Category Archives: Equipment

A couple of years ago I wrote How to take a picture of the moon.   It was, as you might guess, a lesson on how to take photos of the moon with your dSLR.  You may all now compliment me on my creative and clever naming scheme– I spent hours wordsmithing that one.  It’s my masterpiece.

In it I wrote “The first thing you want is the longest telephoto lens you can get, so that the moon looks like something other than a white dot. 200mm is about the shortest, 300mm is better, and 500+ is even better than that.”  That’s a true statement, but it lacks any substantiating evidence.  As you know, I’m a huge fan of experimentation and examples.  You can probably guess that a longer lens is better for shooting a far-away object, but how much better is it?

A few months ago, my friends at the absolutely fabulous equipment rental company BorrowLenses.com had a crazy sale on super telephoto lens rentals, so I did something I’ve wanted to do for a long time– I rented an obscenely large lens.  Specifically, I picked up the Sigma 800mm f/5.6 super-telephoto lens.

If you’ve never seen an 800mm lens, you should.  This beast is almost two feet long, about six inches across at the front element, and weighs in at a whopping 13 pounds.  It comes in its own well-padded metal carrying case and a sherpa to carry it, and has its own gravitational field.  OK, I made up the part about the sherpa, but it should come with one.  Maybe my trusty Gitzo tripod needs a name?

In any case, the moon.  I timed my rental so that it coincided with the next full moon.  I had an evil plan!  My plan was to steal a bunch of photons from the moon so that I could show you, dear reader, what the moon looks like when captured with various focal lengths of lens.

In order to do this, I packed the following gear:

• My trusty Canon 5D Mark II
• The abovementioned Sigma beast
• Canon 70-200 f/4L IS
• Tamron 1.4X pro teleconverter
• Tamron 2X pro teleconverter
• Tripod
• Cable release

My plan was simple: I would set up the tripod and shoot the moon with various combinations of lenses and teleconverters to show the image size of the moon with each combination.  For example, I could use the Canon lens at 200mm, and then add a 1.4X teleconverter to show what it looks like at 280mm.  Then I could do it with the 2X teleconverter to show 400mm, and finally with the two teleconverters stacked to show 560mm.  Stacking teleconverters really isn’t a good idea, since it causes your images to get all soft and cuddly, but it’s certainly OK just for demonstrating what the focal length looks like.

When you look at these images, bear in mind that they’re taken with a full-frame camera.  If you have a cropped-sensor dSLR, as most people do, imagine that at portion of the outer edge of each image has been cut off.  This Wikipedia image has a pretty good comparison of sensor sizes.  Look at the APS-C for Canon or Nikon, and that’s about how much you would cut off the edge of my images to get them to look like yours.  All of these images have a full-size version available if you’re logged into Flickr.

	200mm
	280mm = 200mm +1.4X teleconverter
	400mm = 200mm +2X teleconverter
	560mm = 200mm + 2X teleconverter + 1.4X teleconverter
	800mm
	1120mm = 800mm + 1.4X teleconverter
	1600mm = 800mm + 2X teleconverter
	2240mm = 800mm + 2X teleconverter + 1.4X teleconverter

As you can see, longer lenses bring the moon in closer. Even 2240mm doesn’t quite fill the sensor on a full-frame dSLR, although about 1600mm would do so on a cropped-sensor camera.

That doesn’t tell the whole story, though– you don’t have to fill the whole frame in order to get a decent photo of the moon.  If you click through and look at the full-size image taken at 400mm, you’ll see that it has a fair bit of detail in it.  Still, when it comes to shooting the moon, longer is better.  This is one case where size really does matter.

If you decide you want to rent a long lens and try it yourself, I heartily recommend BorrowLenses.  The Sigma that I rented is pretty expensive unless you have other uses for it, but I heartily recommend the Canon 400mm f/5.6L for shooting the moon.  It’s quite reasonably priced for the focal length, and it has very good image quality.  Add a 1.4X teleconverter to it if you need additional length.  It’s also a lot easier to wrangle than the beast.

There are a couple of other things to know.  You really want to use a tripod, or something else to stabilize your camera, when you’re working with long lenses.  This will keep your images from having ugly camera shake.  The downside of this is that the moon moves pretty rapidly through the sky, so if it’s been a couple of minutes since you aimed the camera you’ll probably need to look through the viewfinder again and see if the moon is still in the frame.    Also, working with long lenses can be its own challenge.  One technique is to rest your hand on top of the lens, just above where it sits on the tripod.   This article explains it, and has a great illustration too.

Now what are you waiting for?  Go shoot the moon, and share your images with us.

I’m a gearhead, and always have been.  It’s an engineer thing, I guess, but photographic equipment is inherently interesting to me.   I like playing with different kinds of equipment, and experimenting with new techniques.  I also find myself wanting for specialized equipment from time to time, such as a very long telephoto lens.

A few weeks ago I decided that I was curious about tilt-shift photography.  It’s a fairly esoteric type of photography that’s used for architectural photos, landscapes, and special focusing effects.  Tilt-shift lenses are expensive, though– the cheapest Canon, the TS-E 24mm f/3.5L, runs around $1200 mail-order.  That’s a lot of money for something I probably wouldn’t use very often, and it’s way more than I’m willing to spend on my curiosity.

What’s a budget-constrained gearhead to do?

For about $50, I could rent the TS-E 24mm for a week, and I did.  None of the photos that I took with it were terribly interesting, but that wasn’t my goal.  I really just wanted to play around with it and get a better understanding of how tilt-shift photography worked.  Buying a lens for that purpose would have been cost-prohibitive, but renting was an affordable alternative.

Renting equipment is a great way to try something out before you buy it.  Do you really want that specialized macro lens, or a fisheye?  Rent it and try it out  before you plunk down a lot of cash.  Lenses are the most common things to rent, but you can also get camera bodies, lighting equipment, tripods, and more.  I discovered my favorite tripod by accident, when I rented it for a weekend.

I especially like rental for long telephoto lenses, since I don’t need one very often and they’re terribly expensive.  My next rental will be the Sigma 800mm f/5.6 super-telephoto lens.  I have it reserved for pickup next week, and I’ve timed the rental so that it occurs during the next full moon.  If all goes well, I’ll be updating “How to take a picture of the moon” with some new examples.  Wish me luck!

So maybe you want to rent equipment yourself.  How do you do it?

Most big cities will have at least one camera shop that rents equipment.  Check your local yellow pages, call around, or search the web to see what you can find.  The advantage of this is that you can often pick something up immediately.  Supporting your local camera shop is also worthwhile.  The downside is that local rentals have a tendency to be a bit on the expensive side.

Another option is one of the internet-based rental houses.  Several of them have sprung up in the last couple of years, and I’ve personally done business with a few of them.  They have their inventories online, and ship equipment to you when you rent it.  You keep the packing materials, and at the end of the rental period you repackage the gear, put the return shipping label on the package, and send it back.  Doing this takes longer than renting locally, but you often get a better selection of equipment than you can get locally, and the prices are better.

As I said, there are quite a few different internet-based rental companies.    All of the ones that I’ve done business with have been very good, but I’m particularly enamored of BorrowLenses.com.  They have an excellent selection, their prices are competitive, and I’ve gotten spectacular service from them.  Additionally, they are local to the San Francisco bay area, which is a huge advantage for me– I can order things online, then swing by their shop and pick it up, thus saving myself shipping charges.  I even enjoy their Twitter feed, which contains interesting information for photographers as well as occasional sales.

Rental is a great option for short-term needs, trying something out before buying it, or just playing around.  I highly recommend it as an alternative to buying.

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?

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.

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.

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.

In my last entry, I said that you usually don’t care about DPI.  You should definitely read that and understand it before you dive into this entry.

Now that I’ve told you why you don’t care about DPI, I’ll tell you the one time that you do– when you’re printing an image.  That’s the one time that DPI comes into play, and when you get to it you’ll really care.

For print resolution, there are really two things you care about– dots and inches.  Dots are easy– that’s the number of pixels you have in each direction of your image.  If your file starts out with a resolution of 3600×2400, you have 3600 pixels/dots on the long side, and 2400 pixels/dots on the short side.  That’s pretty obvious, right?

The second number is inches.  If you’re going to print your photo at 8×12, there are 12 inches on the long side and 8 inches on the short side.  I know, I know, but I’d really rather state the obvious and get it over with rather than having some poor guy in the back scratching his head.  Besides, if you’re not American you probably grew up with the metric system, and you think an inch is something that should be scratched.

Ahem, OK.

We were talking about DPI.  Right.  As I said earlier, DPI stands for Dots Per Inch, and it’s a measurement of how much to stretch the image out when it goes on a piece of paper.   Working with DPI requires some really simple math.  Duck, because I’m going to hit you with a formula.  Ready?

Pixels / DPI = Inches

That wasn’t so bad, was it?  That’s really the core of what you need to know about DPI.  Let’s walk through it.

Remember our 3600×2400 image?  Let’s figure out what happens if we print it at 300DPI.  For the long side, we have 3600 pixels.  If we divide that by 300DPI, our printed image will be 12 inches.  For the short side, 2400 pixels divied by 300DPI will be 8 inches.   See?  That wasn’t so hard.

Now, try it yourself.  What happens if you print it at 200DPI?  Go ahead.  I’ll wait.  Here’s a pretty picture… you can think of it as the equivalent of on-hold music.

You’re done?  Did you figure out that it would be 18×12 inches?  If so, give yourself a gold star.  You did the math correctly.  If not, let’s walk through it.  3600 pixels divied by 200DPI = 18 inches.  2400 pixels divided by 200DPI = 12 inches.

Most printers will have some native resolution that they want you to send them files in, often 240DPI or 300DPI, but check the doicumentation for the device you’re printing on.  If you just send the image to the printer at that resolution, you now know how to figure out how big the print will be.

Often, however, you want to go tthe other way– you have an image, and you want to print it out at a fixed size.  In order to do that, you just swap the equation around a little bit:

Pixels / Inches = DPI

It’s the same equation as before, only we’ve rearranged the terms ala Algebra 101.  You do remember Algebra 101, right?  If not, just trust me.

What this means is that if you have a 2400×3600 image and you want to print it out at 4×6, you can do a little bit more basic math.  In particular, 3600 pixels / 6 inches = 600DPI.  Since DPI is essentially always the same horizontally and vertically, it works out well that 2400 pixels / 4 inches = 600DPI.

(Note:  Everything I’m writing today assumes that the aspect ratio of your image is the same as the one that you want to print at.  If you have a rectangular photo and you want a square print, you’ll need to start by cropping or padding the iamge to the right aspect ratio.  That’s not a topic I want to cover today.)

So what happens if you have a 2400×3600 file, you want a 4×6 inch print, and your printer really insists that you send it 300DPI files?  In that case, you have to resize your image.

The mechanisms for doing this will vary greatly depending upon what image manipulation software you’re using, and resampling is an art unto itself.   One way to do this is to do the math yourself and figure out how many pixels you need (in this case, 6 inches * 300 DPI = 1800 pixels on the long side, and 4 inches * 300 DPI = 1200 pixels on the short) and then resize the image to those pixel dimensions.  In Photoshop you cantake the easy way out and let Photoshop do the math– resize the image, set the DPI and the inches on each side, and let it figure out how many pixels the resulting image has to be.  Other image manipulation software is probably similar, but I’m not familiar with the exact mechanisms.

Most consumer-grade printers have drivers that are pretty smart about resizing images on their own.  My Epson R1800 will let me send any size image to it, and I can change one setting to tell it to fit the image on whatever size paper I’ve chosen.  That’s simple!  You still want to understand the basics, though, so that you know if your image will turn out OK. The lower the DPI, the fuzzier your image will look when it’s printed.  200DPI or more should certainly give you acceptable images, and for very large prints you can go lower– people stand farther away from big prints, so they won’t notice if the print isn’t completely crisp and perfect.

If you’re resampling the image, you can generally make it smaller without losing a lot of image quality.  There’s a limit to how much you can make it bigger, though.  When you make an image bigger (called upsampling, among other things) the software has to guess at what information it should fill in.  Newer programs are pretty good at this, but they’ll never produce anything as good as if you’d captured more pixels to start with.

Does this all make sense?  I hope I’ve left you with a better understanding of DPI.

I see this question, or some variation on it, over and over again:

“I just got a new camera, and it shoots at 72DPI by default.  How do I change it?  Won’t 300DPI give me higher-quality images?”

It’s a common question, and a very common misunderstanding about DPI.

First, let’s start with the camera.  Your camera’s sensor has some native size, some fixed number of recording points (remember the sensor gnomes?) on its sensor.  Each recording point records one pixel of the image.  Every image that’s shot with the camera has that size no matter what.  Using the Canon Digital Rebel XTi as an example, the sensor is 3888 pixels wide and 2592 pixels tall.  If you multiply those numbers together you get 10,077,696, which is why it’s called a ten megapixel (ten million pixel) camera.

Remember that.  As long as you shoot at the XTi’s maximum resolution (and by that I don’t mean DPI, I mean L or L+RAW) you’ll get an image that is 3888 pixels wide and 2592 pixels tall.  Some cameras let you shoot smaller images, by changing the size from L to M or S.  If you do that, you’re shooting at whatever size that particular setting gives you, but it’s still independent of DPI.

So what’s DPI?  It stands for Dots Per Inch. For our purposese, a dot is the same as a pixel, so it would be pixels per inch. (There is a technical difference between dots per inch and pixels per inch, but for purposes of this discussion we’ll treat one pixel as being the same as one dot– it’s one unique spot of data in our digital image)  DPI is not really a part of the image itself, and doesn’t change anything within the image.  Rather, it’s a number that’s stuck onto the side that tells a printer how big it should print out the image– imagine someone handing the file off to be printed, and sticking a post-it note on the file so that the printer will know how big to make the image.  If the image is 72DPI, the printer will print out 72 dots in every linear inch.  At 300DPI, the printer will print 300 dots in every linear  inch.

If you’re working with an image on the computer, and never printing the image, DPI is completely irrelevant.  A 3888×2592 image at 72DPI is exactly the same image as a 3888×2592 image at 300DPI or 1DPI, or a million DPI.  Really.

The thing about DPI is that you can change it arbitrarily, and it won’t affect the image.  As long as it stays 3888 pixels wide and 2592 pixels tall, you can rip off the 72DPI sticky note and change it to any other number, and you still have exactly the same data in your image.  That means that you don’t really care what DPI the camera sticks onto the side when you first take the picture– changing it in-camera won’t change the information that you capture, and it’s easy to change it later if you want to print the image out.  Plus, if you’re printing the image you probably will want to resize it, crop it, or make other adjustments.

And that, in a nutshell, is why you probably don’t care about DPI.  Unless you’re printing the image out, DPI is a completely irrelevant concept, and one you basically just shouldn’t worry about at all.

Next up, I’ll explain how DPI works when you’re printing.