Olympus-OM
[Top] [All Lists]

Re: [OM] Ponderings about Full Synchro Flash

Subject: Re: [OM] Ponderings about Full Synchro Flash
From: HI100@xxxxxxx
Date: Thu, 16 Dec 1999 14:24:10 EST
mail@xxxxxxxxxxxxxxxx writes:

<< Olympus used the technology from Minolta. Unfortunately, they stopped 
further
 developing it for OM after the F280 while Minolta continued. It made the 
Super FP
 5400HS flash with a Guide Number of no less than 54m,  >>

This sounds almost a physical impossibility, since to achieve a GN of 54m  
for normal flash requires an energy for a single short duration flash of 
around 100J. In FP mode you need to have many flashes something like 20-30 so 
since the energy available is what you can store in a capacitor at the start 
of the flash the energy per flash drops proportionately giving you very low 
GN's. To achieve a GN of 54m and provide say 20 flashes for the FP duration 
would require you to store over 2000J. This is the territory of the very 
largest studio flashes with line operation.  My guess is the Minolta flash 
achieves the 54m GN in normal flash mode and is significantly lower in FP 
mode. 

Interestingly Olympus does have a patent or two on FP technology but probably 
not the primary patent. 

A common question on this list is what reflectivity is used for simulating 
film reflectivity  on the shutter curtain and often people say that it is the 
same as an 18 0rey card. One of the Minolta patents on regular OTF metereing 
(US patent 3687026), specifies that a value of 26.7 hould be used. 

Regards,
Tim Hughes
Hi100@xxxxxxx

< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >


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