Taping Hotshoe

Hi,

I am still shooting on film, using F80 housed in a Sea&Sea housing. I am limited to 125 shutter speed. I heard somewhere that you can tape on pin on the flash hot shoe connector on the camera, which will alllow you to go higher than 125 speed.

Any advice on how to do this ? Any draw backs ( i..e dont work or TTL de-activated ? )

Hi!

If the camera automatically switches to 1/125 while a strobe is connected this most probably has the following reason:

The shutter is limited to a max. sync speed of 1/125. If you set a higher speed the second curtain will start moving before the first reached the other side. Belwo tha max. sync speed, the whole image area is visible for some time during the exposure. The strobe has a chance to illuminate the whole area in one go. shutter speeds exceeding tha max. sync speed cause one part of the image area still or already covered by one of the shutter curtains. What you get is a dark band extending from one edge of the image. Which edge it is and teh size of the area depends on the direction of the shutter (horizontal, vertical) and at which position the strobe is fired (first or second curtain and ignition delay).

Horizontal shutters tend to sync below 1/125, vertical may do up to 1/250 because of the shorter distance from edge to edge.

Given this, it'll make only sense to go for shutter speed below the max. sync speed, in your sample 1/125.

You may experiment with taping and find out the functionality of the pins yourself.

Known connectors:

The frame is general signal ground.

The (larger) center pin fires the strobe.

Known functionality:

There's a Quench signal to stop the strobe in TTL

There's a Ready pin that tells the camera that the strobe is charged

There may be others to tell the camera details about the strobe.

You may find out the Quench as follows:

First, use either some old film or something of similar colour or rflection so the TTL sensors will get some reflection (you may waste real film material but it's not necessary). Put it across the shutter in place of the film. The naked black back plate may not reflect enough light for this test.

Tape one of the pins in question. Fire a shot with the strobe pointing far away from the camera. This should result in a full power flash. Do one pointing towards the lens (at about f:5.6). If this results in a full power flash you most probably taped the Quench. If the flash is very short and weak you didn't tape the Quench signal and TTL works well.

If you can't get a "Ready" reading in the viewfinder although the strobe is fully charged and ready to fire, you taped the Ready pin. This pin may cause to switch the camera to "strobe mode".

If your camera allows some custom setting like slow sync etc. (which is availabel with some cameras) you may forget all the above and use this setting to allow any shutter speed below max. sync.

Helge ;-)=)

The trick of taping up hotshoe connectors only works on digital cameras that do not have a mechanical shutter. The D70, for example, uses an electronic shutter and the camera imposes an artificial limit for flash synch at 1/500th. By taping the contacts you can exceed this value, although then you start to experience problems with the strobes not having enough time to fully discharge during the exposure!

Unfortunately all film cameras have to have a mechanical shutter!

Alex

Alex, Re "The D70, for example, uses an electronic shutter and the camera imposes an artificial limit for flash synch at 1/500th. "

As I understand the D70, it has a mechanical shutter good to 1/500 sec. and an electronic that extends this speed to 1/8000sec. when no strobe is attached. So when using an Ikelite manual slave for example, the D70 doesn't know there is a strobe attached and can go to 1/8000 sec. Taping the D70 hot shoe should be able to accomplish the same thing for direct connected non iTTL strobes. But I haven't tried this. I'm waiting for someone else to try it first.

Peter, I have done the equivalent to taping the contacts in my tests with the D70 already posted here (I actually got the camera not to recognise the strobe by turning the strobe off rather than by taping contacts - my subtronics still fire after they are turned off until the large capacitors are empty - but the effect is the same).

http://www.wetpixel.com/PNphpBB2-viewtopic...ic-t-6169.phtml

I suspect you are right about the mechanical/electronic switch in the D70 shutter for fast shutter speeds. I am hoping that the D2X will have a manual overide to swtich from mechanical to electronic shutter, but I suspect it will be mechanical throughout (unfortunately for us UW photographers).

Alex

Peter, I'm not sure how other housings might react to this but, with my Subal housing, if I insert the plug into the camera hot shoe and push it all the way in, it will only allow me shutter speeds up to 1/500. If I pull back slightly, there is an audible click, on the hot shoe plug then I will get the higher shutter speeds.

FWIW

Rand

That's a useful tip, Rand. I have never tried that. (So long as it cannot completely disconnect underwater inside the housing).

I suspect you are right about the mechanical/electronic switch in the D70 shutter for fast shutter speeds. I am hoping that the D2X will have a manual overide to swtich from mechanical to electronic shutter, but I suspect it will be mechanical throughout (unfortunately for us UW photographers).

 

Alex

An electronic shutter is possible because of the interline CCD design in the Sony sensors that goes in the D70 and not with the any CMOS design I've seen. You'll likely be subject to the limits of the mechanical shutter again.

That's a useful tip, Rand. I have never tried that.  (So long as it cannot completely disconnect underwater inside the housing).

It's still pretty secure, the adjustment backwards is very slight. I stumbled on it completely by accident. I was having trouble with the Low focus assist light coming on and slowing down the shutter response. While trying different settings, I'd inadvertantly not seated the connector fully forward and the light quit coming on, also noticed the increased shutter speed above 1/500 was possible too.

Just dumb luck.

Rand

thanks guys, will try it out, but it does not look too promising on film then !. Cheers