Getting exposure right w/o a light meter, flash

Canon EF 100mm f/2.8 USM Macro

03/23/2007 11:50:21 AM · #1

I have a Nikon D50, an SB400 flash, and a single 40 w/s strobe.

I have figured out how to get decent exposure with natural / ambient light using a grey card and the meter that is in the viewfinder - not sure I'm doing it properly, but it seems to be working.

But I was playing around last night, and using the SB400 and strobe - I wasn't able to really determine what the exposure should be. I ended up just doing MANY shots trial & error and watching the histogram.

What should I be doing to get a good exposure when I'm using the flash or flash/strobe ?

Spork99

OM System OM-1

03/23/2007 12:18:51 PM · #2

Originally posted by kashi:

What should I be doing to get a good exposure when I'm using the flash or flash/strobe ?

Buy a flashmeter.

Canon EF-S 17-55mm f/2.8 IS USM

03/23/2007 12:21:07 PM · #3

Originally posted by Spazmo99:

Originally posted by kashi:

What should I be doing to get a good exposure when I'm using the flash or flash/strobe ?

Buy a flashmeter.

You cough up the cash for me and I will !

In the meantime, while I am saving the money (since I'm an at-home mom with no real income, this could take a while), what can I do ?

idnic

Canon EOS-60D

03/23/2007 12:25:34 PM · #4

Kashi, try these settings & see how it works for you.... ISO 100, shutter speed 1/125th, aperature F4.5. Then take a few test shots and adjust your light strength until you get the look you want. Without a meter you're going to have to do some trial & error, but that should give you a good starting point.

As for on camera flash or built-in flash, those settings probably won't work - but again, gives you a place to start & you can make adjustments as needed to get the exposure right.

Canon EF-S 17-55mm f/2.8 IS USM

03/23/2007 12:34:12 PM · #5

Originally posted by idnic:

Thank you Cindi, I'll try that.

The lowest settable ISO the D50 has is ISO 200. And I'm shooting, mostly, children (infant, 2yrs and 4yrs old), so need a fast shutter.

idnic

Canon EOS-60D

03/23/2007 12:38:06 PM · #6

Originally posted by kashi:

The lowest settable ISO the D50 has is ISO 200. And I'm shooting, mostly, children (infant, 2yrs and 4yrs old), so need a fast shutter.

But your strobes won't fire with a shutter speed faster than 1/125th. So you're stuck with that setting - with enough light that is PLENTY for a fast kid. :)

Canon EF 24-70mm f/2.8L USM

03/23/2007 12:49:45 PM · #7

Originally posted by idnic:

But your strobes won't fire with a shutter speed faster than 1/125th. So you're stuck with that setting - with enough light that is PLENTY for a fast kid. :)

Plenty fast for *most* kids at least. I hadn't realized that the strobe wouldn't fire with a faster speed - that would likely explain away some of the issues I'd been having with it. Thank you.

Note to self - next time, don't buy a box that had already been opened. Lack of instructions makes me feel foolish online.

Telehubbie

Canon EOS-40D

03/23/2007 12:56:49 PM · #8

If you're using just flash on the kids, the quick burst of the flash will "freeze" the kids despite what shutter speed you use, so 1/125 should be fine. But if you're combining ambient light with flash then you'd have some trouble with slower shutter speeds.

Message edited by author 2007-03-23 12:57:28.

Canon EF 24-70mm f/2.8L USM

03/23/2007 01:04:18 PM · #9

Originally posted by Telehubbie:

If you're using just flash on the kids, the quick burst of the flash will "freeze" the kids despite what shutter speed you use, so 1/125 should be fine.

Okay - this makes sense to me.

Originally posted by Telehubbie:

But if you're combining ambient light with flash then you'd have some trouble with slower shutter speeds.

Unfortunately, this does not

Telehubbie

Canon EOS-40D

03/23/2007 01:18:43 PM · #10

Example: say you were using natural (ambient) light with a flash for fill, and your shutter speed was set to expose for the natural light at say 1/60th or slower, if the kid moved suddenly you'd get some blur.

DjFenzl

03/23/2007 01:27:24 PM · #11

Just bring bearmusic along with you, he can evaluate an exposure just by looking at the scene ;)

Some things to remember (which you may already know)...
The shutter speed controls the ambient light in the shot
The aperture controls the strobe light
1 stop will either halve or double the light in the exposure.

Your histogram only shows luminosity so be careful, if you have bright colors in the scene it may lie to you.

Canon EF 100mm f/2.8 USM Macro

03/23/2007 01:51:57 PM · #12

Originally posted by Telehubbie:

1/60 is not fast enough to catch my kids regardless.
I'm still not 100% following what you're trying to say though.
The way I'm reading that, I'm going to end up with blur with the flash or without.

Originally posted by Megatherian:

I knew the 1 stop halve/double bit.

I'm not understanding how the shutter controls ambient light, but aperture controls strobe light.

Spork99

OM System OM-1

03/23/2007 01:54:11 PM · #13

Originally posted by kashi:

Originally posted by Spazmo99:

Originally posted by kashi:

What should I be doing to get a good exposure when I'm using the flash or flash/strobe ?

Buy a flashmeter.

You cough up the cash for me and I will !

In the meantime, while I am saving the money (since I'm an at-home mom with no real income, this could take a while), what can I do ?

This one will do the trick and is under $60

hsolakidis

Nikon D50

Nikon AF-S DX Zoom-Nikkor 18-70mm f/3.5-4.5G IF-ED

03/23/2007 02:09:04 PM · #14

Flash duration - Extremely short, powerful light. Consider this. If, in complete darkness, you take a flash photo at 1/125 and 5 sec, the photos will be the same. The flash only fires for a fraction of a second, and shutter speed doesn't affect it. The aperture, however, does.

On the other hand, the shutter speed WILL make a difference to how much ambient light you let in. (Of course, so will the aperture).

It's a bit of a balancing act.

Good luck

Harry

Bear_Music

Samsung Galaxy S24 Ultra

Sony 24-70mm F4 Vario-Tessar T* FE OSS

03/23/2007 02:11:30 PM · #15

Originally posted by kashi:

I'm not understanding how the shutter controls ambient light, but aperture controls strobe light.

The duration of the strobe is extremely short, but it is very bright. If you were shooting in a dark room, the shutter speed would be irrelevant; you'd use whatever aperture was correct for the amount of light the flash is delivering. If you're shooting flash with ambient light, the aperture is still controlling the exposure off the flash, but the shutter speed will control how much the ambient light is a factor in the image.

In other words, in a normally lit room with flash + ambient light, the correct aperture might be, say, f/11 (for the flash) and if you used a 1/2 second shutter speed the ambient light would be a big factor in the final image, whereas at 1/250 shutter speed the ambient light would be insignificant.

R.

I see Henry beat me to it. So here's a little more:

You're in an enclosed room with all the lights on and your strobes set up. You have calculated that the correct aperture for the flash you are using is f/11. Now you turn off the lights so the room is black, and you do a whole series of exposures from 1/250 all the way to 1 second, all at f/11 and using strobes only. The images will be identical to each other.

Now do the same thing with the room lights on: the images will vary dramatically in how the surfaces lit more by the ambient light and less by the strobe appear.

You do this outdoors, it's called "fill flash"; commonly used for outdoor portraiture where you expose correctly for the scene and the flash adds "fill light" to the shadowed portions of the subject, making the lighting much less harsh looking.

Message edited by author 2007-03-23 14:16:25.

DjFenzl

03/23/2007 02:16:47 PM · #16

(I knew at least one other person would post the answer by the time I got done writing. I missed it by 2)

Message edited by author 2007-03-23 14:17:50.