I have no EE experience nor led construction. I suppose the phosphors like yAG
( to add yellow) are glommed onto the top of a standard high efficiency blue
led to extend the spectrum. Even adding another phosphor still results in a
discontinuous emission spectrum which can confound proper color balance on film
or digi sensors.
Mike
On Jan 5, 2015, at 10:05 PM, Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
wrote:
> Dr. Flash asks: What are compensating phosphors? Not the definition but
> describe the physical hardware.
>
> Dr. Flash
>
>
> On 1/5/2015 7:13 PM, Mike Gordon via olympus wrote:
>> Dr. No Flash fan writes:
>>
>> <<I am likely no never buy another flash, but will transition
>> <<to LED panels instead.
>>
>>
>> tungsten on left, "white" LED with compensating phoshors on right.
>>
>> http://www.screenlightandgrip.com/images/generators/LED_Model_Comp.jpg
>>
>> Loss of cyan balls up the dress rendition.
>>
>> http://www.screenlightandgrip.com/images/generators/LED_Effect_on_Skin_Color.jpg
>>
>>
>> Skin renditon upset by steep drop off in long wavelength light---if the
>> color is not in the light it can't be reflected at all. This can make
>> it very difficult to fix in post even shooting a target.
>>
>> I don't know how long it takes the phosphor light to decay but suspect
>> dramatically longer than usual strobe thus no help stopping motion
>> for macro flash with critters. If using continuous LED light though, no
>> worry about sych speed and can bump up shutter speed to a degree.
>>
>> Bottom line--unless the phoshors have improved (perhaps they have) not
>> sold on LED. Suspect the manufacturers just might be spinning the
>> data on the LED panels. I bet Tim knows the scoop on this.
>>
>> Student of Dr. Flash, Mike
>>
>>
--
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