[LargeFormat] Re: rainbows, was R O Y G B I V

[Dave Mueller]

A polarizer will help a great deal.  In fact, it will sometimes allow 
you to see a rainbow that you normally wouldn't see.  We have a fountain 
in Pittsburgh, you can get a rainbow in the mist almost anytime the Sun 
is behind the fountain simply by using a polarizer.  The colors should 
not shift in a rainbow, since you're actually photographing the light 
itself, not a reflection from some material like the bluebells.  A lot 
of flowers shift colors because of UV and IR reflections that the film 
does (or doesn't) record.  A slow shutter speed will allow a more 
"solid" rainbow since it will allow more empty space to be filled in by 
water droplets (same concept as using a slow shutter speed for 
waterfalls etc).

Dave

philip lambert wrote:

>I probably used an exposure of about 1/250 for the shot of the rainbow that
>disappointed.  The rainbow lasted five minutes, maybe less. I can't see how
>a shorter shutter speed would achieve an improvement. The problem probably
>lies in the way the film emulsion sees the light which is different to the
>way the eye sees it.  I see bluebells as blue but all too often the photo
>shows a reddish blue and it would take some work on the computer to fix it.
>Maybe a digital camera would be capable of a realistic rendering in
>experienced hands. Philip
>----- Original Message ----- 
>From: "john frost" <johnfrost@sprintmail.com>
>To: <largeformat@f32.net>
>Sent: Friday, December 12, 2003 12:45 AM
>Subject: Re: [LargeFormat] Re: rainbows, was R O Y G B I V
>
>
>  
>
>>As with cars, people, and aircraft, their motion through the frame may
>>be fast enough to NOT be recorded, if using a slow shutter speed. If you
>>want to capture the reflection (or refraction)of a drop (or molecule) of
>>water, a faster shutter speed is needed.
>>
>>john (:>)))
>>
>>Alan Davenport wrote:
>>    
>>
>>>At 11:47 AM 12/11/2003, you wrote:
>>>
>>>      
>>>
>>>>A slow shutter speed allows the water molecules to run away (turn),
>>>>thereby loosing their contribution to the color.
>>>>        
>>>>
>>>Are you serious? Hmmm.  My understanding of the physics of rainbows, is
>>>that the bow is produced by internal reflections and refraction through
>>>water droplets, i.e., rain.  I doubt if the fastest shutter could keep
>>>up with motion at the molecular level...
>>>
>>>
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