How would I know what f/stop to chose

[hagsweet]

I had my camera on aperture priority first shot f/8 second shot f/22; the shutter speed changed from 1/20 to /25. The f/22 was not intentional, but I think it is a better capture, I'm trying to figure out I would have know this at the time.

Appreciate any in-put.



f/8; shutter 1/25



f/22; shutter 1/20

[kencaleno]

Second shot is a terrible capture-underexposed-anything smaller than F11 will have diffraction issues,softening the focus-By the way; Exposure for first one would have been f8 at 1/125 and second one f22 at 1/15; assuming an EV of 14.6 with an ISO of 100

[Samanax]

Were you using flash when you took these pictures?

[Chip]

I too am curious what you were trying to do here. Experimenting with different apertures just to see the difference?

[OsmosisStudios]

I partially agree with ken: the second one is very underexposed. However, I find the first to be overexposed.

[hagsweet]

thank you all for commenting. I was out shooting early in the morning (maybe not early enough). I was trying to take a picture of this wood scuplture and chose f/8 thinking it was a "sweet spot" on the lens, the f/22 was an error I didn't discover until I was viewing on my computer. The f/8 is over-exposed and the f/22 under-exposed - I'm thinking maybe what I need is to understand "exposure" before aperture?

[Chip]

Thanks for the background, hagsweet. First of all, don't worry about making mistakes - I've learned more from my mistakes than from my good shots. Second, it does seem that getting a handle on exposure might be a good next step for you. If so, the first 4 tutuorials at this link may help.

Basically, the higher the f# (aperture value for a lens) the smaller the aperture - less light goes through a smaller aperture. Which means that when you went go from f/8 to f/22, the camera tried to counteract the smaller amount of light coming through the aperture by letting in more light via a longer shutter speed.

(ISO is the third part of the exposure triangle, so ISO plays a role, too.)

In tricky exposure situations like the one in the shots you posted, the camera's meter will make its best guess as to what the proper exposure should be. Some times, the camera's meter gets it wrong. With experience, you'll be able to anticipate or recognize these situations and correct for them while shooting.

Also, if your camera has a histogram, reading up on it in the user's manual might be helpful. It can show you - right when you take a shot - whether the shot is exposed properly or poorly.

With practice and experience, you'll figure this all out.

[hagsweet]

Thank you all that replied - some really great tips; I do have a histogram on my camera, and I think it will be especially useful and reinforcing that I'll learn from my mistakes another good bit of advice

[wulf]

Originally Posted by Samanax

Were you using flash when you took these pictures?

I think this was about understanding light and exposure rather than using strobes and other lighting gear. I've shuffled it across to a different section.

For me, the breakthrough with exposure came when I got a handle on the fact that there are three in camera variables to match with the subject and the light available in the scene.

Shutter speed: the faster it goes, the less time there is for light to get into the camera so the resulting image will be darker. A fast shutter speed freezes motion; a slow one can allow you to create dynamic effects with motion blur but also risks fuzzing everything up with camera shake.

Aperture: how large a hole the light has to get through. A bigger number means a smaller hole and thus the resulting image will be darker. Most lenses tend to produce the sharpest results a stop or two down from wide open (and watch for the diffraction Ken mentioned). Aperture also affects depth of field so again has artistic consequences (sharp portrait and blurry background? Picking a wide aperture will help).

ISO: how sensitive the camera is to light. A bigger number amplifies the effect of the light, meaning you can get away with a faster shutter or smaller aperture but will also increase the noise of the image.

Those are your three key tools for affecting how much light is available to form your image, hence why people talk about the "exposure triangle".

Wulf

[countrygal]

I recently took a picture of a landscape - the surroundings were very bright and no matter how much I adjusted the ISO and speed it still seemed to be too bright and I couldnt seem to get the right setting.

What am I doing wrong? any comments would be greatly appreciated.

Thanks

Megan