How to read the camera back EV table of the Rolleiflex 3.5E
Steven Woody
the talbe is below,
1 2 3 4 5 6 7 8
------------------------------------
f/22 250 125 60 30 15 8 4 2
f/16 125 60 30 15 8 4 2 1
f/11 60 30 15 8 4 2 1
f/8 30 15 8 4 2 1
f/5.6 15 8 4 2 1
f/4 8 4 2 1
f/3.5 6 3 1.5
f/2.8 4 2 1
i've not managed to find a way to read the table, it looks so confusing
to me.
-
woody
dadiOH
What's so confusing? The top row lists EV values, the column under each
gives the shutter/f-stop combinations for that EV value.
--
dadiOH
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Steven Woody
dadiOH wrote:
> Steven Woody wrote:
> > hi,
> >
> > the talbe is below,
> >
> >
> > 1 2 3 4 5 6 7 8
> > ------------------------------------
> > f/22 250 125 60 30 15 8 4 2
> > f/16 125 60 30 15 8 4 2 1
> > f/11 60 30 15 8 4 2 1
> > f/8 30 15 8 4 2 1
> > f/5.6 15 8 4 2 1
> > f/4 8 4 2 1
> > f/3.5 6 3 1.5
> > f/2.8 4 2 1
> >
> > i've not managed to find a way to read the table, it looks so
> > confusing to me.
>
> What's so confusing? The top row lists EV values, the column under each
> gives the shutter/f-stop combinations for that EV value.
that's just what make me confusing: i think every combinations in each
column should have same EV, but it's not. for example, in column one
(EV=1), ( f/22, 1/250s ) differs with ( f/16, 1/125s ) in the term of
expusure value.
Peter Irwin
> that's just what make me confusing: i think every combinations in each
> column should have same EV, but it's not. for example, in column one
> (EV=1), ( f/22, 1/250s ) differs with ( f/16, 1/125s ) in the term of
> expusure value.
The table on the back of the camera is for exposure times
of one second or longer for exposure values 1 to 8.
Exposure value 1 is 250 seconds at f/22
or 125 seconds at f/16 or a mere 8 seconds at f/4.
Peter.
--
pir...@ktb.net
Steven Woody
oh! i understand, thank you. one more question: what's the Rollei's
formula for EV calculation? i heard, (1s, f/1) = 1(EV), and, in the
case, f/22 is 9 stop smaller compared to f/1, but 250s is 8 stop longer
compared to 1s. there is one stop difference. any idea?
Peter Irwin
>
> oh! i understand, thank you. one more question: what's the Rollei's
> formula for EV calculation? i heard, (1s, f/1) = 1(EV), and, in the
> case, f/22 is 9 stop smaller compared to f/1, but 250s is 8 stop longer
> compared to 1s. there is one stop difference. any idea?
>
The easiest way to figure EV is to think of it
as being the sum of the aperture value (AV) and
the time value (TV).
Value Aperture Time
----- -------- ----
0 f/1 1s
1 f/1.4 1/2s
2 f/2 1/4s
3 f/2.8 1/8s
4 f/4 1/15s
5 f/5.6 1/30s
6 f/8 1/60s
7 f/11 1/125s
8 f/16 1/250s
9 f/22 1/500s
10 f/32 1/1000s
EV = AV + TV so:
1/125s at f/16 is 7+8 or EV15
1/1000s at f/5.6 is 10+5 also EV15
You could try googling:
<http://www.google.ca/search?hl=en&q=apex+system+exposure>
Peter.
--
pir...@ktb.net
dadiOH
Good luck in photography.
dadiOH
I see what you are saying...been a long time since I used my Rolleis and
they don't have that table anyway. Peter Irwin's second post gives you the
straight scoop but the practicality of the system boggles my mind :)
I assume you have the EV numbers on the shutter or aperture setting knobs
and that they will lock so they synchronize. If so, I'd totally ignore the
table and just set the shutter/aperture combo I wanted and then lock the
knobs so that a change in one will change the other. Alternatively, if you
have a meter that reads in EV values, set the aperture/shutter knobs to
reflect the value, lock and then turn either knob to get the shutter speed
or aperture you want.
Q.G. de Bakker
> oh! i understand, thank you. one more question: what's the Rollei's
> formula for EV calculation? i heard, (1s, f/1) = 1(EV), and, in the
> case, f/22 is 9 stop smaller compared to f/1, but 250s is 8 stop longer
> compared to 1s. there is one stop difference. any idea?
EV = log ( (f-number ^ 2) / shutterspeed) / log(2)
"shutterspeed" is the actual duration of the exposure, i.e. 0.008 s for
1/125 s, etc.
So for instance, 250 seconds, at f/22:
EV = log( (22 ^ 2) / 250) / log(2)
= log(484 / 250) / log(2)
= 0.95
Why not 1?
Because of nominal vs real issues.
The true shutterspeed range consists of values that change by factor 2 each
step.
250 seconds isn't part of that range. 256 seconds is.
And the true f-number range consists of values that change by a factor
sqr(2) each step.
f/22 isn't part of that range. f/22.63 is.
Use those real values, and the result is the one expected: "1".
That is: it is very close, because 22.63 is a rounded value. 22.627417 is
the correct one.
;-)
Same, of course, with speeds shorter than 1 second.
1/125 in reality is 1/128 = 0.0078125 sec.
So 1/250 sec at f/22:
= 1/256 = 0.00390625 sec. at f/22.627417
EV = log( (22.627417 ^ 2) / 0.00390625) / log(2)
= 17