Decent exposure
---------------
I wrote previously[1] about shooting film in
manual mode without a lightmeter. I really
enjoyed the process, want to do more of it
and really get good at estimating exposure
with nothing other than my eye and brain.
For the last roll I put through my Spotmatic,
for each shot I set the camera to my best
guess and then check with the meter before
taking the shot. I definitely got better
toward the end of the roll. At some point I
told myself that I should stop checking and
go with my instincts, but I was very rarely
able to overcome the temptation. I think I'm
going to take the battery out for the next
roll so I have no choiced but to trust my
gut, like when shooting my FED.
Part of getting better throughout this last
Spotmatic roll was just experience, but a big
part was lots of reading and study. This
post is my effort to share some of what I
learned but also systematise some of the
things I think I've figured out for myself,
just to help clarify my own understanding.
I'm going to propose an alternative set of
rules of thumbs to the traditionally Sunny
16. I want to emphasise that I haven't
actually tested these rules yet. I'm going
to with my next few rolls. For now they're
just ideas. They are nothing radical, they
are 90% the result of applying standard
exposure arithmetic to the traditional
recommendations to come up with a system that
makes more sense for me, based on my style of
photography.
The classic rule-of-thumb for manual shooting
is the so-called "Sunny 16 rule"[2], which
tells you that on a sunny day you can get a
correct exposure by setting your aperture to
f/16 and your shutter speed to the value that
is closest to the reciprocal of your film
speed, e.g. 1/125 for ISO 100, 1/500 for ISO
400, whatever. Of course you don't have to
actually shoot at that setting, but it's a
starting point for adjustments, e.g. instead
of f/16 at 1/500 you could shoot f/22 at
1/250 or f/11 at 1/1000.
All well and good, but what do you do in the
not uncommon situation when it's not actually
sunny? Obviously if it's less than sunny
you'll need to expose for longer, and/or open
the aperture wider, but by how much? After
shooting semi-automatic modes on cameras with
built-in meters for years, I have very little
intuition about judging how many stops darker
than "sunny" a given situation is.
With a little searching I came across an
expanded version of the rule, which offered
recommended apertures for various other
weather conditions. They are:
Light Aperture
----- --------
Sunny f/16
Slight overcast f/11
Overcast f/8
Heavy overcast f/5.6
Sunset f/4
To some extent, this doesn't help too much.
It just replaces the problem of guessing "is
this light two or three stops weaker than
sunny?" with the problem of guessing "is this
weather *heavy* overcast or just ordinary
overcast?". It's not totally useless,
though, it's informative just to know that
there are about four stops of exposure
between the brightest and dimmest levels of
sunlight. More detailed guides to using this
rule (which, by the way, are rarer than you
might hope - the vast majority of online
articles about the Sunny 16 rule are written
for people, and maybe even by people, who
don't even understand the basic idea of the
exposure triangle!) have made this a bit
easier to judge by describing typical
shadows. When it's "heavily" overcast, no
shadows are visible, when it's "normally",
shadows are faintly visible, when it's
"slightly" overcast shadows are clearly
visible but have soft edges and when it's
"sunny" shadows have clear, solid edges. I
like this advice, it removes some guess work.
One thing I don't so much like about this
extended Sunny 16 rule is that it's stated
in what we might think of as "shutter
priority" format: as the lighting conditions
change, you keep your shutter speed fixed at
1/ISO and change your aperture to let in
more/less light.
I understand *why* the rule is formulated
this way: it's easy to state one rule which
applies for all film speeds when you link
film speed to shutter speed, because film
speed and shutter speed both vary linearly
with amount of exposure, whereas aperture
f-stops have that pesky sqrt(2) factor in
there. So, the rule more or less has to be
stated this way for the sake of generality.
Fair enough.
But as an actual table of settings to study,
memorise and use in the field when shooting,
this makes very little sense for most people,
or at least for me. Shutter priority is for
sports photographers! If you are
photographing mostly stationary things, then
shutter speed makes very little difference
to how the resulting photo will look - any
two speeds fast enough to avoid camera shake
are identical. In contrast, aperture can
have a dramatic effect on the result. It
determines depth of field, and also
influences image quality; Most lenses give
their best results around f/8 or f/5.6, and
suffer increasingly worse problems
(diffraction, soft edges, vignetting,
chromatic aberations) as you push them to
either extreme.
I think it makes much more practical sense to
try to memorise an "aperture priority" table
of rule-of-thumb expoures. Yes, a table like
this is ISO-specific, but plenty of people
only shoot one film stock anyway, and I get
the impression that few routinely shoot more
than two speeds. Let's convert the extended
Sunny 16 table above into a table for
shooting ISO 400 film, which I would say is
the mostly likely candidate for a general
purpose film speed, and at f/8, which is
again a typical "general purpose" aperture
("f/8 and be there", as they say) at which
most lenses will perform well, DoF is wide
enough that you have some margin of error for
focussing, etc.:
Light Shutter @ ISO 400 f/8
----- ---------------------
Sunny 1/2000
Slight overcast 1/1000
Overcast 1/500
Heavy overcast 1/250
Sunset 1/125
Well, that's not ideal, is it? Shooting on a
sunny day requires a shutter speed of 1/2000.
Most classic film cameras from the 60s or 70s,
or at least the Japanese SLRs that I'm most
drawn to, have maximum shutter speeds of
1/1000, or sometimes even 1/500. According
to this table, they're unusable at f/8 until
the clouds roll in.
For this reason, ISO 400 film is actually a
touch fast, IMHO, to really be considered a
good general purpose film. ISO 200 honestly
seems better, and while ISO 200 film exists,
there is a much wider range of stock at ISO
400 and ISO 100 (or roughly 100 anyway, for
whatever reason manfacturers seem to like
producing just slightly faster films, e.g.
Ilford FP4 is rated at ISO 125 and Kodak make
Portra in ISO 160), and those speeds have
much better availability both online and
offline than ISO 200.
So, what do we do? Well, personally, almost
all my cameras can do 1/1000 and I'd be
reluctant to acquire any more which can't.
So, one option for me is to deliberately
overexpose every shot by one stop, yielding
this table:
Light Shutter @ ISO 400 f/8
----- ---------------------
Sunny 1/1000 +1
Slight overcast 1/500 +1
Overcast 1/250 +1
Heavy overcast 1/125 +1
Sunset 1/60 +1
Now, this is a very practical table! Every
shutter speed which is fast enough to be shot
handheld with a 50mm lens with no risk of
blurring is used, and it lets me shoot in any
daylight condition outdoors at a very nice
aperture of f/8. Of course, sometimes I
might want to use something other than f/8,
but in those cases I will usually only want
to move one or two stops away from this
table, whereas the traditional extended Sunny
16 table is likely to have the reference
point for a given lighting condition much
further away from what I want. But, this
nice table has come at the cost of +1
overexposure across the board. How do I feel
about that?
Well, not fantastic to be honest, but I don't
doubt that it will yield workable results.
Modern film stocks have quite wide exposure
latitutde and tolerate overexposure better
than underexposure. In fact, quite a lot of
people online think that a lot of films look
*better* when a little overexposed and so add
half or a full stop, even when shooting
automatic or semi-automatic with a light
meter. Personally, I'm not at all convinced
that I know better than the big film
companies with expensive measuring equipment
and decades of careful calibration
experience, and I think a lot of the talk in
forums etc. about routine overexposure is
because people like to feel special by not
shooting at "box speed" like the masses but
instead applying their own secret adjustment.
But I admit I could be wrong about this, and
at the end of the day, the web is full of
pages showing the same photo taken on various
film stocks at box speed plus one or two
stops over or under, and I can't deny that
one stop of overexposure, even if not
necessarily *better* looking, certainly does
not look bad and is very, very usable.
Certainly, it looks better than an equivalent
amount under exposure. So, I think it's a
perfectly decent price to pay for a very
practical rule-of-thumb table for shooting
without a light meter.
Before going any further, I'll say that the
table above for ISO 400 film shot at f/8 with
one stop of overexposure also applies, as-is,
to ISO 100 film shot at f/5.6 with the
recommended exposure. f/5.6 generally still
seems to be within the "sweet spot" of image
quality for most good lenses, and the DoF is
still very workable, so by just remembering
to do one adjustment of aperture you can use
one set of light-to-shutter-speed mappings
for the two most common types of film. Heck,
keeping in mind that this whole thing is just
a rule of thumb and not an exercise in
precision, and also remembering the wide
exposure latitude of modern films, I might
even offer this: if your lens allows
half-stop adjustment of aperture, set it
*between* f/8 and f/5.6 and then use the
table above for ISO 100, 200 or 400! You'll
be underexposing by half a stop compared to
Sunny 16 if you're shooting at ISO 100
(although not if you're shooting FP4 or
Portra 160!), overexposing by half a stop at
ISO 200, and overexposing by 1.5 stops at
ISO 400. None of these should be
disasterous, and then you can use one table
of values for any film speed that's commonly
encountered today. Nice! For the rest of
the post, though, I'll continue talking about
ISO 400 at f/8 with one stop of overexposure.
So, the extended Sunny 16 rule, which we've
now converted to a more useful aperture
priority format, covers typical outdoor
daylight shooting conditions, which
admittedly covers a lot of my photography.
But it doesn't help you out at all if you
want to shoot indoors, or at night, or during
the day but in deeply shaded areas like a
forest. To get a feel for how to work in
these conditions, you need to to graduate
from describing your light in weather
forecasting terms to using Light Value (LV)
numbers[3,4,5].
The LV system is a way of assigning numbers
to the amount of light reaching your camera
from a subject. LV0 is defined as the amount
of light which would require an exposure time
of 1 second at f/1 for ISO 100 film. An
increase or decrease of LV by 1 corresponds
to one stop more or less light. The "sunny"
condition in the Sunny 16 rule correspond to
LV15. The three resources linked above have
tables full of approximate LV values for a
range of different indoor and outdoor
lighting conditions and subjects, and I've
found them really valuable. There is far too
much information in them to remember
completely, but you can easily extract some
useful things to remember, e.g. typical
indoor lighting is 9 stops dimmer than
"sunny" outdoors - there's no use in actually
memorising the absolute LV values. Something
I really like about the table at Ken
Rockwell's site is that it recognises that
the amount of light on e.g. typically
overcast days varies by latitude. His table
has entries for "California bright overcast"
and also "Dark, dreary overcast day in
Boston, London or Paris". The dark and
dreary days in relatively Northern cities are
actually one stop darker than the "sunset"
condition of the Sunny 16 rule (which
presumably is sunset on a clear day), and
I've definitely had days here in the past
month which my Spotmatic metered at about
this level. So contrary to what I said
earlier, I actually now think of there as
being a five stop range of brightness in
outdoor natural light, depending on the
weather.
The table below extends my earlier "aperture
priority Sunny 16 for ISO 400 at f/8" table
below the "sunset" condition all the way
down to LV0. The settings it shows for ISO
400 are derived according to the following
strategy: keep aperture at f/8 for as long
as possible, using longer shutter speeds to
compensate for decreasing light. Once
shutter speed hits 1/60, start opening up
the aperture to let more light in instead,
so that handheld shooting remains viable
as long as possible. Once aperture hits
f/1.4, which is already in the realm of rare
and expensive fast glass, finally start
decreasing shutter speed to 1/30 and lower.
But beyond 1/15 (which some people claim can
be shot handheld with a 50mm lens if you are
careful, who knows if they're just
bragging), just start to accept the
inevitable underexposure as being preferable
to badly blurred shots.
LV ISO 400 settings
-- ----------------
15 (sunny) 1/1000 f/8 +1
14 (slight overcast) 1/500 f/8 +1
13 (overcast) 1/250 f/8 +1
12 (heavy overcast) 1/125 f/8 +1
11 (sunset, deep shade) 1/60 f/8 +1
10 (dark and dreary) 1/60 f/8
9 1/60 f/5.6
8 (bright office) 1/60 f/4
7 (typical indoors) 1/60 f/2.8
6 (dim home) 1/60 f/2
5 1/60 f/1.4
4 1/30 f/1.4
3 (bright night street)1/15 f/1.4
2 (typical night st.) 1/15 f/1.4 -1
1 (dark outdoors) 1/15 f/1.4 -2
0 1/15 f/1.4 -3
I didn't bother coming up with this table
because I plan to actually memorise and use
it as a guide - that's not really practical.
I did it because I wanted to get a better
feel for what sort of practical limits are
imposed on your shooting by certain film and
lens speeds, if you follow common sense
principles. An important take away, for me,
is that if you are only planning to shoot
outdoors while the sun is up then you are
*absolutely* just fine and dandy using ISO
100 film (which everyone knows is "slow
film") and a lens with maximum aperture of
f/3.5 or f/2.8 (which, again, everyone knows
is "slow glass"). With ISO 100 and f/2.8
you'll be able to shoot handheld when it's
"dark and dreary" without even using your
lens' fastest setting. You really only need
ISO 400 if you plan to shoot indoors
(something that photography has really
opened my eyes to, if you'll pardon the pun,
is how amazingly adaptable the human eye is
to different levels of light. Who'd have
thought the light in a typically lit home was
*five hundred and twelve* times dimmer than a
sunny day outside?!). And you really should
only bother chasing fast lenses if what you
acually want is extremely narrow depth of
field and crazy bokeh effects during the day;
any realistically specced lens is seriously
struggling to be shootable handheld outdoors
at night at ISO 400, whilst indoors even f/2
is probably enough. You'll pay more to go
from f/2 to f/1.8 or f/1.7, and then a lot
more to go to f/1.4, and a whole lot more to
get to f/1.2. But you're only getting
fractions of a stop more with each upgrade,
when several whole stops are what you would
actually need. Faster film, or push
processing, are really the only viable
options for handheld night shooting. Or
flash, of course, but I know next to nothing
about flash photography, so can't really say
anything about that.
I'm really excited to try shooting a roll
without a meter using nothing but my aperture
priority version of the Sunny 16 rule for ISO
400 with one stop of overexposure. I'm
hoping it will let me shoot manually much
faster than the traditional Sunny 16 rule,
which usually has me working in two steps:
first adjusting from the "sunny 16" anchor
point to somewhere else, based on the
lighting, and then shifting from *that* point
to one that gives me a more usable aperture
value.
[1] gopher://zaibatsu.circumlunar.space:70/0/~solderpunk/phlog/look-ma-no-lightmeter.txt
[2] https://en.wikipedia.org/wiki/Sunny_16_rule
[3] https://en.wikipedia.org/wiki/Exposure_value
[4] https://kenrockwell.com/tech/ev.htm
[5] http://www.fredparker.com/ultexp1.htm