Olympus-OM
[Top] [All Lists]

Re: [OM] OM-2N questions

Subject: Re: [OM] OM-2N questions
From: "c.e.packard" <packardc@xxxxxxxxxx>
Date: Mon, 01 Jan 2001 15:36:41 -0600
It seems that there is an autolimiter circuit designed to close the
shutter after a time in order to conserve the batteries.
The manual states under the section 'Automatic Exposure Control' -
"Your OM-2 provides for automatic exposures from 1 second to 120 seconds
(with ASA 100 at normal tempurature and humidity)...". This seems
consitent with the opertaion of my OM-2(n)s with the lens cap, on the
viewfinder blocked and the shutter set to "B" and the camera switched to
"AUTO".
Under the section "Manual Exposure Control" It does state explictly that
the "B" (bulb) setting is not connect to the exposure control. This
tells me that the shutter will stay open as long as the shutter release
is depressed.
Below is a portion of the thread I mentioned which talked about this
subject.
Charles Packard

An excerpt from a thread titled "Auto Exposure Times & The Ideal Meteor
Catcher" 1999 archives
David [Haynie] wrote:

> It's really based on measured EV rating, I think, rather than time. So

> you'll get longer exposures with slower film, at least within some
> limits, and of course, this doesn't take into account reciprocity
> failure. Here's the specs I have:
>
>       OM-2     60sec @ ASA100 (approx -5 EV)
>       OM-2n   120sec @ ASA100 (approx -6 EV)
>       OM-2sp  120sec @ ASA100 (approx -6 EV)
>       OM-4    240sec @ ASA100 (approx -7 EV)
>       OM-4Ti  240sec @ ASA100 (approx -7 EV)

I did some tests with my OM-2n and got the following results using a
body
cap (ie. no light):

ISO 100         3 Min 48 Sec
ISO 1600                3 Min 44 Sec
ISO 25          3 Min 48 Sec

The thing to keep in mind is that even though it gives you a long
exposure
there is no guarantee of the accuracy.  My guess is that with very low
light
levels, leakage currents within the exposure/timing circuit probably
have a
major contribution in determining the actual length of the exposure.
Perhaps the "spec" is the longest exposure for which the exposure/timing

circuits are reasonably accurate.

>
> None of the amature series OMs need apply (they're around around 0EV,
> maybe 2sec at ASA100).

I got the following results with my OM-10

ISO 100         8 Sec
ISO 1600                <2 Sec
ISO 25          26 Sec

Wayne Harridge




< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >


<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz