More of a Photo Question than a Photo Tip

[BrokenBiker]

I didn't really know where else to post this thread, but I figured to start it here thinking that someone else may learn from it.

I was playing around w/ aperature and shutter speed settings tonight w/ my camera to experiment w/ shooting indoors w/ poor light. I shot a picture of a beer bottle from approx 5' away w/ a single lamp lit a little over 10' away. I was able to adjust the shutter speed for exposure well enough, but I was only able to get one focused properly on the bottle.

To explain my process a little...I'd take a few shots, then look at them on the computer. When I found one that focused on the bottle well, I tried to duplicate it. Unfortunately, I never could. I think this is largely due to different focal lengths on the zoom.

At any rate, I understand the concept of focal length, aperature, and shutter speed; however, I can't seem to be able to apply it all on purpose. Are there rough estimates to help calculate where the focal point will be when adjusting focal length and/or aperature? Or do you simply have to "get to know" your camera?

Below is the one good picture from tonight.
EXIF:
Focal Length: 37.8mm
Shutter speed: 1.0 sec
Aperature: f3.5
ISO: (Not adjusted) 125
Diaphragm value: F2.8--I don't know what this is....My camera's smallest aperature setting is 3.5 (see above)

I have a Sony DSC H5...a point-and-shoot...

[henrique]

If I understand your issue the problem is focusing. No matter the focal length you will need to focus properly on your subject. Your subject might not be in the center of the scene. Know where your camera focuses. If it focuses in the center then center your subject, focus, move your camera to frame the scene then shoot.

You might be able to adjust focusing on the center, nearest object, etc.

Good luck!

[ramblinray]

I assume you are really asking about Depth of Field (DOF). DOF is dependent on aperature and distance from subject. Do a google search and look for a DOF calculator and you should be all set.

[BrokenBiker]

This camera has an adjustable auto-focus point, which in this case was centered on the beer lable on the bottle.

I think part of the problem might've been the low light. Sometimes this camera has a problem focusing on something if there's not enough light...even though between the shutter speed and the aperature, it will still showing a '0' for the overall light level.

I didn't know they made DOF calculators. I'll check 'em out. That sounds like exactly what I'm looking for.

[CaptainTom]

On the "old" film cameras, DOF was always marked on the lens.
You would focus (manually) on you subject, and the DOF scale would let you know what to expect at each aperture setting. Your P&S doesn't do this, so if you can print out the DOF tables it will give you a pretty good idea of what to expect.

[KeithAlanK]

I have experience with Sonys and H-series cameras.
More light will definitely help, and you need to make sure the focus brackets are on the subject--they can be moved and you want them on the label, even if you have to half-press the shutter to achieve focus-lock then recompose the sccene.
Also, manually set the white balance to match your lighting, to remove the orange color-cast caused by tungsten bulbs in this case.

In addition, low light means a slow shutter speed, so a tripod is almost mandatory for sharpness.
What looks like bad focus can actually be motion-blur caused by the camera not being steady enough.

[texaskev]

I think your question has been answered above. Just found it interesting that your late night test subject is the same as mine. I have 100s of shots of low light Mic Light! lol

[shutterdrone]

... also remember that when working with shallow DOF, very minor changes in relationships between your subject and the film/sensor plane can really blow your focus. If you have a multi-zone focus setting on your camera, and you can manually set it - it is generally best to compose first, set the focus manually, or with a specified focal point (say, a left one for the shot you have) and then shoot. If you focus with a shallow DOF with the object in the center of the frame, and then move the object to the left of the frame - your object no longer shares the same relationship to the sensor as when you focused. Remember that DOF is not only about distance, but also about spatial relationship. (Which is what makes tilt+shift lenses such awesome beasts.)

See the following:

http://visual-vacations.com/Photogra...pose_sucks.htm

!c

[AndrewCCM]

Originally Posted by shutterdrone

... also remember that when working with shallow DOF, very minor changes in relationships between your subject and the film/sensor plane can really blow your focus. If you have a multi-zone focus setting on your camera, and you can manually set it - it is generally best to compose first, set the focus manually, or with a specified focal point (say, a left one for the shot you have) and then shoot. If you focus with a shallow DOF with the object in the center of the frame, and then move the object to the left of the frame - your object no longer shares the same relationship to the sensor as when you focused. Remember that DOF is not only about distance, but also about spatial relationship. (Which is what makes tilt+shift lenses such awesome beasts.)

See the following:

http://visual-vacations.com/Photogra...pose_sucks.htm

!c

Very good tip here. So true.