Friday, April 04, 2008

Light Faster With a Cheat Sheet

Heading into the weekend, here's a little tip to help to make you more intuitive with your flash.

One of the first hurdles in learning off-camera flash photography in the manual mode is knowing where to set your flash for that first test exposure. For beginners, it can almost seem arbitrary or random. More experienced photographers, on the other hand, always seem to get it pretty close on the first try.

Raising your first test shot "batting average" is as easy as 1,2,3. Hit the jump for a tip that's so easy, you'll probably wonder why you weren't already using it.
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Today we are gonna make a cheat sheet for your flash in three simple steps. Think of it as an mental reference point, to quickly get you in the ballpark for your most common shooting setups.

The only things you'll need are a small piece of light colored tape (I used electrical tape in white) a Sharpie (or similar, fine-point permanent marker) and a few minutes.

Here's the process:


Choose a Typical Working Distance and Modifier

Let's say, for instance, that you normally shoot people, at a lighting distance of about 6 feet, with a shoot-through umbrella.

Set up your flash and umbrella in your living room and point it at something of reasonably normal tonal levels about six feet away.

Choose a good working aperture for your portraits -- say f/8, for instance. Set your camera to a standard ISO -- say, ISO 400. And be sure to do this indoors at your max sync speed (usually 1/250) to knock out the ambient light portion of the exposure.


Zero In a Power Setting

Now, fire some test frames, adjusting the flash's power output until your exposure looks good. You'll end up with a power setting in the manual mode. Say, for instance, that this setting ends up to be 1/4 power.


Write it Down

As shown in the photo above, write the settings down on a piece of tape and attach it to your flash. In your case, you might down:


STU-ISO400-6ft-f/8-1/4


This will tell you that, through your shoot-thru umbrella, you can expect f/8 from 6 feet away at 1/4 power at 400 ISO.

Are you always gonna shoot with those parameters? No, of course not. But it is a good starting point for choosing your flash's power level. And if something changes, you'll quickly be able to interpolate a new starting point.

For instance, say you wanted to shoot at f/4 instead of f/8. You'd just drop the power two stops (to 1/16th power) before firing your first test.

If you wanted to move the umbrella in closer - say to about four feet, you'd know to either close down a stop to f/11 or drop the power from 1/4 to 1/8. In the example above, my Nikon SB-800 has a reminder to me that in a direct mode (at ISO 400, 50mm zoom) I can expect f/8 from 1/32 power at about 6 1/2 feet.

(FWIW, I am constantly surprised at how powerful these little flashes are in direct mode.)

The point is to have a normal rational starting point from which to shoot your first test pop. You'll then find that your first guesses are always pretty close, and the direction you have to go to fix it is pretty obvious.

Okay, so the direction you need to go to fix light quantities is usually pretty obvious. The problem is when you are, like, six stops off. Or is it four stops? It all looks the same -- nuclear.

Having a nice little cheat sheet on your flashes will get you in the ball park before you fire your first pop. Then, making a quick fix very easy. And pretty soon, you will not even need your cheat sheets to get close on the first try.

Reverse-engineering exercise:

If you like, take a shot at deciphering the lighting on the photo of the flash up top. Leave your thoughts in either the comments or on the photo's Flickr page. I'll post a setup shot next week.


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Related post:

:: GN: Your Free Flash Meter ::


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31 Comments:

Anonymous zeb palmer said...

Great advice - as always

April 04, 2008 1:51 AM  
Blogger Tim said...

Good tip.
Perhaps the greatest hurdle to overcome for some folks is be willing to stick something directly on their strobe! ;-) [gasp]

In the beginning, I would even have a kite string attached and wrapped around the strobe with knot markers tied at set distances.

Sometimes those "low tech" solutions are the best and fastest when in a shoot.

April 04, 2008 3:42 AM  
Blogger Gordon McKinney said...

I have a cheat sheet with flash power levels and other goodies for free on my blog:

http://www.night-ray.com/

April 04, 2008 5:13 AM  
Blogger Carlsen said...

Awesome advice!

I'm in the 'random' group, and this is definitely helping change that. And it's so obvious, hehe.

April 04, 2008 5:38 AM  
Anonymous Anonymous said...

nice tip, and a very cool illustration photo!

April 04, 2008 6:32 AM  
Blogger Andy said...

Sir Hobby,

Perhaps a quick explanation of the dreaded inverse square law could benefit the average reader here?

April 04, 2008 6:41 AM  
Anonymous photopoppy said...

Well, I see some flare at the top suggesting that there's a flash up there providing some backlight.

Based on the reflections on the strobe, there's white reflectors on the left and right.

I *think* there's a white reflector in front too, so that the one flash in back is providing all of the light. The strobe is just shiny enough to use a light tent on, and that's what I would do with it - assuming I had made one yet.

April 04, 2008 9:21 AM  
Blogger Scott Piner said...

So I get this part...

Move the light closer = stop down the aperture or stop down the flash.

Move the light further away = open up the aperture or increase the power on the flash.

But where does ISO fit in? Does ISO become equivalent to moving the light?

April 04, 2008 10:15 AM  
Anonymous Terri Ann said...

Great tip!

I find myself wasting time trying to find the right settings and this will really help a lot. I'll have to create a mini notebook to keep in my flash's case for all the different kinds of setups I use on any regular basis.

April 04, 2008 10:40 AM  
Anonymous Anonymous said...

nice tips but I always have a better cheat sheet with me. Light meter lol. maybe and maybe and tape measurement hehehe

good advice for reuseable quick setup . But everyone who is using manual flash should have known this (science 101 ? record and repeat tests ?)

April 04, 2008 10:43 AM  
Anonymous John Sartin said...

Gordon McKinney, Your blog is awesome. What a great reference. Thank you so much for posting it.

April 04, 2008 12:50 PM  
Blogger Michael said...

"Set your camera to a standard ISO -- say, ISO 400"

Another very insightful practical tip. Was intrigued as to why ISO 400 was suggested for indoors. Always thought 100 iso was recommended

April 04, 2008 1:49 PM  
Blogger Avlor said...

That so rocks! This is just in time for a camera club field trip I'm heading up. I may have a chance to go there a bit ahead of time and take notes... That would help so much. Thanks for the super idea and being a springboard for another!

April 04, 2008 1:52 PM  
Blogger Ken said...

>> Scott Piner said...

>> But where does ISO fit in? Does ISO become equivalent to moving the light?

It might be easier to think of ISO as the equivalent of changing the aperture. If you move the light back, you could open the aperture OR increase the ISO. If you move the light closer, you close the aperture or reduce the ISO. You could do both in some situations. If you move the light to half the distance (2 stops more light), you could reduce the aperture 1 stop and reduce the ISO 1 stop.

April 04, 2008 2:21 PM  
Anonymous Keith said...

Good advice. I've been doing this mentally for the year or so I've been working seriously with off camera flash. I am able to get accurate flash exposure using these mental notes when using my 580EX's on manual with PW's on older film cameras. Writing it down just makes that much more sense!

April 04, 2008 2:29 PM  
Blogger Matt T. said...

Hi David, completely off topic here, but I thought the segment of your readership who still own G7's might be interested in the fact that there is now a firmware hack (temporary only, resets when you reboot the camera) to enable RAW output from a G7. It takes a bit of doing and a second program to convert the resulting .CRW file into a Adobe readable format, but its available.

See this site for details, and the converters can be found here for PC and here for mac. Enjoy!

April 04, 2008 4:56 PM  
Blogger jledgerkc said...

This site has a nice interactive way of understanding the relationship between ISO, aperture, and shudder speed.

http://www.photonhead.com/beginners/stops.php

April 04, 2008 5:00 PM  
Anonymous Rob said...

This question is a bit off topic but hopefully that's ok. First off great site.

My question is about white balance, to achieve the look of white light in my pictures should I match the temperature of the ambient? or am I trying to negate (neutralize?) the temp. I can't seem to get this right for some ideas I have.

Thank you for the site and big thanks if you have the time to respond.

April 04, 2008 7:11 PM  
OpenID apartmentseven said...

http://dimchevski.com/journal/tangerine-winter-trees/

Ummm. These are awesome. Orange Peel Trees. Light it.

April 04, 2008 7:43 PM  
Blogger Canon Blogger said...

Like someone else said upthread "it's so obvious"...in my struggles to learn off camera lighting, the concept of establishing a baseline never occurred to me. Just one question: when you refer to power levels (1/4, 1/2, and 1/8 powers), would the equivalent on Canon flashes be the +/- 1/3, 2/3, 1, etc.?

April 05, 2008 12:21 AM  
Blogger focusfinder said...

Useful tip, thanks.

It's been said many times in the industry that you can't make a decent shot without camera tape, gaffer tape , or, more often, both.

I'm a great fan of the manual flash mode and radio triggering.

Peter Bryenton
BryPix

April 05, 2008 7:46 AM  
Blogger Lianna said...

@Canon Blogger: No, the values you speak of sound like Flash Exposure Compensation values (which is what you get when you use E-TTL). To be able to set flash output manually you need to first set your flash to manual mode by holding the mode button for like 2 seconds. Note however that the 420EX doesn't support anything other than E-TTL, so if you happen to have that flash your master flash *must* be in E-TTL mode to be able to use the 420EX at all. The 430EX, 550EX and 580EX all support manual flash output.

@David: Thanks for yet another informative post. So far I've been using E-TTL (so that I can use my 420EX too) but I might now be doing more with manual flash output with just 2 flashes, if only to learn. I sort of knew the theory behind this all already, but your post (and my subsequent tests) made it come alive for me.

April 05, 2008 8:48 PM  
Anonymous Anonymous said...

Thanks. Write stuff down is great advice because I can't remember anything! And its better than a notebook because its stuck right to the flash in question.

April 05, 2008 11:01 PM  
Anonymous Drew M. said...

If you don't want to stick anything on your flash, you can always take a picture of it and then 'protect' it so it won't get deleted.

Also, I looked at gordon mckinney's website @ www.night-ray.com and looked over his EV cheatsheet. A lot of good info there.

Now I've got his cheatsheet in my camera's memory card.

I guess now I can call it my chimpsheet... ooh.. ahh. :)

April 06, 2008 2:41 AM  
Blogger Danie said...

@Andy
Inverse square law:

The brightness of a subject fallsoff to the inverse square of the change in distance from the subject: roughly something like:

f8 at 2m, becomes f4 (2 stops up) at 4m.

2 metres sq gave you 4 meters, inverse gives you 1/4. 1.4 light is 2 stops (remenber it is exponential).

so brightness proportionate to 1/change in distance in metres

easy, hey.

Now for the strobe:

get the exposure at full power at 1 meter. use that as the base. I know my studio flashes like that, i a not too reflective environment.

April 06, 2008 9:28 AM  
Anonymous Jeremy said...

I'm going to go way out there on a limb for the shot setup...

Flash fired behind the subject flash into an umbrella mounted on a lightstand/tripod with the camera???

April 06, 2008 12:06 PM  
Blogger Canon Blogger said...

@Liana - Thanks, I had thought they were EV adjustments, not power levels. I am working with the 550EX, so the manual mode is available, but in taing the flash off camera, I need to put the flash in slave mode, which requires the ETTL for the ST-E2 to function and trigger the flash (at least from how I tried, maybe I was doin' something wrong...)

April 06, 2008 8:55 PM  
Anonymous tomasek said...

@Danie

About the brightness law.

If 580EX (II) @full power gives at ISO 100, 24mm: @1m - f/22, then @2m it should be f/11 (2 stops) or f/16 (1 stop)?

April 08, 2008 6:12 AM  
Blogger Danie said...

@ tomasek

Sorry, all - stooopid mistake on the inv sq law. The change in distance is the FACTOR by which it changes, sorry dumb moment there. The post should've read like follows

The brightness of a subject fallsoff to the inverse square of the change in distance from the subject: roughly something like:

f8 at 2m, becomes f4 (2 stops up) at 4m.

The distance factor (2x) sq gave you 4 , inverse gives you 1/4. 1.4 light is 2 stops (remenber it is exponential).

so brightness proportionate to 1/change in distance in metres

easy, hey.

Now for the strobe:

get the exposure at full power at 1 meter. use that as the base. I know my studio flashes like that, i a not too reflective environment.

@tomasek:

If 580EX (II) @full power gives at ISO 100, 24mm: @1m - f/22, then @2m it should be f/11 (2 stops) BECAUSE the distance change factor is 2. (1/4 power equals 2 stop reduction)

Hope that clears it up!

April 08, 2008 10:33 AM  
Blogger Lars said...

Great Idea.
and great blog alltogether.
Just one question. We know that the f-stops refer to the length of the lens. A 50mm at f2 means that the aperture opening is half the length of the lens, so 25mm in this case.

So does the cheat sheet only work with the lens it was found with ? I mean a 100mm lens lets in more light at f4 than a 28mm lens at f4, no ?

Or is this not true. Do all lenses at the same aperture let in the same amount of light ??

Cheers,
Lars

April 14, 2008 4:12 AM  
Anonymous waltography said...

surely a wide lens at F4 compared to a long lens at F4 will let the same amount of light in.
This is a great little post, thanks. another tip to perhaps add to this is the string attached to the light? I can alaberate on this if you like?
thanks for your time and sharing some great tips
Richard

April 22, 2008 5:24 PM  

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