Forums > Photography Talk > Power Level knob" for Hotshoe Flash?

Photographer

Silverlight Images

Posts: 584

San Antonio, Texas, US

I have several promaster flashes that either go Full power or 1/16, but I'd love to have more range, ie a  power knob does anyone know of any way this could be done?

I could have sworn I saw a tutorial years back!

Jul 11 13 02:30 pm Link

Photographer

Zack Zoll

Posts: 2621

Glens Falls, New York, US

Silverlight Images wrote:
I have several promaster flashes that either go Full power or 1/16, but I'd love to have more range, ie a  power knob does anyone know of any way this could be done?

I could have sworn I saw a tutorial years back!

The good news is, it's very easy to do that from an electrical design standpoint.  The flash runs off of a capacitor(not the batteries), and it simply discharges a certain amount of power when you fire.  Putting a variable resistor in the middle of that circuit is pretty easy; the flash still drains as much power as a full power shot, the recycle time is the same, but only 1/2 or 1/4 of the power goes to the flash tube.

The bad news is, the flash is built with a compact circuit board(as opposed to much more expensive, point-to-point hand wiring), and fiddling with it could very easily damage the unit beyond repair.  Plus the layout of the board may mean that the only way to put in the variable resistor is to remove other important components ... and on a printed board, it's incredibly difficult to tell which components are essential to operation, and which only serve certain functions, like metering.

Considering the money you'd waste on replacing the flash several times over, I'd just buy a new one.  Nikon's SB-24 is my favourite off-camera flash:  it doesn't go below 1/16th power, but it has all the stops up the that point, it's reasonably powerful, has an acceptable recycle time, a PC sync port, and can usually be purchased used very cheaply.  It's an older model though, so I'd do some research before trying to fire it from your hotshoe.

Jul 11 13 06:16 pm Link

Photographer

ChangingFaces

Posts: 197

Dallas, Texas, US

Jul 11 13 06:33 pm Link

Photographer

JTCrosby

Posts: 114

Richmond, Virginia, US

Not a change in the flash but if you need to lower the output they do make ND gels. I personally have not used the ND gels only color gels but I do know several manufacturers make them and it would seem to be a cheap easy way to lower output on the speedlight.

Jul 11 13 07:31 pm Link

Photographer

Silverlight Images

Posts: 584

San Antonio, Texas, US

Zack Zoll wrote:

The good news is, it's very easy to do that from an electrical design standpoint.  The flash runs off of a capacitor(not the batteries), and it simply discharges a certain amount of power when you fire.  Putting a variable resistor in the middle of that circuit is pretty easy; the flash still drains as much power as a full power shot, the recycle time is the same, but only 1/2 or 1/4 of the power goes to the flash tube.

The bad news is, the flash is built with a compact circuit board(as opposed to much more expensive, point-to-point hand wiring), and fiddling with it could very easily damage the unit beyond repair.  Plus the layout of the board may mean that the only way to put in the variable resistor is to remove other important components ... and on a printed board, it's incredibly difficult to tell which components are essential to operation, and which only serve certain functions, like metering.

Considering the money you'd waste on replacing the flash several times over, I'd just buy a new one.  Nikon's SB-24 is my favourite off-camera flash:  it doesn't go below 1/16th power, but it has all the stops up the that point, it's reasonably powerful, has an acceptable recycle time, a PC sync port, and can usually be purchased used very cheaply.  It's an older model though, so I'd do some research before trying to fire it from your hotshoe.

Thanks Zack! The ones I have are fairly disposable but the Nikon sounds interesting I'll check it out.

Jul 11 13 08:04 pm Link

Photographer

Silverlight Images

Posts: 584

San Antonio, Texas, US

ChangingFaces wrote:
A Vivitar 285 has this option http://m.adorama.com/newui/search.aspx? … 13139046h2

Oh yeah! I have one that works pretty well (though I forgot it has that option as mine got damaged.

Jul 11 13 08:06 pm Link

Photographer

Silverlight Images

Posts: 584

San Antonio, Texas, US

JTCrosby wrote:
Not a change in the flash but if you need to lower the output they do make ND gels. I personally have not used the ND gels only color gels but I do know several manufacturers make them and it would seem to be a cheap easy way to lower output on the speedlight.

A good option, I'd probably need to get a gel holder since I can never get the colors on/off that easily.

Thanks for the input guys!!

Jul 11 13 08:08 pm Link

Photographer

Dream-foto

Posts: 4361

Chico, California, US

ChangingFaces wrote:
A Vivitar 285 has this option http://m.adorama.com/newui/search.aspx? … 13139046h2

Which is nothing more than replacing the cds (sensor) with a 100K ohm potentiometer


http://phoduct.wordpress.com/2012/03/13 … fications/

You could do much the same for any flash with an auto circuit.

Jul 11 13 09:04 pm Link

Photographer

SKITA Studios

Posts: 1566

Boston, Massachusetts, US

Not sure if your Promasters support the quench pin, but if they do, look at the Radiopopper JrX Studio triggers.  You need a Nikon or Canon RPCube but they work fairly well and you get to control your knobs at your camera instead of off-cam flash...

Jul 12 13 06:55 am Link

Photographer

Mikey McMichaels

Posts: 2311

New York, New York, US

ND gels on top of a Sto-Fen work. If you don't want the omni, you can tape them in place.

Jul 12 13 05:20 pm Link

Photographer

Silverlight Images

Posts: 584

San Antonio, Texas, US

Great ideas! ... sounds like I'm gonna have a busy weekend!

Jul 12 13 08:01 pm Link