Camera sometimes doesn't take the shot?

[Kayzle]

Now keep in mind I'm learning this all as I go...

I just got my nifty fifty the other day and was playing around with TV and AV mode and I noticed at times the camera wouldn't shoot. It was like it would attempt to focus and then decide it wasn't possible so it wouldn't shoot, I'm assuming this is because whatever setting I had it set on wasn't appropriate but I was wondering if someone could explain this more in depth, if it helps I had the aperture set at 1.8 for most of the shots

also while I've got you all here...what settings would you guys recommend using this lens for general shooting, I'm sure it all depends on the situation I'm in but maybe you guys have suggestions.

[Daniel Bates]

There is a setting in the Custom Functions menu of most Canon cameras that switches between AF-priority and release-priority shooting. In AF priority, the camera will not take an exposure unless the autofocus is locked in; in release-priority, it will shoot when told to regardless of the AF. I reviewed the menus on the Rebel XS (1000D) and it doesn't look like your camera has that functionality. I have had to bypass that shooting mode before with other cameras; my solution is to switch the lens to MF (manual focus) mode.

For general shooting with the 50mm f/1.8, I would suggest stopping the lens down to ~f/2.8 and using a low- or mid-range ISO like 200 or 400 and whatever shutter speed is necessary for a proper exposure. If conditions are too dark, feel free to bump the ISO up and open the lens to f/1.8 if you need to. The 50/1.8 isn't the sharpest 50mm lens ever made, but it is very good for its price point.

[Kayzle]

Great help, so the darker the light the wider the lens should be?

[Daniel Bates]

Exactly. You have three options for controlling your exposure: shutter speed, aperture, and ISO. The slower the shutter speed, the more light can get onto the sensor. The wider the aperture (smaller numbers, like f/1.8), the more light can pass through the lens. And the higher the ISO, the more the image is "amplified" - but much like turning up the volume knob on a radio, you get increased noise along with the brighter picture.

[Kayzle]

How do you decide what shutter speed in appropriate, it's been explained to me before by a friend but I'm not sure it soaked in..it's relative to the movement you want to capture right?

[Daniel Bates]

Right. For fast action, you want a fast shutter speed so the movement won't get blurred. Conversely, if you want to capture motion, then you would use a slower shutter speed. I'll define by example:



I used a fast shutter speed - maybe 1/4000th of a second - to freeze the tennis ball as it came off the racquet.

Whereas:



Here I used a 1/8th second exposure to blur the passing scenery and show a sense of speed.

There is a useful guideline for the minimum shutter speed that will let you capture steady handheld images without the effects of camera shake - take your focal length and use it as the shutter speed. For example, the average photographer could hand-hold your 50mm lens at about 1/60th with no camera shake, but would need to shoot at least 1/320th with a 300mm lens. This is because longer lenses amplify the effects of even the slightest tremble.

[Kayzle]

Man I sure have a lot to learn, I've kinda fgured out each thing, but I'm still not sure how to put it all together haha, ill get it eventually

[Daniel Bates]

It took me several months with a Pentax ME Super and a photography textbook to figure everything out theoretically, and another couple of years with a digital camera to understand how to apply the concepts to real photos. Don't worry - as soon as you master exposure, you'll find something else to tackle. There is no end of learning in photography!

Right now I'm (slowly) trying to learn HDR and proper post-processing workflow, though my photographic endeavours have fallen behind video projects.

[toverman]

The 50 f/1.8 is a great lens, but sometimes it's best to focus manually (switch on the lens AF/MF set to MF). It will "hunt" if you've got a moving target or in a low-contrast situation.