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Week 2: aperture


As well as controlling how much light hits the sensor, the aperture affects the depth of field of your photograph. This is one of the most creative aspects of photography, and once you can control it you are well on your way to being able to call yourself a photographer. 


APERTURE & EXPOSURE

Last week you learnt about the absolute basics of exposure. How the camera sees the world as grey, and how it is programmed to turn every photo it takes into an average, 18% grey tone. You had a go at taking photos which should have been all white or all black. You saw how - if left to its own devices - the camera will turn both your white paper and your black paper to a mid grey tone.

Hold onto that knowledge - we’ll be coming back to it in a couple of weeks. Before we bring it all together, you need to understand 3 other things: aperture, shutter speed and ISO. These are the 3 controls that the camera uses to change how much light reaches the sensor when it takes a photograph.

We’re going to cover them a week at a time, starting today with aperture.

WHAT IS APERTURE?

The aperture is an adjustable hole in the lens that can get bigger or smaller, to let in more light or less light. When you change the size of the aperture you not only change how much light is coming in, you also change the depth of field of the photograph. And that’s what you’ll learn about in this email.

The image-making process (on auto or program modes) goes like this:

1. The camera measures how much light there is

2. The camera calculates how much light it needs to make the 18% grey image

3. The camera chooses an aperture, shutter speed and ISO which, combined, will create the 18% grey image

4. You press the shutter and get your photo

The aperture is one of the 3 things the camera has at its disposal to control the amount of light hitting the sensor and create an exposure:

- the aperture is a hole in the lens which can be made bigger or smaller

- the shutter speed is a curtain across the sensor which opens and closes to let light through

- the ISO is a measure of how sensitive the sensor is to light.

You might ask why does the camera need 3 different options? Why not just one?

This is the why you have a DSLR, not just a phone camera.

The 3 different options don’t just control the amount of light hitting the sensor, they all have a creative effect. And aperture’s creative effect is to be able to affect how much of the image is in focus, also known as the depth of field of an image. If you reduce the depth of field to cover only your subject (eg the single flower in the header image), then everything falling outside that area will be blurred (in that case, the background). 

With shutter speed, you can affect how sharp an image is, and the ISO affects the amount of "noise" or grain in your image.

To keep this email manageable I have put the rest of this lesson in a short blog post. It has a couple more examples, instructions on how to go onto aperture priority mode, and a downloadable quiz and checklist. It also has private access to the entire aperture video lesson from the video version of A Year With My Camera, plus a limited time 50% off coupon for the whole 6-lesson Get Off Auto video course:

THIS WEEK'S PROJECT

Take 2 photos which are exactly the same, except for the aperture. The aim is to see what depth of field is, and how your aperture can control it. This works best with a single subject, like a flower or a cup, set up with a plain background some distance away. You should be able to blur the background with your large aperture photo.

You also need to know that the depth of field starts from the point you focus on, and extends in front and behind that point - so it’s very important that you focus on your subject for this exercise, not on the background. Use manual focus if your camera keeps focussing on the background.

There’s no rush. Take it step by step. Go onto aperture priority, dial in f4 or whatever your smallest number is, find your well-lit subject, focus on it, take the photo. Do the same with f16 or whatever your largest number is. (I demonstrate this in the video available in the extended lesson.)

1. You’ll need a brightly lit place, ideally out of doors, so you can work with your smallest aperture easily.

2. Take your first photo on aperture priority, focussing on your subject, and with the largest number aperture.

3. Take exactly the same photo, but with the smallest number aperture.

4. Your first photo should have a small depth of field and your second photo should have a large depth of field.

TROUBLESHOOTING

If you are having trouble blurring the background, watch the video in the expanded lesson from 18:23 - I run through the main problems students have with this exercise and offer solutions.

RECAP

1. Read this email, and the expanded lesson. Watch the video.

2. Put your camera onto Aperture Priority Mode.

3. Do the project: take 2 photos, 1 with your smallest and 1 with your largest aperture.

4. Try and blur the background when using the largest aperture (which will be the smallest number).

5. Don't try and learn all the numbers, or think you have to remember everything in this lesson. If you can do all the steps whilst reading the instructions, you are on track. There will be plenty of opportunities to practise this again throughout the year, and I will keep reminding you what to do and when to do it.

6. Don't forget - done is better than perfect.

Some reminders...


Have you joined the private Facebook group yet? It's the best place to meet people and share your progress. The group is closed to anyone not doing the course, so you will need to answer the question about this email when prompted. You can use anything from any email as your answer, but an easy to remember phrase is, "done is better than perfect".

Click here to join the private Facebook group

And we're also on Instagram - use the #AYearWithMyCamera hashtag, and the #Make30Photos hashtag as well if you're working through those prompts.

Click here to follow @AYearWithMyCamera

Click here to follow @EmmaDaviesPhoto

The course is available in workbook form:

Details about the workbooks

There is a time-limited discount coupon available for the first module of the video version of AYWMC for the duration of this 6 week course only:

Claim 50% off Get Off Auto module

Next week: freezing and blurring the action with shutter speed.

See you in the Facebook group. Ask any questions you have about the project over there. Post your homework photos in the thread, "Homework thread 21 September". There will be a link to the thread in the pinned post.

Have fun, Emma

 
 
 
 
Emma Davies Photography, Marigold, East Bracklesham Drive, Bracklesham Bay, Chichester, PO20 8JW, United Kingdom

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