Rand wrote:
Set aperture to f8.3 or whatever fraction the shutter speed is off by.
But
you are going to need to test to even know what the shutter is actually
producing speed wise. Its probably not very accurate any more.
On Mar 31, 2014 4:32 AM, "Jonathan Turner" <pictures@xxxxxxxxxxxxxxxxxxx>
shutter speeds and apertures are far from accurate even in brand new modern
camera - t stops were the standard for accuracy.
A time back I tested a whole bunch of cameras and the only things close to
accurate were Pentax K1000's with the old cloth shutter.. their accuracy
across a dozen or so cameras was within 10% of stated speeds. The electric
cameras of the day (Canon T90's, EOS's Minolta and Nikon AF cameras) varied
by as much as 100% from the stated speeds - with a stated speed of 1/2000
and 1/4000 being identical - generally they were out across the full range
between 12-60%
Apertures similarly are far from their stated values in a lot of lenses, and
seemed more guides than anything hard and fast.. and as anyone who's used
an enlarger knows, opening a lens to f5.6 and closing a lens to 5.6 will
produce 2 different apertures. Only a small difference, but if you're
aiming for precision the guide was always either stop down or up, not both.
And of course the marked aperture assumes the lens IS the focal length it
claims to be. a 43mm lens marked as a 50mm with apertures appropriate for a
50mm aint going to be accurate.
So while the shutter speeds may be those odd variants we don't see so much
any more, odds are the OP can treat them as being the same as the more
familiar speeds unless the exposures are way off.
Of course the easy way to test and see for sure is to use the soundcard
(microphone input) on a computer and record the shutter speed for
evaluation.. bearing in mind that leaf shutter speeds are pigish things.
where do you measure the speed? the center of the lens? te edge? if near
the edge are you measuring under an opeing blade or a point where the blade
moves ou the way quickest?
Best bet is in the middle witha diffuser under the lens, then look at the
soundcard output and work from when the lens is allowing about 50% of the
light through to when it's closed of to 50% of the light.., or 30% depending
who you ask =D
Here's two simple shutter speed tester circuits and guides that i just
googled:
http://www.mraggett.co.uk/shuttertester/shuttertester.htm
http://www.willegal.net/photo/repair/shuttertester.htm
To repeat what others have said however, neg film won't just tolerate longer
exposures but will give you better images if 'over' exposed - increased
density gets you off the toe of the film's sensitivity and colours will
definately be more saturated.
I recently bought an old large format field camera that came with a lens
which is so old it has shutter speeds that don't correspond with my light
meter; it has 5th, 10th, 25th, 50th, 100th, 200th, instead of the normal
shutter speeds (8th, 15th, 30th, 60th etc.)
So my problem is trying to work out what the correct exposure should
be...working from my meter. I'm shooting colour negative, so I'm guessing
it can take a bit of latitude either way, but can't quite work out if I
should go with an exposure that is slightly over, or slightly under what
the meter says. For example, if my meter reading is F8/125th, should I
shoot at F8/100th, or F8/200th?
f8 1/100
5th, treat as 1/4
10th " 1/8
1/25th " 1/30
1/50th " 1/60
100th " 1/125
1/200th " 1/250
k
