gregh

Does anyone know any good guides/FAQs which talk about various settings and how they affect the picture?

specifically things like ISO settings, long shutter, exposure compensation, and light metering modes.

cheers,

Greg

john_s

iTrader: (1)

Can't think of any online off the top of my head (prob. have some links at home), but it will be covered by any decent photography book.

As a quicky for now though....

ISO - the speed of the camera / film, ie how much light it needs to respond to to get correct exposure. A faster ISO (higher number) needs less light (ie shorter exposure and/or smaller apperture), but will typically have more grain (film) or noise (digital).

Long shutter - a shutter open for a longer time lets more light in for the exposure, but a long shutter period will also blur any motion in the photo.

Metering modes - how the camera reads the light level, eg spot, centre weighted average, etc.

HTH

John.

gregh

cheers John,

So for taking pics, of say, cars on a track I should use a higher ISO?

For taking, say a picture in a dark forest I should a long shutter or a lower ISO, but with a tripod or something similiar??

How about those pics you see where moving water is blurred, what settings do I use to acheive that?

regards,

greg

IWatkins

Greg,

Basically, you set up the camera to take the picture you want.

Ideally, you keep the ISO as low as possible at all times, this will cut down the amount of noise. Only increase it if you need the faster shutter speeds.

Cars on track ? Again depends what you want but use shuter priority and set to say 1/125 of a second to get some wheels and background blur. You can let the aperture take care of itself. If there isn't enough light to support this then you can increase the ISO.

Dark forest, then you want to have a small aperture so that the whole scene is in focus. Shutter speed will take care of itself but you will probably need a long exposure so a remote release and a tripod will be necessary. Leave ISO as low as it will go for maximum detail and minimum noise.

Blurred water ? Same as dark forest. You want everything to be in focus so small aperture. Shutter speed should come out slow. If it doesn't stop down the aperture even further until it forces a slower shutter speed. The other way is to set a shutter speed, say 3 seconds. Hopefully you camera will then be able to stop down the aperture enough so that the shot doesn't overexpose. If not, you will need a neutral density filter to reduce light levels.

I could go on and on, but I'm already making sweeping generalisations. Understanding aperture, shutter speed, ISO and how they interelate, and what effect they have of the final image (depth of field etc.) is key.

I can't find the site that I usually refer people to at the moment, but if I find it, I'll post it.

Cheers

Ian

gregh

cheers Ian, I will be using an Ixus 400, and I'm not sure how I change the aperture on that???

Franx

Do you not have the instruction manual? Sorry for stating the obvious...
Otherwise, try buying a magazine like 'practical photographer' or similar. They tend to have a lot of information on that type of thing - not camera-specific, but it'll give you the right idea

Daryl

I don't think you can set the aperture on the Ixus 400, but in 'manual' mode you can select the shutter speed. Once you understand the relationship between aperture and shutter speed, you should be able to have reasonable control over the aperture the camera selects. Basically, the slower the shutter speed, the smaller the aperture.

gregh

yes I have the manual, it explains how to change things but doesn't explain the affect they have.

Hi Daryl- yes I can control shutter speed, that's just the info I was looking for thanks. I have options of 1, 1.3, 1.6, 2, 2.5, 3.2, 4, 5, 6, 8, 10, 13 and 15

Any rough guide as to what is appropriate for each speed or range of speeds?

regards,

greg

Mr.Cookie

www.dpreview.com and click on the learn tag

AndyC_772

iTrader: (2)

Greg

Those don't sound like shutter speeds - I'd expect your camera to cover a range something like 1 sec to 1/1000 sec or thereabouts. The numbers you've mentioned sound more like a range of f/stops (ie. apertures), although normally f/2.8 is about the widest available.

To give a feel for the numbers:

1/10 to 1 sec (or longer) - indoor or night photography. Tripod essential. Long shutter speeds (1 sec+) are what you want to blur running water; in order to achieve proper exposure in this situation you'll need a low ISO setting and a small aperture so as not to overexpose.

1/10 to 1/50 - indoors, just about hand-holdable.

1/50 to 1/200 - outdoors, though unlikely to be able to freeze motion. Speeds around 1/125 are good for motorsports if you can pan smoothly and want to blur wheels and background.

1/250 and faster - outdoors, suitable for freezing motion.

ISO, aperture and shutter speed are the three variables that control the overall brightness of the image:

- ISO controls the amount of light that's required to produce a correctly exposed image. Low ISO means that a lot of light is needed to produce the image, but the end result is a high quality, low noise image. High ISO settings (which correspond to fast films) produce an image with relatively little light, but the image will be noisier and less detailed.

- Shutter speed simply controls the length of time for which the sensor (film) is exposed to light. If the camera and subject are both steady, changing shutter speed only affects the brightness of the image.

- The aperture, which is the size of an iris diaphragm positioned between the lens and the film. If the aperture is wide (small f/ number), then lots of light is allowed in and it's possible to shoot with fast shutter speeds and/or low ISO settings. With a small aperture, longer shutter speeds and/or higher ISO settings are appropriate. Changing aperture also affects depth of field (the range of distances either side of the principal focus point over which subjects are in focus) - small apertures give large DoF, wide apertures give shallow DoF.

Depth of field also depends strongly on magnification - the relative size between the subject and its image on the sensor. On a camera with a small sensor, magnification is always small and DoF is large - you'll probably find that your photos alwats tend to have everything in focus all the time. With a larger sensor (such as in a DSLR or with 35mm film), magnification is larger and DoF is shallower. This opens up more creative possibilities and is generally reckoned to be an advantage.

Macro photography is an area in which DoF is also critical - here the object is always to get high magnification, so DoF is very shallow even with a small sensor. For this reason, macro shots are usually taken with a small aperture (to get the DoF as large as possible) and often a flash is used to provide the necessary extra light.

The best way to learn the interaction between all these parameters is to stick the camera on manual and play with each one in turn. Letting the camera do anything automatically will only cloud the issue and make it harder to work out what effect your adjustments are having.

The nice thing about digital is that you have instant feedback and every shot is free. Take advantage!

Daryl

They are the shutter speeds (between 1 and 15 seconds) that can be selected with the long-shutter mode, in Manual.

As far as I can tell, the manual mode on the 400 is really what is known as shutter priority, or Tv in SLR speak. The speeds you have quoted are the same as on a Canon SLR.

Presumably you can also manually select faster shutter speeds than those. Assuming that is the case, then I would advise that you take all your pictures using this mode, it will give you far more creative control and you will soon figure out what works best in any given situation.

25 years ago, shutter priority mode was the 'latest thing' on Canon SLRs such as the AE1

gregh

ok, thanks for all the info, just the kind of stuff I was after!!

the tech specs say the camera has:

Aperture range F2.8 - F4.9
Min shutter 15 sec
Max shutter 1/2000 sec

...but I can't see any way to change that, looks like in manual all I can adjust it "long shutter mode", ISO, and manual exposure

AndyC_772

iTrader: (2)

If the aperture range is limited only to f/2.8-4.9 then that's not really enough to provide useful exposure control. For comparison, the lens I most often use on my SLR offers f/2.8-f/22. By changing lenses and zooming I can get from f/1.4 to f/32.

That probably explains why aperture control isn't provided. It's also true that because the sensor is small, DoF is always large and so there's little to be gained by using a small aperture. Small sensors need all the light they can get to produce a low-noise image, so a large aperture is almost always appropriate.