Testing the power of a Flash???

clive_odonohoe

hi,

I have two Nikon SB800's and in college they have another two SB800's I can use. I bought both of my flashes brand new and are great but I want to get more to do more complex lighting setups. With Nikon's newest flash, the SB900, I am unable to buy a brand new SB800 so I want to buy some second hand ones.

The only thing I want to be able to test it, is there anyway I can test whether the flash has lost some of its power due to a lot of use. I would like to have all my flashguns holding a similar amount of power. I'm sure I can just test the flash against one of my own and see if there is much of a difference, but is there any other way that is technically better for comparing the power output of a flash?

Thanks

Clive

melekalikimaka

have them surround a tall object, equal distance from each other pointing directly at the object, set to same power all round, if there is shadow on one side, the one the shadow is pointing to is weaker...


or i could be talking out my ass...

melekalikimaka

or have just a one light set up, ambian light and camera settings unchanged and use a light meter with each flash to see i any is weaker, or stronger

clive_odonohoe

No I think these are good ideas which were close to what I was intending to do. Thanks for the suggestions

mrmac

I would imagine you could make a setup with your flash mounted on a light stand, and measure it's output using a light meter, at set distances i.e. 1m, 2m, 5m.
I would advise doing this indoors, with identical background ambient light.

TBH - I've never heard of anyone having "power loss" with a flash. It either works, or it doesn't! I have an SB-25, which came out in 1988 - and never misses a beat!

Edit: can I ask why you need this precision?

eas

mrmac wrote: »

Edit: can I ask why you need this precision?

that's the question I'd ask as well. Unless you plan on using your flashes at 100% for most shots I wouldn't think it matters. And, if you need all flashes at 100% for most of your shots I'd say it would be time to consider another light source.

mrmac

eas wrote: »

.... I'd say it would be time to consider another light source.

Have to agree. You have two SB800, and you're considering getting more!?
I think it'd be cheaper to buy studio strobes - unless you absolutely need battery power.

Or you could sell your two SB800's and buy four SB400's, with enough money for a pocket full of batteries!

BTW - I'd know someone who'd buy a good SB800 :cool:

Rojo

When I go back to college in September, I know just the person to ask...



"Dedicated flash units..."

clive_odonohoe

I think your right mrmac, if all the features of the flash work fine on my camera everything else with the flash should be ok.

I think I will hang on to my SB800's, I dont think I'd ever get rid of them, certainly not for SB400's Those flash units are far too basic, the only function they have is an on/off switch.

I'm using SB800's because I can use nikon's CLS with these and are far more portable for lighting location work. I understand that battery power is a main concern when using flashguns but for me at the moment, they are more useful for the work I do.

ValueInIreland

'Don't want to be a smart ass- but has hanyone heard of a flash meter?? Or if you are shooting digital it is easy - just shoot at full power on one flash and adjust the appeture until you get the correct exposure (use the histogram), then do the same with the second flash gun.

melekalikimaka

ValueInIreland wrote: »

'Don't want to be a smart ass- but has hanyone heard of a flash meter?? Or if you are shooting digital it is easy - just shoot at full power on one flash and adjust the appeture until you get the correct exposure (use the histogram), then do the same with the second flash gun.

light meter is quicker

clive_odonohoe

melekalikimaka wrote: »

light meter is quicker

I'd agree with melekalikimaka, and will do this when I inspect the flash.