Recently a number of people have asked for my advice on buying a digital SLR (DSLR) camera. I'm not going to go into the pros and cons of DSLRs versus point and shoot cameras - I'm assuming that you already know that you want a DSLR.

The first thing that I would advise is that you go and read Philip Greenspun's excellent article, Building a Digital SLR Camera System. I found earlier versions of this article to be very helpful. Not only does Greenspun suggest what to buy, he suggests a possible acquisition plan as well as photographic projects that you can do given what you have got.

Beyond Greenspun's article, I have some additional comments based on my experiences during the last 18 months or so. Call it

"Things I wish people had warned me about"

1. It's the system, stupid

If you think that there is any chance that you are going to get bitten by the photobug, you need to know that it's about the whole camera system, and that you are going to get poor very fast. That said, you can also get very very far on "cheap" equipment.

2. Canon vs Nikon vs ???

You can take great pictures no matter which brand of DSLR you buy. Canon and Nikon are the most popular brands. Part of the reason that I chose Canon was that most of the people that I know also shoot Canon, and so there is the theoretical opportunity to borrow equipment from your friends. I've only done this a handful of times, so this partially depends on how many friends you have and so on.

Other big factors in the Canon vs Nikon debate:

• Lens quality - different people have different opinions on the quality of the lenses. So far, I've never been able to tell the difference.
• Lens selection - which manufacturer has the focal length/aperture combinations that you are likely to want
• Low light sensor performance - Canon has traditionally been the leader here, but it appears that Nikon wants to catch up
• Possibility of full frame sensors/cameras - Canon makes both cropped and full frame sensor SLRs. For the moment, Nikon only makes cropped frame SLRs. Personally, it's still a large number of years before I can justify paying what Canon is charging for a full-frame SLR, unless I find a way to support my habit, er, hobby
• Flash systems - Nikon builds a wireless flash controller into most of their DSLRs. I wish I had paid attention to this. I don't know that it would have caused me to over to Nikon, but it is a very nice feature.

There are real differences in "feel" and control ergonomics, which you should be aware of. If you think you'll care, then you need to find a way to physically hold the camera in your hands.

3. Body vs lenses

My take on this: a lot of the expense of bodies is the electronics (compare prices with film bodies) and electronics are on Moore's law. Lenses are made of metal (or plastic) and glass and are not on Moore's law. The body you like today will be cheaper next year, often by a lot. You should know that Canon and Nikon release new models in a price category every 18 months or so, around the dates of the two big photo shows, PMA and Photokina. It's like Macs and Macworld.

I bought the least expensive body that I could, the Digital Rebel XT (EOS 350D for the rest of the world), and it's served me well. The only major limitation that I ran into was the absence of a PC-Sync cord connector, which makes it tough to control external strobes or non-Canon flashes. There's a workaround for this, but I didn't learn this until I tried to fire a strobe from my camera. I'm ready to move up, but the body that I'm ready to move up to doesn't exist, and there isn't enough benefit to moving up to the 30D to be worth the money.

I think its better to save some of that money that Moore's law will ultimately recover, and invest in lenses. To wit:

4. Primes vs Zooms

When I started out, I mostly wanted zoom lenses, because of the convenience of not having to switch lenses. When I shoot events, I prefer zooms. After you use a lens where you control the zoom manually, you will go insane waiting for the zoom motor in a point and shoot camera. Ok, sorry, that was off topic. I am finding that I am getting more interested in shooting people, and some of my best people shots have been shots with one of my prime lenses. I'd suggest not going hog wild buying lenses until you figure out what you really want to shoot, and then figure out whether zooms or primes are better suited to your style. Most good photo processing software will give you a facility so that you can figure out which focal lengths you are using most often.

5. Flashes

We have all seen tons of hideous flash pictures. This turns lots of people off flash photography, and the notion that you would spend money to get an external flash seems kind of crazy. I would point out that lots of pictures that you and I see every day we created using artificial light, either flashes or strobes, and the knowing how to use external lights is worthwhile. Getting a good external flash definitely changed my attitude about flash pictures.

See David Hobby's Strobist blog for great lessons and cheap ideas.

6. Cases

Once you start getting gear, you'll start getting cases. So far, I've managed to escape with 2 cases, but the combination of cameras, lenses, laptop or no, easy access during a shoot, weather proofing, padding, and sufficient capacity is just likely to make you nuts. Every camera forum that I've visited has innumerable threads about the "right case". We're just doomed on this one.

7. Tripods and other supports

Camera motion contributes to fuzzy pictures. I've discovered that I move a lot more than I thought when I shoot a picture. I have some lenses with image stabilizers in them, and that helps. I have a cheapo video tripod that I use in a pinch, and it definitely makes a difference. Getting a good tripod is pretty high on my list of camera purchases. This article by Thom Hogan is in the "we're doomed" category. I don't know that you have to go all out for what Hogan suggests, but I do know that I am in serious fiddling with the head land.

8. Filters

Before I knew anything about photography, I assumed that photographers just went out there and snapped their shots. Now I know that many pictures are made via modifications, either with filters or in the darkroom/post processing. In the digital age, the are a large number of effects that can be done in post processing, which reduces the need for filters (yay, less to carry).

Lots of people will give you their opinion on whether you need a skylight/UV filter to protect the front element of your lens. I have a UV filter for my smaller diameter lenses, but not for my larger diameter lenses. I can't see much of a difference.

The one filter that I think you need to have is a circular polarizing filter, because it's a filter you want a lot -- it makes a big difference in lots of outdoor situations. It's also impossible to achieve the effect of a polarizer in post production.

9. Flash Cards/Readers

It seems like there's no such thing as enough flash cards. I started with a 1GB card. That was a lot for a while. Then I started shooting RAW, and I needed another 1GB card. Now I'm finding that I'm shooting even more at events, and that filling up cards at the wrong moment is bad. More cards? At least Moore's law works on flash cards.

I'm probably going to get a flash card reader - USB to start with because they are cheap. This means I can pop a card out of the camera and let it upload while I keep shooting. Also it would mean that I am not using the camera battery to download, which is a factor when traveling - anything to avoid packing another battery charger.

10. Computer Software/RAW

Most cameras come with photo processing software, but everyone I know uses some other software. There's Picasa (PC) which is free, and iPhoto on the Mac. There's also the public beta of Adobe's Lightroom (Mac and PC), and Apple's Aperture on the Mac. I am using Aperture and am pretty satisfied with it now, but I am probably going to buy a copy of Adobe's Photoshop when it comes out native on Intel Macs. Why? Selective image editing. If you want to perform an edit to just a part of an image, you need Photoshop or something like it, and most of the something like its don't run on the Mac.

Other resources

Phil Askey's Digital Photography Review is the best source of information on cameras. He does the most thorough reviews that I have seen. There are other sites that I consult, but I'll go to dpreview first. They have RSS, go subscribe. There is also a huge selection of photography related sites and blogs.

Having a nice camera is not enough. You must learn to use it. If you only buy one camera book then I'd suggest "Understanding Exposure: How to Shoot Great Photographs with a Film or Digital Camera (Updated Edition)" (Bryan Peterson). I've recently published a list of good books. The photo section includes the most helpful of the various photo books that I've read.

Another thing that's been really helpful to my development as a photographer is Flickr's RSS features. I subscribe to RSS feeds of both individual photographers and the photo pools of Flickr groups. That gives me a personalized daily flow of inspiration.