Hi Dado, Fernando, Andrew and all.
From: "Dado dela Cruz" <dado@xxxxxxxxxxxxxxxxxxxxxxxx>
>
>Kumusta* Carlos!
[snip]
>*Filipino word for How are you
It's funny how much it resembles the equivalent spanish expression 'Como
estas' (sorry for the lack of diacritical marks ;-)
>The explanation on "why the longer exposure for MC
>lenses seems very logical.
Thanks, but that's just a conjecture. I think that a LED glowing in the
dark should be something really *tough* to meter by any camera, plus the
LED itself has a lens built in, making noticeable brightness changes
depending on the viewing angle -- unless both cameras and the LED were
*exactly* at the same place in all tests, Fernando's results would be
useless (lo siento ;-)
From: Andrew L Wendelborn <andrew@xxxxxxxxxxxxxxxxxx>
>
>Out of curiosity, I just tested a 2n. Body cap on, black bag over viewfinder.
>Shutter closed at 3m20s. Will try the other 2n when its film is finished.
Mine did about 3 min. I've got another OM-2n (which badly needs a CLA) that
closes at 3m23s.
The 'plain' 2 max. exposure time depends on the ASA setting. I've tested
33s @ 1600, a bit more than a minute @ 400 and well over 5 min @ 100, IIRC
-- I don't want to burn a nice pair of 357s ;-)
From: Fernando Gonzalez Gentile <fgnzalez@xxxxxxxxxxxxx>
>
>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.
I don't think the coating would act like a filter. And, even if it would,
don't forget that the typical green MC reflections come from the *rejected*
light *over* the lens surface (not from the light *thru* the glass), thus
in extreme cases it would act like a pinkish filter.
>> 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.
I have almost no experience with Velvia -- the only roll I've shot of it
has no long exposures.
>W/ Ektachrome 100, star trails come up very colorful on a black sky @ +2, f
>5.6.
Star images should be less affected by reciprocity failure, and *accurate*
exposure calculation is quite difficult: the actual focal length *does*
matter here, not just f/stop, exposure time and film speed.
>E200-135 can't be found here but I know this is why astrophotogs prefer it,
>haven't tried Sensia400.
E200 makes beautiful astro pictures, but Sensia 400 is faster and cheaper
;-) Another good thing of the E200 (for astropics) is its excellent
response to H-alpha wavelength (656 nm), which corresponds to the typical
red glow of emission nebulae -- spectacularly rendered by E200.
>My rules of thumb on compensation are for my OM2, might not be applicable to
>the 2n.
I have no reason to believe they would be different, besides maximum
exposure time versus film speed (constant on the 2n, variable on the 2)
However, I *suspect* that later models (OM-4/Ti, and maybe OM-2S too) have
some kind of 'reciprocity failure compensation' device. I think this didn't
work OK on my now sold OM-4 -- when exposure times in auto should be
slightly longer than approx. 45 sec, it went all the way to 3 min!
From: "Dado dela Cruz" <dado@xxxxxxxxxxxxxxxxxxxxxxxx>
>
>Hola Carlos!
>
>I'm interested to see your "long exposure" pictures. Can you show some?
Sure... <http://cjss.galeon.com/zuiko/astro/index.html>. Sorry for the poor
quality of my scanner :-(
From: Fernando Gonzalez Gentile <fgnzalez@xxxxxxxxxxxxx>
>
>I have posted a Provia 100F w/o compensation of abot 4 minutes exposure at
>TOPE Landmarks. Some opinions about color shift were posted there.
I don't think a single scanned pic is a valid reference to evaluate
reciprocity failure. Much better would be a series of pics of the same
scene & lighting, with different exposure times (and apertures, to
compensate). For instance, if auto exposure @ f/1.4 is 1 second, @ f/16
that would be about 2 minutes. Add a ND filter and you may get a much
larger range of times.
Enjoy,
...
Carlos J. Santisteban
<cjss@xxxxxxxxxxxxx>
<http://cjss.galeon.com>
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