Since there are 3 important variables here: aperture, shutter speed and ISO, I would Google for Exposure Triangle Cheat Sheet for example. Here are a few:

• Manual Mode Cheat Sheet ^[1] (Muddyboots Photography Blog)
• Exposure Chart Cheat Sheet ^[2] (Flickr)

• My Exposure Triangle Cheat Sheet ^[3] (glark.org)

My Exposure Triangle Cheat Sheet (glark.org) link has been broken, image attached below instead:

Other broken links have been removed. Unfortunately, they were not able to be recovered from archive.org

There's really only one thing you need to memorize and it's easy: a list of standard f-stops in graduations of one f-stop (1, 1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32, 45, 64, 90). Once you notice that every other one doubles (with some rounding starting at f/11), you only need to remember the first two, 1 and 1.4. (Usually you can see this sequence printed on your lens, but knowing it will speed things up, as I'll explain.)

As @Matt Grum and @sebastien.b have pointed out, you are balancing three things ^[1] (four with flash, but for simplicity I won't get into that here): aperture (f stop), exposure time (shutter speed), and sensitivity (ISO value). The trick is to avoid making a complex calculation all over again from scratch each time you decide to alter one aspect of the picture. Instead, start with any combination of settings that gives approximately good exposure. From that point on, change your settings by balancing them in pairs to keep the exposure the same or modifying only one to change the exposure.

"Balancing in pairs" means that you make exactly offsetting changes in two settings. When you double the exposure time, for example, either halve the ISO or change the aperture to keep the total light the same. Here's where your memorized list of f-stops comes in: to compensate for increased exposure, you have to increase the f-stop (this perhaps is the most confusing aspect of the whole procedure, but it's easily learned). In this example, you need an increase of one whole stop to make up for the doubled time. That means from 1.4 to 2 or 2 to 2.8, etc. (If you're good at multiplying in your head, just multiply by 1.4. If your lens or camera wheel has detents at half stops or third stops to give tactile feedback, just count two or three clicks, respectively: this lets you keep your eye in the viewfinder, which is essential when photographing fast-changing scenes.)

Here's a worked example. You are in AV mode (aperture priority) set at f/8. Suppose your camera meters for 1/100 second and automatically sets the ISO to 400. Let's see what adjustments it will take to create a shallow depth of field ^[2].

To reduce depth of field, you know you'll need to increase the aperture, probably by quite a lot. The offsetting therefore has to come from reducing the shutter speed and/or the ISO. Reducing the ISO is good--it eliminates some noise--so that's the first thing you might do. Then you make up any of the rest with shutter speed. E.g., if you want to shoot at f/2, you can quickly count mentally 2 - 2.8 - 4 - 5.6 - 8: four stops. Change the ISO by comparable factors of 2: 400 - 200 - 100 (that's often as low as you can go): two stops. You need two more stops to offset the change in aperture, so count 1/100 - 1/200 - 1/400 in shutter speed. (In some cameras you might need to round 1/400 to 1/500. If you're not good at doubling and halving numbers in your head, it's still easy to memorize some basic sequences, such as 50 - 100 - 200 - 400 - 800 - 1600 - 3200 - 6400 for ISO and 1/2 - 1/4 - 1/8 - 1/15 - 1/30 - 1/60 - 1/125 - 1/250 - 1/500 - 1/1000 - 1/2000 - 1/4000 for shutter speed. Say these to yourself a few times before you go to sleep at night and you'll know them the next morning.) Because you have now perfectly offset the change in aperture, you know the exposure is still correct. Moreover, because you can perform this counting mentally (and quickly, with a little practice), you know the answer without having to change any settings on your camera. This flexibility lets you go through various options beforehand, making any compromises you must, and enables you to nail the desired settings the very first time.

To summarize the example: after observing that a decent exposure can be obtained with f/8 at 1/100 sec ISO 400, by a simple procedure of counting through a series of f-stops, shutter speeds, and ISOs you can obtain your desired setting (whether it be a targeted f stop, exposure time, or ISO) completely without reference to any cheat sheet and without any arithmetical calculation. This will be far faster and more convenient than having to refer to written guides and doing a calculation for every change of settings that you are contemplating. After doing it a few hundred times it will be second nature and you won't even realize you're going through these steps. Now you're free to keep both eyes on the scene and focus on the art instead of the technique.

What are the basic calculations you're referring to? Other than doubling/having shutter speed or ISO when I open/close the aperture a stop I don't find myself doing any, I just fiddle with the settings 'till the image looks right on the LCD. After a while you get a feel for what settings work in what circumstances and the process becomes much quicker.

Here's an example of where I bluffed my way through an entire shoot in manual mode with manual flash, just using the camera's LCD screen as a guide:

This headshot of Oliver, editor of law journal Ebor Lex, done in a standard meeting room in a very short timescale. I thought it would be an interesting subject for a "stream of consciousness" post showing every shot that was taken during set-up and and trying to explain what was going through my head at the time. This is not supposed to be a perfect example of how it should be done, merely a record of how it was done.

It's important to have some idea what you're trying to achieve before you start so I decided I wanted something edgy, like this shot ^[1] but with a more traditional background. That look was achieved by having a pair of softboxes very close to the subject, angled slightly toward the camera so I started off with the lights in that position.

No light meters no modelling lamps, what follows is exactly what I saw on the back of the camera at each stage...

I didn't have a wide lens with me so no setup shot but here's a diagram to help you visualise what's going on.

First step, set up the background light (a projector screen makes the perfect background). I used a bare speedlight angled down so that the natural falloff would provide a nice gradient from light to dark. It's close to the screen with no light modifiers so it will be nice and bright so I set it on something like 1/4 power on for faster recharge. The camera is in manual, max shutter speed I can use with flash is 1/200s, for safety I go one setting lower, 1/160s. Middle of the road aperture of f/5.6, two stops down from wide open. ISO 100. Subject in place. Bang.

The image as it comes up first is on the left, I hit the "info" button straight away to get the histogram view (right). Background is a bit darker than I wanted, so I crank the flash up a stop. Bang.

That's better. The blinking area on the info screen indicates pixels which are blown out (i.e. have hit 100% white) since the camera can't record more than 100% white detail is likely to be lost. As the background is plain and I want it to be white I'm not bothered by this. I turn the background light off and the main light on. It's in close so power is set low. Bang.

Notice the timestamp (14:46), one minute has elapsed so far! The light is more extreme than I wanted. Move the softbox toward me a little. Talk to the model, explain what's going on. Bang.

Light is still too oblique. Move it round a lot, which involves moving the table slightly and costs some time. Bang.

Getting there, but need to move the light a little bit more to throw some light on the other side of Ollie's face. Decide to move the tables out of the way completely, which takes a few minutes (pro-tip: move the furniture before you begin, or better still, get someone else to do it for you). Bang.

That looks like what I want but it's overexposed. Instead of moving I drop the ISO a stop to 50 (there's very little difference between ISO 50 and 100, we're not taxing the DR or noise here). Bang.

Little is still a little to bright (see blinkning image, right). Can't lower the ISO so I have to power the flash down a little. Bang.

Main light is how I want it, now I position the fill light. I've deviated from the original symmetrical setup in favour of a strong light from the left so I move the smaller softbox back to provide a glancing rim light. Use the same setting as the main light, knowing it'll be darker as it's further away. Bang.

Looks pretty good, there is still a little bit too much shadow on the face so I move the fill light closer in and toward me. Reassure model that we're almost there. Bang.

Both lights are how I want them, The image is a little overexposed but nothing RAW can't cope with. The purpose of turning off the back light was check the main lights don't interefere with it. As you can see they clearly do, but they add a uniform pattern of light so all I have to do is turn the background light down a stop to compensate. Bang.

All looks fine, take a step back (I'm using a prime lens) to give wider view for more cropping options. Accidentally nudge the shutter speed to 1/100s (the flash is easily overpowering the flourescent room lights so it's not a problem). Explain to the model we're going for a take. Bang.

Zoom in and check the pose, all looks good. Explain to the relieved model he can relax now. Time from the first test shot to completion: 11 min. Pack up, go home. Here is the final lighting set up:

I filled in the shadows a little in the raw conversion, applied a few curves adjustment layers in photoshop and tweaked the colour balance. Finally the image was rotated slightly and cropped, leading to the finished version (click for larger):

image http://www.mattgrum.com/blogimages/headshot/oliver_medium.jpg ^[2]

Sure there are charts of aperture vs shutter speed vs ISO in different types of light, but you then have to judge the light, just as there are charts of hyperfocal distance vs subject distance etc. but you have to judge your subject distance, so instead of doing that and then looking up an f-stop value, why not just learn to judge what aperture you need straight off and not have to rely on a data sheet?

Digital is very good for trial and error shooting so my advice is to just get out there and wing it, since cheat sheets are only as good as your judgement anyway.

You used to be able to buy them -- I found one in my mini camera museum earlier today:

You could make something up similar?

For the exposure, you can try an analog light-meter, like the Gossen Lunasix ^[1]. Yes, I know it sounds like I did not understand your question. But I did, please keep reading.

This kind of light-meter is made of two parts:

1. A proper light meter that displays the luminance of the scene with a thin needle on a logarithmic scale (the scale with a yellow background at the top).
2. An analog calculator (the big round dial) that converts the luminance reading into ISO/f-number/shutter-speed combinations.

You don't need the meter part (thus you could buy an old broken meter). You don't need batteries either. But you do want the analog calculator: it is really the ultimate exposure cheat sheet!

Here is how to use it:

1. Memorize (or print) a table like this:

   LV      conditions
   15      bright sun (distinct shadows)
   14      shaded sun (fuzzy shadows)
   13      cloudy, clear (no shadows)
   12      open shade
   ...
   

   Warning! The table here is just an example, the actual Lunasix luminance scale is offset by a few stops from this LV scale.

2. Display the luminance corresponding to your working conditions on the small yellow-background scale at the bottom.
3. Display your ISO speed on the small ASA scale on the right.
4. Now you can read on the top circular scales all the f-stop/speed combinations that will give you the correct exposure.

Oh, BTW, although you do not need the meter to be functional, it will not hurt if it is. ;-)

Starting out you can really take advantage of your cameras auto mode as a manual mode cheat sheet. Take a picture in auto then see what settings the camera used for auto then replicate those exact settings in manual then see how you can improve on them.

Memorize a few starting points for common scenes:

• The "Sunny 16" rule: in direct sun, your exposure should be close to ISO 100, f/16, 1/100s. Open up a stop for overcast days.
• A well-lit indoor room should be somewhere around ISO 400, f/4, 1/40s. (Of course, I never seem to have photo opportunities in well-lit rooms; I always have to open up a stop or three.)

From there, just use the LCD on the back of your camera. This is what histograms are for.

I'm not quite clear on what cheat sheet means: hard copy? (as in crip note in your pocket or tethers to wrist or tripod?) But your question does give me an idea:

• Snap images of pages (or smaller) in the camera manual (say, one snap for any page/list needing to be referred back to later while shooting. Then...
• Keep these stored in the camera's "memory" card. (My camera also lets me organized shots and clips as a searchable album.) Then, whenever I need to cheat...
• Push playback;
• (Invoke album);
• Find page and memo info;
• Tap shutter;
• Make setting change; then,
• "Voilà!" Back in business.

Eventually it should even be feasible (and provide some fun) to include or contrive good-shot results (complete with full shot-settings info overlay) that illustrates settings for particular shot effects, to be stored as my camera's "in situ" manual-shooting guide.

Hmm! I can see it now. Out with Camera Owner Manuals. In with CamIntegral Manuals. Remember, you saw it here first !

If it is too bright

• Reduce the ISO
• Lower the aperture or
• Increase the shutter speed

If it is too dark

• Do the opposite

In my opinion, the best way to learn is to go and take pictures, instead of using that time to read tables.

Experiment with one of the 3 variables at a time. You do not need to wait until there is a family event, pull a chair, and start taking pictures of the room you are in. Pull the chair to the porch, and take photos there.