Help - how does a flashgun interact with my camera settings?

kitschenalia

kitschenalia

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I have the cheapest flashgun for my camera, a £30 Jessops one which is now no longer available... basically can anyone give me the lowdown on how a basic flashgun will interact with my camera settings? I usually shoot fully manual, but am prepared to consider also shooting in AV mode if this helps me grasp flash.

My camera doesn't adjust the recommended exposure settings in manual (when I'm looking through the viewfinder at the wee bar graph to decide how much aperture or SS to dial in) so I never know whether it will be exposed correctly. It doesn't seem to acknowledge that the flash is on board. I have the flash strength dialled down to -2 within the camera menu because my flash is so basic that you can't do that on the flash itself. But I can't use it for fill flash, as I just get white faces. Sometimes the light "ETTL" lights up and it behaves a bit differently but it's not always lit up and even then the metering guide within the viewfinder is no help to me.

Any help whatsoever gratefully received.
 
kitschenalia said:
I have the cheapest flashgun for my camera, a £30 Jessops one which is now no longer available... basically can anyone give me the lowdown on how a basic flashgun will interact with my camera settings?
Click to expand...

Assuming it's the Jessops 300AFD you've got, the answer to your question is "it won't".


That particular flashgun only has one power setting - full, any adjustments to the exposure need to be done by playing around with the aperture (and shutter speed) on your camera.
 
OK I'll go with the Nikon Version assuming a TTL flash

'P' mode. Will default to f4 1/60 when a TTL flash is attached. Will then use TTL to flash the correct exposure.

'S' mode. Will leave shutter speed as you've set it. Will try and open aperture enough to get a correct exposure without flash, and will then use those settings for TTL flash

'A' mode. Will leave aperture as you've set it and try to use shutter speed to get a correct exposure without flash. Will the use those settings for TTL flash

'M' Mode. Will leave shutter and aperture as you've set it and then use those settings for TTL flash

Assuming a manual flash you need to work out and apply correct settings for your other exposure variables
 
kitschenalia said:
I'm not the quickest with technological stuff, but basically does the above suggest that the exposure has to be correct in the first place WITHOUT flash? Then flash is added on top of that? Sorry I am such a dunce :-0
Click to expand...

no - your camera in A or S mode will try and meter for the correct expoisure, and use settings as close as it can to those. Then it'll meter the flash
 
not giving up yet. Remember thhis is only true for a TTL flash. In the same way as your camera will meter to give you the correct shutter/apperture values, your flash also needs to meter. It sends out a load of pre flashes and uses that information to work out (in conjunction with the shutter/aperture values from the camera) how much power it needs to give to get the exposure right
 
kitschenalia said:
Thank you. My flash has an ETTL light at the back, which is sometimes lit up yellow, but even so I don't ever remember it firing out little flashes.
Click to expand...


the pre flashes fire so rapidly that to you or I they'd appear part of the main flash
 
kitschenalia said:
Thank you. My flash has an ETTL light at the back, which is sometimes lit up yellow, but even so I don't ever remember it firing out little flashes.
Click to expand...

Set the camera to manual with a shutter speed of 2 secs.
Set the camera to Rear Curtain sync.
Take a picture with the flash, you should be able to see the pre flash(es) which will occur when the shutter opens and then the main flash just before it closes.
 
kitschenalia said:
I usually shoot fully manual, but am prepared to consider also shooting in AV mode if this helps me grasp flash.

I have the flash strength dialled down to -2 within the camera menu because my flash is so basic that you can't do that on the flash itself. But I can't use it for fill flash, as I just get white faces.
Click to expand...

You need a flash with manual control if you want to manually adjust the strength of the flash. The 300AFD doesn't do that either.

To use fill flash on a bright sunny day, if you find that faces are whiting out even on the lowest ISO, you could use a faster shutter speed. Basically, with the flash attached, the fastest shutter speed you'll get is 1/200, which will still be too long if your aperture is wide. In order to use a faster shutter speed you'll need a flash with a high-speed sync mode. The 300AFD doesn't do that.

When you are setting the exposure manually, looking at the "wee bar graph" ;) you are seeing the exposure for the scene without flash.

The problem with covering the flash head with a hanky is that with TTL, it is the pre-flash which determines the flash exposure. If your pre-flash is also having to blast through a hanky, the main flash might well be at full power, which will run down your batteries quickly (and shorten the life of your flash gun).
 
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