Posted by Daryl George on December 29, 2000 at 06:51:32:
In Reply to: Re: flash advice posted by Les on December 27, 2000 at 16:01:01:
: Jon,
: Anything you get will work with the lens, however because
you've moved up to 4x5, to get good depth of field and sharpness,
you need to shoot around f11 to f16 for interiors, f8 for headshots
and the like. This means the little flash off of your 35mm
: doesn't have enough umph.
: The two flashes I use with my Crown Special (which is what you have) is a Metz 60 CT1 and a Norman 400B.
: The Metz is thyristor controled and its helpful. The Norman is straight manual but has one stop more output than the Metz.
: The Guide numbers for the Metz is 197 with 100 speed film. To give you a comparason, a No 5 flash bulb has a guide number of 320 for 100 speed film.
: Both of these have a shoulder pack to contend with and the Norman pack is quite heavy. Norman also makes a 200C which has the same output as the Metz and is still all manual and much lighter.
: When I was researching Norman, most of the repair and used equipment guys said to pay the extra money and get the 200C, not the 200B. Another caveat is if you are buying used, particularly the Metz, get the serial number and check with Bogen about repair. A lot are grey market and you'll have to send them to Germany if they need repair.
: I paid $200 for the Metz, 4 times that for the Norman. Sunpak also makes large flash units but I've never used them.
The guide number for a #5 flash bulb is much lower than 320 for ISO 100 film (assuming the shutter speed is accurate.) Data sheets from Kodak and the flash bulb manufacturers from the 70s list a guide number around 160 when using a polished 5" reflector. My experience tends to confirm this.
Back in the 50s, the film manufacturers were listing film speeds exactly half of those currently used today. I have data sheets for Plus X and Tri X from 1953 indicating tungsten speeds of 40 and 160, respectively. Given the type of metering available at the time, this provided a generous safety margin. However, it causes a lot of confusion when using the exposure tables printed on flash bulb cartons from that era.
The Metz 60 CT1 with a guide number of 197 would be a very close approximation of the Graflite with 5" reflector and a #5 bulb.