Olympus-OM
[Top] [All Lists]

Re: [OM] Be careful where you sit...

Subject: Re: [OM] Be careful where you sit...
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Sat, 03 Jan 2009 22:49:02 -0500
Are you sure?  I'm not.  Try measuring a light in your house with your 
light meter.  First from 1 meter, then from 1.4 meters, then from 2 
meters.  Bet you find a 1 stop drop in each measurement.

Dr. Incandescent


C.H.Ling wrote:
> Sorry, I don't understand, if you have not use flash, your shooting positing 
> should not affect the exposure value. The only posssibility is the stage 
> lighting has power reduced.
> 
> C.H.Ling
> 
> ----- Original Message ----- 
> From: "Chuck Norcutt" <chucknorcutt@xxxxxxxxxxxxxxxx>
> 
>> ... in the auditorium that is.  Some of you may recall this series of
>> shots from my grandaughters' dance recital in 2007.
>> <http://www.chucknorcutt.com/dance_recital_2007/index.htm>
>>
>> There was a similar recital in 2008 but I didn't like any of the shots
>> and hadn't processed them at all.  Actually, "didn't like them" is a
>> serious understatement.  Motion blur was everywhere due to low light
>> levels and very slow shutter speeds.  Finally my oldest granddaughter
>> bugged me to prepare some 33 images for her where she either appeared in
>> them or she liked them for other reasons.  Those can be seen here:
>> <http://www.chucknorcutt.com/dance_recital_2008/index.htm>
>>
>> In going through them I became even more painfully aware of the
>> difference in light level between the two events but couldn't figure out
>> why it should be.  In 2007 I had set the camera at ISO 3200, shutter
>> speed at 1/160 (for a 28-80/2.8 lens) and ended up shooting most images
>> at from f/4 to f/5.6.  In 2008 I tried the same thing but quickly found
>> that I couldn't maintain 1/160 shutter speed.  I was shooting at either
>> f/2.8 or f/3.2 and at 1/80 or 1/60 second or even much slower.  With
>> fast moving dancers it was very difficult.  I found myself trying to
>> anticipate when the dancers would be be coming to a halt in order to
>> reverse direction but not always very successful at all.
>>
>> Finally I extracted the EXIF data from all the photos from both years.
>> I averaged the shutter speeds and apertures from all the images and
>> found that there was approximately 1-2/3 stops difference between them.
>>   I also noticed that in the 2008 series that I had (very soon in the
>> shooting) accidentally set a -1/3 stop exposure compensation level by
>> brushing that silly big dial on the back of the Canyons because I hadn't
>> locked the settings.
>>
>> The next question was: Why would there be such a great difference in
>> illumination level?  Certainly the light level varies from scene to
>> scene on the stage but for the overall performance to have much dimmer
>> stage lighting didn't seem to make sense.  I queried Dr. Flash on the
>> subject who reminded me that all light (not just flash light) falls off
>> in proportion to the square of the distance.  "I know", says me "but I'm
>> pretty sure I was sitting about where I was the previous year".  "Prove
>> it" he says.
>>
>> I asked my wife where she thought we were sitting in 2008 relative to
>> 2007.  "I think maybe 3 rows further back" she says.  That squared with
>> my impressions as well.  So I dragged out a couple images from both
>> years, both shot at 80mm and compared the image height of people at
>> center stage.  Knowing their approximate height allowed me to estimate
>> that the center of the stage in 2007 was about 40 feet away from us.
>> But the center of the stage in 2008 was about 65 feet away. Well, that
>> was a big surprise.  25 feet was a lot more than 3 rows back.  In fact,
>> that's about 1-1/3 stops.  Close enough to tell me that my gross
>> estimates of exposure and distance were close enough to explain the
>> cause of the problem.
>>
>> So, when you take your camera into the auditorium sit as close as you
>> can to the stage.  Just like flash, seemingly small changes in distance
>> can have a major effect on the amount of light you have to work with.
>> In my case it went from pretty good to awful by moving back 25 feet.
>>
>> Chuck Norcutt
>> (with assistance from Dr. Flash)
>> -- 
>> _________________________________________________________________
>> Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
>> Archives: http://lists.thomasclausen.net/mailman/private/olympus/
>> Themed Olympus Photo Exhibition: http://www.tope.nl/
>>
>>
> 
-- 
_________________________________________________________________
Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
Archives: http://lists.thomasclausen.net/mailman/private/olympus/
Themed Olympus Photo Exhibition: http://www.tope.nl/

<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz