why would my ISO be set to 3200 for white backdrop shoot?

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tikigod19

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Hi all I have just bought a 3 head flash kit with softboxes for use with a white backdrop (I used to use continuous video lights instead).

I set the 2 back ground lights to almost full power, with the front flash at about half and with the exception of a bit of bleed from the rear flashes onto the subject all was fine, HOWEVER ive noticed (too late now!) than on 80% of my pictures the ISO was set to 3200...

I had the nikon D90 on manual (obviously not manual ISO though) with the shutter at 160 or 200 and the iris set anywhere from f8 to about f16 as no matter what I did everything was massively over exposed. Ideally I'd like to use f4 or so for depth of field but everything was so bright I had to do what I could to reduce it. I also put the exposure compensation to -2.5 on the camera.

I know one of these things would have resulted in the ISO going crazy but I dont get why, I thought ISO was boosted in dark conditions not over exposed conditions...

any help much appreciated!!
 
The light meter only see's the UNLIT backdrop when metering, and if you are using AUTO ISO I presume it has upped the ISO to light it appropriately. The problem is, when you fire the trigger, the camera settings are locked in - just as you add a tonne of flash to the mix :)

Solution?

Turn off AUTO ISO.

Gary.
 
Should be on manual for studio work, use flashmeter to get correct exposure (approx 1/60, F8, ISO200 (ish))
 
:agree: with EG & daugirdas here - especially the slap comment :lol:

ISO is usually at the highest quality setting for studio work i.e. ISO 100 or 200; but having it set higher can help with recycling times and allow for higher f-stops if the flash power isn't sufficient

Only any normal camera and size of print these days ISO 400 is as near as damn the same quality as ISO 200 - and using 400 makes life easier on your flash and hence batteries too :)

DD
 
Auto iSO? Just been let on a silly setting? who knows.

Pop your camera in manual, on the lowest possible ISO for any studio shoot (unless you really do want noise, or are working on something really really specialist which needs it
 
wow, what a forum! Thank you all for your replies.

I had the camera in manual but not being a pro I didnt realise this excluded the ISO.

The thing that confuses me is that I had 3 150w modelling bulbs on in between shots and (as I have no where else to put the backdrop) I was in near a large french window so I dont think the ISO was metering in between flashes as even with no flash there's no way a 3200 would be needed.

Although thinking about it, maybe it would when taking into account the f16 or so and the minus figure that I dialled in.

What a silly mistake.. still you live and learn! Some of the grain looks great on the odd black and white image but the rest are ruined... Just a pain that it takes over an hour to get everything out and set up again, really wish I'd got it right the first time!

When I did set to approx f8 nd shutter 100th everything was massively over exposed, would this simply be a case of having the flashes turned up too high?

I'm thinking of investing in a light meter and then trying to learn a bit more about the flashes like what the 1/64, 1/32 etc on the intensity dial on the back refers to...

SO much to learn!
 
I would suggests setting to ISO 100 or 200, f8 and around 1/125 for exposure. Start with one light on the background, set to lowest power. Now, see how the background looks and how increasing the power from the flash affects the shot. Play with one light, then add another when you're comfortable. See how aperture affects the light independently of flash power. If you have too much stuff going on its impossible to learn. Just change 1 thing at a time and see the effect. I'm slowly learning but it's not easy, especially when you have more than 1 light to think about :)
 
You might want to take a quick look at my absolute beginners guide to off camera flash thread located HERE.
 
thanks so much guys. Just arrived home from hospital with our beautiful first baby so I expect it won't be long until I get the equipment out and use all of your fantastic advice!
 
tikigod19 said:
thanks so much guys. Just arrived home from hospital with our beautiful first baby so I expect it won't be long until I get the equipment out and use all of your fantastic advice!
Click to expand...

Congratulations, we have to have pics :thumbs:
 
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