Banquet Photo with flashbulbs report.

[Neal Shields]

http://largeformatphotography.info/lfforum/topic/499876.html

In the above post I asked questions and got a lot of good answers about taking a banquet photo at our clubs Christmas dinner.

In a nut shell: I blew it. However, I learned a great deal, had fun, and will probably try again next year.


http://truckgenerator.com/subdomain/sueandneal/Banquit1200croped.jpg

What worked and what didn't:

The plan to trigger a 4x5 camera for the type 55 from the 8x10 shutter with a graflex solenoid, worked. Just bairly though. The batteries (two lantern batteries in series) would not fire the flash bulbs and the solenoid even with capacitors. I had to hook a battery charger up and then the batteries, charger and the caps would fire all seven bulbs and trigger the second camera.

I had one flash on the camera and strung 6 more out at about 15 foot intervals on the left side of the room. The bulbs were in parallel and there was probably about 80 feet of wire between the last bulb and the camera. Mostly they all fired. I had a few duds or bad contacts, don't know which..

I decided to cheat and get some light to the other side of the room by using a old studio strobe with a built in slave sensor. I was going to trigger a second strobe off that. Didn't work. The flash bulbs wouldn't trigger the strobe. I guess the ramp up and burn time is too long for the slave to recognize it as a flash.

What didn't work.

I got there two hours early and that just wasn't enough time. Also I had never used a view camera indoors and didn't completely antisipate how dark the ground glass would be. I had focusing targets to sit on the table but wasn't prepaired with enough lights to light them. So I missed the focus quite a bit.

I didn't check the shutter calibration on my 8x10 lens as I had intended. (I have a tester) But I figured, who ever saw an old mechanical shutter that was FAST at the slow speeds? Well I have now. Set at 1/25 which was necessary to use the X sinc with bulbs (didn't have an M sinc) my shutter is closer to 1/50!! That was enough to cost me several stops of burn time on the bulbs. Although the type 55 was close to perfectly exposed and the Tri X should have been (adjusting from 50asa to 320 asa) the 8x10 negatives were at least 5 stops underexposed. Even 15 minutes in D-76 wasn't enough to get a good negative.

Anyway thanks for everyone's help and if I get something next year, I'll let you know.

[Ralph Barker]

Well, this exposure looks pretty good, all things considered, Neal. Too bad about the 8x10, though. Glad you had fun with it. Bare-bulb Maglites make good focusing targets in the dark. Next year, you'll nail it for sure.

[Paul Coy]

Neal,

I was hoping that you would have success with your project as I have been wanting to do the same thing with bulb flash.

When you say that you wired 2 lantern batteries in series, that would be a total 12 volts, correct? I would think that using that much power with a capacitor would produce enough "umph" to fire both the solonoid and the bulbs. I was also under the impression that batteries in parallel was to be used with capacitors to fire a B-C circuit.
I guess I don't understand why extra batteries and capacitors could not fire your bulbs. I am wanting to do just that; use a large 6volt lantern battery to fire up to a max of 6 bulbs. If that doesn't work, then figure out how to make a battery -capacitor system as others have suggested in various forums.

Can you tell me more how you wire your flash system and why? Oh, and I have tried firing a slaved strobe from a flashbulb and your right, it doesn't work. To slow.

I think it's great that you tried using bulbs. They are a gas!!

[Neal Shields]

I wired the two lantern batteries in series to get 12 volts and then charged two large capacitors with them. I think that would have been more than enough except for the distances involved. I am sure I got a lot of current drop through the almost 100 feet of wire.

I was afraid to use much more than 12 volts because I was too lazy too look up what the max voltage on the solenod was.

However, one time I pluged the solenod into the wrong plug and put 12 volts to it continiously for over a minute and it didn't seem to hurt it.

Neal

[Frank Petronio]

What did the client say...?