Sense check for a black background with the RB

steveo_mcg

steveo_mcg

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Steven
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I'm trying to take a photo with a "fake" black background with just the flash and separation from the back ground.

According to my shiny new flash meter my settings at the subject are F4 1/500 and at the back wall f0.5. My gut says that a ~6 stop difference should render the background black but I thought I'd garner opinions.

The reason asking and not just trying is I'm too cheap to waste a roll of quite rare film and the kids likely won't behave twice. I've tried it with my D3100 and I still get some relatively well lit background though I can't remember what my settings are for that, this is spill from the flash/umbrella not ambient and I've no other modifiers so I think I'm stuck there.

I'm planning to use Pan 25 in the RB for the shot so I've got another 2 stops of sync speed on and 2 in the film stock over the DSLR and I wonder if that will do it if not I guess I'll need to look at a backdrop or a modifier of some description.
 
My limited experience tells me it's darn near impossible with an umbrella.

When I want a black BG I use a large softbox. If you're stuck with an umbrella I think you'll need more like f11 with the brolly very close to subject and a long way from BG.
 
Yeah I was afraid of that. I've got the umbrella a few cm from the subject and the room is a few m long. According to the meter this should be okay but I expect you're right.

Now do I splash out on a softbox or do I wait for a calm overcast day and try it in the garden...
 
If it's spill causing the background light bleed i'd be taping some card gobo's (go-betweens) onto the edge of the umbrella to block it.
 
Alternatively, if you're going to the Megameet I'm happy to bring down my 40ish cm popup softbox for you to borrow?
 
stevelmx5 said:
If it's spill causing the background light bleed i'd be taping some card gobo's (go-betweens) onto the edge of the umbrella to block it.
Click to expand...

Can you show me an example, I'm not sure how this would work... well not with out permanently ruining the umbrella.

stevelmx5 said:
Alternatively, if you're going to the Megameet I'm happy to bring down my 40ish cm popup softbox for you to borrow?
Click to expand...
Thanks for the offer but tragically I can't get down for it.
 
I always recommend David Hobby (Strobist) for lighting advice. I've just found this post and whilst it's talking about a gobo on a speedlight the principle is the same (but you may need more tape to hold it onto a brolly!)

http://strobist.blogspot.co.uk/2006/03/lighting-101-cereal-box-snoots-and.html

The only question I'd have is if the background is a few meters away, which way is the brolly facing? Is it in front of your subject facing towards the background? As Simon said above, you may be better closing down the aperture more to kill any background light and moving the brolly in closer.
 
stevelmx5 said:
I always recommend David Hobby (Strobist) for lighting advice. I've just found this post and whilst it's talking about a gobo on a speedlight the principle is the same (but you may need more tape to hold it onto a brolly!)

http://strobist.blogspot.co.uk/2006/03/lighting-101-cereal-box-snoots-and.html

The only question I'd have is if the background is a few meters away, which way is the brolly facing? Is it in front of your subject facing towards the background? As Simon said above, you may be better closing down the aperture more to kill any background light and moving the brolly in closer.
Click to expand...


Cheers Steve get you now, not sure how that would work on a brolly though. But I might try with out. I've read the strobist stuff before, ages ago but its sometimes difficult to reconcile the the blast a few dozen test shots to dial in approach with the more methodical approach "we" need to take, especially with the bigger cameras.

Brolly is above and slightly to one side of the subject and facing the back wall the subject has their back to the wall. On the DSLR the "correct" settings are something of the order of F8 and 1/160, F11 nearly gets me there and upping the blacks in the LR might get the job done but the subject is a little underexposed. I can't move the brolly any closer, its nearly on the subjects head! :).

Theoretically, with the lower ISO and faster sync speed the RB should do the job but I'm not sure.
 
LMAO..... It means, turning the light & brolly away from the background so you get no spill. No tar needed lol. Best bet is to YouTube it as there are many demos on this

Hope that helps
 
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