Auto Exposure Lock (AE-L) with Nikon D90

I thought this topic would be helpful to all of you who are interested in DSLR photography but fairly new into this field. I spent few hours and days to understand and implement Auto Exposure Lock feature and I feel like it worth to share with you all. Although the idea is same for every DSLR camera, I am taking reference of Nikon D90 for menu settings and have included couple of photographs I have taken with my D90. If you are using other DSLR camera than D90, you may have to go through different menu options but you can always refer your camera manual for quick search.

What is an Auto Exposure?

Camera automatically controls your camera exposure setting under different environmental situation depending upon lighting condition. For example, if you are shooting any dark subject as a main subject with white background (enormous amount of light), your camera sets the exposure as per background and your main subject will come dark. There is a separate post demonstrating that effect with snow background. If you are interested looking that example, please follow my post from reader’s question on how to use AE-L/AF-L correctly? That’s why you have to lock the exposure to proper place to expose our main subject properly.

When should I use AE-L function?

This can be useful when taking photos so that consistent exposure is achieved across all images, or when you wish to expose for the background and then recompose and shoot a photo so that you can achieve better lighting effect on your subject over different environmental condition.

How to set Nikon D90 for AE-L?

1. Press the Menu button on the left hand of your camera.
2. Navigate to your Custom Settings Menu (Pencil icon).
3. Go to f Controls menu, option f4 is for AE-L/AF-L button.
4. Set option according to your need. Every option is self described.

I recommend using following setting under f4 menu.
AE lock (hold) : It will only lock AE and hold that setting till you pushed AE-L/AF-L button again.

Now after the setting is done, This function locks the camera exposure for as long as the AE-L button is pressed. You can see Exposure Lock button to the right of your viewfinder, which is  labeled with AE-L/AF-L. Once you pressed this button, you can see AE-L icon on the left corner when you look through your viewfinder.

Now let me describe when to use it with couple of photographs.

Without auto exposure lock

Without Auto Exposure Lock

I took this picture without locking exposure. Camera controlled exposure according to white sky background and my main subject (Building) came out dark.

auto exposure lock

With Auto Exposure Lock

Now what I did is I focused on walkway (you can see walkway at the left bottom of picture) only (because it matches to that building color) and locked the exposure to that settings so that any bright background won’t affect exposure anymore. Now no matter what the background will be, exposure is locked with desired settings.

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About UM3$H

UM3$H is the founder and editor of Daily Photography Tips. Learn more about him here.


  1. Very helpful article. You made it so clear to understand. Thank you very much. Now I totally understood what AE-L means in DSLR camera. Keep writing wonderful stuffs.

  2. Thanks for demonstrating with the example. I have experienced such problem can experiment it.

  3. Thanks guys. I am glad that you like this article. Keep visiting.

  4. Thanks
    Finally I understood what & how the AE-L/AF-L is used.

  5. Excellent tutorial. Thank you for your help. I was taking beach photos with people and I realize that I should know how to use AE-L lock as soon as possible. I am using Nikon D300s. I never think that taking great pictures of the beach, ocean you should be great photographer, and camera technics expert. I rely on Adobe Lightroom to fix photographs, because you couldn’t stop time. Great tutorial. Thanks, do you have your YouTube page. Please email me at

    • We are glad that you like our article. Glad to help but unfortunately, we don’t have Youtube page. However we do have Facebook page where we invite our readers to share their ideas and photographs.

  6. or u can use manual program 🙂 and spot metering like i do all the time 🙂

  7. btw the article for ae l is very very nice
    i ve just wanted to point that it can be frustrating to do that all the time , and sometimes u forget the ae l button pressed …and it can be quite frustrating

    all the best from Romania, nice tut

  8. Thanks for explaining AE-L in very simple words, I am a new owner of D90 and not being able to understand this feature properly, thanks again.

  9. Just a question, won’t the sky be overexposed then?

  10. It will be little bit because exposure is being calculated based on dark side of the frame. You have to calculate that trade off and decide which part of the picture is important to you. If you need to expose sky (background) and buildings (foreground) equally, you may have to use Graduated ND filter (GND) and exposure lock feature together.

  11. Cherag Tantra says:


    That was a nice article does explain the concept very well, however I have a question, actualy more of a clarification.

    While you suggested to focus on the walkway considering its closer to the colour tone of the building and lock the exposure, wouldn’t it be more advisible to focus on the building altogether to get the correct exposure? or the reason to focus the walkway is because you are closer to the walkaway, hence closer to the incident light falling on it to give you an accurate reading.

    Also most importantly I assuming that the light conditions are similar across all areas of the image i.e. foreground as well as the background.

    Looking forward to your revert.

    Many thanks.

    • Cherag,
      Thanks for stopping by again. You are right. If the subject was closer, I would have focused on that and get the actual exposure based on actual tonal settings. But it was little further and I was worried about too much external light will give me wrong exposure information. That is the reason I tried to find matching color tones nearby.

      If I am shooting any portrait, I always focus on person’s face or tonal area to get the exposure I wanted to be.

      Hope it helps.


  12. Cherag Tantra says:


    Thanks for your response, just one more question 🙂

    Instead of locking the exposure on the walkway as used by you in your scenario, if I lock the exposure on a 18% Gray card would it give me a correct exposure as well?

    • True! Cameras are designed to pick up exposure based on 18% gray but it might not work all the time and you may have to use exposure compensation setting but it works out most of the time with modern DSLRs. Using 18% gray card is intended and popular for getting correct White balance as well.

      I read somewhere that if you forgot to bring your gray card with you, you can use your palm (which is one stop brighter than gray card) and once you set the exposure, reduce the exposure by one stop before taking the shot. But I preferred exposure lock to the subject method in that case. 🙂

  13. Is there a way to assign AE-Lock (Hold) to the Function button on the D90?


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