers.  Hey, it’s not much but it’s what I have to offer.

If you’re interested, drop me email telling me a little bit about yourself and what you’d like to write about.  My email address is pattib (at) pattib (dot) org.

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How to annoy your humble author

I’m in London for a long weekend, and spending a lot of time in tourist areas while I’m here.   As you might well guess, this means there are lots of people walking around with digital SLRs around their necks.  In the past year or so, dSLRs seem to have really moved into the market that digital point & shoot cameras used to occupy.

I’ll tell you a little secret, if you promise not to be too terribly shocked.  I’m a gear snob.  When I see cameras, I check them out.  What kind of camera is it?    Is it old or new?  What lens is on it?   Does the user look like they have any clue?

I’ve seen several low-end dSLRs on this trip, but I’ve also seen quite a lot of higher-end ones.  40Ds and 50Ds seem to be surprisingly popular.  I’ve seen spotted a 5D Mark II.  I pay more attention to Canons than other brands simply because I’m more familiar with the product line, but I’ve also seen plenty of Nikons and a few others.  Almost all of the cameras I’ve seen have tended toward the newer end of the spectrum.

Since I started writing this blog, I’ve also gotten into the habit of glancing at the exposure mode dial on top of the camera.  What I’ve seen makes me both angry and sad.

Nearly every camera I’ve seen this trip has been in some sort of automatic mode.  Most of them are on green boxes, or on one of the silly picture modes.  I even saw someone with her camera in flower mode while I was standing in line waiting for theatre tickets.  About five seconds after I noticed this, she picked up the camera and took a picture of a statue on the other side of the square.   It will probably work out sort of OK for her, since a bright sunny day gives some exposure latitude, but it’s far from optimal.

I did see a few people with their cameras in aperture priority mode, which is what I would choose if I was walkabout in a city.    See f/8 and be there for more discussion.

I’m sure that a lot of these people will get home and wonder why they spent all that money on a camera that takes sort of OK pictures.  That makes me sad.

Oh, yes.  Remember the guy with the 5D Mark II?  He had close to five thousand dollars worth of equipment around his neck, and the camera was in green box mode.  That just pisses me off!  If you’re going to drop serious coin on a high-end camera, learn to use the bloody thing.

And if you ever see a pink-haired woman on the street checking out your camera, make sure it’s not in green box mode.  You’ll make me happy.

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Should I buy a new camera? Which one?

As I said in my last entry, I get a lot of questions from a lot of people who want to upgrade their dSLRs.  These people often have the vague notion that a better camera will take better pictures, but that’s often not the case.  As we’ve already seen, expensive cameras aren’t filled with Magic Crystals that cause the camera to take perfect pictures.

This particular series of articles was triggered by a reader named Erin, who asked me the following question:

This has been a great information source for me thank you so much! I feel I am at the max on my newbie camera (Canon Rebel XTi) and need to get a more sophisticated camera now – scary thought :( but I am glad I am realizing the limitations, it shows I am learning something. Do you have any recommendations for the next step camera?

We had a good discussion about it, which you’re welcome to read for yourself if you’d like.   Like many people, I suspect that Erin was vaguely expecting that I would recommend the Cakon D283M20LMNOP as the perfect upgrade from her XTi.  Instead, I responded by asking questions.

When people want to upgrade their camera bodies, I generally try to talk them out of it.  As I said in my last entry, the quality of a photographer’s images are far more dependent on the skill of the shooter and the lenses used than they are on the camera body.  I would hate for someone to spend a lot of money on a new camera only to be disappointed that they didn’t get a miraculous improvement in their images.

Does that mean that you should never upgrade your camera body?  No way.  I’ve done it twice since I bought my first dSLR, and I haven’t regretted either one.  I generally ask potential upgraders one major question, and that question is big enough that I’m going to ask it in bold:  In what way are you feeling limited by your current camera?

What I’m looking for in the response is for them to articulate a concrete reason or reasons why the current body is holding them back, and then why a new body would help them overcome that hurdle.  There’s no right or wrong answer except for vague, fuzzy notions about better pictures.

Here’s the story of my first dSLR upgrade:

It’s 2 a.m.  I’m standing on top of a hill in Henderson, Nevada, trying to get the perfect panoramic image of the Las Vegas skyline.  I’ve been playing in the World Series of Poker for two days straight, and I’m exhausted.  I’ve also just made some money in the event, so I have about ten grand burning a hole in my pocket.  It’s surprisingly cold for June.  It’s windy.  I’m freezing my butt off, and I really just want to get the shot so I can go to sleep.  Because it’s a panoramic image with lots of shots, I have the camera in manual everything mode, including manual focus.   This should be easy– I level and align the tripod, focus, set the exposure, then just rotate the camera while taking a sequence of exposures.  I’ve done this dozens of times, and I can do it in my sleep.

Well, except for one thing.  I can’t focus!  I was using a Canon Rebel XT, and that camera has a viewfinder that wants to be postage-stamp sized when it grows up– it’s really tiny.  I have a very clear memory of watching the red neon on the side of the Rio swim before my eyes, and I just could not get it to focus.   I’m generally an extremely calm person, but I quite literally found myself yelling obscenities at the camera, and barely managed to keep myself from throwing the camera over the side of the ravine.

I bought a 5D about 12 hours later, and I have no regrets.

When you read that story, can you see where I was feeling limited by my body?  I bet you can.  The small viewfinder made it too challenging for me to focus manually.  I do a lot of manual focus work, not just panoramas, so this was a big deal for me.  There were other reasons as well, chief of which was that the Rebel’s high-ISO performance was giving me too much noise.  I do a lot of indoor, low-light shooting, so having better performance at higher ISOs would give me more latitude with those shots.  Did it work?  Just today I was notified that three of my images have been selected for an upcoming art show.

So going back to my question– yes, you should upgrade when you can articulate a clear set of reasons why your current body is holding you back, and why a new body will help you overcome those problems.  Making that list is really good discipline, since it helps you think through the issues and come to a decision.  You might find out that you don’t really need a new body after all, just a change in the way you use your current one.

Articulating your reasons for upgrading has a really nifty second benefit, too– it’s a perfect shopping list for your next camera.  If you know you need a camera with a larger, brighter viewfinder, you can narrow your focus to just cameras that fit that need.  If you need faster shooting, say because you do a lot of action sports shots, that’s a deciding factor.  If you need a camera that also cooks your dinner and whispers sweet nothings in your ear, well, go read science fiction.  Or invent one and get rich.

Oh, yes.  There’s one other “bad” reason for upgrading– I need more megapixels.  Unless you’re doing lots of printing at large sizes, you probably don’t need more megapixels.  More megapixels sounds cool, but in reality the bigger images can just be a hassle.  They take more space on your flash cards, more space on your computer’s hard drive, and are slower and more cumbersome to edit.  I say this with the conviction of someone who owns cameras of 8, 12, and 21 megapixels… and multiple terabytes of disk space.

So yes, you should buy a new camera if you understand exactly what problem a new camera will solve.  The one you should buy is the one that meets those expanded needs.

I hope this saves you money!  And thank you Erin for giving me the final nudge to write this article.

Next, I’ll talk about how to choose your first dSLR.

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I want a camera that takes better pictures!

I hear this, or sentiments like it a lot:  “I want a new camera so that my pictures will be better.”

I’m going to tell you a very special secret.  In fact, it’s such a big secret that even professional photographers, camera reviewers, and photography journalists don’t know about it.  Don’t ask me how I learned about it, and don’t tell anyone I told you because if they find out I’ll be in big trouble.  OK?  Promise?

OK, here’s the deal.  Every single camera ever manufactured contains a secret ingredient.  The name of that ingredient is a closely-guarded secret, and even I don’t know it, so let’s call it Magic Crystals.  Magic Crystals were first discovered by Ansel Adams when he was a young photographer trying to take photos inside of a cave in Yosemite.  Young Ansel quickly realized the potential of these crystals and added them to his camera, and that’s how he became successful.

You see, Magic Crystals are the secret ingredient in every good photograph.  Nobody really knows quite how Magic Crystals work– science has tried to understand them, but they’ve come up blank.  The only thing that we know is that Magic Crystals make good photographs.   Big expensive cameras contain more Magic Crystals than small, cheap ones, and so expensive cameras take better pictures than cheap ones.  The cheapest cameras can only make out vague shapes and colors, much like when you wake up without your contacts.  Expensive cameras have so many more Magic Crystals that they take great photos.  At the far extreme, there’s a Hasselblad dSLR that has so many Magic Crystals that it takes great pictures without you even having to touch it– you just think about the picture and the camera does the rest.  Before you whip out your credit card you should know that it’ll set you back about $30K.

OK, you in the back.  I can see you looking skeptical.  You don’t believe that Magic Crystals really exist.  You think I’m just making this all up.  You know what?  You’re wrong.  There really is a $30K Hasselblad… and if anyone wants to send me one I’d be happy to put it to good use.  The stuff about the Magic Crystals?  Yeah, you’re right.  I was making it up.

The truth is that the camera body is one of the smallest factors when taking good pictures.  Every dSLR ever made  has the capacity to take stunning, award-winning photos.  Most people think that upgrading their camera body will make their photos better, and they’re shocked and disappointed when I tell them that’s not true.  Either that, or they spend a lot of money upgrading their camera only to be disappointed when the results look just like they did with the old body.

In my not-as-humble-as-it-should-be opinion, there are three primary factors that determine the quality of photographic results:

  1. The skill of the photographer
  2. The quality of the lens
  3. The camera body

Those are listed in decreasing order.

By far, the skill of the photographer is the most important factor in creating quality images.  Imagine finding the best, most expensive camera you can imagine, and handing it to a beginner.  What do you think the results would be?  Mmmmm hmmm.  You’d get exactly the sorts of crappy snapshots that you would grow to hate if you worked in the photo lab of your neighborhood pharmacy.  They’d be badly-exposed, out of focus, abysmally composed, and completely uninteresting for anything other than horror value.

Similarly, if you were to round up a half dozen talented expert photographers and send them off with disposable cameras, you’d likely get some excellent and fascinating results.

Photographic skill comes in lots of different flavors.  First you have to be able to visualize the shot that you want to take, which requires skilled seeing and composition.  Once you’ve done that, you need to be able to translate that image into technical factors– aperture, shutter speed, etc.  And finally, you need to be able to use your camera to maximum effect, handling the intricacies of autofocus, metering modes, and the rest of your camera’s rich and complex feature set.

Which Lens On the equipment front,  improving the quality of your lenses is the best way to improve your image quality.  If you lens isn’t sharp, then no amount of skill will ever overcome that limitation.  Similarly, some lenses are better at rendering colors than others.  You probably won’t notice things like that without doing a side-by-side comparison, but once you do the difference is obvious.  You can click on the image at left to get a larger version, but you probably don’t need to in order to see that one of the lenses looks a lot worse than the other two.

See the muddy colors in the bottom picture?  No amount of skill will overcome that.

Lens quality often comes with a high price tag, but not always.  Of the two lenses that took pretty good shots in the comparison, one of them is the Canon 50mm f/1.8, also known as the nifty fifty.   I’ve raved about this lens before, and for good reason– it has excellent image quality and carries a price tag that’s right around a hundred bucks.

And finally, the camera body does have some bearing on image quality.  For example, some cameras are much better than other at shooting at high ISOs– older and less-expensive cameras will generally have more noise than newer and/or more expensive ones.  They may be better at resolving detail or rendering colors, though in my experience this difference is very slight and is generally hidden by other factors.

More importantly, a new camera may give you new tools that you can use to take better photos.  A spot meter can be a fantastic tool, if you know when and how to use it to best advantage.  Newer and more expensive cameras may have better autofocus mechanisms.  My 5D has a better layout of the controls, which means that I can change the aperture and shutter speed in manual mode more easily than I could with my old Rebel.    The bigger viewfinder on my 5D means that I can manually focus more effectively.    All of those things are tools that I can use to improve my photos, but they don’t help much on their own– I still have to have the skill to use them well.

Now you know that there are no Magic Crystals that will help you take great pictures– it mostly comes down to skill, and the quality of your lenses.  A new camera can help, but it won’t be a silver bullet.

I’ll talk more later about how to know when it’s time to upgrade, and how to choose a new camera when you decide it’s time.

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The Advantage of Practice

One of the things that I always encourage photographers to do is to experiment with new techniques and practice the things that they’ve learned.  You’ll see experiments and exercises scattered throughout this blog, and there’s a very good reason for that– doing something and seeing the results will always give you a better understanding of something than just reading about it.  When you practice, the techniques sink into your brain and they’ll be available in the future if you ever need them.

The Roman philosopher Seneca once said, “Luck is what happens when preparation meets opportunity.”  As far as I’m concerned, Seneca speaks the truth.  You never know when some interesting and unusual photographic opportunity will fall into your lap, and if you know what to do you’re more likely to get the shot.

This evening I was at a shoot that I do regularly– it’s dress rehearsal for a friend’s stage show.  I’ve done this shoot every couple of months for the past few years, and I set up the lighting for it myself, so the technicals of the shoot are easy for me.  I know from past experience what works best, so before the action starts I drop the cameras into manual mode (no surprise there), pick an ISO, aperture, and shutter speed that I know works for the situation, and I’m then free to think about more important things.

Tonight, however, the friend threw a spanner into the works.  “During the first set, we’re going to want to kill all of the lights for a couple of minutes and just use the glowsticks that we’ll have on the stage.” I had a brief moment of thinking that he’d lost his mind, but then I thought about it for a moment and realized that it was no problem.

Colors In Motion
You see, I’ve already done a lot of very similar work, like this image. This was done with LED glow poi, but I estimated that they would have a very similar characteristics, but that the poi were probably a little bit brighter. I knew from experience that I could get good but slightly-underexposed results with glow poi at f/4 and ISO 400, and whatever shutter speed was right to get the amount of motion I wanted.  (One of the interesting things about shooting moving lights is that longer shutter speeds don’t make the image brighter, but instead give you a longer motion trail.  Do you see why that is?)

I was shooting most of the show at f/4, ISO 1600, and 1/60 sec.   I estimated that f/4 and ISO 1600 was probably about right for the glowstick shots, and that I’d probably want exposures of about one second.  I also knew that autofocus wouldn’t work very well, and that I should pre-focus and keep the lens in manual focus mode.l

We discussed what the cues would be for cutting the lights, so I knew when it would be happen.  When I saw the first cue I changed the shutter speed to one second, switched to manual focus,  and waited.  We cut the lights, I got a few shots of pretty moving lights, and then we brought the lights back up and continued with the set.  When the lights were back on I changed the camera back to 1/60 and autofocus.

I got one good shot from that segment, which is about what I would have expected.  The exposure I picked was just about spot on, and because I was shooting in raw mode I had the latitude I needed to make final adjustments on the computer.

IMG_3093

If I’d never practiced this sort of shot I would have had no idea what to do with the unfamiliar situation.  However, tonight practice and experimentation sereved me well– when an unusual opportunity arose, I could make my own luck and get the shot.

Now it’s your turn– go find an unfamiliar situation and play with it, so that the next time you run into something similar you know what to do.  What are you waiting for?

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