Photo Tip Friday - What's That Dial For? Pt. 3

Welcome back to What's That Dial For? 

So far, we have covered what the letters on the dial stand for and an overall look at them. You can read that post which was Part 1 by clicking here. 

Then we covered Aperture Values. It was more in depth than Part 1. You can read about Part 2 here. 

The last post was a bit deep. But I want you to at least try and learn about aperture values. 

This week will be a little bit easier to talk about and understand. 

1) Time Value (Tv) - controls how long the shutter is open for. 

1/500th of a second
On my camera, I can have the shutter open for several seconds or have it take a picture in 1/4000th of a second. Yes, you read that right. 1/4000th of a second! It had better be bright for that shot! 

So leaving the shutter open for longer means that you're letting light in for a longer time. This is used for dark lighting situations. Think night time. 

The faster the shutter moves, the less light it lets in. So taking a shot at 1/4000th of a second needs very bright light to register the "image." The faster shutter speeds can be used to keep your photo from being washed out in bright light and is very effective in capturing movement without making it blurry. 

Helpful hint. If you have a shutter speed of less than 1/25 - 1/15 of a second for a shot, you will need to use a tripod or brace your camera. Set it down, lean up against a wall, set it on a railing.          

As long as I haven't had too much caffeine, I can hold it steady to 1/15th of a second. But I do brace my elbows against my body AND I have learned not to breath during the shot.

You can experiment and see how slow you can handhold your camera or cell phone. In the above photo, I set the camera on the rail on the right to steady it because I had to the leave the shutter for 1/2 a second to make the evening shot be bright enough.

2) ISO - How fast the speed of your film is. 

Let's go back to print days. Remember the range of ISO? 

ISO 100

ISO  64  - slides - highest quality - clearest 
ISO 100 - film - used for SUNLIGHT
ISO 200 - film - used for general purpose
ISO 400 - film - used indoors or to capture movement (sports)
ISO 800 - film - used in darker lighting
ISO 1600 - film - used in the darkest situations - think CANDLE - grainy

ISO 1600

My camera, a Canon Rebel T3i, has ISO values of 100, 200, 400, 800, 1600, 3200, and 6400. The great thing about digital cameras is that you can see your photo immediately and adjust the ISO with the click of a button or turn of a wheel. 

If you'll notice from the posts, some of the functions of Av, Tv and ISO overlap.  You can change each parameter and effect the shot. So next post, I will show you shots and how changing the different variables effects those shots. 

But in the meantime, do you use a particular ISO? 

Which is your favorite shot of these 4?

Hope this tips helps! 

Keep on clicking!



  1. I'm still at a point and shoot, but I do have every intention to upgrade, and I already know these are fabulous tips.

    I'm visiting today from Paula's Weekend Blog Party.

  2. Thanks for this very informative post Mary. I still have a lot to learn about my digital camera. I think all the pictures are great but the last one of a lit camera is my favourite. Have a great weekend.