Thursday, April 16, 2009

How to use Manual Exposure on Canon EOS Cameras

This tutorial teaches you how to use the manual exposure mode or "M"-mode on any Canon EOS camera. I will show some examples from my Canon EOS 400D but the techniques should stay the same across different models.

Why would you want to shoot in Manual Mode when you have automatic modes (P/Av/Tv) that can handle almost any light situation automatically? Because they can do it only "almost". Sometimes the light in a scene is too difficult for the light meter. At other times, you want to get the exact exposure of a scene every time. Then you should consider turning your mode wheel to the "M"-mode.

Exposure Basics
First, I will talk a little about the basics of exposure of cameras. The three factors that control exposure are:

  • Shutter Speed - how long you expose the photo (e.g. 1/200)
  • Aperture - How much light you allow through your lens (e.g. F/8.0)
  • ISO sensitivity - amplification of the light on the sensor (e.g. ISO 100)
Changing one of them will affect the exposure of the photo. If you change another factor, you can compensate or amplify the first change.

1/200 at F/8.0To make this more clear, I will explain it by using an example. Let's say the light meter tells you that the scene you are looking at requires a setting of 1/200s at F/8.0 using ISO 100. The picture on the right was taken with these exact settings.

1/400 at F/5.6If you do not want to have a shutter speed of 1/200s, it is possible to set it to 1/400. As you only will have half the exposure time then, you need to compensate to get the same amount of light in your photo. You can either do this by increasing the ISO to 200 (double the sensitivity) or open up the aperture by one stop to F/5.6.

The two pictures above were made with the described change of the aperture. The second image looks almost the same. By opening the aperture, you will have a more shallow depth of field though.

The following exposure/aperture settings will also produce an correctly exposed photo:
Time:1/251/501/1001/2001/400
Aperture:F/22F/16F/11F/8.0F/5.6
The table only shows one-stop increments. Most cameras support 1/3 stop increments, so there are 2 more possible combinations per entry. For more information take a look at F-Numbers on Wikipedia.

Reading the Histogram
The most important measurement tool for the manual mode will be the histogram. It tells you the exact distribution of tonal values in your photo. This means you can determine if your image is correctly exposed (you can find more information here). I will not go into detail about how a correctly exposed histogram should look like because this depends pretty much on the scene. What is important is to recognize and under- and overexposed image.


The picture above shows an underexposed, correctly and overexposed version of the photo. As you can see, the underexposed image lacks all high tonal values. The overexposed version does look quite OK in the histogram, but the high tone values start gathering at the brightest value. This leads to 100% white pixels in some areas.

Manual Exposure
Now you know all the basics that you need to know in order to operate your camera in manual mode. All you need to do is to set set the initial exposure and then work with the histogram until it looks right to you.

In order not to start with a random guess about correct exposure values, it can help to set the camera into Program mode (P) and copy the suggested values to manual mode. Also, the camera shows the light meter in manual mode. The light meter is the bar that reads -2..1..0..1..2 and has a blinking bar. Try to get the bar to stop below 0 (you need to half-press the shutter button to get it to work).

Then you can adjust your settings by changing either the exposure or the aperture value. Canon cameras support 1/3 stop increments. So when your image is underexposed by one exposure value (EV) or stop, you need to open up the aperture by 3 times 1/3 steps or increase the exposure time by 3 steps (double the exposure time).

On the Canon EOS 400D you can change the exposure time by turning the wheel next to the shutter release button. The aperture can be changed by simultaneously pressing the Av button next to the screen and turning the wheel.

To check your photo's histogram, take a picture and show the picture on your camera. Now press the DISP. button until the histogram is shown on the screen. The histogram has four gray vertical bars on it which are spaced at one-stop increments. This means that if you change the exposure time by one stop, the whole histogram will shift by exactly one bar. This is very useful to estimate how much you should change your settings.

Bar number 2 from the left is the 18% gray bar. This means that your camera will try to balance your picture around that exposure in auto mode. To verify this, you can take a shot of a clear blue sky or a white wall in auto mode. Then you should see a large peak of the histogram exactly there.

Now change the settings of aperture, exposure time and ISO as you like. When you have found the correct settings, you can take as many pictures of the same subject at the same light as you like. No matter what disturbs the camera's light meter, you will not get under- or overexposed photos.

When to use Manual Mode
I use manual mode in the following situations:
  • Night shots
  • When using an external flash (in order to balance between flash and available light)
  • Difficult lit indoor scenes, especially with backlight
  • changing lights that do not affect the subject directly
But you can find out for yourself when to use the manual mode. Whenever you get wrong results for a type of subject, start to think about going manual.

Do not forget to switch the camera back to an automatic mode afterwards. It's too easy to forget that the camera will not set the correct exposure automatically. This can ruin some shots if you don't think about it.

If you have any questions or find some parts of this tutorial not understandable, please leave a comment! I'll try to clarify it for you then.

42 comments:

Anonymous said...

i am a rookie. a friend has the same 400D and while shooting a soccer game he had his M setting in continuous shooting ISO at 200
1/1250 and his 400D shot in continuous. mine didnt. could something be wrong with my camera. i have the same card etx..

theowl84 said...

i'm sorry, i can't really tell you why it doesn't work for your camera. can you do continuous in other modes than M? Did you check all your settings, is continuous really on for you?

Veon said...

I can't find out how to change aperture in M mode :S

theowl84 said...

You need to press the button that says "Av" and turn the wheel next to the shutter button at the same time to change the aperture in M mode

Veon said...

Thnx a million! I've had this camera for a really long time without knowing that.

stumpedbytechnology said...

I've had my 400d a long time but have only recently found the time and inclination to start taking some serious photos. I had a nightmare recently with trying to take photos and achieve a t-stop of 3.5/4.0 on ef lenses 18-50mm and 55-200mm. Sometimes it would let me open up to these stops and sometimes it just wouldn't. Even more annoying was when it allowed me and then as I went to my subject to take an light reading with an external meter, I would come back to the camera to find it had dropped my stop back to 5.6 again and wouldn't let me go back sometimes, even if I was drastic with my shutter speed changes. I was always shooting in M mode. Please Please help. I want full control of my camera not partial.

theowl84 said...

Hi stumpedbytechnology,

i think your problem is not the camera but your lens. I'm not sure about the 18-50 lens you have (or did you mean 18-55mm F/3.5-F/5.6?) but your 55-200 definitely explains your problem.
Ordinary zoom lenses have a variable maximal aperture, and it decreases the more you zoom in. For example the Canon 18-55mm allows a maximum of 3.5 in the 18m position but only 5.6 when zoomed to 55mm. There is no way around this other than buying a lens that supports the same aperture over the whole zoom range (such as the 17-55 F/2.8).

Lizzie's Insomnia said...

Thank you thank you...I do not had the written instructions with this camera and have just started using manual and could not figure out from site after site how to change the f stops...so simple when one is told....

Canon Josh said...

Thanks for the blog. Helped me try new things, and gte to grips with manual mode.

I recently purchased a cheap lens end, which has two seperate parts. Fish eye and macro, and when put together it creates a wide angle lens. I attach it to my 18-55mm lens, Cannon 400d.

Would anyone happen to know how to shoot with a fisheye? As I can't get any foscused shots, and everything from exposure to that goes wrong... anyone help me pleasE??

Anonymous said...

I just bought the canon eos rebel t1i and i set it to manual and i can't change the exposure it's on -2. I tired and it just goes back to it.

Marta said...

Thank you! Your explanation was really helpful :)

Erica said...

hey,where did you go? I need more help.

theowl84 said...

what help do you need? I'm always interested in things to post here.

Canonboy said...

For those Canon 400D EOS owners that have 'lost' the instruction book or bought the camera without it, you can download in PDF form the complete instructions from the Canon website, and from one or two others posted on Google.
Excellent advice given on this site!
I too have had the Canon400d for three years or so and although I gave a quick look at the instruction book I tended to use only auto settings -until recently, when I began to read the whole book. This camera can do amazing things by th e looks of it.
Thanks for all the information!

Anonymous said...

Hi I have just bought the Canon EOS 1100D and cannot find how to set it to buld for a long exposure any ideas?

Anonymous said...

Hi
I own the same camera for some few years now. I know how to change the aperture but The F stop shows 'F00'since yesterday. How can I fix this problem?

Many thanks
kk

theowl84 said...

Sounds like a problem with the camera-lens communication to me. Try cleaning the metal contacts on your lens and in your body.
Hope that helps,
matthias

Thiet ke logo said...

Thank you! Your explanation was really helpful

alina.mkp said...

hi :)
sorry for busting in
i don't even know if your blog is still active, but i just had my 400d from a while now, and never used manual mode (think i was afraid of it), but curiosity made me interested in it, and your post was very very helpful - and really thank you for that :) - but i have a question: the light bar keep's going to -2, i tried increasing iso, increasing/decreasing aperture and shutter speed.. but nothing. i can't manage to keep the light bar at -1 or 0 - all images are sooo underexposed and dark, and if i take a photo in bright light it jumps at +1/+2 and the images looks over exposed and whitey
really sorry if this is a noob-ish question...but at this point it lost me :(
really appreciate your support, as well as your comments and articles

theowl84 said...

Are you sure you are in manual mode? If the image is too dark, simply increase ISO (eg 100 to 200), reduce shutter speed (eg 1/60 to 1/30) or increase the aperture (eg 1/4 to 1/2.8). All three changes should give you brighter images. When the meter reading is wrong, I usually dial in one setting, snap a picture and then change the settings until I get the desired exposure.

alina.mkp said...

Thank you very much for your response! Indeed it worked! I seemed to change all at once (apperture,iso etc) and i couldn't make it work, but after i taked step by step,as you suggested, i was amazed by the power of manual mode :) since then i shoot just manual, it takes a little more time and more preparation, but the results are a lot better :)

Thiet ke logo said...

Many thanks for your detailed explanation.

Neso said...

Wow I got this camera and was using it like cell phone camera without any ideas u gave me new world to enter thanks man

lee woo said...

Exposure from a young age to the realities of the world is a super-big thing. See the link below for more info.


#Exposure
www.ufgop.org

Rics Angel said...

I just got this eos 400d this week, itried to read manuals on how to shoot at night but d camera did'nt work. Just want to ask d correct or best settings on taking pictures at night.

Any response will be appreciated tnx in advance.

Rics Angel said...

I just got this eos 400d this week, itried to read manuals on how to shoot at night but d camera did'nt work. Just want to ask d correct or best settings on taking pictures at night.

Any response will be appreciated tnx in advance.

theowl84 said...

Honestly, the most correct "setting" is to use a tripod or any stable base where you can rest your camera. This will allow you to do long-exposure shots without shaking. For starters, maybe use the AV mode and set to aperture to a small value (e.g. F/4) and let the camera determine the time. Or set both exposure time and aperture in M mode, take several shots and experiment until you get the desired results - digital photos don't really cost you anything.

Silvia Jacinto said...


I must say that you have a very good article.Continue to inspire your reader and Have a good day! You can also visit my site indicated below and share it with your friends.

n8fan.net

www.n8fan.net

Sajid Ali Khan said...

very nice thanks for help. keep it up. stay blessed...

Anonymous said...

I use canon eos 1300d ....but I can't find how use dis....n how adjust blurr background..

Nhan dien thuong hieu said...

Great, your explanation was really helpful

thiết kế logo said...

great explanation for using camera

Hayley Mitchell said...

Hello.. novice here. Need help! Pretty please x I need to take pictures of fast moving children... doing martial arts.. in a poorly lit sports hall. Do I have the setting on M or Av? My iso is up to 1600.. but after that I'm lost x any help is greatly appreciated x

Izwan Zakaria said...

I don't know if you are still reading this but your article is really helpful in understanding how to use the manual mode. I am sure many people hope that you will keep on writing. Best of luck!

Byrishetty Abhishek said...

Hi I am having cannon 1200d when every I take pictures it doesn't come clear in manual mode how to fix it ? What is setting should I do in it for good quality image

Thiet ke catalog said...

Many thanks for your detailed explanation

Thiet ke brochure said...

Any response will be appreciated tnx in advance.

Thiet ke bao bi said...

very nice thanks

Thiet ke profile said...

Thanks for the blog.

Nhan dien thuong hieu said...

Thank you very much for your response!

Thiet ke ho so nang luc said...

great explanation for using camera

A Ramkhi said...

I have 1300d.... Whenever i see histogram review of a pic.. Some times it looks like having noise... And it is only for few pics.. What to do.. Should i return it.?? I have bought it few days back only