Basics of Photography Explained: Aperture, Shutter Speed, Exposure, Depth of Field

[TROLL]

Thought this might be useful to some of the guys here looking to understand how to control their photos a bit more. This site has a separate page for each section, and it is a very worthwhile read to someone looking to take some photos, not have their camera take the photos for them.
You can navigate the page at the bottom, where the links say: Introduction || about aperture || about shutter speed || about exposure || Glossary || Relative: Depth of Field
If, after reading this you have any questions, feel free to ask and myself or anyone else with the answer can help. Please do not ask any questions without first reading these articles in full as they are the foundation that you're going to need before you're able to understand anything else.

http://www.mir.com.my/rb/photography...tter/index.htm

Or, here's my own little writeup I made in another thread, based off of info I found online, including wikipedia...

Originally Posted by TROLL

There's a lot to learn... kids spend a semester on just the basics. You seem pretty eager to learn and you're taking the suggestions people are giving you so I guess we can continue to try and help. I also recommend reading your cameras manual at least once, maybe twice. Understand what every button is on your camera and how it works and if you're not sure then do some research to look it up.

You'll definitely want to move away from shooting in an auto mode, but before you can do that correctly you need to learn the basics so that you understand how to use your camera skillfully as a tool and be able to effectively produce the photos that you intend to.

I ended up just putting together a pretty lengthy intro guide to photography here. I typed some of the info myself and referenced wikipedia for some other that I couldn't figure how to word/explain clearly. There is a lot of good info here and will get you started, but there is still a lot to learn. Its a process... we're all still learning.

I have not gotten into how to make a good exposure (which can vary a lot by the shooting situation)... but its really late so that will have to be left for another time. If someone else want to step up and write something out for that then awesome, or if not I'll try to get around to it.


ISO
Film speed is the measure of a photographic film's sensitivity to light. Film with lower sensitivity (lower ISO/ASA speed) requires a longer exposure and is thus called a slow film, while stock with higher sensitivity (higher ISO/ASA speed) can shoot the same scene with a shorter exposure and is called a fast film.
The lower the film speed the less sensitive it is to light and the higher film speed the more sensitive it will be to light. The lower ISO you use the less 'noise' you will have as well which means the quality of the photo will be better. The higher film speed you use the more noise you will have and the quality of the photo will drop, but when you need to use a high ISO, you need to use a high ISO. Rule of thumb is to only use as high an ISO as is necessary... sometimes it is and thats fine, but when its not, go low.
(read more at: http://en.wikipedia.org/wiki/Film_speed)

low iso/noise vs. high iso/noise



Exposure (part 1)
The "correct" exposure for a photograph is determined by the sensitivity of the medium used. For photographic film, sensitivity is referred to as film speed and is measured on a scale published by the International Organization for Standardization (ISO). Faster film requires less exposure and has a higher ISO rating. Exposure is a combination of the length of time and the level of illumination received by the photosensitive material. Exposure time is controlled in a camera by shutter speed and the illumination level by the lens aperture. Slower shutter speeds (exposing the medium for a longer period of time) and greater lens apertures (admitting more light) produce greater exposures.
Ultimately, there is more than one correct exposure, as a scene can be exposed in many ways, depending on the desired effect a photographer wishes to convey.
(read more at http://en.wikipedia.org/wiki/Exposure_(photography))


Shutter Speed
This is the length of your exposure. The shorter the exposure the less light allowed in. The longer exposure the more light it allows in. Shutter speed will also affect how much motion is stopped. A faster shutter speed will stop more motion and a slower shutter speed of a moving object may appear as a blur.
Also make sure that if you are shooting handheld that your shutter speed is fast enough that you don't cause any camera shake. Rough rule of thumb is your shutter speed should be 1/x where x = the focal length you are shooting at.
(read more at http://en.wikipedia.org/wiki/Shutter_speed)

different shutter speeds



Aperture
This is the intensity of your exposure. There is a diaphragm inside the lens which adjusts larger and smaller to let more or less light through. Think of a pinhole's worth of light vs a quarter size opening's worth of light. Also remember that f/22 is a small aperture (small opening), and f2.8 is a large aperture (large opening)... so the numbers seem backwards.
(Read more at: http://en.wikipedia.org/wiki/Aperture)

Small vs. Large aperture





Exposure (part 2): How Shutter Speed and Aperture work together to make the correct exposure
Factors that affect the total exposure of a photograph include the scene luminance, the aperture size (f-number), and the exposure time (shutter speed); photographers can trade off shutter speed and aperture by using units of stops. A stop up and down on each will halve or double the amount of light regulated by each; exposures of equal exposure value can be easily calculated and selected. For any given total exposure, or exposure value, a fast shutter speed requires a larger aperture (smaller f-number). Similarly, a slow shutter speed, a longer length of time, can be compensated by a smaller aperture (larger f-number).


Depth of Field
The portion of a scene that appears sharp in the image. Although a lens can precisely focus at only one distance, the decrease in sharpness is gradual on either side of the focused distance. A large depth of field would make everything in the photo in focus, no matter if its 2" away or 2 miles away... this is commonly used for landscapes. A small depth of field would mean that only the point that you focused on is sharp, and fades to a blur quickly. This is more commonly used for portraits or other situations where you want to isolate your subject.
You can achieve a large depth of field by using a smaller aperture, and you can achieve a smaller depth of field by using a larger aperture.
(read more at http://en.wikipedia.org/wiki/Depth_of_field)

Shallow Depth of Field (DOF)


shot at f/32


shot at f/2.8


White Balance
Different light sources have different colors of light that they emit. The human eye is very good at adjusting to this so most dont realize that a flourescent light has a green tint and a tungsten light has a amber tint, for example. The camera will pick up these tints unless you adjust for it, either in camera, or in post processing. Its a good idea to try and make this adjustment in camera before you shoot, and do any fine tuning in post processing later if needed.
In photography and image processing, color balance is the global adjustment of the intensities of the colors (typically red, green, and blue primary colors). An important goal of this adjustment is to render specific colors – particularly neutral colors – correctly; hence, the general method is sometimes called gray balance, neutral balance, or white balance. Color balance changes the overall mixture of colors in an image and is used for color correction; generalized versions of color balance are used to get colors other than neutrals to also appear correct or pleasing.
(read more at http://en.wikipedia.org/wiki/White_balance)


RAW image files
A raw image file contains minimally processed data from the image sensor of a digital camera. Raw files are so named because they are not yet processed and ready to be used with an image editing program.
Because Raw files have minimal processing done in camera, they allow much more adjustment in post processing without as much image degradation. Basically, they are more forgiving in the cases where your exposure isn't quite right.
Raw image files are sometimes called digital negatives, as they fulfill the same role as film negatives in traditional chemical photography: that is, the negative is not directly usable as an image, but has all of the information needed to create an image.
(read more at http://en.wikipedia.org/wiki/Raw_image_format)

Originally Posted by TROLL

Haha I dont know what came over me last night but I just came home and started typing and organizing and came up with that. Figured maybe some of the guys here could work to correct/clarify/add to what i typed and we can maybe have a sticky in the photo section for people to read when they're just getting into it.



Auto Exposure Modes:

Auto (A) - uses flash when the camera sees fit

Program (P) - doesn't automatically use flash, you have to turn it on if you want it

Portrait - automatically uses the largest aperture possible (while still keeping a shutter speed in the cameras range) for the smallest depth of field to isolate the subject

Landscape - automatically uses the smallest aperture possible in the shooting situation (while still keeping a shutter speed in the cameras range) for the largest depth of field. I'm not sure if it will also not adjust the shutter speed so that it is fast enough to avoid handheld camera shake.

Sports - automatically uses the highest shutter speed possible (based on the allowable aperture range)

Night - allows the shutter speed to drop below handheld shutter speeds (usually about 1/20 or 1/30) and assumes you're shooting on a tripod. The longer shutter speeds are often necessary to expose photos to expose fully at night, with or without flash.



Semi-Auto and Manual Exposure Modes:

Aperture Priority (Av) - You select the aperture you want to use yourself, and the camera calculates what it believes is the correct corresponding shutter speed based on the ISO that is set and the luminance of the shooting situation.

Shutter Priority (Tv) - You select the shutter speed you want to use yourself, and the camera calculates what it believes is the correct corresponding aperture automatically based on the ISO that is set and the luminance of the shooting situation.

Manual (M) - You select both aperture and shutter speed. You have help to set this properly... there is a light meter built in onto almost all cameras which will guide you to what the camera believes is the correct exposure. This is a very helpful tool and should definitely be used, but also consider that the camera isnt always right, especially in tougher lighting situations, which is why sometimes you need to override its suggestions (and why all other shooting modes sometimes wont work).



Looking through the viewfinder: Light Meter
This will vary by camera but here is what the viewfinder looks like on a Nikon D40x. Take a look at the labels for each thing. Also notice the light meter exposure scale toward the middle with a 0 in the center and + and - on either end. There is a lot more to making a 'good' exposure, but just to get started, practice getting the meter to read as close to the center of this scale as you can.

[naDintheHat]

Thanks Troll, i finally got enough cash to pick up my camera this should be helpful with understanding the basics. But I will be up for pointers once i start taking the photos.

[TROLL]

Yeah before anyone is allowed to ask any specific questions they HAVE to learn a few basics first. I'm sure there are many helpful sources out there but I found this one tonight and it looked decent.
But seriously when people ask me specific questions they dont understand the answers because they dont have the proper basic background to comprehend why it works the way it does.

[sisforsurfing]

Good link, Bryan. I also can't recommend enough taking a Photo 1 or Basic Photography class at a community college or as an elective if you're still in school. Teaching myself the past 4-5 years would have been much more rewarding if I'd had some of my professor's insight that I have now.

[dt98gsr]

Some good basic info on that link, but there grammar is a little off.

Besides that it was helpful.

[TROLL]

Originally Posted by dt98gsr

there grammar is a little off.

oh god cant help myself... its "their"

[WhiteXFire]

Originally Posted by TROLL

oh god cant help myself... its "their"

Heh, that was "ironical"...

[Spocknasty]

http://www.cambridgeincolour.com/tutorials.htm

More tutorials / facts.

[96Stang]

very much to take in...but seems very helpful...i will be using this while practicing with my new film slr cam i got for xmas from the gf

canon eos k2 slr...fun stuff for myself the beginner...anyone have any input for a newb such as myself

[ozthunder]

I know i'm late, but thanks for this post. As a proud new owner of a camera that is not attached to my phone, this is awesome.

[namdoogwerdna]

^ Me too!

[Chris215]

here's a decent tips article on automobile photography i found.
http://www.cobracountry.com/fototips/

[i like rice]

Originally Posted by Chris215

here's a decent tips article on automobile photography i found.
http://www.cobracountry.com/fototips/

too bad most of those images aren't that great, though.

[TROLL]

a flash page that gives a visual explanation of f stops... good for those who dont quite understand what number represents what inside the lens...

http://www.photoworkshop.com/photo101/lens_aperture

[CleanNeon98]

Are there any articles that focus specifically on Depth of Field?? For the love of me, I cant get that "sharp subject, blurry background" look, only sometimes by accident.

[Zillon]

Originally Posted by i like rice

too bad most of those images aren't that great, though.

I've seen a lot worse.

Namely, PhotosGuy on POTN. I'm sorry, but his work is not that great for all the criticizing he does.

Good link, Bryan. I've stumbled over the page a few times before, it's a good starting point for beginners.

[i like rice]

Originally Posted by CleanNeon98

Are there any articles that focus specifically on Depth of Field?? For the love of me, I cant get that "sharp subject, blurry background" look, only sometimes by accident.

Longer focal length, larger aperture. You're limited by the lenses that you have. A longer prime lens, such as the 50 1.8, 50 1.4, 85 1.8, will all give you good separation from the focal point & the background. This is why I use my 70 200 lens more often than the 16 35.

[CleanNeon98]

Originally Posted by i like rice

Longer focal length, larger aperture. You're limited by the lenses that you have. A longer prime lens, such as the 50 1.8, 50 1.4, 85 1.8, will all give you good separation from the focal point & the background. This is why I use my 70 200 lens more often than the 16 35.

Well im using the kit lens right now. What I notice is that to get a good sharp focus and blurred background I have to be fairly close to the subject (with a 18-55 that means right next to it) and what happens then is I sometimes get a bit of distortion in the corners. I know that im not using the camera to it's full potential yet, I am only shooting on M mode, havent really played with the others, and there is a "depth of field" button near the lens that I have no idea what to use for.

[TROLL]

narrow DOF is more emphasized as your focal length gets longer, and a larger DOF is more emphasized as you move toward a wide angle lens... look at NFL photos where the player is sharp and the fans behind him are totally unrecognizeable... for all we know big foot could be back there, cant really tell. thats because they're shooting with a 400mm f2.8 most likely and the combo of long lens and large aperture are a tag team combo.
shooting wide open on any lens will also reveal any flaws it has in image sharpness, so unless you're using a high quality zoom or prime lens, it probably wont be tack sharp when you shoot wide open.

[i like rice]

Originally Posted by CleanNeon98

What I notice is that to get a good sharp focus and blurred background I have to be fairly close to the subject (with a 18-55 that means right next to it)

This doesn't make sense since you're moving yourself closer to the background by shooting at a wider focal length. Step back further, shoot at 55mm (f/5.6 on the kit lens) and create more distance from the background.

You can still get a decent amount of blur at f/5.6, you just need more distance from the background.