Flash usage

Chunkey Monkey

Chunkey Monkey

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Mark
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Back in the days of film I owned a Minolta 700si with the 5400HS flash and used this in auto mode for flash.
Now im using DSLR and a separate fash gum on program mode but would like to understand the reasoning for using flash in manual mode, What are the benefits please.
 
Manual Flash, or Manual Camera?

I'll give you both.

Manual flash:
Your DSLR measures the flash exposure off the sensor, as such it becomes a very complicated 'guess' at the exposure, with film and auto flash - the exposure latitude of film meant that metering wasn't so crucial, with your DSLR metering is much more crucial. Shooting with a Manual flashgun means that you can meter and get easily consistent results.

Manual Camera:
In tricky conditions (and always when indoors), because your camera will often attempt to get a correct exposure for the ambient light using the flash as fill (they're treated as separate exposures).

We can often get predictable results indoors by setting an exposure to underexpose the ambient by maybe a stop and using the flash to light the subject, leaving a pleasantly underexposed background. We can vary the amount of ambient we balance using shutter speed without affecting the flash exposure (so even if we're shooting manual flash).

*caveats:
Assuming we're within the flash sync speed range (would include HSS if available)

You can program your camera to automatically ignore ambient and prioritise the flash once a flash gun is attached.
 
Phil V said:
Manual Flash, or Manual Camera?

I'll give you both.

Manual flash:
Your DSLR measures the flash exposure off the sensor, as such it becomes a very complicated 'guess' at the exposure, with film and auto flash - the exposure latitude of film meant that metering wasn't so crucial, with your DSLR metering is much more crucial. Shooting with a Manual flashgun means that you can meter and get easily consistent results.

Manual Camera:
In tricky conditions (and always when indoors), because your camera will often attempt to get a correct exposure for the ambient light using the flash as fill (they're treated as separate exposures).

We can often get predictable results indoors by setting an exposure to underexpose the ambient by maybe a stop and using the flash to light the subject, leaving a pleasantly underexposed background. We can vary the amount of ambient we balance using shutter speed without affecting the flash exposure (so even if we're shooting manual flash).

*caveats:
Assuming we're within the flash sync speed range (would include HSS if available)

You can program your camera to automatically ignore ambient and prioritise the flash once a flash gun is attached.
Click to expand...

Thank you that helps me a bit, How do i set the camera to prioritise the flash when fitted ?
 
mark2002 said:
Thank you that helps me a bit, How do i set the camera to prioritise the flash when fitted ?
Click to expand...

You can set the flash sync speed to not drop (more flexible with better cameras I believe). Not sure where it is on the menu's of the 60d.
 
Phil's advice is spot on as usual. I think if you use av mode it tries to expose for the background and the flash is for fill for the subject on Canon. You don't necessarily want to expose for the background and it can lead to long shutter speeds.

I have been using flash in Ttl and camera in m. You can then select whatever aperture and shutter speed ( up to max sync speed) you want and the flash adjusts to expose the subject correctly.
 
Another good reason for using manual flash is that it teaches you how flash works.


Steve.
 
Robclarke said:
Phil's advice is spot on as usual. I think if you use av mode it tries to expose for the background and the flash is for fill for the subject on Canon. You don't necessarily want to expose for the background and it can lead to long shutter speeds.

I have been using flash in Ttl and camera in m. You can then select whatever aperture and shutter speed ( up to max sync speed) you want and the flash adjusts to expose the subject correctly.
Click to expand...


Hi Rob, ive been playing aroung in manual selecting the shutter and apature I would use, but cannot get TTL on flash only E_TTL there is a manual setting on flash fro 1/128 to 1/1 do i need to select any within these and if so i assume the camera doesnt meter for this ?
 
mark2002 said:
Hi Rob, ive been playing aroung in manual selecting the shutter and apature I would use, but cannot get TTL on flash only E_TTL there is a manual setting on flash fro 1/128 to 1/1 do i need to select any within these and if so i assume the camera doesnt meter for this ?
Click to expand...

On Canon it's called ETTL, other manufacturers call it other things (Nikon iTTL) - but it's all TTL (Through The Lens) metering. Usually a pre flash measured at the film plane.
 
Phil V said:
On Canon it's called ETTL, other manufacturers call it other things (Nikon iTTL) - but it's all TTL (Through The Lens) metering. Usually a pre flash measured at the film plane.
Click to expand...

Ah im with you now, but thats not using manual flash though is it
 
mark2002 said:
Ah im with you now, but thats not using manual flash though is it
Click to expand...

No, he said he's shooting with the camera in Manual and the flash in TTL. So it's Auto flash to balance with the Manual ambient exposure.
 
Phil V said:
No, he said he's shooting with the camera in Manual and the flash in TTL. So it's Auto flash to balance with the Manual ambient exposure.
Click to expand...

Yes thats how i understood him, I was merely asking what are the benefits of using flash in manual ( if any ) as well, IE no auto at all
 
The benefits of Manual flash are covered in my post above;

Your DSLR measures the flash exposure off the sensor, as such it becomes a very complicated 'guess' at the exposure, with film and auto flash - the exposure latitude of film meant that metering wasn't so crucial, with your DSLR metering is much more crucial. Shooting with a Manual flashgun means that you can meter and easily get consistent results.
 
Phil V said:
The benefits of Manual flash are covered in my post above;

Your DSLR measures the flash exposure off the sensor, as such it becomes a very complicated 'guess' at the exposure, with film and auto flash - the exposure latitude of film meant that metering wasn't so crucial, with your DSLR metering is much more crucial. Shooting with a Manual flashgun means that you can meter and easily get consistent results.
Click to expand...


Thanks for your help but you are talking a language i dont understand as yet, but thanks again.
 
There are two good books on this one is called hot shoe diaries the. Other is called speedlighter's handbook.
 
mark2002 said:
Thanks for your help but you are talking a language i dont understand as yet, but thanks again.
Click to expand...

Sorry.
The auto flash (called ETTL for Canon) measures the correct flash exposure by firing a small preflash and measuring the light falling on the shutter curtain. The camera calculates the amount of light that the flash needs to output based on that measurement and sends the instruction to the flash.

Like all auto metering, it can be fooled by brighter or darker than 'average' subjects. Some people say its easy to manage the auto mode to get a correct exposure (using FEC available from a button on your top plate), others say that if you have to manipulate the auto mode to get a correct exposure, you might as well do all the hard work yourself and know that you're doing it right, which takes us to Manual!

Manual flash is controlled either by adjusting the actual flash output (which, once set is a constant but you can set the flash power as a fraction), or by altering the amount of flash hitting the sensor (by altering the aperture) or by altering the amount of light the camera needs (by changing the ISO).

Manual flash output can be calculated, by using the guide number of the flashgun. There are tables online, or you could use a calculator and the inverse square law. The problem with the calculation though is photographic:gag:.

People like me will tell you never to use on camera flash straight on to the subject, because the light is ugly:thumbsdown:. So you need to bounce the flash, or get it off camera and use a modifier (umbrella or soft box). Calculating flash power through a modifier might lose a stop of power(ish), but calculating flash distance when bouncing off a ceiling becomes guesswork when you can't physically measure the distance and then you still need to lose maybe a stop for the lack of reflectivity of the ceiling itself.

That sounds very complicated, because it is! So we're probably better just measuring the light than calculating it:thumbs:. To measure the flash falling on your subject, you can either buy a flash meter or use the cameras review screen and histogram.

It sounds fiddly, but once you know that a head and shoulders portrait (55mm) at a standard room height is f5.6 iso 200 flash on quarter power for correct exposure, then you can step back a bit to get 3 people in and go to f5 etc. or zoom out and keep the same distance and settings.

Sorry if that's still complicated but it'll fall into place once you start using it (honest). And if you get panicked, just switch to ETTL:thumbs:.
 
Phil V said:
Sorry.
The auto flash (called ETTL for Canon) measures the correct flash exposure by firing a small preflash and measuring the light falling on the shutter curtain. The camera calculates the amount of light that the flash needs to output based on that measurement and sends the instruction to the flash.

Like all auto metering, it can be fooled by brighter or darker than 'average' subjects. Some people say its easy to manage the auto mode to get a correct exposure (using FEC available from a button on your top plate), others say that if you have to manipulate the auto mode to get a correct exposure, you might as well do all the hard work yourself and know that you're doing it right, which takes us to Manual!

Manual flash is controlled either by adjusting the actual flash output (which, once set is a constant but you can set the flash power as a fraction), or by altering the amount of flash hitting the sensor (by altering the aperture) or by altering the amount of light the camera needs (by changing the ISO).

Manual flash output can be calculated, by using the guide number of the flashgun. There are tables online, or you could use a calculator and the inverse square law. The problem with the calculation though is photographic:gag:.

People like me will tell you never to use on camera flash straight on to the subject, because the light is ugly:thumbsdown:. So you need to bounce the flash, or get it off camera and use a modifier (umbrella or soft box). Calculating flash power through a modifier might lose a stop of power(ish), but calculating flash distance when bouncing off a ceiling becomes guesswork when you can't physically measure the distance and then you still need to lose maybe a stop for the lack of reflectivity of the ceiling itself.

That sounds very complicated, because it is! So we're probably better just measuring the light than calculating it:thumbs:. To measure the flash falling on your subject, you can either buy a flash meter or use the cameras review screen and histogram.

It sounds fiddly, but once you know that a head and shoulders portrait (55mm) at a standard room height is f5.6 iso 200 flash on quarter power for correct exposure, then you can step back a bit to get 3 people in and go to f5 etc. or zoom out and keep the same distance and settings.

Sorry if that's still complicated but it'll fall into place once you start using it (honest). And if you get panicked, just switch to ETTL:thumbs:.
Click to expand...

Phil thanks for your help, having read that now I see where your coming the part ive highlighted in red expains full what i needed to understand. I know how to use the camera in full manual mode without flash and now understand how to apply it to the flash gun manually.
 
mark2002 said:
Phil thanks for your help, having read that now I see where your coming the part ive highlighted in red expains full what i needed to understand. I know how to use the camera in full manual mode without flash and now understand how to apply it to the flash gun manually.
Click to expand...

Just remember you'll have to experiment with your own flash to get the correct settings.
 
yes I understand now put flash into manual and select one of the following 1/1 to 1/128 to find the required light
 
Quick question is "zoom" the same as "power", just interpretted in a different way?
Or does zoom actually affect the arc of light produced?
 
Durbs said:
Quick question is "zoom" the same as "power", just interpretted in a different way?
Or does zoom actually affect the arc of light produced?
Click to expand...

No.
A modern flash head zooms to match the coverage angle of the lens, it does effect the power of the flash, but that isn't its purpose, and it's not that predictable either.
 
Durbs said:
Sort of like an in-effective snoot?
Click to expand...

Sort of, but even at telephoto settings it'll not be that narro or have such a regular shape as a snoot provides.
 
Phil V said:
On Canon it's called ETTL, other manufacturers call it other things (Nikon iTTL) - but it's all TTL (Through The Lens) metering. Usually a pre flash measured at the film plane.
Click to expand...

Some film SLRs used to work like that, off the film plane. Olympus OM-2 was the first) but the flash exposure was measured very differently - in real time, and quenched (no pre-flash).

DSLRs are different again. They can't read off the film/sensor plane because it's shiny and not the convenient mid-grey of a film emulsion. So they have to issue a pre-flash and that is measured in the same way as ambient light, by metering sensors in the pentaprism, before the mirror rises and the shutter opens.
 
HoppyUK said:
Some film SLRs used to work like that, off the film plane. Olympus OM-2 was the first) but the flash exposure was measured very differently - in real time, and quenched (no pre-flash).

DSLRs are different again. They can't read off the film/sensor plane because it's shiny and not the convenient mid-grey of a film emulsion. So they have to issue a pre-flash and that is measured in the same way as ambient light, by metering sensors in the pentaprism, before the mirror rises and the shutter opens.
Click to expand...

Thanks Richard. Every day I learn something here.
 
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