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[OM] Re: Long exposure capability of OM2n

Subject: [OM] Re: Long exposure capability of OM2n
From: Fernando Gonzalez Gentile <fgnzalez@xxxxxxxxxxxxx>
Date: Wed, 19 May 2004 10:03:54 -0300
on 19/05/2004 05:17, Carlos J. Santisteban Salinas at cjss@xxxxxxxxxxxxx
wrote:

>> My observation is that with MC lenses, exposures are longer, contrary to the
>> belief  that multicoated lenses transmit more light.
For a moment I thought a red diode woud be less readable by the SBCs due to
the green coating of the MCs. A green one might be seen better. Of course
this would be assuming that an MC lens works like a green filter, nonsense.
> 
> A possible reason would be the light scattering (?) caused by the higher
> reflections on the SC glass -- *maybe* such a puntual light source is
> somehow 'less detectable' than a slightly spreaded one.
Let alone the G.Zuiko I have, it's very flare prone so light scattering
might be also. I have some beautifully underexposed flared pictures. Wish I
could show you my latest.
> 
> However, exposure variation from SC to MC, according to these tests, is
> *negligible*: the higher difference in the same batch was 1/4th of a stop,
> and all the rest were around 1/6th of a stop -- the ISO speed of different
> batches of the *same* film may differ up to 1/3th of a stop, a higher
> difference than all of Fernando's results.
Yes they are.
> 
> Most important, if the slides are coming back OK, just don't worry about
> the meter ;-)
> 
> Oh, a few words about reciprocity failure... this has a noticeable effect
> on 'classic' films (most B&W, for instance) although not that terrible. But
> several modern films (Kodak E200, Fuji Sensia 400) have almost *no*
> reciprocity failure at all -- at least within exposure times up to a few
> minutes, as the OM's can manage.
Sometimes yes, sometimes no. IMHO, P100F behaves as you say, but a difficult
late night shot I did w/velvia 50 came out right @ +1.
W/ Ektachrome 100, star trails come up very colorful on a black sky @ +2, f
5.6.
E200-135 can't be found here but I know this is why astrophotogs prefer it,
haven't tried Sensia400.

My rules of thumb on compensation are for my OM2, might not be applicable to
the 2n. 

/F.


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