My Thoughts on Digital Cameras

Pete Su
2003-11-27

My first experiences with "real" photography consisted of taking black and white pictures in junior high school with my dad's old Canon SLR. I still remember the match needle meter, loading film in the dark, and discovering the magic of the dodge and burn. I didn't do any serious photography until twenty years later after getting my PhD and picking up a modern Nikon SLR. After discovering the joys of slides on a light table, I returned to my old roots, shooting a lot of Tri-X, developing the film, making prints on glossy fiber paper. All of this happened as digital cameras started to make their way into the mass market. I have done a few extended projects on subjects here in Pittsburgh and have many pretty prints to show for them. Of course, you have to come to my house to see them.

In the past year, I have started using digital cameras much more heavily than conventional film cameras. I had to provide my parents with a steady stream of pictures of their new grandson. Having no time to get prints made, make them myself, or even scan film, I bought a digital point and shoot for this purpose. Later on, I progressed to a Nikon D100 digital SLR (and still later to a D70).

Being known as a photo geek, I get a lot of questions about which cameras I like, and how the new digital stuff compares to the old film stuff. This page summarizes my thoughts. I assume you know a bit about basic photogaphy, and a bit about the basics of digital cameras and computers.

A small digression. You will not see, on these pages, any reference to "analog" media, as opposed to "digital" media. In my opinion, "analog" is a stupid way to distinguish film cameras from digital cameras. If you want more insight as to why, you can maybe ask me later.

Short Summary

It all depends on what you want to do.

Extended Thoughts

The rest of this page will discuss what kinds of digital cameras are available and then I'll go into what I like and don't like about using digital cameras.

Digital Camera Mechanics

If you spend any time looking at information on digital cameras, you will note that there are basically three classes of digital capture devices.

The third class of device is generally not affordable by the normal human, and not all that convenient to use in most situations. Therefore, I'm mostly concerned with the first two.

Digital cameras work by using a piece of hardware called a CCD (or CMOS) sensor to capture light from the scene and convert it into digital data. This sensor is made up of millions of light gathering sites. The sites capture brightness information for one part of a scene and convert this information into a single digital value that is usually 12 bits long. So, the CCD looks at what you pointed the camera at and converts it into a large collection of numbers between 0 and 4096. To be confusing, these light gathering sites are also referred to as "sensors" or "pixels". I use both words.

The camera then takes the image data and processes it to reconstruct things like color information and whatnot. The sensor in the digital camera acts a lot like slide film. You have a lot of latitude for underexposure and not much for over. I generally set my camera to underexpose a bit on purpose. Sometimes this works perfectly, sometimes I get frames that are a bit dark. But, it's almost always possible to rebalance things in Photoshop and bring back the shadow detail without blowing out the highlights. If you blow the highlights out in the capture, you are toast.

The nominal "resolution" of the camera is usually quoted as the number of sensors in the chip that the camera uses to do capture. Each sensor corresponds to one "pixel" in the final image. Except, this is sort of a lie. Each sensor in a CCD or CMOS array can only capture black and white information. The most common way to get a color image from such a device is to overlay a color filter array over the sensor. The filter is usually a single piece that sits over the CCD. It puts a single color filter passing Red, Green or Blue over each pixel in a particular pattern. Each light gathering site now captures a single number that indicates how much Red, Green, or Blue light hit it. The image processing hardware and software when read this data and construct an image file with three numbers, one for each color, at each pixel.

So, somehow we've gone from one color value at each pixel to three. Where did all that new color data come from? The simplistic answer is that the software guessed. The more complicated answer is that there are algorithms that can reconstruct the color data very accurately under most circumstances. Of course, nothing is perfect, and there are simple cases where these algorithms fail.

Point and Shoot

Point and shoot cameras cover a lot of ground in the digital world. They range in price from around $100 to around $1000, and they range in resolution from 640x480 pixels to 8 megapixels. But, all point and shoot cameras have basically the same characteristics, which can be summed up as follows:

A small sensor.

Regardless of the resolution of the camera, most point and shoot cameras use a sensor that is something like 1/4" to 1/2" on its long side. The sensors are referred to using a weird and confusing naming scheme that has more to do with aspect ratio than actual size. Most of these sensors are made by Sony, although Fuji appears to make their own as well.

The small sensor is significant because it limits the camera in two ways: performance in low light, and performance related to noise in the picture. Small sensors need a lot of light, and small sensors are noisy. I don't really want to get into why this is the case. But in general it is.

A bad viewfinder.

Bad viewfinders. Point and shoot cameras generally have either a reverse telescopic viewfinder or an electronic viewfinder like a camcorder. Both of these suck. Of course, film point and shoot cameras suck the same way. Luckily, with digital point and shoots, you can use the LCD on the back. It doesn't tell you a whole lot about things like focus, but it's better than nothing. And, the swively ones can be handy for waist level shooting. LCDs don't work well in full sunlight.

A slow image pipeline

Do the following experiment. Pick up a point and shoot digital camera. Point it at a second hand and hit the shutter button. Then bang on the button until it takes another picture. What you'll find is that the delay between the two pictures will usually be somewhere between a little more than a second to several seconds. The most common value is about a second or two.

Note that I am not talking about shutter delay here. Most point and shoot cameras have shutter delay, but it can be minimized by prefocussing or whatnot. What I am talking about is how fast the imaging pipeline resets itself so you can take another picture. In general, the imaging systems in point and shoot cameras are simple and slow. They do not allow the camera to snap another shot while still chewing on a picture. You have to wait until everything is done before the camera lets you shoot again. This makes taking pictures of things that are moving or otherwise changing quickly sort of frustrating. More on this later.

A small battery

You tend to get a hundred to a couple of hundred shots out of a battery. You can't really hope for more. There are exceptions, mostly in point and shoots that are larger.

That about sums it up. If you plow through all the camera review pages, you will find that all the specs basically add up to the same thing.

Shooting with a digital point and shoot is all about working around these three limitations. Here are some things I do:

Since the viewfinder sucks, don't use it

Rather than getting frustrated with not being able to compose shots tightly and carefully, just don't compose at all. Point the camera roughly where you want to shoot and fire away. If you don't do this totally mindlessly, you can use the LCD to get a rough composition and then just use the sheer volume of pictures you capture as a way to fine tune things. This leads to the next thought.

Pre-Focus (Updated in 2006)

I can't stress this enough. The autofocus systems in point and shoot cameras are slow. If you use them for every shot, you will miss every shot. But, you can tell the camera to pre-focus. Usually you do this by pointing it at something that might be a good picture and holding the shutter button down half way. The camera will flash or something to tell you it focused. Then when the time is right, jam the shutter button down the rest of the way to take the picture.

Use Continuous Drive (Updated in 2006)

The only thing point and shoot cameras do slower than focus is write files to a flash card. Even worse, in their normal mode of operation, you must wait for the camera to write the file before you can take another picture. This is because the poor CPU can't handle doing file I/O and taking pictures at the same time. But, most point and shoots have a "continuous frame" mode where they buffer pictures in memory until their internal memory is full, and then they flush the buffer all at once. You can usually fire off five or ten shots this way. This is what you want to use. Set this mode on the camera every time you turn it on.

Take tons of pictures (updated in 2006)

A shot with the average point and shoot costs you between 1MB and 3MB of storage on your computer for a single JPEG file at the highest quality setting. This means that a reasonably large flash card will hold about 100 to 300 pictures before running out of space. The average laptop hard disk will hold 10,000 pictures easily. You have plenty of memory and no film costs, so burn pictures. Just don't do it mindlessly. Have your camera set in continuous frame mode and pre-focused on any good opportunity. You have to think ahead. When you see the good picture, point the camera and jam down the shutter button and take ten frames. This gives you back ups and the possibility to catch something that happens just after you shoot, which is sometimes when the really good stuff happens. Now go back home and throw away the bad ones.

Don't use the Idiot "Modes" (added this in 2005)

Many point and shoot cameras come with scene modes like "night" or "portrait". Avoid these. Usually they are trying to be smarter than the camera can be, and may constrain the camera to not take the shot when you want it to take the shot. For example, Portrait mode might prevent you from taking the shoot unless the camera could lock focus and manage a decent shutter speed. This will annoy you.

Instead, put the mode dial on "P". This tells the camera to choose exposure settings for you but to otherwise leave you alone. If your camera does not have such a setting, then read the manual and figure out which of the scene modes is the least constrained.

Never use the flash.

Chances are, if it's too dark to get the picture without flash, the picture wasn't worth getting.

Edit edit edit.

Let me repeat. Edit edit edit.

This is the flip side to shooting a lot. You have to be mentally prepared to throw away the bad stuff. Really, no one needs to see all 500 frames of the baby at the beach when just the one that's really good will do. If you can't decide which is best, ask your friends. They'll thank you when they download your web pages.

Avoid contrasty light.

This means don't shoot in full sun, or under bright lights in a dim room. The sensor can't handle the range and so you end up with black spots everywhere or blank white spots where faces should be. The best day to take pictures with a point and shoot is a bright overcast when everything is perfectly even.

Bring an extra battery.

The batteries don't last a long time, bring an extra.

SLR

Digital SLRs trade size and cost for performance (although the new Canon Digital Rebel is nearly the same size as some point and shoot cameras). If you compare point and shoots to the new class of digital SLR cameras, you will find that:

The viewfinder is a lot better.

Look through my Canon S30 and then look at the same scene through a Nikon D100. The S30 shows you what is sort of in the top half of the scene, with a lot of junk that isn't really in the shot. And, you can't tell what is in focus and not in the viewfinder or even in the LCD. Also, you can't see the LCD in sunlight. The D100 will show you what is in the shot with proper framing and a pretty good indication of what is in focus and not. For an even better experience, look through an FM3A film camera.

The sensor is a lot bigger.

The sensor in the average digital SLR is usually around 1" long on the long side, which means that it is much much larger than the sensor in the average point and shoot. This means that pixel for pixel, pictures look better. If you take an identical shot using a Nikon D1 and my Canon S30, both of which capture about 3 megapixels, you will find that the Nikon always does a better job. At equivalent settings, there will be better color, less noise, and maybe even more detail in the shot from the Nikon. I can shoot at ISO 400 with the D100 and get barely any noise at all. At ISO 400, the Canon makes images that are barely usable.

Everything is faster.

I can turn on my Nikon D100 and take a shot in less time than it took you to read this sentence up to the word "shot". At the same point in time, my S30 will still be turning on. Also, the image processing pipeline in the D100 is much smarter and faster. Assuming there is enough memory left, it will overlap processing images with further shooting, so I don't have to wait for the camera until I fill the shot buffer, even if I'm not shooting continuous frames. The D100 only has room for 4-6 pictures, but newer cameras like the Canon 10-d and the Nikon D2h can shoot 10 or even up to 40 pictures before giving up.

Using the D100 is pretty much just like using a film camera, except the viewfinder isn't quite as nice. What you pay to get all this luxury is about $500 to $1000 extra dollars, and a lot of size and weight. I don't have a workarounds section here, because you don't need any. The thing just works like every camera you've ever owned, except there are no film costs. So shoot away!

Finally, one further note to make is that the fancy digital SLRs generally give you a lot of flexibility in how you can post-process the stuff you capture. More on this later in the section on things I like.

For more basic technical info, look here: http://www.photo.net/digital/cameras/basics/.

What I like

Here are the things I like most about shooting with digital cameras.

Per frame cost is "free".

It's not really free because disk space isn't really free. But it may was well be. The biggest files I shoot with my Nikon cost 10MB per frame. At current disk prices, this is about $.01. Multiply by two to take backups into account. Still a lot cheaper than film.

Lots of shooting flexibility

Carrying a digital camera is like carrying a film camera loaded with slow color slide film, fast color slide film, tungsten film, and black and white film all at once. And, you get to pick what film you use on a frame by frame basis. Going from outside to inside? No trouble, just shift the ISO up 2 stops. Shooting under wierd mixed lighting? No problem. Capture RAW and then rebalance it all in Photoshop. It's just amazing.

No scanners

I hate scanning film.

Color darkroom as cool as my black and white darkroom.

Photoshop, and most of the Photoshop-like tools give you the ability to manipulate color photos as easily as I used to dodge and burn black and white prints in the darkroom. You can adjust levels, color balance, sharpness, contrast, and almost anything else with a level of precision that is simply not possible in the darkroom. I never wanted to do my own color printing because these sorts of adjustments are too hard (for me). But Photoshop makes it possible. Of course, high quality color printing still requires a lot of tedious work with color profiles and all that. But even simple dumb prints that I've had made look pretty good.

Digital SLRs take this one step further by allowing you to capture just the "RAW" CCD data from the sensor with no image processing whatsoever. You can then post-process this file using any one of several different pieces of software on your desktop computer to get to the final image. The range of adjustments is phenomenal. I use the Adobe RAW plugin that comes with Photoshop. It's just amazing. Just the auto white balancer is worth the price of admission.

Some point and shoot cameras also capture RAW files, but it's not as heavily used, and makes the camera even slower than it used to be.

Automatic Cataloging

With a program like iView MediaPro and a bit of discipline, it's easy to keep track of all the pictures you've taken, when you took them, how you took them, which lens you used, whether you used flash, what the exposure was, and on and on. With a bit more work, you can tag the pictures with keywords, people who are in them, and all that. And, you can keep track of all of this across backups to multiple disks, CDs, DVD or whatever. All of this is way beyond putting film strips into PrintFile pages and keeping those filed by hand. I love it. I hate putting film strips in PrintFile pages.

Easy to share with your geek friends

I can make web albums in 5 minutes after I get done shooting. This means people see the stuff I shoot. With film, things being the way they are, it can take a year or two before anyone sees prints of what I've done. I have 5 or 6 year old negatives that I want to print but probably won't until my son is in college. Of course, all your friends have to have computers and Internet for this to work.

Digital prints are better than they deserve to be.

I get prints from Apple through iPhoto. Apple gets the prints from oFoto. I use iPhoto to pick which files I want to print. They get uploaded to oFoto and I get prints a few days later. I don't do any color profiling or special adjustments except to match gamma. There is no way this should work. But, the prints I get look great. The color is right, they are sharp, and I have even gotten 8x10s from JPEG files from my 3 megapixel point and shoot that are as good as any 8x10 print I have ever done. This is not how it is supposed to work, but it does. These are the nicest non-custom color prints I've ever had done. It doesn't really motivate me to ever shoot color film again.

The pictures are always with me.

They are on the web, they are on my laptop, they are in my screensaver. It's great.

What I don't like

Backups

This is the flip side of the nearly automatic cataloging. Most of the ways we have to store data in digital form are not all that permanent. The best you can do is to make multiple copies of everything and hope that all your disks don't fail at once. Keeping track of what you have copied and what you haven't is sort of a chore, but it's important to get right. You don't want to lose that perfect picture just because you got sloppy.

I generally keep around three copies of every picture file I have. One on my laptop, one on an external firewire drive, and another on another external firewire drive which I keep at work. My plan is to buy a new firewire drive every year and just keep making copies.

Color is a pain

Even as good as Photoshop is, it's hard to get color that looks the same everywhere, especially on web pages. It's really annoying. The work that you need to do to really be sure that you'll get a print that looks like what you see on your computer is astounding. For now, I'm willing to be sloppy.

Black and white output stinks

There is no black and white digital output that has the same look and feel as nice prints made on nice glossy fiber black and white paper. This is not to say digital prints are not as good. They just are not the same.

Also, most black and white digital prints are done on color printers, so the color profiling issues from above also apply to black and white prints. This means I have to understand color printing to do my own black and white, which is annoying.

Backups

It's worth repeating. This is a pain.

No big prints

I don't print bigger than 11x14, so I generally don't care. But you can print 35mm or 120 film up to 20x30 without working too hard. It's not clear that current affordable digital devices will do as well at those sizes.

Wierd Depth of Field

Depth of field is always longer with digital cameras, since the sensors are smaller than 35mm film. This is especially true with the point and shoots. It's almost impossible to get a really blurry background with a camera that uses one of those tiny sensors.

No small fast cameras

In the film world, things like a Leica, the Konica Hexar or even some high end point and shoots are responsive enough to be used without a lot of compromises, but still much more portable than an SLR. There is no such digital camera. In general, even the Hexar-like point and shoot machines just are not as nice to use. What the world needs is a digital camera with the body of (say) a Canon G5 but the internals (say) of the Digital Rebel SLR. This way, you get a relatively more portable package but with a high quality high resolution sensor and a fast image processing pipeline. As it is, we have a lot of expensive point and shoot cameras that still make you wait 2 seconds between shots.

More time on computers

I use computers too much, and this just makes it worse. But I guess that's just life.

Conclusions

So, after all of this, my final thoughts on digital are: it all depends on what you want to do. If you want great photos that are easily sharable and convenient to edit and share, then digital is great. I can think of no better way to share baby pictures in this day and age (except for the one aunt with no Net).

On the other hand, when I have the time, digital does nothing to kill off what I would use black and white film for. I won't be making many black and white snapshots, but for those times when I really want a nice print, I can't imagine not doing it in a darkroom somewhere. Darkroom work takes much more time than I have right now, but with luck I'll get back to it at some point. For now, working with digital pictures is just fine with me, and I can do it in small chunks of time while playing with my son. So the lure of the darkroom is actually not that strong.

Random Notes, Questions, Myths and such

Isn't a 6 megapixel camera really a 2 megapixel camera?

This question is complicated. On the face of it, the only "real" data that the sensor in a digital camera directly captures is a single R, G or B value at each pixel. This means that in theory you need 3 pixels for every single pixel of "real" RGB data in the final image. But, image data is fantastically redundant. The fact that there are ways to compress images by a factor of 10 with little or no loss in subjective quality, means, in some sense that you don't need to capture full RGB data at each pixel to construct an image file that is very close to the one you would get if you directly captured RGB at each pixel. This is a long and confusing away of saying "it depends", and that it's plausible that even though at some level image reconstruction algorithms are "guessing", in most situations, they will tend to guess the right answer.

How many megapixels are in a frame of film?.

There is no simple way to answer this question. A frame of color film is made up of dye particles that end up where they are through a process that involves chemically developing three layers of black and white film and then bleaching the result and coupling the right dye to the right layer of film via some magic of chemistry that I really don't understand. In other words, it's magic.

A digital color image is created, as we have seen, by capturing image data at millions of sites at once, and then running some software that guesses the color that should be at any given point in the image. In other words, it's magic.

So, how are you going meaningfully compare the final resolution of these two processes?

Subjective and anecdotal evidence suggests that current generation digital cameras seem to be able make files that can make prints up to 11x14 or slightly larger that are as good or better than similar prints made from 35mm film. But YMMV.

Personally, I would never shoot 35mm color film again. I have no reason to. But black and white, and larger film sizes, are a different story.

Won't digital cameras ruin photography forever?

They've said this about every new format and style of camera back to when people stopped using glass plates and started coating plastic. I see no reason why digital should necessarily change things more than anything else did. It still takes the same set of skills and passion to get a good picture and present it well.

Aren't point and shoots just toys that can't take a good picture?

If you use the camera with full knowledge of its limitations and quirks, you can get good photos from anything. At some level, it's not the camera that matters, it's how you use it and the subject matter you pick that matter. Also, see the toy camera page for some real toys.

What kind of digital camera should I get?

I don't really know. But, don't buy a Sony because memory stick is stupid. For general use, I like the Canon point and shoots a lot. For more advanced use, I use a Nikon D100. It has the advantage that it uses Nikon lenses that I already own. The Canon SLR bodies are also excellent. Don't spend more than $500 or $600 for a point and shoot because at that point you might as well just shell out for a Digital Rebel or whatever. Maybe someday someone will make a camera that is the size of a Leica with the performance on a Canon or Nikon SLR body. But don't hold your breath.