Archived posting to the Leica Users Group, 2003/03/24

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Subject: Re: [Leica] perplexing question using studio strobes
From: Mark Rabiner <mark@rabinergroup.com>
Date: Mon, 24 Mar 2003 16:02:56 -0800
References: <a0106000d-1024-A78D9D1C5E1911D79C89003065C7DF66@[10.0.1.2]>

Adam Bridge wrote:
> 
> Let's see if I can explain this well enough.
> 
> I was asked to shoot a few publicity stills for two women starting their own
> exercise salon. The ladies wanted to pose against a white background so they
> could easily photoshop the background away and plug the images into their
> brochure.
> 
> So I said I'd shoot this. I have a set of those trusty portable strobes with
> diffuser boxes on them and a flash meter.
> 
> I used Ektachrome 100.
> 
> I also took my D30 to use as a "polaroid" checking lighting with the histogram
> function, looking at shadows etc. (It works great, the only better thing would
> be to run the camera to a monitor.)
> 
> After I finished the shoot and had the film processed I saw a gradual "creep"
> toward the blue in the background. Some of this was my fault. As we played with
> different poses I didn't enforce the discipline of checking the lighting values
> each time. But even when I did, especially for the portraits at the end, there
> was still this blue shift in the background.
> 
> There were windows but the day was mostly overcast and the room was not brightly
> lite by daylight.
> 
> Could this be a shift in the strobes? Does under exposing Ektachrome move the
> color balance to the blue?
> 
> Thanks for any thoughts.
> 
> Adam Bridge
> --

You set the backdrop up outside or by open windows?
As the light during the day changes id does not perhaps make a
significant change in the exposure you're subject gets if you use a
higher sync speed. (Which means you're not using a Leica M!)

What WILL change is the color temperature as the sky gets bluer.

Ah i see there were windows well that's my vote for the culprit The seem
innocuous but they ain't. It's that seemingly innocuous little variable
and poof. Mine are boarded over.

Someone may say it could have been the strobes getting bluer and i wont
argue as I'm not an electronics expert i just know in 20 years using
Balcars with a White Lightning thrown in its not happened to me at the
end of a bulbs life.

Even if you were using a Hasselblad and your sync speed was 1/500 this
would be an issue. Location Catalog shooter are very aware of this. But
By now I bet don't care it gets fixed in Photoshop.


Mark Rabiner
Portland, Oregon USA
http://www.rabinergroup.com
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In reply to: Message from Adam Bridge <abridge@mac.com> ([Leica] perplexing question using studio strobes)