How far is "infinity?" - Not a metaphysical query

Daguerreotype type wrote:
> On Thu, 5 Mar 2009 14:44:15 -0500, "Jay Kneese"
> wrote:
>
>> "Daguerreotype type" wrote in message
>>
>>> I have a Canon A580 digital camera. It has a "Landscape" setting that
>>> I suspect focuses on infinity. Not sure about that but I suspect it.
>>>
>>> How far away should something be before I tell the camera that it
>>> should focus on infinity? Is 100 feet infinity for this camera? More?
>>> Less? Sometimes I try to take photographs of the Moon, definitely at
>>> "infinity," and I'd like to know if "auto" or "Landscape" is the best
>>> mode for that. At some point I may ask how to keep the full Moon from
>>> overexposing itself, but I'm trying to work that one out on my own
>>> right now.
>>>
>>> I ask because the auto focus doesn't always focus on what I want to
>>> capture and I frequently don't have the time to try to coax it into
>>> automatically locking onto what I want to get a shot of.
>> Now that you've gotten some theoretical answers, I'll try to give you a
>> practical one. If your zoom is set to wide angle, you can safely use 50 -
>> 100 feet as "Infinity". As you zoom toward the telephoto end, you need to
>> think in terms of 200 feet or more. As the other posts implied, you can
>> calculate the "exact" distance to focus on, but you don't always have a
>> calculator and formulas handy. Do some test shots and examine the results
>> for sharpness and you will soon get a practical idea of where to set the
>> focus.
>
> Okay, thanks. I should probably reiterate that what I'm using is a
> Canon A580 point and shoot camera. The lens says "5.8-23.2 mm
> 1:2.6-5.5" and I can get up to 4x zoom on it.
>
> So if I don't zoom at all I should figure that something between 50
> and 100 feet would be infinity? And 100 feet would pretty definitely
> be infinity, then, right? And if I zoom at something distant then at
> 4x I should expect the infinity to be 200+ feet?
>
>> As for full moon exposure, remember that the full moon is lighted by by the
>> sun, so basically, you use the same exposure as a sunlit landscape on
>> earth - maybe a half-stop more.
>
> Oh, thanks, I hadn't thought of it that way! With this camera I don't
> have a lot of control, even in the "manual" mode. I can play with the
> exposure a little bit but it never compensates enough to keep the full
> Moon from just burning a white spot.

I didn't believe you but it seems true

http://www.steves-digicams.com/2008_reviews/canon_a580.html
# Auto, Easy, Camera M and 12 Pre-programmed creative scene modes for
beginners
# Exposure compensation: ±2EV in 1/3-step increments

Camera M does sound like a Manual mode in quotes and 2 stops exposure
compensation might not be enough...


>> Again, experiment. Keep in mind that as the
>> moon goes toward crescent, you will have to increase your exposure. There
>> are some good charts online if you give Google a whirl.
>
> I've found that I can just about get some decent shots of the crescent
> Moon if the sky's light enough. The problem is that the camera is
> seeing half a degree of lit up Moon amid a lot more dark sky. This
> particular camera doesn't seem to have a way to set things in real
> detail. OTOH I can grab shots fast. I'm just trying to find a way to
> get more things at a distance in focus and the "Landscape" mode seems
> to be a way of doing that.
>
>> Good luck!
>
> Thanks, I'll need it.


--
Paul Furman
www.edgehill.net
www.baynatives.com

all google groups messages filtered due to spam

On Fri, 06 Mar 2009 20:18:09 -0800, Paul Furman
wrote:
>....
>I didn't believe you but it seems true
>
>http://www.steves-digicams.com/2008_reviews/canon_a580.html
># Auto, Easy, Camera M and 12 Pre-programmed creative scene modes for
>beginners
># Exposure compensation: ±2EV in 1/3-step increments
>
>Camera M does sound like a Manual mode in quotes and 2 stops exposure
>compensation might not be enough...

Yeah, it's not. Other things aren't either. It's a useful camera, but
it's also pretty frustrating at times when I know what I need to do in
order to get a shot but the camera just won't do it.