1/3 Stop (Kodachrome, Ektachrome and 1/3 stop II)
Colin Kee Lin Wong
To those of you who replied to the newsletter "Kodachrome, Ektachrome
and a 1/3 stop", thank you. Let me first say that the response was warm and
encouraging. However, I may have made a mistake in clarity in one of my
questions. It pertains to 1/3 stop.
Let me rephrase it again. I am using the Nikon N6006 with a built-in
spot meter. The time is noon. The sky is blue and cloudless. I am using
Kodachrome 64. However, I decide to change the ISO to 80 as I've been told it
would saturate the film. Here's the situation.
1. I spot on the northern sky at 45 degrees. Exposure: 1/60 f16
2. I changed ISO to 100. Spot again at sky. Exposure: 1/60 f16
3. I changed the ISO to 120. Spot again. Exposure: 1/60 f16
My question. The camera gives me a reading of 1/60 f16 on all three
occasions. I am using shutter priority program. Now this is where the confusion
is. Does the camera ACTUALLY perform a shutter speed of 1/60 and f16? OR...
Does it perform step 1/3 stop toward underexposure by slightly altering either
the aperture or the shutter speed, even though the camera says otherwise?
People say changing the ISO from 64 to 80 will saturate the colors.
But if the camera does indeed give an accurate 1/60 f16. Changing the ISO will
only skew the exposure towards 1/60 f22. And if there's enough skewing the
camera will physically change to f22. Otherwise, if the skewing is not enough
it will still stay at f16. This is the first scenario.
The second scenario. Camera may tell you one thing, but it does
something else on the other hand. LCD may display 1/60 f16, but because of
the change in ISO, it may actually be f18 or f20, by the 1/3 stop. That is,
as one of you guys said, a continuous step change according to the ISO.
I have got an equal number of responses that favor the first scenario
with those who favor the second scenario. So AGAIN, What gives?
Colin Wong
InterNet: ckw...@uokmax.ecn.uoknor.edu
David Rounds
: Let me rephrase it again. I am using the Nikon N6006 with a built-in
: spot meter. The time is noon. The sky is blue and cloudless. I am using
: Kodachrome 64. However, I decide to change the ISO to 80 as I've been told it
: would saturate the film. Here's the situation.
:
: 1. I spot on the northern sky at 45 degrees. Exposure: 1/60 f16
:
: 2. I changed ISO to 100. Spot again at sky. Exposure: 1/60 f16
:
: 3. I changed the ISO to 120. Spot again. Exposure: 1/60 f16
:
:
: My question. The camera gives me a reading of 1/60 f16 on all three
: occasions. I am using shutter priority program. Now this is where the confusion
: is. Does the camera ACTUALLY perform a shutter speed of 1/60 and f16? OR...
: Does it perform step 1/3 stop toward underexposure by slightly altering either
: the aperture or the shutter speed, even though the camera says otherwise?
According to the N6006 instruction manual, the exposure can be adjusted in
one EV (1 stop) steps in Shutter-Priority and Manual modes and will be
steplessly adjusted between 1/2000 and 1/30 in Programmed-Auto and
Aperture-Priority-Auto modes. Therefore, all three examples will use
exactly the same exposure but if you switched to either P, Pm or A modes,
there would be a difference even though the meter may not show it.
When I first got the N6006 I did a couple of test rolls and noticed that
I could see definite differences in some of the series shots where I had
used different metering modes (matrix, CWA or spot), even thought my logbook
showed that the indicated speed and aperture were the same (all in Pm mode).
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David R. Rounds | ...!uunet!bcco!dave
Barber-Colman Co. | da...@bcco.com
Loves Park IL | (815) 877-0241 x3945
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The views presented here are the author's and do not reflect an official
position of my employer or of any other party.
Tim Conrow
>pa...@hacks.arizona.edu (Paul Frankenstein, M.D.) writes:
>
>>In article <911113014...@fozzie.nrl.navy.mil>, phil...@FOZZIE.NRL.NAVY.MIL (Lee Phillips) writes...
>>To the best of my (limited) knowledge, Nikon (his camera is a Nikon 6006) has
>>never had any lenses or cameras that could "indicate" anything between stops.
>
>As a piece of info, the F4s will show 1/3 stop increments when used in
>manual mode. Now, if you could only change the exposure by 1/3 stops in
>manual mode.....
Can't you? Won't exposure compensation do this in manual mode? Or
overiding the ISO setting? The exposure compensation dial allows 1/3
stop increments, doesn't it work as expected in manual mode? My 8008s
manual is at home, I can't check, but I'd be very surprised if this
didn't work. The compensation bar graph, when added to the shutter or
f-stop settings, also indirectly indicates the exposure to the same
precision.
In non-manual modes, presumably (untested) one could read the
displayed settings (rounded to 1 stop), manually set them in manual
mode and see how far off of exact exposure the setting is (using the
meter bar graph) to 1/3 stop precision. A pain, I agree, but would it
work? The assumption is that the automatically metered exposure is the
same as that indicated by the zero point of the exposure bar graph in
manual mode. True?
-- Tim Conrow t...@ipac.caltech.edu
Carl Madson
Sigh. I had hopes along the same lines, Tim, regarding 1/3-stop control via
exposure compensation (F4S, et al.). What you eventually realize is that M mode
is honest-to-Buddha MANUAL mode, and it shoots exactly what you set on the
aperture and shutter speed controls. Exposure compensation and ISO (same
effect) affect the meter INPUT, but that only changes the ideal exposure that
appears in the readout (as a bar-graph), NOT the true exposure (that which is
set on the controls).
As you surmise, the only method is to select the metering you wish in M mode
and then alter the aperture setting in rough 1/3-stop increments via watching
the bar graph change. This may seem like a reasonable solution, but consider
the situation when you're shooting with strobes and a flashmetered exposure,
and want to put that exposure directly into the camera. Unless the ambient
levels keep your bar-graph within the +-2 stop range of the display, you won't
be able to play the watch-and-adjust game.
Considering you don't even have detents on the lenses at 1/2-stops (a la
Canon), it's amazing pro Nikon types haven't bitched about this more. I shoot
mostly slide film in my F4S, and 1-stop control just doesn't cut it. You can
certainly guesstimate at 1/2-stop apertures, but you shouldn't have to--and
you should have better than 1-stop shutter speed control if you want to do
your bracketing that way (especially since the shutter itself will fire over
the continuous range of speeds). The EOS-1 method of selectable 1/3-stop
control when you want it is great. Maybe on the F5...
--Carl Madson, SRI International, Menlo Park, CA
David Jacobson
t...@nijinsky.ipac.caltech.edu (Tim Conrow) writes regarding
setting aperture and shutter speed on Nikon cameras to 1/3 stop
values:
>Can't you? Won't exposure compensation do this in manual mode? Or
>overiding the ISO setting? The exposure compensation dial allows 1/3
>stop increments, doesn't it work as expected in manual mode?
No, the exposure compensation only affects the meter. In those modes
where there meter affects the exposure, ie program, aperture pri., and
shutter pri., the affected meter then also affects the exposure. But
in manual mode, it only affects the little bar graph.
Think about it, what would the display mean if you had exposure
compensation set? Would it mean the shutter speeds are off by the
compensation amount, or the f/stops are off? That would not be a good
idea. You really want the display to show what is really happening.
You can set the aperture to anything you want in manual mode, since
that is strictly mechanical. But shutter speeds are limited to whole
stops. And all this makes for a rather irksome problem if you want to
use a mirror lens in manual mode---you are stuck with only whole stop
control.
There is one very difficult way to get around it. You can set the
mode to aperture priority, then use the compensation control as a kind
of shutter speed dial. The shutter speed will be seen to change every
3rd click of the compensation. I presume the middle value that
displays a given shutter speed is pretty close to right on, and the
other two are 1/3 over and 1/3 under.
> [stuff deleted]
>The assumption is that the automatically metered exposure is the
>same as that indicated by the zero point of the exposure bar graph in
>manual mode. True?
True.
>-- Tim Conrow t...@ipac.caltech.edu
I wish Nikon had provided for 1/3 stop readout and setting. But in
their wisdom they didn't. Nikon probably figured that amateurs will
use program mode and pros will bracket like crazy, so no one needs it.
-- David Jacobson
Don Smith
I'm trying to follow up on Carl's post with the screwy news system on
this site, excuse the absence of a quote.
Several people have been talking about exp. compensation dials, wether
or not you can set a Nikon lens at +- 1/3 stop increments etc. and
someone wondered why "pro Nikon" types hadn't complained about having 1/2
stop increments on lenses.
Pro's never complained about it because it's really not a question. If
the ideal exp. is supposed to be f/8 then I can bracket in 1/3 stop
increments and clearly see the results in the slides.
If someone is doing some demanding technical work then they just use
ND gels to get that perfect 1/3 stop bracket.
It's like exp. compensation dials. No pro Nikon types ever bitched and
moaned about not having them in 35mm camera's for one very simple reason,
no one ever Fucking Needed them. We still don't.
If you wanted to shoot ASA 64 film at 80 then you just set you meter
for ASA 80. Pretty simple I'd say.
IMHO Nikon et al just put some basic knowledge into a little gizmo so
that the general public and detail oriented people would somehow be
impressed with "progress" instead of spending 5 minutes with a friend who
could explain it to them.
1/3 stop indicator's on Nikon lenses? I've never seen 'em, I've never
had 'em and I don't expect to. I bracket like that all the time and hot
damn, it seems to work for me. <shrug>
Don
d...@polari.UUCP
Carl Madson
reading more than a few articles by pros who found both exposure compensation
and the 1/3-stop controllability of the EOS-1 to be very handy indeed.
I'm sure you also see the difference in your slides when you bracket by
"1/3-stops" -- but without any indicators, how do you really KNOW what your
camera was set at? Granted, you may not care, and the difference may not be
much worth worrying about (say, less than 1/3-stop if you're good at inter-
polating the aperture ring), but that sure as hell isn't very scientific. How
do you guarantee repeatability, for tests or shoots? If, as you say, you can
see the difference in your shots with 1/3-stop variation, wouldn't it be more
useful to have repeatable control at that level of resolution? Isn't repeat-
able success the supposed hallmark of a true 'pro'?
Sure--nobody NEEDED in-camera metering, because they had their Westons. But
I daresay most pros in the field take advantage of TTL metering, and appreciate
its convenience and accuracy. Most old-school types bitched about autofocus,
including and especially pros, but if you took a survey of pros today you'd
certainly find an appreciable percentage (say, 30% or more) who regularly use
and appreciate AF for what it helps them achieve.
Cameras today DO have more bells and whistles than most anyone can rightly use,
including pros and fanatical amateurs. But it's using a broad brush to damn the
inclusion of useful and potentially useful features as ridiculous, simply
because you haven't found a need for them. I thought AF was kind of superfluous
at first, but I gave the later versions a shot and have found them useful. Note
that it's also useful to be able to easily turn such features OFF when you
don't need them.
Yeah, you could use ISO instead of exp. comp. for various shots -- many cameras
(F3 included) make the controls concentric, as they perform the same function.
However, you can add user convenience by separating exp. comp. and alerting
the user that e.c. is being used (say, a light in the viewfinder). I've found
that to be useful, preventing my screwing up the rest of the roll, and I like
to think I'm pretty attentive (a 'pro' mind-set, if you will) when I'm out
shooting.
You can perform some of the 'magic' of an SB-24 by figuring out the fill-flash
exposure yourself, but no pro would call you a hero -- 'stupid' would probably
be closer. Such modern photographic tools facilitate better, more professional
images.
I recall a host of folks calling the Mac a 'toy' initially, for showing pic-
tures instead of providing users with 'what they really need'. Turns out that
thousands of serious, professional users find the Mac/GUI concept to be useful
and preferable to them in doing their work. New approaches come from a willing-
ness to discard the anchors of habit and familiarity, and re-think the overall
goals of any given design and how they might be achieved.
By the way, if you used the ND approach for accurate bracketing, and your meter
said to shoot at 1/60 @ f/8, would you use a +0.1 ND for the underexposure
bracket, and a -0.1 ND (light amplifier) for the overexposure? ;-}
Robert McArthur
[...]
> Several people have been talking about exp. compensation dials, wether
>or not you can set a Nikon lens at +- 1/3 stop increments etc. and
>someone wondered why "pro Nikon" types hadn't complained about having 1/2
>stop increments on lenses.
> If you wanted to shoot ASA 64 film at 80 then you just set you meter
>for ASA 80. Pretty simple I'd say.
Actually, on the FE2 there is a compensation dial from -2 to +2 in 1/3
increments. It is much handier to use than changing ASA since I, at least,
often forget to change the darn thing back... The exposure compensation
on the FE2 turns on a light in the viewer so I know when I'm compensating.
Personally, I hope you enjoy mucking about with gels etc but when walking
for a week, the less I carry the better. Also, usually I don't have the
time to muck about when shooting (landscapes,wilderness or macro for me)
because of variations in the light and subject, to muck about taking off
or putting on filters. It *has* to be on the camera. To me, the dial is
much superior to changing the ASA (having had to do both at various times)
and costs very little (IMHO) to add to a camera. It dosen't need to be
electronic for those (including myself) who prefer a fully manual. etc etc.
Robert
--
Robert McArthur Centre for Resource and Environment Studies
Australian National University
ACSNet r...@arp.anu.oz.au ACT Australia 2601
Pegasus|PeaceNet|EcoNet peg:robert (06) 249 4760