Crown Graphic flash woes.

[robert_macdonald]

I recently picked up a Crown Graphic. This is my first 4X5 camera.

Anyone who has used one of these knows they're not hard to use. My

problem is with the flash. I have it set to its proper X setting and

am using 1/50th of a second as my exposure at ususally f8. My film

was HP5. The negs I developed with a flash were very thin, while ones

I shot sans flash were fine. I tried the ground glass and saw the

flash through it when I fired the shutter. The negatives I shot today

using FP4 had the same problem, but were a little better, but not

much. Any advice?

[glenn_thoreson]

Which shutter do you have? What kind of flash are you using? It sounds like either your flash is not powerful enough, or you are having a sync problem.

[dryfly]

Assuming that you are not trying to illuminate something very far away (which won't work), you should only have the sync at "x" for electronic flash. If you are using flashbulbs like a real Graphic user should, try setting the shutter on F or M depending on the bulb. Bulbs take longer to build up to full light output than electronic flashes, and the shutter is probably closing before peak light so you can see some effect, but not the full output.

[silent1]

Also, with nearly any bulb (not counting the very slow burning FP type), you'll get about one stop more exposure at 1/25 or 1/30 than you will at 1/50; the bulb has a burn time of between 1/40 and 1/30; 1/30 with M sync (starts the bulb as the shutter starts to open) will catch almost 100% of the bulb's light, while X synch (fires the flash at peak opening) at 1/50 will catch less than half -- maybe a lot less than half, depending on the bulb's ignition curve.

 

Now, if you're using electronic flash, it might be that your synch is firing as M when you think it's X -- if this is your situation, try holding the cocking lever when you release, and then let it travel very slowly, looking for how big the shutter opening is when the flash fires. It will be either barely open (M synch) or very close to 100% (X synch). If barely open, your shutter is acting like a stopped-down aperture and underexposing (since the flash only lasts a millisecond, the shutter doesn't have time to open significantly during the flash duration).

[darin_cozine]

If you are using electronic flash and it is firing when you trip the shutter, then you most likely have a metering problem. Are you using the flash in auto mode or are you using a flash meter?

[robert_macdonald]

Im using a Vivitar 215 auto. I am usually around six feet away from my subjects. I'm thinking that I need to move down to 1/25 or open up another stop. It could be the flash isn't powerful enough, but I figure at six feet it should be able to do the trick. The shutter is a Synchro Compur on a 127mm f4.7 Ektar lens. I probably just need to experiment with it more. Thanks for your imput thus far.

[dan_fromm2]

So you're using a little automatic flash. What is its full power ISO 100 Guide Number? Are you running it on manual or automatic? If automatic, which f/stop have you asked it for?

[robert_macdonald]

I'm running the flash in automatic. I set the guide to 100 where it indicates 7 feet at f8. Tonight I tested some more. I went down to 1/25 at f8. It was a little better, I think If I open up one more stop I'll have it.

[dan_fromm2]

The slower the shutter speed, the more exposure you get from ambient. Sounds like your flash is not putting out as much light as you think.

[silent1]

This still sounds to me as if the flash is firing too early (or late) in the shutter's cycle; the slower speed setting may be masking the problem by allowing the shutter to be more open (but still not fully so) when the flash fires (or, as others suggest, simply allowing more ambient light exposure). Try dismounting the lens and viewing a white background through it, which will be illuminated by the flash when fired; fire, and try to fix in your mind the size of the aperture you see in the lens by the flash; compare that to the f/8 opening you see by ambient light. Same? Smaller? If smaller, it's a flash timing issue; you may have a synch leaf that's bent (or incorrectly bent), causing the flash to fire too early or too late.

 

A shutter with 1/50 and 1/25 is an older one -- is the synch an aftermarket upgrade? Hmmm. Wouldn't think so with X and M selections. Correcting flash timing isn't easy to do, but S. K. Grimes company can surely do the job, and it's likely other shutter repairers like Carol Flutot can handle it as well. I wouldn't hesitate to try it myself, but I wouldn't have more than $20 or so into a lens and shutter in the first place (and in fact none of my large format gear has synch at all).

[thirteenthumbs]

I use a test method simular to Donald's but fire the shutter with the aperture wide open and if any shutter balde is present in the opening when the flash fires the timing is off.

[robert_macdonald]

Well I switched flashes, the result was great! The flash was a Sunpak Auto 2000 DZ. I did up some contact sheets tonight and was quite pleased with the results. Thanks for your help guys.