using flashmeter for bulbs

[Ian Gordon Bilson]

Of the various f/meters I have used,only one -Gossen Profi-flash,had a fixed "gate speed",at 1/125s.
But, I intend to test my Sekonic 408 now.
Thanks for the headsup.

[Jac@stafford.net]

The Sekonics made since at least the model L-308S can read flashbulbs in daylight. Be certain to use cord-mode and choose the correct shutter speed on the shutter, then set that shutter speed on the meter. Use M synch, of course. Not using cord-mode can lead to a complete failure of the meter to read because bulbs have a less profound onset than electronic flash, so that gross overexposure is likely - only the ambient will be measured.

[Jody_S]

The meter willl not help. Use the guide number that should be on the bulb package. We used these for decades prior to the advent of electronic flash.

If you want to know if your meter is working then, why not try it and compare the reading to the tables on the back of the flashbulb package? Or use a dSLR on 1/15 - 1/30 or so, to make sure it's reading the entire flash duration. For that matter, if your shutter doesn't have an 'M' mode, a few tests with a dSLR will also tell you your minimum shutter speed that will capture the flash output. It shouldn't take that many flashbulbs to test to get a baseline of how you need to meter before you start with the 8x10 sheet film.

[DrTang]

Okay - here is the deal

I have several barrel lenses that I was planning on shooting with my top rangefinder speed graphic -
on the side on the back of the camera is a fitting for a special flash cord that goes to a bulb flash reflector deal


what I want is..to use barrel lenses on my speed graphic... somehow synched to the back FPS ... and measure the bulb output with my minolta flashmeter III

I will probably be wanting to have the handle mount flash bulb deal with reflector aimed into a umbrella off camera


I don't want guide numbers..I don't have a shutter other than the built in FPS (which has a synch out so apparently it was made to work at some speed and with some bulbs)


am I living in a fools paradise?

[Jac@stafford.net]

I have several barrel lenses that I was planning on shooting with my top rangefinder speed graphic -
on the side on the back of the camera is a fitting for a special flash cord that goes to a bulb flash reflector deal

The cord you need is part #A20.

To fire flashbulbs with the focal plane shutter of a Speed Graphic you can use any flashbulb with a Time setting (position O). The unhappy news is that to use any setting other than Time, you need flashbulbs #31 or Superflash #2A . Shoot these at with focal plane duration of 1/1000 or 1/250 second but not 1/500. Yes, it's not intuitive.

I leave it to the reader to find equivalents to those two bulbs. Perhaps from Megaflash.

[DrTang]

The cord you need is part #A20.

To fire flashbulbs with the focal plane shutter of a Speed Graphic you can use any flashbulb with a Time setting (position O). The unhappy news is that to use any setting other than Time, you need flashbulbs #31 or Superflash #2A . Shoot these at with focal plane duration of 1/1000 or 1/250 second but not 1/500. Yes, it's not intuitive.

I leave it to the reader to find equivalents to those two bulbs. Perhaps from Megaflash.

whelp - that tears it

too much expense & trouble - I'll need to stick my barrel lenses into shutters with x synch then


thanks for the info

[Jac@stafford.net]

If it helps at all, it is not difficult to modify a Packard shutter to trip any flash when the blades reach wide-open.

I made a box that sits on a lensboard with a universal lens holder. The holder is large enough to accommodate lenses up to 3.5" diameter, and the shutter up to about 4.5".

EDIT: Forgive. I just found your post mentioning that you made a synchronizing Packard recently.
http://www.largeformatphotography.in...ckard-shutters

[Brassai]

There are special bulbs available for focal plane shutters--they have "FP" after their size. I've used a couple with my Leica IIIf. If I remember right, they are designed to have a longer burn time so they will stay lit as the slit in the shutter moves around.

[Jac@stafford.net]

There are special bulbs available for focal plane shutters--they have "FP" after their size. I've used a couple with my Leica IIIf.

True, in part. Not all focal plane shutters work alike.

[Jim Jones]

There are special bulbs available for focal plane shutters--they have "FP" after their size. . . .

The FP-26 flash bulb reaches its peak output about 12ms after the sync contacts close, and declines to half-power at about 40ms. This seems too fast for a large format shutter. The larger type 2A reaches maximum output at about 18ms, and maintains much of this output to about 70ms.