Auto Mode in Photography: What’s Happening Under the Hood?

Auto mode in photography is pretty self-explanatory, right? You just turn the camera on, point at what you want to take a picture of and click away.

But what’s happening under the hood when we’re shooting in auto mode is a different story. There are multiple decisions that your camera will make in order to get what it sees as a proper exposure.

So in this article, I’ll go over what decisions your camera is making and why when you take a picture. Additionally, I’ll be talking about some specific instances when you’d be better off getting away from auto mode and shooting in manual or a semi-auto mode.

What Does Your Camera do in Auto Mode?

There are essentially six things a camera does when shooting in auto mode, which I’ll cover here.

1. Takes a Meter Reading: The first thing your camera will do when shooting in auto mode is to take a meter reading of the scene it’s pointed at. In other words, your camera will take a measurement the light it sees. From there, it makes adjustments to your aperture (the size of the hole that lets light into the camera), the shutter speed (the length of time the camera’s shutter is open, exposing the sensor to light) and ISO (the sensor’s sensitivity).

2. Adjusts Aperture: As stated previously, aperture is the size of the opening within a lens that lets light into the camera, allowing it to reach the sensor and record the light. When this opening is larger, it allows more light to enter the camera and vice versa; when it’s small it lets less light in. So in theory, when your camera’s meter sees a bright scene, it’s more likely to choose a smaller aperture accordingly. And for dark scenes, it’s more likely to choose a bigger aperture.

3. Adjusts Shutter Speed: A camera in auto mode will also choose how long its shutter opens and exposes the sensor to light, before closing again. A faster shutter speed means the shutter stays open for a shorter period of time, which lets less light in so a camera will be more likely to choose a fast shutter speed when it’s pointed at a bright scene with lots of light. On the other hand, a slow shutter speed leaves the shutter open for a longer period of time, letting more light in – which is more suited to darker situations.

4. Adjusts ISO: ISO is like a digital camera’s film. The more sensitive it is (and the higher the number it is) the more light it will capture. The less sensitive and lower the number of ISO, the less light it’ll let in. So for bright scenes, your camera will err on the side of choosing a lower ISO. For dark scenes, high ISO.

5. Chooses a White Balance: What balance refers to the color cast of an image, or rather how accurate colors are reproduced by the camera. Images with blueish color casts are referred to as ‘cool’, while images with a more red/orange color cast are referred to as ‘warm’.

When shooting in manual mode, you have the option of choosing your white balance manually or setting it to automatic and having the camera do it for you. The correct white balance to use for night photography is going to be different from your white balance in daylight, and it’ll be different under fluorescent lighting, etc.

I personally always shoot with automatic white balance even if I’m shooting in manual. With white balance, many cameras are good at getting it right in-camera, plus, you can always adjust white balance later in post without damaging your image.

In my opinion, if you can set it and forget it, more power to you. I’d much rather be focusing on my compositions than fiddling with my camera settings.

6. Fires the Flash (if needed): In automatic mode, if what’s seen by the camera’s meter is sufficiently dark, it will pop up the flash (if the camera has a pop-up flash of course) and fire it straight onto the scene it’s pointed at.

While this is great if you have no other option and are taking pictures in a really dark environment, it’s not always (usually) the way to go. Direct flash can be an aesthetic that people like (gritty street photographers or event photographers are more likely to embrace it), but overall is not a flattering look for your subjects. Harsh, direct light is not the type of light you’ll see modeling/advertising photographers using to make their subjects look beautiful – they’ll soften the light as much as possible.

So while there are certain instances where using direct flash is fine (although some photographers would tell you to never, ever use direct flash), I think it’s best to not use direct flash until you get more confident in your photography and have more of an idea of the aesthetics you personally like. In which case you can simply switch your camera to ‘P’ mode, which does everything a camera does in auto mode, aside from using flash – it won’t do that.

When/Why Should You Use a Mode Other than Auto?

There are plenty of situations that call for using a mode other than auto mode in photography. And not surprisingly, there are way more instances where you should not use auto mode than use it if you’re serious about your photography.

I have nothing against shooting in auto mode. When I got my first DSLR I had a great time just leaving the camera how it came (set to auto) and snapping away. My friends might not have liked having a camera shoved in their face every waking hour of the day but that was their problem.

Shooting in auto allowed me to get used to handling my new camera, but more importantly, to start practicing composition and paying attention to light. Composition and light are about tied in terms of their importance within photography, and I view the two as far more important than any other concepts in photography. So I view it as a positive experience that I was able to take my time, not worry about having to fiddle with my settings and focus on the important things in photography at first.

That being said, if you don’t get out of auto mode, you’re shooting yourself in the foot. There are several reasons why, which I’ll cover here.

1. Depth of Field Control: A big reason to get out of using auto mode is being able to control the depth of field of your images. Depth of field refers to how much of an image is in focus.

In say, portraits, you’re more than likely going to want a shallow depth of field in order to draw attention to your subject and blur out the background, which can be distracting. On the opposite side of the spectrum, when you’re taking pictures of landscapes you’ll most likely want a small aperture and more depth of field so you can capture as much detail as possible.

Obviously using auto mode doesn’t give you the control to choose the size of your aperture because the camera will choose it for you, so if you need a specific depth of field for a certain type of shot, auto is not the way to go.

2. Motion Blur: If you’re using auto mode, you can’t choose a minimum shutter speed, which means sometimes the camera will choose a shutter speed slower than you want, resulting in blurry images/blurry subjects. And conversely, if there’s an occasion when you intentionally want to blur a subject, your at the whims of your camera.

If you get out of auto mode, you have the ability to choose whether you want to use a fast shutter speed and freeze the action or if you want to drag your shutter speed and get some motion blur in your shot.

3. Grain/No Grain: Most photographers want to limit the grain in their images as much as possible, save for some specific instances when it’s specifically called for. Whether you like grain in your images or not, you still have to know what will result in grain and what won’t.

High ISO will give you grain. Low ISO results in just the opposite. There’s nothing inherently wrong with grain in photography (although you do lose some detail) but the key is knowing when to utilize it and knowing when you want it. When using auto mode, you don’t have control over whether you’ll get grain or not because the camera chooses the ISO for you.

4. Flash/Natural Light: With auto mode, you don’t have control over whether the camera will fire its flash or not. And in my experience, cameras in auto mode are programmed to fire the flash way more than I’d like.

For most types of photography, direct flash should only be used in emergencies, when there’s literally no other option. But the majority of cameras in auto mode will shoot with flash if you’re in any lighting conditions less bright than outdoors with super bright sunlight. If you’re indoors with the lights on and even with bright natural light coming through windows, cameras in auto mode are liable to use flash unnecessarily.

So if you don’t want straight-on flash (which is rarely a good thing), you’ve got to get out of shooting in auto.

When IS an appropriate time to shoot your camera in auto mode?

While I very, very rarely shoot my cameras in auto mode, I don’t have anything against it per se. The problem with it though is the lack of control over your results. But here are some of the specific instances I can think of off the top of my head where it’s appropriate to go ahead and fire away in auto:

-When you’re just starting out: As I touched on briefly earlier, it’s obviously perfectly fine to shoot your camera in auto when you get your first one. It allows you to get a feel for handling it and just becoming familiar with a camera’s ergonomics.

It’s less intimidating, which for beginners, is always a good thing. You don’t want to lose interest in photography right away just because you can’t figure out how to get the dang camera to work properly.

Additionally, whether you’re a beginner or a pro, there’s nothing wrong with taking your first few shots with a new camera to get a sense of its image quality. That’s a great thing about digital photography is the instant fee back, so I see no problem taking advantage of it.

-Casual Settings: I take a camera with me everywhere I go. But if I’m out with friends having a drink or something, I really don’t want to be fiddling with my settings if I’m going to be taking pictures. I want to be able to take a picture if I see a cool moment and move on with my life.

I’m way more likely to use auto mode in tough lighting conditions. If I’m at a dark bar or night club and I know I’m going to need flash and am having trouble getting to a proper exposure in manual mode, I’ll switch to auto and let the camera do the work.

If I’m in a well-lit situation and wanted to use an automatic mode, I would use a different mode, something like P mode or aperture priority. That way, I wouldn’t have to deal with my flash popping up and I would have more control over the final result.

-In Emergencies: If you’re a working professional photographer, occasionally instances will come up where you just have to be like “fuck it – I don’t have time to dial in my settings” and you quickly switch to auto mode to get the shot. I’m talking fast-pace, highly important situations.

Bride and groom come out of a dimly lit church into extremely bright sunlight? There’s no shame in putting your camera in auto if you get caught off guard.

It’s infinitely times better than to get the shot at randomly chosen settings than to not get the shot at all. Getting the shot is everything in certain types of photography – in wedding photography in particular, you’re documenting the most important day of the couple’s lives. You’re much better off getting the shot than messing around with your settings and missing the moment.

Will your clients know you shot a certain picture in auto?

They won’t have the slightest idea.


What is photography really about? Yeah, it’s about documenting and creating memories that you can keep forever.

But when we consider why we do it, it should be about having fun. Because otherwise, what’s the point?

If shooting in auto mode makes you happy, then there’s absolutely nothing wrong with that. If you’re going to get serious about photography then you’ll have to learn the other modes, but for the instances laid out above, there are several cases where it’s perfectly fine using auto mode.

If you’re unsure of any of the terms used in this article, be sure to check out our photography glossary.

Photo of author

Brandon Ballweg

Brandon Ballweg is a photographer from the Kansas City area. He is the founder of ComposeClick.

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