The other day a friend asked about getting a new camera — he wanted to get something better than his point-and-shoot, and indicated that he was looking at the Nikon D40. I sat down to write him a quick top-of-mind email on things to consider and how to judge between cameras, and it turned into a really long post. I thought it would be worth sharing in case anyone else is contemplating their first Nikon SLR purchase.

It’s really raw, as I wrote it late at night and didn’t even do a read-through before hitting Send. My apologies for any inaccuracies or overgeneralizations it may contain!

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You’d mentioned that you were looking for a digital SLR to take higher-quality photos of your daughter, etc than what your compact camera was doing. Here are some thoughts off the top of my head.

The digital SLR market is primarily split between Nikon and Canon… there are other manufacturers (Sony, Fuji, etc) but they’re extremely marginal. The difference between Nikon and Canon is minor but (like the Mac/PC thing) hotly debated. Nikon tends to have better ergonomics and is ahead in some areas of lens technology… Canon cameras tend to feel cheaper in the hand and have a poorer UI, but they have a somewhat broader range of low-end lenses (I think). They also tend to have less noise at high ISO values.

Quick primer on ISO values, aperture, etc… exposure on a digital camera is controlled by three things – ISO, aperture, and shutter speed. Shutter speed is fairly obvious… faster shutter speeds mean less light comes in, thus the photo gets darker. Aperture (the f/stop) is how wide or narrow the iris at the back of the lens is… smaller f/stops (like f/2.8) are wider openings than larger f/stops (like f/16). Confusing, but true. Lenses always have a maximum f/stop, which is the *lowest value* (eg most open or maximum iris size) that they support. For most consumer lenses, this is around f/3.5 for wide angles and f/5.6 for zooms. Consumer-grade lenses often give a range… for example, a 17-80mm f/3.5-5.6 means that at 17mm (wide angle) the widest f/stop is f/3.5, while at 80mm the widest f/stop is f/5.6. f/stops are in powers of something like 1/root two (f/1.2, f/2.8, f/4, f/5.6, f/8, f/11, f/16)… each stop wider means that the front lens diameter needs to be roughly twice the size. Pro-level zooms have a constant aperture… eg a 70-200mm f/2.8. These guys are *huge* but since they have such a wide aperture, they let in a lot of light and thus can be used in dim light. All that glass also makes them very expensive.

Quick note before I forget… you won’t always be shooting at the lens’s widest aperture. Wide apertures like f/2.8 give a very shallow depth of field (the amount of the photo that’s in focus), while narrower apertures like f/16 put a lot more of the scene in focus. For example, if you were taking a photo of your dog at f/2.8, the mountains, trees, barn in the background will be out of focus. If you take it at f/16, everything from your dog on back will be in focus. (I took all of our honeymoon photos in Hawaii at the widest f/stop, so all the photos are kind of blurry. I didn’t learn about depth of field for another six months or so!)

That leaves us with ISO. This used to mean the sensitivity of the chemicals on the strip of film, back in the day… higher ISO films would expose the same photo in a shorter amount of time, so you could use a higher shutter speed or take photos in dimmer light. Nowadays, the sensor in a digital camera has a base sensitivity of, say, ISO 200 — and higher ISO values are obtained by doing analog amplification of the data coming off the sensor. Amplifiers aren’t perfect, so they introduce noise… generally you’re good up to around ISO 800 without much noise. Above that, you’ll see splotchy red/green/yellow dots in a random pattern around your photo. This can be removed by photo software like Aperture, Photoshop, and the like, but you lose detail. Higher ISO values often cause the photo to be less saturated (eg the colors aren’t as vibrant) as well.

These three things — ISO, shutter speed, and aperture — are important because of something called ‘reciprocity’. Simply put, it means that there are many combinations of ISO, shutter speed, and aperture that gives a correct exposure for a certain scene. (”Correct exposure” meaning that a medium-grey object in the scene comes out as medium-grey in the final print.) Doubling the f/stop lets in half the light… halving the shutter speed lets in twice as much light… doubling the ISO value ‘lets in’ twice as much light (via amplification). Thus, a given scene would be correctly exposed at ISO 200, 1/200th of a second, f/8… or at ISO 400, 1/200th, f/11… or at ISO 200, 1/400, f/5.6. You choose the parameters to optimize for a given effect — a higher shutter speed if you want to stop action, a higher f/stop if you want more of the photo in focus, a higher ISO if you’re in dim light and can’t get a fast enough shutter speed at your widest aperture.

There’s a general rule of thumb, by the way, that you shouldn’t take a photo (without a tripod) at a shutter speed less than 1/(your focal length). So, if I’m using a 50mm lens, I want to stay above 1/50th of a second. Lower than that, and the shakiness of your hands shows up in the final result. Some lenses have “Vibration Reduction” (on a Nikon lens, or “Image Stabilization” for a Canon lens… abbreviated VR and IS, respectively) built in, which is extremely cool — one of the glass elements in the lens is able to pivot, and the lens contains accelerometers that detect motion and counteract it by pivoting the lens in the correct direction. This means you can be zoomed in at 200mm and take sharp handheld photos at 1/50, for example — way, way outside the 1/(shutter speed) rule. Amanda’s lens has this and it’s awesome!

Alright – so now you know about the technical aspects of photography. I’m a Nikon fan (they feel great and have a good UI – they’re like the Apple of cameras), so I’m going to frame this discussion from a Nikon point of view.

The current Nikon consumer lineup (prices from B&H Photo Video and are for the kit which includes a Nikon 18-55 consumer zoom lens):

• D40/D40x: D40 is 6 megapixel, D40x is 10MP. Only supports AF-S lenses (which have the autofocus motor built in). Must buy the D40 with 18-55 or 18-135mm lenses as a kit. Takes SD cards. $499 / $699 with 18-55mm lens. Review here.
• D80: 10MP, supports both AF and AF-S lenses. Can buy body-only, or with 28-105, 18-135, or 18-55 lenses as kit. Takes SD cards. $979 with 18-55mm lens. Review here.

The next camera is the D200, which is $1800 with an entry-level lens… it takes CompactFlash cards, supports non-AF lenses in addition to AF and AF-S, has incredible autofocus for sports photography, etc etc etc. It and the newly-announced D300 are the ‘prosumer’ cameras, for folks who have lots of money but don’t necessarily make a living with their cameras. This is probably more camera than you’ll use, at least for the first 5-10 years… I haven’t exhausted my D70 (the predecessor to the D80) yet, for example.

So, the decision between the D80 and D40 is mostly about the lenses they can use. The D40 also displays the current camera settings on the back LCD rather than on a separate small LCD near the shutter. All digital SLRs display this info in the viewfinder as well. I probably should note – digital SLRs make you use the viewfinder, you can’t look at the back of the camera and compose a shot. You probably knew that, but I didn’t want to leave it out!

Back to lenses: whether only being able to use AF-S lenses is an issue depends on the kind of shooting you expect to do. You’ll want one lens to stay on the camera for most of your shooting… this lens should go to 17 or 18mm on the wide end, and should go to at least 70mm on the long end. Some older Nikon lenses only go as wide as 28mm… that’s not wide enough for the new digital bodies. The sensors in all consumer SLR cameras are slightly smaller than normal 35mm film, which means that all your lenses act like they’re 1.5x longer – in other words, a 200mm zoom gives the same picture on your digital SLR that a 350mm zoom would on a film SLR. This is great, since most people want a longer zoom – but it also means at 28mm isn’t very wide any more.

You’ll also want to stick with Nikon-brand lenses. Sigma, Tamron, etc all make compatible lenses (you’ll need to find out what their AF-S equivalent is, if you’re looking for one that works with the D40), but they tend to not do as well in terms of image quality. Dealers also make a lot more profit selling you a third-party lens than they would selling you a Nikon lens, since the markup is greater (though the third-party lens is cheaper)… beware of that.

So, for the lens you use all the time, you have a couple of options regardless of which camera you choose. (All the current Nikon consumer zooms are AF-S.) The 18-70mm lens is a great performer… it’s very sharp and 70mm on the long end is a long enough zoom for most situations. Unfortunately, it’s not offered as part of a kit anymore (it was when I bought the D70) so you’d need to buy the D80 or D40x as a body-only and add the lens on. The 18-135mm is respectable, and it’s part of both the D40 and D80 kits.

If you have $800 sitting around, the 18-200 VR is Nikon’s newest and most impressive consumer zoom lens. It has vibration reduction and is one heck of a long zoom… this is the lens that stays on Amanda’s camera 24/7, and she loves it. It’s sharp, VR works beautifully when there’s dim light, and it’s just fun to use.

Beware of deals that pair the 17-55 and 55-200 lenses… they’re both mediocre performers, and you will *really* hate changing lenses every time you want to shift from wide angle to a moderate zoom.

A general rule of thumb re: the body/lens thing is that the majority of your investment will be in lenses, not the camera… it makes no sense to spend good money on a camera and then cheap out on the glass that you’re sticking in front of it.

Of the 18-70, 18-135, and 18-200 options, I’d pick the 18-200 if you can afford it — or pick up a body-only kit for the D40x or D80 and get the 18-70.

If you didn’t get the 18-200, you might find yourself wishing for a really long zoom for things like birds, the zoo, etc. You can pick up the non-AF-S 70-300 lens for ~$150 if you have the D80… otherwise you’ll want to pick up the AF-S VR 70-300 (vibration reduction again) for closer to $500.

One other thing you might be interested in is the ability to take photos indoors, in natural light with no flash – it’s a great effect but requires a very fast lens to capture enough light with a short enough shutter speed. The 50mm f/1.4 is the classic lens for this… it’s fixed-focal-length, not a zoom (this sort of lens is called a ‘prime lens’, for various reasons), and there’s no AF-S version — so it’ll only work with the D80. It’ll run you $300, or $120 for the ever-slightly-slower 50mm f/1.8. (”Slower” meaning it lets in less light by virtue of having a narrower maximum aperture than the f/1.4 lens). At $120, the 50/1.8 is a bargain and it opens up a whole new world of photography. Flash photography looks very dull and flat compared to what you can do with natural light.

As a comparison, most consumer lenses have a maximum of about f/4 at 50mm. f/1.4 is two stops faster, so a scene that would require a shutter speed of 1/25th of a second at f/4 can be captured at 1/100th of a second at f/1.4. Remembering the 1/(focal length) rule, this makes the difference between a shot you miss and a shot you can easily get.

Depth of field gets super-narrow at f/1.4 and 1.8, so focusing will be very important. If you focus on the tip of your daughter’s nose rather than on her eyes, you’ll notice! Just because f/1.4 is the lens’ maximum aperture doesn’t mean you’re stuck there, though… you can easily ’stop down’ to f/4, f/8, whatever by turning a dial on the camera to get some depth of field back. Prime lenses are also much, much sharper than zoom lenses (for what it’s worth). The 50mm f/1.4 is what’s on my camera 99% of the time. If I feel the need to zoom in, I just walk closer to the subject :-)

So you’re probably completely overwhelmed by now – I hadn’t realized that I was going to be writing a book here! I guess it’s time for ‘what I would do’. I’d probably buy the D80 with the 18-70… the 18-200 is expensive and well worth it, but might be out of the budget. The D80 with 18-135 would be just fine instead of the 18-70, though the image quality isn’t as good.

A few months to a year after buying the D80, I’d spend $300 and get the 70-300 and 50/1.8 lenses as well. That gives you a ‘normal’ lens for your day-to-day outdoor stuff, a long zoom for trips to the zoo or the park or whatever, and a fast prime for indoor, low-light work. Learning to shoot photos with the prime lens also forces you to think more about composition – it has done more for me as a photographer than any amount of reading ever has!

I’m sure I probably missed something in here, but at this point I don’t know what it is. Things to remember:

• More megapixels doesn’t make for a better camera (6MP is plenty unless you’re going to print above 8×10).
• 10mm at the wide end (eg 18mm versus 28mm) is a huge difference, 50mm at the long end (70 versus 135mm) is a much smaller difference.
• If you shop online, shop at B&H Photo Video or Adorama – they’re both well-respected camera stores. Never shop at Kit’s, Ritz, or the other chains.
• See if you can find an independent camera shop in Nebraska, and solicit their advice… go hold the cameras in your hand and see how they feel. (Canons always feel cheap and plasticky to me, and I can’t get past that.)
• Thom Hogan is a very well-respected reviewer… see his site for reviews. Stay away from Ken Rockwell, he has a reputation for “reviewing” things he’s never had his hands on.
• Crumpler (Australian brand with a weird website) makes great camera bags. You’ll never find The Perfect Bag, though you can come close after a few tries.
• Don’t buy a “UV filter”, even when the salesman tries to convince you that you need one – modern cameras have a UV filter built in, and you don’t want to ruin your nice lens by putting a cheap piece of glass or plastic on the end of it. (The “it’ll protect your lens element from damage” argument is a good one, though – keep a lens hood on there all the time, and that should do it.)
• If you’re shooting outdoors, do buy a multi-coated *circular* polarizer… B+W is a good brand. Buy all your filters at 77mm diameter, then buy (cheap) step-down rings to fit the polarizer to your lenses… don’t buy a $100 polarizer for every lens! Like polarized sunglasses, you can rotate the polarizer to make the sky darker, get rid of reflections on leaves, glass, and water, and generally make colors more saturated if you’re in direct sunlight.
• Take most of your photos in portrait (vertical) orientation. Keep your elbows tucked in when you shoot a photo, with one hand holding the camera and the other supporting the lens barrel.
• DP Review has a great set of Nikon forums if you have questions – be sure to browse the archives first.
• You probably don’t need to buy a tripod… I never use mine.
• If you take a lot of indoor group photos, you’ll want to buy an external flash like the SB-600… buy a Sto-Fen diffuser cap, and if you’re indoors with a low ceiling point the head up at a 45 degree angle. Part of the light will go forward (thanks to the diffuser cap), part of it will bounce off the ceiling — it lights your subject very gracefully. For extra credit, take the diffuser off and bounce the light off a nearby wall.
• If your photos come out a funny color, you forgot to set the right white balance!
• Always check your ISO setting when you turn on the camera… ISO 800+ for indoors, ISO 200-400 for outdoors in sunshine, ISO 400-800 in cloudy weather.

That’s all!

Best of luck and feel free to ask questions,
Matt