Off Camera Flash Tutorial: Lesson 2, Exposure

Posted in: Tips!

Welcome back! This is part 2 of our Off Camera Flash Tutorial. By now, you should have set up your off-camera flash from lesson 1. There’s nothing like learning by doing – so, we’re diving in!

This article gives me a chance to post a photograph of my son. Hehe. This stinker is almost 17 months. Help!

F/stop controls your flash exposure.

Step 1. Google your camera’s sync speed. Go do it right now. Go, go, go. My 5D Mark II has a sync speed of 1/200. You will NOT be able to photograph at a faster shutter speed than your sync speed. Why not? Because you’ll end up with photographs like this (ignore the horrible overexposure).

Shutter speed at 1/320. This photographer did not follow Step 1. Oh wait, that's me.

Step 2. Camera and flash should both be set to manual. Then, go set up an indoor space for you to take some test shots. You probably want to photograph something inanimate at this point. An object will have boundless patience versus a small child (who has none). My flash & umbrella was set up about 4 feet from my teddy bear at about 45 degrees. The teddy bear was about 5 feet from the wall.

Looking to figure out where to place your light? Check out strobox.com.

Step 3. Set your f-stop to f/5.6, your shutter speed to your sync speed (in my case 1/200), ISO 100. Why these settings? We have to start somewhere. If it were sunny outside, I would probably start at f/16. If I were photographing in open shade, I’d try starting at f/8. Overcast? Indoors? Maybe f/5.6.

Flash should be at full power. 1/1.

Take a photograph with these settings. What happens? I’m horribly overexposed:

f/5.6, 1/200, ISO 100, flash full power 1/1. We're blinding the poor animals.

How do we fix this?

Step 4. Adjust your f/stop. Why? Because f/stop controls flash exposure. I’m overexposed so I’m going to stop down. If you’re underexposed, open up. If f/5.6 gives me overexposure, let’s try f/8. Don’t adjust anything but your f/stop.

f/8, 1/200, ISO 100, flash full power 1/1. Hey! We're getting there.

Almost there…! Let’s try f/10.

f/10, 1/200, ISO 100, flash full power 1/1. Woot!

But… ew, I don’t want to shoot at f/10.

You want to shoot at f/5? How do you get correct exposure? Most of our cameras’ f/stops will adjust in 1/3 stops. Going from f/10 to f/5 is opening up six 1/3 stops – or 2 whole stops. Go ahead and count it, how many times do you have to dial to go from f/10 to f/5?

Why is this important? Because now, we’re going to adjust our flash power to compensate for the extra light we’re letting in. Instead of full power at 1/1, I’m going to adjust my flash power to 1/4 power (2 stops down).

f/5.0, 1/200, ISO 100, flash 1/4 power.

One more example: if I open up one more stop from f/5 to f/3.5, I have to adjust my flash power by one stop as well (f/3.5, 1/200, ISO 100, Flash 1/8 power).

f/3.5, 1/200, ISO 100, flash 1/8 power.

The same concept will apply to your ISO settings. If you go one stop from ISO 100 to ISO 200, you either have to adjust your f/stop or your flash power accordingly.

But what about shutter speed?

Shutter speed controls ambient exposure. If there is no ambient light, adjusting your shutter speed will make no difference.

This was taken with my original settings of f/10, ISO 100, full flash power but my shutter speed was adjusted to 1/60th of a second.

Lesson 3 will look at shutter speed and ambient lighting more in depth. For extra credit, adjust your shutter speed to see how it changes your photograph.

Here are the links to Off Camera Flash Tutorial Lesson 1, Off Camera Flash Lesson 2, and Off Camera Flash Lesson 3.

17 Comments

Comment by paveiphotos — September 7, 2010 @ 5:18 am

This was great! Thank you! Love the little bear by the way! precious!

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Comment by Amy Hoogstad — September 7, 2010 @ 7:14 am

SO HELPFUL!! Thank you so much:)

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Comment by Inspire Me Baby — September 7, 2010 @ 7:54 am

Thanks! ;)

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Comment by Sara P — September 7, 2010 @ 8:37 am

This was amazingly simple to understand. And so helpful! Thanks so much. I learned a lot.

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Comment by Raquel — September 7, 2010 @ 10:22 am

I just had an ‘ah-ha’ moment!!! Thank you SO SO Much for unscrambling my mind, you’re awesome!!! =)

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Inspire Me Baby Reply:
September 7th, 2010 at 11:16 am
I love ah-ha moments! :)

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Comment by Shannon — September 7, 2010 @ 12:13 pm

you can photograph with a high speed shutter — I thought you could do it with high speed sync?

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Inspire Me Baby Reply:
September 7th, 2010 at 12:21 pm
For Canons at least, high speed sync works only if your flash is on your hotshoe, connected with a OC-E3 or other compatible TTL cord, or fired via Canon’s wireless flash system. At least that’s my understanding! ;)

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Comment by Amy Bickel — September 7, 2010 @ 4:07 pm

That fstop garble confuses the hello kitty out of me.. I think my brain is scrambled… i get the one stop two stop but trying to figure out what fstop to use is what I struggle with…

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Inspire Me Baby Reply:
September 7th, 2010 at 5:32 pm
Hi Amy ~ try the lesson at home. Start with f/5.6, 1/200, ISO 100, flash full power. You’ll most likely be over-exposed. Then ONLY adjust the f/stop. Try taking f/8, f/9 and so on until you have the correct exposure. Hope that helps a little!

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Pingback by Off Camera Flash, Baby!: Lesson 3, Ambient Light - Inspire Me Baby — September 9, 2010 @ 3:04 am

[...] to our last of the series on off-camera flash! Find lesson 1 here and lesson 2 here. Now that you’ve figured out how to correctly expose a photograph with f/stop, what does [...]
Comment by rosemary tufaro — September 9, 2010 @ 9:38 am

I usually use my qflashes, manual set the lights… same set up with pocket wizard and then meter. I would love to master this for a back up and smaller equipement. question: do you leave your sb 800 or 900 on ttl? and then adjust the output level 1/1, a 1/3 stop down, etc? Can you meter this way and see exact results instead of eye balling on the back? I have tried this before and had inconsistant results… compaired to manual q’s. that is why I am picking your brain. ;) thanks.

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Inspire Me Baby Reply:
September 9th, 2010 at 10:02 pm
Hi Rosemary! Thanks for the comment, I actually have the speedlight on manual as well. Getting the right exposure this way is actually pretty quick once you get the hang of it.

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Comment by Angela — September 9, 2010 @ 7:37 pm

Thanks so much for sharing:D Hoping I can figure it out.

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Comment by Rachel — September 14, 2010 @ 12:08 am

Thanks for an interesting tutorial. I had never considered the sync speed till I read this.

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Pingback by Off Camera Flash, Baby!: Lesson 1, Get Your Flash off Your Camera!!! - Inspire Me Baby — September 28, 2010 @ 8:23 am

[...] your flash off camera and make sure it works. Here are the links to Lesson 1, Lesson 2, and Lesson [...]
Comment by Denise George — January 3, 2011 @ 12:39 pm

Thank you for this tutorial. I printed it out for future reference… Seems very helpful but I need to try it out for myself before I completely understand it.

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