a complete noob (idiot) with a Nissin

timmygcsc2308

timmygcsc2308

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Timmy
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now..I'm really sorry and feel like a complete tit but I really need some help with the latest addition to my kit bag - a Nissin Di622 for my D90.

I've RTFM, looked on t'interwebs for ultranoob guides but not getting anywhere :shake:
basically what I'm not understanding is this:
I've set the flash on the hotshoe, and put it in TTL mode and turned my D90 on - D90 recognises it as attached and shows on the top panel and info screen that external flash is connected..super. In the D90 menu, flash mode is defo set to iTTL. So I should be good to go.
I read through this tut:
http://nikonclspracticalguide.blogspot.com/2008/01/nikon-flash-two-separate-metering.html
from what I understand, the iTTL system will talk to the metering system and adjust the flash power accordingly for correct exposure, so long as I don't exceed the flash sync speed, it's all good.

So I switch the dial to manual mode, dial up f/8 and 1/50 shutter speed, and I takes this picture:
1285879157.jpg

cool....
....well no..because when I take the shot the metering is showing as underexposed off the scale. The picture is not underexposed though :shrug:

No matter what setting I dial in it only becomes 'properly' (that is 0EV) at about 1.x seconds shutter speed. And it doesn't change whether I have the room fully lit or lights turned completey off - exactly the same.

And also the flash gun isn't firing anywhere near full whack, when I take a shot it's ready to fire again instantly.
If I switch the Nissin to full power manual, the shot is obviously waaaay over exposed at f/8 1/50, but it does fire with full burst and takes 6 seconds or whatever to recycle.

So am I missing an obvious trick here or does it sounds like the iTTL isn't playing ball? :shrug:
 
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ok do I just ignore my OVF meter? I just set the aperture to f/22, shutter speed to 1/200 (max sync speed of D90) and when I pressed the shutter it fired off a hardcore blast of light which did make the Nissin recycle for about 6 seconds and it still exposed correctly, but again the EV meter in the OVF was showing way under exposed

But ok...so whats the deal here then? :-/ iTTL is working because its obviously putting out more power as I make the shutter speed faster - but is it the light meter becomes redundant or is something not right?
 
I'm guessing the metering system doesn't take the flash into account? It just measures the exposure at ambient lighting. Otherwise in iTTL mode the meter would constantly read 0 (unless maybe you changed the flash exposure) which would be pretty useless.
 
ok...yes from digging around it seems the meter doesn't take the flash into account.
Can you please explain why it would be useless for the EV to be constantly at 0? thicko here.. :cuckoo: I think I kinda get it but..:shrug:
 
Dial in 1/60 f2.8-f4 iso 1600 keep room lights on. Bounce flash. I think that then you will expose for some ambient light and flash will fill in the rest. Pished at the mo, on the Gold Labes so may be on the wrong tracks here.:beer:
 
it meters for the ambient, so the ambient was very dark but you threw a **** load of flash at it to balance that exposure ;)
 
It's only useless when you're letting the flash itself decide how powerful to fire. Rather than think why is it useless let's think why it's useful, and there's several reasons.

1 is you can control the recycle speed of the flash. So if you need the flash back extra rapid you could set your cameras exposure closer to zero and the flash will fire on a lower power.

Another reason is there might be a difference between the "colour" of the ambient lighting vs the flash lighting. So if you want to kill the ambient you might want to fire pretty close to the max sync.

To follow on from that point what if your were using a gel on your flash to get a certain colour? The power the flash fires at will matter quite a lot here, but if the EV was always at zero you could never really judge roughly what power it would be firing at.

Apart from all the above, it's easier to manufacture an ambient only meter without having to add "calculations" to what adjustment the flash power will make. Plus, it's more processing power for the camera to worry about.

Also, to be honest, what I'm saying above are just examples of why I'd personally reckon it's more useful to meter the natural light as opposed to natural + flash compensated for. Realistically if you were using advanced lighting techniques or were required to think about a lot of the above you'd probably be on manual power anyway.
 
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karmagarda said:
It's only useless when you're letting the flash itself decide how powerful to fire. Rather than think why is it useless let's think why it's useful, and there's several reasons.

1 is you can control the recycle speed of the flash. So if you need the flash back extra rapid you could set your cameras exposure closer to zero and the flash will fire on a lower power.

Another reason is there might be a difference between the "colour" of the ambient lighting vs the flash lighting. So if you want to kill the ambient you might want to fire pretty close to the max sync.

To follow on from that point what if your were using a gel on your flash to get a certain colour? The power the flash fires at will matter quite a lot here, but if the EV was always at zero you could never really judge roughly what power it would be firing at.

Apart from all the above, it's easier to manufacture an ambient only meter without having to add "calculations" to what adjustment the flash power will make. Plus, it's more processing power for the camera to worry about.

Also, to be honest, what I'm saying above are just examples of why I'd personally reckon it's more useful to meter the natural light as opposed to natural + flash compensated for. Realistically if you were using advanced lighting techniques or were required to think about a lot of the above you'd probably be on manual power anyway.
Click to expand...

thanks alot mate, that makes sense, and I think I finally understand now ;)

thanks too David :) and Nigel...have some coffee :p
 
The camera is indicating the correct exposure for the ambient light. It hasn't got a clue how much flash exposure to give because there is no flash light to measure.

When you press the shutter release, the gun fires a measured pre-flash which the metering system then reads and sets the power for the main flash. When the shutter is fully open, that is then fired at the correct power.

This all happens at lightening speed. You cannot distinguish the two flashes visually, so it looks just like one flash.
 
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