Science Forums 2

[alexander]

The digital shutter i am referring to works similar to the smaller digital cams, they drain the CCD, turn it off, then open up the shutter wide, control the time turn when its collecting light by turning on the CCD, turning off the CCD again and closing the shutter. As i said, mechanical shutters are not too too fast, so when you shoot above their working range, and my camera once again goes to 1/6000, it starts using digital timing at fully open shutter...

But yes i was about to say, that the quality of a picture will differ if you have a camera with a normal shutter, as the CCD would be less exposed to light, giving you both the ability to shoot old style, and drain the CCD before timing how long it stays on, giving you more true readings...

I will confirm, most handheld digital cams have a digital timer vs an actual shutter or a combination like in the higher end cameras.

Anyways, back on topic of photography, lets discuss another technique. Actually speaking of flash photography and shutter speeds, how once can get shutter speeds of 1/11000 or faster to photograph things like say, fast flapping insects in mid flight, to freeze them in motion and ofcourse properly expose

First of all what is a flash (well from now on i will call it a strobe, that would be more correct)? A strobe is a device that uses a pulse of electric power through a small xenon-filled tube to produce a flash of bright light to, for instance, help correctly expose the subject on the picture. Now, you can go extremely crazy with flashes, and they can be useful, but lets discuss what purpose a flash can take that most people don't think about.

So a strobe lights up an object, we dont need it during the day, right? Wrong actually, one of the more widely used purposes of a flash by the pros is to use it as a fill light. Everybody likes to see strong shadows, err, well actually, when you are taking a picture of a person outdoors, or even indoors, those are something you are trying to eliminate, harsh shadows can make the whole picture look bad, so to remedy this, one can use the flash (ballancing the power to fill in shaded areas, but not to make it obvious that you are using the flash). Course noone does this better then David Hobby, the godfather of the off camera flash world and a master light manipulator, as an example of such a fill, examine this photo ( http://www.flickr.com/photos/davidhobby/2591107875/sizes/l/in/set-72157602259318619/ ), or even better this one (http://www.flickr.com/photos/davidhobby/3250091189/sizes/l/ ), and guess how many strobes are lighting the subject...

Anyways, another use of the strobe is to freeze subjects. A standard flash, like an sb800, on 1/16th power will produce a flash of light lasting about 1/11,000th of a sec. This will properly expose the subject it is facing, fixating it in the shot at that instance. This ofcourse meaning that if you are shooting in dark conditions, at say 1/80th shutter speed, you still have around 274/22,000 of a second before your shutter closes

SB800 has a long tube (longer then some other flashes, certainly longer then anything built in), shorter tubes built into a point and shoot would likely produce a faster exposure speed at a low power target here is to get the flash to expose your subject right. Then, think of it as a frozen image, meaning that that area is already properly exposed, now you can play with camera shutter to achieve the right exposure for the background. (use F-stop to control depth of field then set shutter to correct background exposure (or one you are looking for))

This would be the ggist, the beginning stages of how to effectively use a flash, as long as you remember that it allows you to vary exposure between foreground and background, and that you can effectively use it in light and dark to fulfill different tasks, your journey into the world of manipulating light is getting more interesting.

Another way to use a flash to liven up the shots would be to take an ambient reading at dusk, power your flash to low power, drop ambient by 1 or 2 stops to still get a crisp subject, but a much more defined background (much more dramatic clouds, sun, colors, what have you)