Starting at the beginning or Part 1 - ISO

I shoot Canon, so most of the controls might be in Canon-speak. ;) I'm also still learning, but I'm about to take that darn test that says I know what I'm talking about. So, I hope this will help you as it's helping ME clarify everything so I can score really well on that test.

A or AV is aperture priority
S or TV is shutter priority
M is Manual
P is photo priority (basically auto without the camera choosing ISO or flash)

Before we go too far, I want to make sure EVERYONE understands the relationship between aperture, shutter speeds, and ISO. They all 3 affect the light that is coming into the camera and being captured on the film/digital sensor, and understanding how they work is crucial to properly exposing your images manually. Before I get into why I choose which one, what I'm thinking when taking a photo, etc. I want to go over these basics.

We all know that ISO 100 needs a brighter light than ISO 1600. ISO numbers show a sensitivity to light, and the lower the number the finer the grain in the film. For digital cameras, we see "ISO equivalents" and it measures how sensitive the sensor is to light, and it works the same way as the film - it's a measurement of the "grain" which produces noise in the final image. While it's nice to be able to shoot indoors without a flash and keep good shutter sppeds with ISO 1600, it comes at a cost. ISO 1600 has a LOT of noise in it, lets not even discuss what ISO 3200 has in terms of noise.

I'll go back and tell a quick story from this past May. Airing my dirty laundry so to speak, and why I'm still "growing" as a photographer. I was shooting a wedding with a friend, and we were down in a "hollow" in Middle Tennessee in the deep dark of the woods. Bright sunny day, but down in the "hollow" I needed 1600 ISO to get my shutter speeds fast enough for the aperture of 4.0-8.0 that I was varying between. As expected those photos are really nice, but have a lot noise. Well, we get to the top of the hill, in a more open area. I start to shoot the little kids, and I had put the camera in AV mode (do this sometimes in a fast moving situation with kids). I was not paying attention to my in camera meter OR shutter speeds. I was tired (it was about 4 hours into the wedding shooting). I finally chimped (which is looked at the back) and saw WAY OVERBLOWN! I could not figure it out! My shutter speeds were maxed out. I looked at the camera for a good minute or so, then DUH!!! I still had ISO 1600 set! I moved the ISO down to 200 and immediately my images were better exposed.

Luckily, my friend was also capturing images at this point. We did not have to rely solely on MY images alone. This is why I do not like shooting a wedding alone.

Okay, so that little story should tell you why you need to know these relationships, because at some point you will see an image on your camera during an important moment and need to know what to do to make it come out properly.

GO FIND YOUR CAMERA MANUAL!!!! :) I'll wait for you. If you can't find it, look it up online. Put this somewhere that you can reference in case I ask you to adjust something, and you don't know where it is!

Got it? Good...

Move the dial to what on Canon cameras is A or AV mode, and on Nikon it's A mode. Those of you with other brands, if you have trouble please let me know. AV or A mode allows you to set the aperture setting and choose your ISO, and the camera will figure out the best shutter speed for you based on it's "metering" and such.

Figure out how to change the ISO manually. (Look at the manual, if you have trouble contact me and I'll help you figure it out) Usually there is a menu setting to change it, or a button that says "ISO" on it that you have to push (and sometimes in combination with another button/dial to change it).

The in camera meter is located in 2 places - when you look through the Viewfinder it's the bar that has -2...-1...0...1...2 in some fashion. In Canon it's across the bottom, and I think in Nikon it's along the right side. The 2nd place is on the top (well, okay, from looking at online views of Rebel XS and the Nikon D60...it's not viewable there...if it has live viewing on the back, it might show it there). Really, you only really care about it through the viewfinder.

Also in the viewfinder (and sometimes on the top or on the back) you will see the corresponding numbers to SS and Aperture.

So, in A or AV mode, I want you to set the Aperture to the smallest number you can (for some this will be f/1.8 for other it might be f/3.5 or f/4.0 or f/5.6).

Now, set your camera to ISO 100 and focus on something in the room. Find that meter and settings...you don't have to take a photo, but you have to focus and get the exposure readings. Write down them down with a notation that it was for ISO 100.

If you are in a dimly lit room, I would expect the photo to be a little blurry due to camera shake of a very slow shutter speed! Is that what happened to your photo? It would for me at ISO 100 (see post below this one).

Now, change the ISO to 200 - retake the photo and write down the SS it gave you. Repeat for ISO 400, ISO 800, and ISO 1600. What did you see happen?

The Shutter Speeds should have increased. Not only that, but they should have at least doubled. Did they "double" or close to it?

Thus, a LOW ISO number means "slower" shutter speeds than a HIGH ISO number would give you in the same light. Lower number film speeds (or ISO) are considered "slow films" while higher numbered ones are considered "fast" films because of this.

If you are out, say in the botanical gardens and you took a photo of you child in the bright sunlight. It would need a lower ISO number. If you then stepped into a really shady area, then you would need to bump up your ISO number to a higher one so that you can keep faster shutter speeds. If you are outside taking photos, getting nice crisp exposures, then move indoors with the same ISO and get blurred images remember to check to see if your ISO is appropriate for INDOORS. Back in my "old" days when I shot film for the yearbook, we had to finish out an entire ROLL of film before changing the ISO to one more suited for indoors (or heavy shade). Now aren't you glad you have a digital camera?

I couldn't find any good photos of this to share in this post, but rest assured I will share some soon (even if I have to take them with the purpose of showing you all the differences).

Any questions? (next up is Aperture)