Understanding F-stop

[bsinmich]

The f stop has nothing to do with the number of people in the photo. It does have to do with the opening of the lens to let in more light. The amount of light required to make a good picture is just as related to the shutter speed as the f stop. Using a smaller f stop (larger number) will give more depth of field to allow a little more depth to the image. If you are shooting outdoors or where there is adequate lighting you would probably want to use something like f8 to get a little more depth of field in the photo. A lens is usually at it's best when it is used inthe middle of it's range on f stops. This hold true to almost all lenses from a Leica to a Brownie. Your camera will give better results using a smaller f opening, (larger number) rather than wide open.

 

[480sparky]

.........Anything that is on a plane parallel to that plane and at whatever distance your lens is focused to away from the plane of the sensor will be in focus.....

Not always. Some lenses have the property of 'field curvature'. Meaning the 'plane' of focus is a part of a sphere.

 

[Josh66]

The sensor is the thing behind the shutter curtain that records the image. It is flat, so the face of it forms a plane. This plane is where you measure the focusing distance from (it's usually marked on the top of your camera somewhere, since you can't actually see it from the outside of the camera - the mark looks like a circle with a line through it - the line is the film or sensor plane; the front of the sensor).

Anything that is on a plane parallel to that plane and at whatever distance your lens is focused to away from the plane of the sensor will be in focus.

edit
If you still don't get it after that, I will draw a picture (unless someone finds and posts one before that). Not meaning to be insulting or anything like that, I think this is just a case where a picture will explain it a lot faster than words.

I think I understand but picture sure would be helpful

I'll see what I can do. I used to be quite the artist, but I don't draw much anymore, lol. I think I can handle this though.

 

[dannyzak]

The f stop has nothing to do with the number of people in the photo. It does have to do with the opening of the lens to let in more light. The amount of light required to make a good picture is just as related to the shutter speed as the f stop. Using a smaller f stop (larger number) will give more depth of field to allow a little more depth to the image. If you are shooting outdoors or where there is adequate lighting you would probably want to use something like f8 to get a little more depth of field in the photo. A lens is usually at it's best when it is used inthe middle of it's range on f stops. This hold true to almost all lenses from a Leica to a Brownie. Your camera will give better results using a smaller f opening, (larger number) rather than wide open.

Thanks, I understand much better now.

 

[Josh66]

.........Anything that is on a plane parallel to that plane and at whatever distance your lens is focused to away from the plane of the sensor will be in focus.....

Not always. Some lenses have the property of 'field curvature'. Meaning the 'plane' of focus is a part of a sphere.

That is usually considered to be a defect though, right? Other than a Lensbaby, I don't know of any lenses that do it on purpose.

I guess all lenses probably have it to some extent, but it's generally something they try to get rid off.

edit
And I'm not entirely sure if that's what is actually going on in a Lensbaby, but I think it is, so I'm rolling with that till somebody corrects me, lol.

 

[480sparky]

That is usually considered to be a defect though, right? Other than a Lensbaby, I don't know of any lenses that do it on purpose.

I guess all lenses probably have it to some extent, but it's generally something they try to get rid off.

edit
And I'm not entirely sure if that's what is actually going on in a Lensbaby, but I think it is, so I'm rolling with that till somebody corrects me, lol.

I doubt it's something that is intentionally introduced into the optics. But all optics, no matter how good or expensive, are always a compromise. Given the need to reduce thing like CA, distortion, flare, vignetting etc., wile trying to maintain sharpness.......it's going to be a balancing act to keep some of them in check, and it's usually at the expense of something else.

 

[Josh66]

Scanning the drawing (more of a sketch) now...

 

[Josh66]

Full size scan, in case that's too hard to read.

 

[dannyzak]

Full size scan, in case that's too hard to read.

Thanks

 

[dannyzak]

Full size scan, in case that's too hard to read.

Do you guys shoot in AP mode most of time when shooting outside, nice sunny day? Is it better to shot in AP or M?
"Nice sunny day outside"
I heard a lot of ppl are shooting in AP then.

 

[Josh66]

It's really just a person choice ... whatever you feel most comfortable with.

For me it depends a lot on which camera I'm using too. I have one camera that basically never leaves manual, one that rarely leaves aperture priority, and one that almost never leaves full auto.
(edit - Those three cameras are also entirely different systems too - it's not like they're just three versions of the same camera... And I have other cameras that only have one mode, so I use that, obviously.)

There's nothing wrong with any of the modes, as long as you know what their limitations are, and how to get around those limitations. Manual and aperture priority are probably the two most commonly used modes among the members here though.