Canon EOS Rebel 300D - Page 10

Kimberly Dow · 02-01-2005, 03:20 PM

Another stupid question Mike -

When you say 1/30 of a second - that would be an ISO of 30? So when you say 1/200 for kids that would be the 200 ISO setting - correct?

That scares me since in those Barbie shots I didn't get anything decent under 800. And she wasn't moving. Maybe too much coffee.

Mike McCarty · 02-01-2005, 03:46 PM

Quote:

Originally Posted by Kimberly Dow

Another stupid question Mike -

When you say 1/30 of a second - that would be an ISO of 30? So when you say 1/200 for kids that would be the 200 ISO setting - correct?

That scares me since in those Barbie shots I didn't get anything decent under 800. And she wasn't moving. Maybe too much coffee.

No my dear. Shutter speed (1/30 th of a second) is totally separate from the ISO number. You can influence SS by changing the ISO, but you cannot influence ISO by changing the SS.

ISO's will range from 100 to 1600 on your camera. Remember when you bought a roll of film? You had several choices of what was called "film speed." That was actually the ISO setting. The ISO definition gets slightly convoluted when going from film to digital, but you could think of it as film speed.

Try this -- without actually taking a picture, set your ISO to 100 and find something specific to point at. Notice the exposure in the viewfinder. You will see two numbers -- the SS and the aperture. It might read: 1/125 ... 5.6. Make note of the one on the left, this is the SS.

Now change the ISO to 400 and point at precisely the same spot. Notice that the SS has increased by a pretty good margin. This is the number you want to monitor. You want to get this number into the 1/125 range with the minimum increase of ISO. At this kind of SS you can stop the movement of most folks in pose. It might not freeze a person running the 100 dash, but that's another story. It's amazing that the SS can go all the way to 1/8000 th of a second. This sort of speed can almost stop a speeding bullet.

Elizabeth Schott · 02-01-2005, 03:54 PM

Quote:

No my dear. Shutter speed (1/30 th of a second) is totally separate from the ISO number. You can influence SS by changing the ISO, but you cannot influence ISO by changing the SS.

See Mike I am not the only blond here!

Maybe Kim wants to know what the 1/30 is by the number that shows up on the shutter speed info. There are numbers like -3 or 3.

If I knew this was going to last forever I would have posted new art work. But thanks for all your help. Now you have to add a Rebel to your bag!

Kimberly Dow · 02-01-2005, 04:08 PM

Ahh - Ok. Thank you kind sir. I did this -
The way it was shown was at IS 100 it said 0"03 - then at ISO 400 it said 13. (that would be 1/130 correct?).

This is photography for dummies for sure.

Now - my aperture said 4.5. I have no idea what this is. Just thought I'd throw that out there in case you wanted to explain that as well.

I really do appreciate this Mike!

Mike McCarty · 02-01-2005, 04:10 PM

Kim,

Look at it this way -- The ISO setting is something you set as a parameter, like you would the white balance or the size of your Jpeg image. It remains set even when you turn your camera on and off.

The shutter speed, however, is a very dynamic number that changes constantly as the scene [light] coming into the camera changes.

Quote:

There are numbers like -3 or 3.

Beth,

This may be an exposure compensation. My camera will adjust in increments of 1/3 of a "stop."

I think the DPreview site is very helpful in describing the different switches of various cameras.

http://www.dpreview.com/reviews/canoneos300d/

Mary Sparrow · 02-01-2005, 04:13 PM

SHEESH, ya'll are WEARING me out! I was following along just fine until these last few and now that ill feeling is sinking over me that I just want to give the camera back. My brain is trying to take in too much today, maybe I should read it again tomorrow.

I need to go somewhere quiet.

Mike McCarty · 02-01-2005, 04:20 PM

This was on the DPreview site:

Mike McCarty · 02-01-2005, 04:47 PM

Quote:

Now - my aperture said 4.5. I have no idea what this is. Just thought I'd throw that out there in case you wanted to explain that as well.

Lets go back to film for a moment. You know that the surface of the negative strip was treated with chemicals and "stuff" that was highly sensitive to light. The more light that it was exposed to the more it reacted. When it was exposed to just the right amount of light it would recreate the scene.

If you turned your camera around and looked into the lens and snapped a picture with a very slow shutter speed you might get a glimpse of what looks like a black curtain that can open in the center and appear as a circle hole (aperture). The camera has the ability to vary the size of the hole opening. The larger the opening the more light will come in to expose the film (chip). The other moderating factor would be how long the hole was allowed to remain open (shutter speed). The combination of the size of the hole (aperture), and duration (shutter speed) will make up the "EXPOSURE."

Aperture is expressed in these terms: 2.8, 4.5, 5.6, 8, 11, 16, 22 and numbers like that (I may have missed one). These numbers represent different size holes (apertures).To further confuse us they are also refered to as stops or f-stops. Shutter speeds are expressed in fractions of a second: 1/30, 1/250, 1/1000 etc.

Imagine how many combinations can be produced with just these two variables.

The camera magically combines the proper aperture and the proper SS to get the perfect(?) exposure. It's just an amazing thing to me that this gadget can be pointed at something and reproduce the image so well.

Mary Sparrow · 02-01-2005, 05:57 PM

So as not to bore you with more test pictures. I just did the same thing Kim did with another still doll model.

I tried out every manual white balance setting on the thing with an ISO of 800, and got nice clear pictures, with obvious differences in color. Then I put it on the automatic setting that just cuts the flash off. Doing that got me the most accurate color, but the face was blurry on the doll. (This was what I was doing the other day with Marc). The next best color was putting it in P mode but automatic WB..they were very close, but the face was clear.

So I suppose, for now, until I really learn this, in order to avoid the blur, I am better off putting it in P mode to avoid the blur and pick the white balance Icon that best fits the situation...which seems like the auto WB was doing the trick. I guess this computerized camera is smarter than me..Whoda thunk it.

Mike McCarty · 02-01-2005, 06:36 PM

Mary,

Be careful how your focusing is set up. Notice on the picture of the race car above that you have multiple possible focus points. This is something that you select on your menu.

With my camera I can choose to have the camera focus on the closest object to the camera (I don't like this method), or have it focus on the center of the viewfinder (I prefer this).

Make sure you are focusing on the face and not the closer knees of the subject, or not focusing on the back of the chair.

I find that when I am trying to learn some aspect of my camera that I concentrate on one feature at a time. It gets too complex when you start mixing different variables into one experiment.