High speed flash synch

While on the subject of flash I tried some interesting experiments with my D100 on my recent trip to Cayman (where downloaded and brought home over 2500 Raw files - lots of pleasing stuff too).

Anyway, as most people now know - to make the D100 fire manual strobes you only connection 2 of the 5 wires in the hotshoe. This way the camera doesn't know that there is a strobe attached but will still send the trigger voltage and fire it. So what we all do is shoot in Manual or Shutter priority mode so we can keep the shutter speed in the flash synch range.

However, because the camera doesn't know there is a flash attached you can increase the shutter speed and see the result of exceeding the synch speed - you don't get flash at the very bottom of the frame because the shutter was covering this bit at the time the flash fired.

So I decided I could use this creatively to let me do fast flash synch. So long as your subject doesn't cover the very bottom of the frame (on a horizontal) you can really increase your shutter speed above the synch speed and still completely light the subject. Great say for a fast moving pelagic against a blue background. I tried the technique successfully a 1/350th while the D100 only synchs to 1/180th!

Just a random thought!

Alex

Question for the un-initiated. Why would you need to synch that fast ? If you are using a wide angle i.e. 18mm or 16mm fish eye.... the speed required until blurr is introduced is very low. I shoot whide angle at very low speeds ( and still get a synch ) and there is no bluring visable.

(shutter speed calculator )

http://www.dudak.baka.com/spcalc.html

I think the faster synch catches the sun rays better right ? Pls. Advise..interested

Yeah, you're certainly right that most of the time UW we can get away with slow shutter speeds.

There are just the odd occasion when a faster shutter speed might be a bonus - such as when snapping a fast moving dolphin when I would like to exceed the 1/180th sec of my D100. The alternative situation might be when you want to keep the background dark or keep the depth of field shallow for creative reasons.

I do agree that this high speed flash cheat is not a mainstream trick. Just might help in some situations.

Alex

Faster shutter speeds are usually suggested for sun rays because the shorter the exposure the less the rays move (during the exposure) and the more clearly defined they are.

ok..... thanks..

Just got my slides developed from yesterday. Using a 16mm fisheye, the results were interesting.

Could take pictures on stationary divers and some fish at 1/4 sec , sometimes with some blurr, at 1/10 it was enough to more or less freeze non-super fast moving subjects. My test subject had a powerfull light, at 1/60 you could barely see it lighting up subjects, but at 1/4 and 1/10 you could see this lovely yellow beam through i.e. soft coral.

Happy with the results

Does sound very nice - especially using a warm tungsten flashlight. I think the most interesting UW images come when we start to push the envelope of the "rules" with things like long exposures.

I have to say that it is one thing i really like about digital is the freedom from just 36 shots and the ability to delete really makes you push the slower shutter speeds. Then I apply it to film shots - once I have a good idea of what I can and can't get away with. I have been shooting slow synch macro all year and find as long as I am prepared to chuck away 3 out of 4 images I will get a good one at speeds as slow as 1/2 sec with the 105 (with my neutrally buoyant Subal rig).

Alex