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bad sector <none@_INVALID_.net> wrote:
> On 06/04/2012 12:47 AM, bad sector wrote:

>> canon sx230?

>> 1080p HD, manual overrides, large pocket size and since it's a year on
>> the market prices have retreated some ($230-300). I never had a Canon
>> but the reviews are generally good.

> I just downloaded the manual and went in for a closer look at so called
> MANUAL focus. There's no sign of numerical distance reference,
> apparently it just allows one to eyeball focus on the monitor. Thus if I
> want to focus at 200 feet I cannot see that number anywhere while
> focusing even manually ((

Why would you want to focus at 200 feet? At that distance
you have 60 feet DOF at the least with that camera.

> Secondary:
> The depth of field table (or rule of thumb if any) that depends on lens
> opening and focal distance, is that about the same on all cameras/lenses
> or is it specific to every lens

It only depends on the aperture and focal length and on the
allowed circle of confusion, which again depends on the factor
between output and sensor size and viewing distance.

-Wolfgang

In rec.photo.digital bad sector <none@_invalid_.net> wrote:
> On 06/07/2012 01:27 PM, Wolfgang Weisselberg wrote:
>> bad sector<none@_INVALID_.net> wrote:
>>> On 06/04/2012 12:47 AM, bad sector wrote:
>>
>>>> canon sx230?
>>
>>>> 1080p HD, manual overrides, large pocket size and since it's a year on
>>>> the market prices have retreated some ($230-300). I never had a Canon
>>>> but the reviews are generally good.
>>
>>> I just downloaded the manual and went in for a closer look at so called
>>> MANUAL focus. There's no sign of numerical distance reference,
>>> apparently it just allows one to eyeball focus on the monitor. Thus if I
>>> want to focus at 200 feet I cannot see that number anywhere while
>>> focusing even manually ((
>>
>> Why would you want to focus at 200 feet? At that distance
>> you have 60 feet DOF at the least with that camera.

> Nothing special, I just threw in a number, or maybe I want the subject
> to just fit into the DOF. I should have been clearer about what I want.
> There are two separate actions the first being fucusING (like in the
> viewfinder) and the other SETting-focus where you set a number for the
> distance. Let'say I want to make a 1 minute exposure of a town at night
> in the snow from a water tower (I actually made a postcard that way
> once). Trying to focus in the viewfinder would be an exercise in
> futility but if I know the distance (and I can guess pretty good) then
> that's where setting the focus distance comes in. In this case it was
> infinity but it serves to illustrate one possible need for the number
> approach.

If you want to set by number you should carry out some experiments to
check the accuracy of the number scale with respect to your
purposes. On some cameras/lenses it's accurate enough, on some it's so
silly you wonder why they bothered to put the numbers there.

--
Chris Malcolm

bad sector <none@_INVALID_.net> wrote:

> distance. Let'say I want to make a 1 minute exposure of a town at night
> in the snow from a water tower (I actually made a postcard that way
> once). Trying to focus in the viewfinder would be an exercise in
> futility but if I know the distance (and I can guess pretty good) then
> that's where setting the focus distance comes in. In this case it was
> infinity but it serves to illustrate one possible need for the number
> approach.

Well, most cameras in the P&S class have a scene mode exactly
for landscapes in the dark. Hyperfocal length.

And since at said 28mm the hyperfocal length is around 2 meters
for this camera ...

-Wolfgang