Help with Flashbulbs and my Graflex please?

[EASmithV]

Ok, here's "The Situation"

I have a Pacemaker Speed, a 152mm Ektar in a Supermatic (X) Shutter, a Graflex Synchronizer flash with a household to bi-post adapter, and 100 P25 flashbulbs.

Now, the cleanest solution would just be to hook the flash up the the shutter and be done with it. However, the shutter is an X sync, so it won't work with flashbulbs?

That's fine. I can hook the flash unit up to my focal plane shutter, right?

Okay. Assuming I can get it properly firing, what am I going to need to do in terms of exposure?

For instance, using a 400 speed film, at 10 feet my exposure would be f_?

15 feet? 20 feet?

[EASmithV]

For the sake of experimentation, I popped one off at 10 feet ISO 400 and my flash meter read f8

[Steve Smith]

Probably easiest to use guide numbers for the flash bulbs if you can find that data.

Working it out backwards from your figures gives a guide number of forty feet (12 metres) at ISO 100.

Aperture = guide No. divided by distance so in this case, 40/10 = f4 for ISO 100 (or f5.6 for ISO 200 and f8 for ISO 400).


Steve.

[Jim Jones]

The X-sync contacts close as soon as the shutter reaches its maximum opening. The light from a flash bulb takes several milliseconds to reach full intensity. If the shutter speed is set slow enough, the shutter will be open long enough to capture all the light from the flash. For a Press 25 bulb, this is about 1/30 second.

[snederhiser]

Hello;
The shutter on the the Graflex is not made for flashbulbs, strobe only! The reason for X-sync. To make this work you need a solenoid that mounts to the lensboard with a mechanical link to fire the shutter. A two prong cord connects this to the 3 cell flash gun. When you press the red button on the flash, the bulb fires 30 milliseconds before the shutter opens. Flash bulbs use a guide number that is located on the packaging. Distance divided into the guide number gives the f/stop. Guide number for 25b flashbulbs, m sync, 1/50 shutter speed, 400asa film, is 360. At 12ft this would be f/32. Do some research on the web, Steven.

[BrianShaw]

1. As others have said, you can't use flash bulbs and X synch.
2. Can't use use 25/5 bulbs (M) with focal plane shutter - you'd need F bulbs.
3. If you have a solenoid tripping your shutter (and its properly adjusted) you can do what you want to do.

Do you have solenoid tripping your shutter?

[Steve Smith]

As others have said, you can't use flash bulbs and X synch.

I'm sure you can with a slow enough shutter speed.


Steve.

[BrianShaw]

I'm sure you can with a slow enough shutter speed.

Steve... maybe, but we are advising a guy who doesn't know how to make even the "normal situation" work so why quibble details of "what if" or more specialized techniques? BTW, even with the slowest FP shutter speed (meaning using any slit shutter opening greater than "O"), there probably would be differences across the frame.

[BrianShaw]

p.s. OP, if my comment above comes off as offensive please forgive me... I have no intention of offending you and every intention of helping you. Shooting Speeders with bulbs is awesome!

[Sirius Glass]

The lens shutter needs to be on M synch and use 5, 5B, 25, 25B bulbs.

The rear shutter is limited to 1/250 and 1/500 with 2A bulbs.

See http://www.jolommen.nl/, on the left select "the World of Graflex, the at the bottom look at "Flashing", "Flashguns", "Bulbs"

Steve