Stop down isn't part of focus except that it lets you see the depth of
field at a given focus at a specific f stop. In older cameras (eg:
Pentax screwmounts) when you adjusted the fstop the image always
darkened or lightened as the lense did not have the automation that
current ones do have. And you are right when the aperature is stopped
down it becomes somewhat more difficult to focus, but then thats what
was lived with with those cameras. Good focus screens also helped a
great deal.
On Jan 25, 2005, at 10:16, Matthew Born wrote:
> Thanks, folks. I appreciate the info. So I take it the 'trick' with the
> manual tubes is to open up for focusing, so as to brighten the
> viewfinder as
> much as possible, and then set the aperature? I was (am) confused by
> the
> expression 'stop down' focusing -- wouldn't closing down the aperature
> make
> focusing harder? Am I missing something painfully obvious here?
>
> And no worries about the zoom -- zooms don't interest me anyway. In
> fact, I
> just looked long and hard to find a tiny, p&s digicam for my wife for
> Christmas -- looking specifically for one that did not have a zoom. I
> figure
> in that price range a zoom would really stink. (I found a Samsung with
> a
> fixed 40mm (equivalent) that does a decent job.)
>
> I'll probably aim for a 50 3.5 eventually. I've had a few good offers
> from
> listers already, though I am indeed spending money I don't have right
> now,
> so it's just winter fun for the mind. Perhaps when I get paid for the
> last
> web site I did :)
>
> Matthew Born
>
> On 1/24/05 9:33 PM, "Listar" <listar@xxxxxxxxxx> wrote:
>
>> It works differently on the manual tubes - as you stop down, so
>> the viewfinder image gets even darker (the side effect of the
>> extension
>> tubes is that the viewfinder image is darker anyway).
>
>
>> Don't be fooled by lens manugacturers describing their Superwizz
>> 28-500 f/8
>> zoom as a macro lens. Whatthey mean is that it will focus closer
>> than Brand
>> X 70-210!
>
>
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