Basic Flash help

EMA747

EMA747

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Andy
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I have never really tried flash photography up to now but I got a Canon 430EXii so I think it's about time I learnt how to use it.

In another thread someone suggested trying this as a first step:
for a quick self-taught lesson set your flash and camera to manual, iso 100, 1/125s, f/1.8, half power on the flash. Now point the flash head at the white ceiling (if you've got one) and take a picture. try adjusting the following and note what happens:

aperture
flash power
iso
shutter speed
Click to expand...

I did that and discovered that it is the flash power that changes the lighting in the image not any of the others.

An effect I like is when the model (or any subject) is really picked out of a dark background by the flash and I am wondering how this is done. How do you get the background darker? How do you know what setting to have the flash on?

This is what I mean. NOT my images just random examples.

http://www.flickr.com/photos/zed_sx/4563411495/

http://www.flickr.com/photos/lucashuffman/4383913686/

http://www.flickr.com/photos/sxsphotography/4471939885/


Sorry for the really basic questions! :(
 
off camera flash

basically you have 2 exposure controlled by some of the same variables

flash is instant so is unaffected by shutter speed (provided its below 1/320th-sync on a 1series) but can also be affected by ambient exposure

ambient light you know

to do what you want you need to pick your ambient exposure at the background (ie underexposed), then add flash to the subject to expose it correctly

this added flash looks better from off camera / modified

a better explanation can be found on strobist.com under lighting 101 :D
 
When I try and underexpose the background ambient light it just stays the same. Is that because the flash is flooding the whole area with light? For a quick experiment I tried a shot of my pot of pens on my desk but the whole desk area came out a pretty normal exposure no matter what setting I adjusted to try and dial down the background.

Should I be in ETTL or M mode?
 
I am in the same boat with the same flash, its a difficult thing to master but for what you want you need the flash on manual off the body and basically find the correct power for outcome you require, obviously the power will depend on distance from subject and ambient light. Am I right?? I will keep an eye on this thread, flash is very confusing if your new to it I am finding lol.
 
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Good to know I'm not the only one! I am totally fine with other areas of photography but flash has got be baffled. It seems to have a totally new set of rules and technical bits and pieces. :thinking:
 
We are discussing black backgrounds here to:

http://www.talkphotography.co.uk/forums/showthread.php?p=3061612#post3061612

like this one:

melblack103.jpg


If anyone is interested.
 
That's the sort of effect I was on about. I'll check out that thread Darren.
 
I see a lot of people talk about FITP triggers and accessories but I can't seem to find their website to check prices. Can someone post a link?
 
EMA747 said:
I see a lot of people talk about FITP triggers and accessories but I can't seem to find their website to check prices. Can someone post a link?
Click to expand...

It's FLASH IN THE PAN he is a member on here. Look in the advertisers section :thumbs:
 
F/number affects everything.
ISO affects everything.
Shutter speed only affects ambient.
Flash power only affects flash.

Which is why Av is usually the best for flash - set f/number and ISO as normal, and use the flash ouput to control the flash and the shutter speed to control the ambient. If you're in E-TTL, it's easy to just use the +/- compensation on the flash to control power, and +/- compensation on the camera to control the shutter speed. They work independently and you can get any level of balance/ratio with that in two seconds by chimping.

You can do exactly the same in full manual, both flash and camera, or a combination of manual or auto on either camera or flash. Depends. I tend to use E-TTL when either I need the shot to be right first time (or closer than I can guess straight off) or if the subject is moving, such as kids. Flash is very affected by distance and E-TTL will adjust the power, and maintain the ratio, when things are moving around quickly. Once it's set you really don't have to worry about it. Fantastic! :)

But if things are relatively static and I'm shooting a few, it's sometimes better to use manual. It only takes a moment or two with a few test shots to get the flash/ambient balance right, and then you know it's going to stay that way.

The other thing in the links you posted is the use of modifiers, mainly big ones like brollies or softboxes. The guy in the field is shot with a big light of some sort, and the girl too, plus a wind machine by the looks.

Edit: I'm not sure what FITP is selling these days, but the short answer to radio triggers is Yongnuo RF-602. Tons on Amazon http://www.amazon.co.uk/s/ref=nb_sb...gers&sprefix=yongnuo+rf-602+wireless+triggers Cheap, reliable, but full manual only.

The other way to trigger remotely is to use Canon E-TTL. For that you need a master unit, such as a 580EX gun (flash and master) or ST-E2 (master only). Or similar third party. These work well, with the exception of bright light outside - all of the camera manufacturers' auto-TTL systems transmit using light signals, not radio, which get washed out in bright sun or at long range (unless you use an extension cord). Expensive.

The ultimate solution is radio E-TTL, from either Pocket Wizard or Radio Popper. Upwards of £400.
 
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I just had another very quick try using what Richard said above. The thing is I can't underexpose the background enough because of the 1/300 max sync speed. Is that just how it is or is there something else I can do to get more underexposure?
 
HoppyUK said:
F/number affects everything.
ISO affects everything.
Shutter speed only affects ambient.
Flash power only affects flash.

Which is why Av is usually the best for flash - set f/number and ISO as normal, and use the flash ouput to control the flash and the shutter speed to control the ambient. If you're in E-TTL, it's easy to just use the +/- compensation on the flash to control power, and +/- compensation on the camera to control the shutter speed. They work independently and you can get any level of balance/ratio with that in two seconds by chimping.

You can do exactly the same in full manual, both flash and camera, or a combination of manual or auto on either camera or flash. Depends. I tend to use E-TTL when either I need the shot to be right first time (or closer than I can guess straight off) or if the subject is moving, such as kids. Flash is very affected by distance and E-TTL will adjust the power, and maintain the ratio, when things are moving around quickly. Once it's set you really don't have to worry about it. Fantastic! :)

But if things are relatively static and I'm shooting a few, it's sometimes better to use manual. It only takes a moment or two with a few test shots to get the flash/ambient balance right, and then you know it's going to stay that way.

The other thing in the links you posted is the use of modifiers, mainly big ones like brollies or softboxes. The guy in the field is shot with a big light of some sort, and the girl too, plus a wind machine by the looks.

Edit: I'm not sure what FITP is selling these days, but the short answer to radio triggers is Yongnuo RF-602. Tons on Amazon http://www.amazon.co.uk/s/ref=nb_sb...gers&sprefix=yongnuo+rf-602+wireless+triggers Cheap, reliable, but full manual only.

The other way to trigger remotely is to use Canon E-TTL. For that you need a master unit, such as a 580EX gun (flash and master) or ST-E2 (master only). Or similar third party. These work well, with the exception of bright light outside - all of the camera manufacturers' auto-TTL systems transmit using light signals, not radio, which get washed out in bright sun or at long range (unless you use an extension cord). Expensive.

The ultimate solution is radio E-TTL, from either Pocket Wizard or Radio Popper. Upwards of £400.
Click to expand...


Hoppy this is great, I have the Yongnuo RF-602's, is it just a matter of trial and error either setting the +/- comp or manual on the flash till you get the exposure your looking for then with experience it will become obvious? I am going to give this a go tonight, my main problem is the settings I should be using so that the flash dosent burn out the subject an it seem s to be just trial and error atm.
 
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ianbarber said:
Can you go into High Speed Sync mode on your camera. I know with my D700 I can go all the way to 1/8000
Click to expand...

Yes, HSS is the answer there, so long as the subject is reasonably close. HSS is a function of the flash, not the camera, and the 430EX does it :thumbs: With some cameras (check handbook) it will switch the flash in and out of HSS mode automatically whenever the shutter speed requires it, so you can prettty much leave it switched on.

Because of the way HSS works (same with Nikon FP flash) a lot of the power is wasted. And the higher the shutter speed, the more is lost. This means that even when the gun is working flat out, range is substantialy reduced.

Everything anyone needs to know about Canon flash in this excellent new book by N K Guy for £19 http://www.amazon.co.uk/Mastering-Canon-EOS-Flash-Photography/dp/193395244X
 
Donki said:
Hoppy this is great, I have the Yongnuo RF-602's, is it just a matter of trial and error either setting the +/- comp or manual on the flash till you get the exposure your looking for then with experience it will become obvious? I am going to give this a go tonight, my main problem is the settings I should be using so that the flash dosent burn out the subject an it seem s to be just trial and error atm.
Click to expand...

RF-602 is manual only - they just fire the flash, so you have to set the power yourself regardless of which unit it is. Otherwise you can use them just like E-TTL in that you can set the camera on Av, which will sort out the ambient exposure, then manually adjust the flash output to match.

Bear in mind that with most radio triggers (except the expensive PWs) there is a slight delay while they process the firing signal. Not really a problem as the RF-602s seem pretty quick compared to some, so just knock the shutter speed back one click from the nominal x-sync speed (or use any longer speed of course). That is, if your normal max x-sync is 1/1250sec, then don't go higher than 1/200sec or you'll get a dark band appearing across the bottom of the picture.
 
HoppyUK said:
RF-602 is manual only - they just fire the flash, so you have to set the power yourself regardless of which unit it is. Otherwise you can use them just like E-TTL in that you can set the camera on Av, which will sort out the ambient exposure, then manually adjust the flash output to match.

Bear in mind that with most radio triggers (except the expensive PWs) there is a slight delay while they process the firing signal. Not really a problem as the RF-602s seem pretty quick compared to some, so just knock the shutter speed back one click from the nominal x-sync speed (or use any longer speed of course). That is, if your normal max x-sync is 1/1250sec, then don't go higher than 1/200sec or you'll get a dark band appearing across the bottom of the picture.
Click to expand...

You are a wealth of knowledge Richard I will give this a go over the weekend, I may post back on here with a few more questions :), sorry about the hijack lol.
 
Donki said:
You are a wealth of knowledge Richard I will give this a go over the weekend, I may post back on here with a few more questions :), sorry about the hijack lol.
Click to expand...

You're very kind Ian, and you're very welcome. So here's a bit more - All About Flash in Thirty Seconds.

1) The larger the light source, the softer the shadows. A big light such as an umbrella or softbox gives lighter shadows with softer edges. Small light source, such as hotshoe flash fired direct, gives dark hard-edged shadows. The size of the light source changes relative to the subject with distance - ie move a softbox back and it will get harder; equally, even a small light source like a Stofen-type diffuser with macro is huge if you're a spider.

2) Inverse square law says that when you double the light-to-subject distance, the brightness is reduced to one quarter. Which is why flash used close falls off very rapidly. Work with it, and the ISL is your friend; try to fight it, and you'll lose.

3) Angle of incidence equals angle of reflection. Light bounces off a surface at the same angle it strikes it, like a snooker ball off the cushion. Vital knowldge when positioning reflectors (and most other things).
 
HoppyUK said:
3) Angle of incidence equals angle of reflection. Light bounces off a surface at the same angle it strikes it, like a snooker ball off the cushion. Vital knowldge when positioning reflectors (and most other things).
Click to expand...

Definitely one to remember, cheers :thumbs:

Just one thing, well two things:

I'm guessing absorption plays a part (i.e. you won't always get the same strength of light reflecting)?

Also, I'm assuming that anything with light hitting it with a level of transparency will break this law and we enter into refraction or perhaps a little of both? (i.e. if a model is wearing tinted glasses or a semi see-through dress)
 
EMA747 said:
When I try and underexpose the background ambient light it just stays the same. Is that because the flash is flooding the whole area with light? For a quick experiment I tried a shot of my pot of pens on my desk but the whole desk area came out a pretty normal exposure no matter what setting I adjusted to try and dial down the background.

Should I be in ETTL or M mode?
Click to expand...

The trouble here, if it hasnt been mentioned all ready, is that its such a small area everything is gonna be hit by flash. In a larger area, the difference between foreground/background distance from the flash is gonna have more of an effect of what gets lit.

So if you have a person in a large room, the flash will reach them, but not the wall behind them. Thats an example of when you can balance the flash and ambient light. Ourdoors shoots in low light is another example.

Adey
 
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gman said:
Definitely one to remember, cheers :thumbs:

Just one thing, well two things:

I'm guessing absorption plays a part (i.e. you won't always get the same strength of light reflecting)?

Also, I'm assuming that anything with light hitting it with a level of transparency will break this law and we enter into refraction or perhaps a little of both? (i.e. if a model is wearing tinted glasses or a semi see-through dress)
Click to expand...

Absorbsion does play a part. If you were bouncing off a mirror then very little, but mostly it's off a ceiling or wall (often not pure bright white to start with) or off a reflector of some sort, so yes there's some loss there.

And if you bounce off a ceiling, the quite narrow beam from the gun covers an area several feet across by the time it reaches the ceiling (which is where the big, soft light comes from) then surface diffusion spreads it even wider so there's a lot of light lost there. And then it has to travel back down to the subject - the total distance as far as the ISL is concerned is the distance from flash to ceiling plus from the ceiling down to the subject.

When you add it all up, bounce flash needs at least a couple more stops of light than direct flash. Much more with a higher ceiling.

For the angle of indicence/reflection thing to work perfectly, the surface must be smooth. In fact, the rule always works absolutely, but very few surfaces are perfectly smooth and actually the surface is made up of lots of many much smaller surfaces, each one lying at a slightly different angle. The end result is that most of the light bounces off at the same angle, but there's a fair amount of spread.
 
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