Shutter speed and irs for GS400
 

Hello everyone,

I can either change shutter speed or irs to adjust the amount of lights coming into the camera. Let's say that I use a tripod, so I don't need to worry about shaking. What should I change to adjust without degrade image quality, irs or shutter speed? Or they are same, I should not bother?

TIA
Leigh

Hello Leigh,
You've actually asked a rather complex question which is not specifically related to any particular camera. It's actually a question most closely related to videography's parent: photography. I'll take a swing at it from a video camera operation viewpoint.

Shutter speed and iris are very different controls. On video cameras shutter speed is analogous to CCD sampling rate. In general, on NTSC cameras, you'll want to try to stay at 1/60 sec. This is the native scan rate for video and the rate at which images will look most natural. Excursions below 1/30 and much above 1/100 will bring visual side effects. Experiment for yourself to see what I mean.

Iris (or aperture) refers to the opening of the lens. This can have some dramatic effects on your image and, next to focal length, is probably your main creative control while shooting. Larger apertures (i.e. smaller f-stop numbers) present shallower depths of field/focus and smaller apertures (i.e. larger f-stop numbers) produce greater depths of field/focus.

Whenever possible don't let exposure run your camera operations. That is, take control of your light if your intentions are to shoot anything remotely important or serious. In general, at least while you're getting started, I recommend leaving the shutter speed at 1/60. Run the camera as if this control doesn't exist...act as if it's locked at 1/60.

So now you're thinking whatsup?! I can only control the iris? Yes and no. Remember, take control of your environment whenever possible. If you're in a low-light situation, too low for the camera or the shot composition turn a light on or move to a brighter situation! This is my #1 bugaboo with folks who whine about "low light" camera capabilities but insist in shooting in setting where night vision infrared would have trouble. Light is your paint!

If you're shooting in an extremely bright conditions use a neutral density filter to control the light coming into that lens. If your camera does not have a neutral density (ND) filter built-in, buy one. They're relatively inexpensive and invaluable for helping to change your exposure game in bright settings. Better yet, buy two at different strengths (they're generally sold in graded densities) so that you're covered for bright daylight as well as bright-but-overcast conditions.

There's no substitute for thoughtful experimentation or for some basic study. Regarding the latter there there many good books on photography and videography. Look in our Read About It forum for some good book tips.

Most important of all: Have fun with your camera!

Dear Ken,

Thanks for the detail answer.

I am sorry that I forgot to mention that is I am interested to use gs400 to take still photo. So how irs and shutter speed relationship in terms of still photo?

TIA

Regards
Leigh

Basically the same; you're taking still frames (photos) with a video camera.

Use a photographic camera to take photographs. Video cameras do a poor job on this task. The right tool for the right job.

I just use whatever I got. I don't want to spend money to buy a digital camera at the moment.

<<<-- Originally posted by Leigh Wanstead : I just use whatever I got. I don't want to spend money to buy a digital camera at the moment. -->>>

Sure, but when you look at the photos that a simple digital still cam takes, you'll probably feel the lack in the video cam in this area. I used to love the stills from me MX8 (a long time ago, that was like 2+ years back), then I moved on to the MX350 + Fuji S602zoom still cam, now I'm still using the MX350 but the still has moved on to the Fuji S2pro DSLR.

Back to the thread's original intent:

Shutter speed = to freeze motion or not. 1/500 everything is frozen stiff, 1/30 motion blurs expected. Image Stabiliser will help with camera shake, but not with object's movement.

Aperture (Iris) = depth of field control. Large aperture f1.6, f2.0 means shallow depth of feild, and things that are not near the focal plane will be blur. Small aperture f11, f16 means large depth of field, and most of everything in the frame will be sharp at most focal lengths.

Correct exposure is always a trade off between Shutter Speed and Aperture. 1/500 at f8 = 1/250 at f11 = 1/1000 at f5.6. Simply put, large opening exposes more light, so shutter must be faster.

In the case of aperture for controlling dof, miniDV cams has so small CCDs that unless you open up to f2.0 or f1.6 and zoom all the way to 8x or 10x, everything will probably remain sharp.

Some good replies to your post Leigh. Remember that any camcorder that doesn't have an external ND switch most surely has in-built and automatic ND filters, and I'm sure your GS400 falls into this category. So when you're turning what you think is the aperture control wheel, you're most probably getting as far as f4.5 and from then on simply dialing in more and more ND filteration.

No harm in that of course, but the 'replay' button on Panasonics displays this as aperture values (f11, f16 etc) and of course this is not the case - it's actually a theoretical value based on f4.5+ lots of internal ND.

As to your using the cam as a still camera I say go for it, but remember that many cameras lose vertical resolution if you drop below the default 1/60 (1/50th PAL) shutter speed. Also remember (as I've explained above) that you can't set f16 for great depth of field - modern camcorders (especially those employing chips smaller than 1/4") won't allow it.

I get great stills from my ancient MX300 (1.8 mega-pixels) but it's as well to know what's going on inside the hardware to get the very best out of it.

tom.