[rollei_list] Re: Rollei Flash

  • From: ERoustom <eroustom@xxxxxxxxxxx>
  • To: rollei_list@xxxxxxxxxxxxx
  • Date: Thu, 10 Jan 2008 09:02:24 -0500

Thanks Richard. Do these guide numbers relate at all to those given to electronic flashes?


Elias

On Jan 10, 2008, at 12:17 AM, Richard Knoppow wrote:


----- Original Message ----- From: "ERoustom" <eroustom@xxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Wednesday, January 09, 2008 6:32 PM
Subject: [rollei_list] Re: Rollei Flash


Miscellaneous package of bulbs. Some say P25 on the top, the others
just say GE. Some are blue, some are clear.
No guide numbers anywhere. Are bulbs still made?

E.
The bulbs with P25 on top a Wabash/Sylvania Press-25 types. If the GE bulbs are the same size they are General Electric Syncro- Flash No.5 bulbs. The two are nearly identical. Both came in both clear and blue types. Blue is for color using daylight film and have a color temperature of approximately 5000kelvins. Guide numbers depend on the size of the reflector and shutter speed. For the relatively small reflector of the Rolleiflash, a film of ISO-100, and a shutter speed of 1/100th the guide number for the clear bulb will be about 250 and about 200 for the blue coated lamps. The largest flashbulbs were the GE No.50 and Sylvania/Wabash No. 3 with light output of 140,000 lumen seconds. These bulbs were meant to be used in full sized photoflood reflectors. With open flash in a 12" reflector the guide number for ISO-100 film is about 800.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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