Manual Speedlights and correct exposure... Help!

TimB

TimB

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Hi all, hope you can advise me!

I'm learning to use lighting a bit more at the moment but I just want to check that I'm going about things the right way.

When i needed a flash previously, I used my little Nikon SB-400 Speedlight mounted on my D90, which, because it communicates with the camera automatically, always gave reasonable results when used with a Stofen omni-bounce. Well, as good as can be expected for a small camera mounted flash.

But... I have bought a couple of large manual speedlights (Yongnuo) and some matching Yongnuo wireless triggers, all of which seem to work well for the price. This was so I can get some practice in with multiple strobe light sources when shooting stuff like a car in a warehouse or portrait type photos.

But, I'm struggling with exposure.

Obviously the camera doesn't know it is triggering 2 strobes when I take a shot, so it is metering and setting itself up for lower light than what will be available during the shot when the strobes fire. Consequently I was getting totally over exposed photos.

I got round this by shooting in manual, setting my ISO nice and low, setting the aperture I want for the shot and then leaving it (plenty of bokeh or whatever was needed), and finally adjusting the shutter speed over a few trial shots until the photo was correctly exposed.

But the problem is if i set the shutter speed too fast, I'm getting a half dark picture due to the sync speed of the flash being too slow to fully light the scene in time.

I suspect I'm really going about things the hard way here! Can someone put me out of my misery please and advise!

Thanks :)
 
Tim, reduce your shutter speed to below the sync speed and adjust up or down to allow for desired ambient light level.

Then reduce the power of your flashes to minimum power, take a picture, check it - and slowly up the flash power if need be, till you get the required look.

Shutter speed doesn't really control flash exposure. Flash power levels do (and aperture)

No doubt I've missed some bits but I'm sure someone else will come along to chip in etc :)
 
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As above. X-sync ceiling on a D90 is nominally 1/200sec, but the radio trigger will reduce that a bit - probably to 1/160sec max or you'll get a dark band at the bottom (google focal plane shutter re this).

Set everything in manual and adjust the exposure for each flash separately, starting with the main/key/subject light. In terms of exposure:

Flash power affects flash exposure.
Shutter speed affects ambient light exposure only.
Aperture affects both flash and ambient.
ISO affects both flash and ambient.

When you've set all the lights individually, fire them altogether to check and tweak. You'll probably find the overall exposure will rise a bit with all guns firing, so finally adjust overall exposure level with either aperture or ISO.
 
This is a HUGE subject to discuss but I can say you are certainly going about this all wrong. You can learn but first stop doing what you are doing - changing the SS is not the way to get the exposure correct.

The shutter speed affects only the AMBIENT light in the scene. Too fast and the background will appear dark. You need to keep the shutter speed at or below your sync speed (best to set at around 1/125th or slower). As noted above if you shoot faster than the sync speed you will see a black bar appear. Just slow the shutter speed to let in the ambient light to balance the scene (if you want that) - The flash will freeze any subject movement so you can go pretty slow to let in ambient light if you want to.

The aperture controls your flash power. Set the aperture you want and amend the flash power to suit (rather than fiddling around) - if you don't have enough power you can also start to increase the ISO which also changes the ambient exposure in the scene.

Easy way to sort this is get a flash meter (something like a Sekonic 308 is perfect). Allows you to do ambient and flash readings.

Think of the shot you are taking as two images in one. Firstly set the ambient level - That may be from zero ambient to correct ambient exposure to perhaps a slight over exposuse of the background - So set your ambient exposure (with the aperture you want to shoot the flash at).

Now go to the flash and up/down the flash power on the flash gun to get the correct exposure.

For example a portrait in a studio
You don't want any ambient in the exposure so set the shutter speed so that when you take a shot without flash the frame is black. Generally in a studio style shot ISO100, 1/125 and f8 would be plenty to get a zero ambient light with f8 giving decent dof for the portrait. Set the flash power to equal f8 on the subject and fire away.

If however you are outside on a nice day with the ambient exposure at ISO100, f16 1/125, a nice way to shoot is to under expose the ambient light by a stop or two as this will make the subject stand out a bit - Here you may want to leave the ISO and SS as they are and set the aperture at f8. Again place the flash and set the power so you get a good exposure. If you then want to darken the background, all you need do is increase the SS a little - that will darken then background without affecting the flash exposure which will remain at f8 on the subject. You can only increase the shutter speed to the sync speed though.

If you want to balance the ambient and flash, you just up the flash power by 2 stops, set the aperture to f16 and you should have a balanced ambient exposure and a well exposed subject.

This is only scratching the surface though.

Cheers
Jim
 
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Wow, thanks for the very detailed replies. Very useful indeed!

I'm just starting out on the lighting path so this is all great info.

I now see that shutter speed isn't really the issue and I need to keep it a little slower for the purposes of capturing the ambient light and also the sync issues.

I'll experiment more with lowering the power of the flash lighting to a level that matches what I'm trying to do rather than forcing the camera to suit the lighting.

Thanks again.

All tips welcome!
 
TimB said:
Wow, thanks for the very detailed replies. Very useful indeed!

I'm just starting out on the lighting path so this is all great info.

I now see that shutter speed isn't really the issue and I need to keep it a little slower for the purposes of capturing the ambient light and also the sync issues.

I'll experiment more with lowering the power of the flash lighting to a level that matches what I'm trying to do rather than forcing the camera to suit the lighting.

Thanks again.

All tips welcome!
Click to expand...

A meter will make life a lot easier when using flash - especially when using multiple flashes (or is that multiple flash?) (we're having a chat in my office here on plural words... lol)

I'd second the Strobist site
 
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Good luck with it all Tim.

By the way, HoppyUK recommends a book on here www.amazon.co.uk/Speedliters-Handbo...105X/ref=sr_1_1?ie=UTF8&qid=1319020617&sr=8-1

After seeing him mention it a couple of times I bought it myself -Thanks Richard :)

It's a great read and massively helpful...so I'd like to pass on the same info.

Edit: One more thing, I don't have any Canon flashes. I Use a Nissin di-622MK2 and 3 x Yongnuo 650s, and the above book is still clear and relevant for me.
 
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I highly recommend Zack Arias 'One Light Studio' DVD's. You can buy them.... or acquire them.

He covers everything you'll ever need to know, especially about controlling exposure with your ISO and aperture.

By changing your shutter speed you're only controlling the amount of ambient light coming in to your shot.
 
Lbm said:
Good luck with it all Tim.

By the way, HoppyUK recommends a book on here www.amazon.co.uk/Speedliters-Handbo...105X/ref=sr_1_1?ie=UTF8&qid=1319020617&sr=8-1

After seeing him mention it a couple of times I bought it myself -Thanks Richard :)

It's a great read and massively helpful...so I'd like to pass on the same info.

Edit: One more thing, I don't have any Canon flashes. I Use a Nissin di-622MK2 and 3 x Yongnuo 650s, and the above book is still clear and relevant for me.
Click to expand...

Yes, excellent book. Glad you enjoyed it :)

But it's about Canon flash, not the OP's Nikon. Just something to note really because most of it is generic, but you need to know the Nikon equivalents, eg 580EX = Nikon SB900, ST-E2 = Nikon SU800 etc.

Another good book is The Hot Shoe Diaries by Joe McNally. He uses Nikon, though it's more of an inspirational/entertaining read than an instruction manual, but he's got some amazing images and he explains just how they were done :thumbs:
 
In my earlier post I meant to say I have 3 Yongnuo 560
 
Thanks again chaps, I have been reading my way through Lighting 101 on Strobist.

Interesting stuff!
 
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