Digital photography versus conventional
Written January 2004, updated 2004, 2007 and April 2009.I've been doing mostly digital photography for a few years now, but in the past I've used slides and SLRs for professional photograpy.
I stopped doing professional photography for a while, and during that period I was pretty tired of all the gear I'd been toting around while using an SRL. I wanted a small, advanced, light digital camera, which is what I found in the Canon Powershot S40 in 2002. A few years later I bought a Nikon Coolpix 2200 because it was smaller and cheaper, and didn't eat batteries. I bought the Sony Ericsson K800i cell phone when it came out (pretty good camera on it), and gave away the compacts after buying a DSLR in 2007.
During the last few years I've seen that there are big differences between the two formats - digital and film.
This page will also focus on some peculiarities of using digital cameras, that you may not consider when you're just starting out.
Focus
Digital compact cameras generally have a problem with focus in low light. Conventional SLR's are generally better, and DSLR's are pretty good depending on the lens. I missed many shots because the Canon S40 had problems focusing, but if I just clicked without waiting to see if it can focus, I'd get the shot - though it may be out of focus. Most compact digital cameras will probably suffer from this malady. I found that when doing macro photos in low light, a narrow beam flashlight directed at the point where the focus assist lamp is hitting, is enough to achieve focus. The K800i has bad auto focus in low light. I must accept the bad focus, or not use it indoors. The 4x5 prints are acceptable, though it does show that the focus is bad - though with a cell phone camera, camera shake is usually a worse problem than focus.
Delay
All digital cameras have a delay from the time you press the shutter until the photo is taken. Some models are better (that's their selling point), but there's a pretty big difference between an old manual focus SLR (if you follow focus the whole time) and a digital or even any other camera with automatic focus. The latest DSLR's have almost no delay. That development was driven by professional photographers. Also check reviews for compacts in regards to relay. But with the older compacts, I routinely missed the shot I would have gotten with my old SLR's.
The effect of the delay is pretty marked, in that you'll never know exactly what's on the photo until after it's taken. Practice, so you'll have an idea of when to start pressing if you're following something with a predictable sequence of movement. Even so, for photos of pets, a conventional camera will waste a lot of film for just a few usable photos. I tended to use the digital for photos of my cat.
Photo quality
This depends on what camera you're using. In the past, you wouldn't have the smooth gradation of tones as you'd get with a good SLR and a good slow positive film. But the better the camera, the better the results. I saw a comparison on Nikon's site, saying a photo shot with conventional color negative film was roughly equivalent to a 6 megabyte file (probably measured in RAW) in the amount of detail it records, while slide film (that the professionals used) would be equivalent to a 30 megabyte file.
In general, when you use color negative film, the printer compensates for bad exposure. When using digital, you need to post process in the computer to get it just right. One of my cameras (S40) tended to overexpose slightly.
I can also usually see the difference in flash photos. The photos are generally sharper than what our compact cameras produce, but with a good eye and experience, you can pick out a digital photo because of the edge sharpness and occasional artifact. The artifacts aren't visible to the naked eye in prints from my camera, but the peculiarities in prints are there once you're attuned to seeing them (talking about the 4 megapixel S40).
In the past I would usually use a compact digital camera rather than my old SLR's because I saw the results right away. Since I now have a DSLR, I don't know what it would take for me to use the old SLR cameras again. I also don't bother with compact digital cameras other than my cell phone, unless I were on a vacation and needed photo quality better than the cell phone and more portable than a DSLR.
DSLR vs compacts: The DSLR's use a bigger image chip than the compacts. Which means that as the megapixels go up, the amount of noise goes up, because each pixel gets smaller. Amateurs tend to think there's no point in getting a DSLR, because compacts are so good. There is a point if you need low noise and very good files - for blowing up. For a family vacation where you expect to make 4x5 inch prints, you wouldn't easily see the difference unless the photographer is extremely good.
Batteries
My old camera eats batteries (S40), and although I have two custom batteries, one is usually shot after just a few shots (just sitting in the camera will drain it and permanently make it weaker). I usually take the charger with me wherever I go. A DSLR that uses the same type of batteries would get a lot more use from them. Simply put, there might be something wrong with the S40. Also, the older the camera, the more it eats batteries, in general.
The Nikon doesn't eat batteries. And the Nikon uses ordinary AA batteries, regular or rechargeable. The Olympus was horrible (my first digicam), but they've made definite improvements in battery usage lately. The flip side of that is that the Nikon is very slow - after you've taken a flash picture with bad batteries, it takes forever to come online again.
Skin tone
I find that there usually are overexposed glittery
areas when I'm doing portraits lit with flash (S40), even when the flash is only
providing fill-in.
Moisture or dry spots will produce these, and it's a dead give away that you've used a digital camera.
In the photo to the right, you can see that highlights are burned out (lips, teeth). This was taken outside with fill-in flash.
Flash
With an SLR, I'd use a dedicated automatic flash (yes, even if they've got built in flash), and so the difference is of course very marked. But even so, I think the digital camera has one more problem with flash - you'll have to compensate for bad exposure on the computer, while a printer will be able to salvage a bad shot from a film camera without you noticing much. I also feel that people seem to blink a lot more when I use my digital camera compared with an SLR. Some people blink in every single shot, which is very unusual! That's one reason I'd use a hot shoe mounted flash on a DSLR - it doesn't produce the blinking problem to that degree, because of the added distance between lens and flash.
I tried to use my lightmeter with the digital camera once (The S40 has manual settings). Let's just say it didn't work. I think you'd have to do a series of tests to figure out the settings properly (just using the ISO settings won't work, since they're off), and even then I'm not sure how accurate it is. Supposedly the ISO settings are accurate on DSLR's. But few use flash light meters these days anyway. The instant feedback from seeing photos right away is enough.
The S40 isn't supposed to be used in the studio, but there are plenty of digital cameras that can be used for that. You'd need a hotshoe or a flash that can be set manually or swivelled. Some DSLR's come with the ability to sync flash, or you can buy a wireless sync unit for the hot shoe. With my camera I'd probably have to fiddle a lot with the settings and possibly put a diffuser in front of the flash to get it to work. I'd need the flash to sync to the lights, but need to knock it down so it wouldn't ruin the lighting.
If you've got an old flashgun (like 20 years old?), watch out, as some newer cameras might get burned out sync circuit! Here's the skinny (from 2004, so I don't know how accurate it is for newer models). But if you want to be on the safe side, pick up a Wein Safe-sync adapter (also useful to block out extra pins on incompatible flashes!)
The Nikon doesn't suffer from overexposed macro shots, like the S40 does. I have to watch it so they don't get too dark. The red eye reduction works on people who always blink with the other camera. Frankly, although the Canon is a far better camera in terms of output, I'd probably rather use the Nikon for pictures of certain blinking people. The regular flash setting is just as bad, though. And here's a pretty big difference: The red eye setting on the Canon produces red eyes, while the Nikon rarely does. It's much more efficient. A series of flashes, as opposed to one brief preflash for the Canon.
Storage
I've got a few big capacity compact flash cards, but for a long vacation, I'm not sure it'll be enough. Either make sure you bring lots of big ones, or make other arrangements.
You can also bring a laptop, arrange with friends with either CD-burners or broadband connections, or find a photo shop or internet cafe with a CD-burner.
Make sure you test everything before embarking on a vacation. Some cards are less compatible. I have some less compatible cards, and some units won't read them. For my DSLr I stick with major brands.