The difference between Exposure comp and changing the ISO of the film???

stradibarrius · Dec 16, 2010

If I wanted to "push" a 400 ISO film to 800, for example, is it correct that I could do this in one of three ways??
1. I could mentally adjust the exposure I see on the meter to one stop faster
2. I could change the ISO setting on the camera from 400 to 800
3. I could dial in 1 stop of exposure compensation

Are these three methods correct?
Is there any difference in the outcome of the negative?

I know this sounds like a very basic question and I guess it is, but I never use Exp. Comp. and I wonder why???

cowanw · Dec 16, 2010

Actually there are onlt two ways.
1 change the shutter speed
2 change the aperture.
The iso and the compensation choose how to do this for you.

tkamiya · Dec 16, 2010

Pushing one stop simply means the combination of aperture and shutter speed results in HALF the exposure - so any method that will achieve this will do that.

1. that will be one stop SLOWER. You want LESS light - not more
2. Yup
3. you will dial 1 stop MINUS exposure compensation

The results will be identical.

Which method will work the best depends on your camera and metering method. If you have any type of automation such as aperture priority or shutter speed priority, changing one or the other will be immediately compensated by moving the other in opposite direction resulting in no net change.

Rol_Lei Nut · Dec 16, 2010

All three methods will work and give the same result, but you're probably better off just changing the ISO setting (also to remind yourself how you exposed your film).

The exposure compensation is usually better used for adjusting the exposure in particular situations (backlight, for example).

Mentally adjusting is always good, but changing the ISO setting just makes things simpler (save mental adjustments for adapting to each scene)...

Les Sarile · Dec 16, 2010

You're correct. And of course the outcome results in the whole scene being 1 stop underexposed. If you "push process" the whole roll, it will develop to "normal" exposure and not 1 stop underexposed. Generally speaking, all negatives can withstand better then 3 stops overexposure and 2 stops underexposure so you may not even notice the difference after normal box speed processing depending on how you get your final results.

23mjm · Dec 16, 2010

I am only speaking about roll film---but my way of thinking is;

Changing the ISO--tends to be a global change--I will set the ISO for the whole roll of film.

Exposure Comp--Is a local change I make to a frame to account for lighting conditions at the time of shooting the frame.

But in the end it is what you are comfortable doing and use a system that works for you. There is no right answer.

stradibarrius · Dec 16, 2010

Rol_Lei Nut said:
All three methods will work and give the same result, but you're probably better off just changing the ISO setting (also to remind yourself how you exposed your film).

The exposure compensation is usually better used for adjusting the exposure in particular situations (backlight, for example).

Mentally adjusting is always good, but changing the ISO setting just makes things simpler (save mental adjustments for adapting to each scene)...

That is what I was thinking. setting the ISO in the camera is the simplest way and using the Exp. Comp dial is used for when the scene, calls for it. The "mental" method seems to be the most difficult and potential mistake laden method.

The whole point of this question is Ralph Gibson says that he overexposes , "pulls" I guess, and over develops, to get his high contrast grainy look. I am going to shoot a few rolls using his method and see what I come up with. I just wanted to get the method straight in my head.

So correct me if I am wrong but if I load Tri-X400, set my ISO for 200 then I am "pulling", over exposing the film one stop. To over develop the film would I develop it at normal box speed of 400????

Q.G. · Dec 16, 2010

stradibarrius said:
So correct me if I am wrong but if I load Tri-X400, set my ISO for 200 then I am "pulling", over exposing the film one stop. To over develop the film would I develop it at normal box speed of 400????

You're "pulling" when you then develop for ISO 200 too.

You would just be overexposing if you go on to develop the film normally.

But yes, that - overexposure and normal development - will increase contrast.
Not as much as underexposure and overdeveloping (i.e. "pushing") though.

MattKing · Dec 16, 2010

I never use "push" and "pull" when I am referring to exposure - I only use those terms when referring to development.

I use "under-expose" and "over-expose" when referring to exposure.

"push" and "pull" are techniques used to adjust the contrast of developed film. They mostly affect highlight densities. They have relatively little effect on the light sensitivity of the film.

If I was aiming to attain grainy, high contrast images, I would over-expose by using a meter set at a lower EI (to increase grain) and increase development (to increase contrast).

And I would use exposure compensation if I was using the automatic exposure functions on a camera and the reflectance of my subject differed from middle gray.

stradibarrius · Dec 16, 2010

Hey Matt, over expose and over develop is what I am going to do and see how it works. I always shoot "manual". I have recently tried using aperture priority to control DOF but I never shoot "automatic", not even when I use my Nikon D300 digital.

MattKing · Dec 16, 2010

stradibarrius said:
Hey Matt, over expose and over develop is what I am going to do and see how it works. I always shoot "manual". I have recently tried using aperture priority to control DOF but I never shoot "automatic", not even when I use my Nikon D300 digital.

Barry:

Have fun with the experiment.

FWIW, I include "aperture priority" metering when I refer to "automatic" exposure, but of course I can remember when "aperture priority" metering was a recent innovation

EDIT: Oh and with respect to your over-exposed and over-developed negatives, don't be surprised when your printing times get quite a bit longer

perkeleellinen · Dec 16, 2010

Regarding the Ralph Gibson technique; I had some success with shooting Neopan 400 @ 200 and then developing as if it was 800. Very dense negs, quite a bit of contrast and grain which was nice. I think the technique needs some careful thought about subject matter in order to exploit the look.

Pumalite · Dec 16, 2010

I recently got 10 rolls of TMax-400 120 expired in 1997. I got normal negatives by pushing the film 2 'ticks'

lxdude · Dec 16, 2010

stradibarrius said:
If I wanted to "push" a 400 ISO film to 800, for example, is it correct that I could do this in one of three ways??
1. I could mentally adjust the exposure I see on the meter to one stop faster

I suggest a change in the terms you use. One stop faster means half the light when referring to shutter speeds, but one stop faster means twice the light when referring to lens aperture settings.
I suggest using "more" or "less", as in "one stop less exposure". That would be a faster shutter speed or smaller aperture.

Galah · Dec 19, 2010

stradibarrius said:
I know this sounds like a very basic question and I guess it is, but I never use Exp. Comp. and I wonder why???

"Exposure Compensation" is a technique for increasing or reducing the exposure (above or below that which would be normally set by the camera's exposure metering system) of one or more frames while the camera is set to one of the "Auto Exposure" modes (either Tv or Av).

This "workaround" was made necessary by the introduction of "Auto" metering. In auto metering, changing either the aperture setting or the shutter setting would simply bring about an "automatic" compensating change in the other variable, so the resultant total exposure would effectively remain constant (whereas in "Manual" mode, changing either one of the variables -shutter or aperture- would result in an actual change in exposure.)

In many cameras (e.g, Olympus OM2n) exposure compensation is actually achieved by what effectively amounts to a manual temporary alteration of the ISO setting, so the lightmeter is fooled into thinking the camera has either slower or faster film than it actually has.

In effect, the answer to your question is: there is no real difference, there are only superficially different ways of achieving the same result.

hpulley · Dec 19, 2010

EC is a relatively new thing. We used to just look at a scene and think to ourselves, "I think the meter is going to read this too bright so I'll adjust the aperture to compensate." With automatic exposure you need EC so you can tell the computer you think the AE is wrong though in a way this is silly. If you know it is wrong then use a manual exposure.

I set the ISO of the film differently when I know I want to shoot a whole roll at a different ISO either because it is expired or because I know I want to push or pull process the roll.

Poisson Du Jour · Dec 19, 2010

Nothing new under the sun in either re-rating a roll or providing exposure compensation either/both more common with reversal film destined for printing and both achieve the same end result. Take a roll of ISO50 film: EI40 is effectively +1/3, EI32 is +2/3; EI64 is 1/3...etc., etc.

Things get a lot more interesting though re-rating the film and providing additional exposure compensation. As far back as 1996 photographers I worked with using reversal film termed this "supplemental stepping" and still very common with contrasty films such as Velvia. Kodachrome 64 and 200 produced on occasion quite unpredictable results with stepping.

Multi-pattern/matrix/evaluative (call them what you like) often can be left to themselves a lot of the time given their algorithm working along the Zone System (IIRC, Nikon was first with this on the FA). In active practice, I summarily rate Velvia 50 at EI32 or 40 (re-rating and pushing or pulling is courting disaster), Velvia 100F at EI80 and Provia 100 as is. If you're unfamiliar with the results experimentation and recording notes is the way to go, and eventually nail it.

Rol_Lei Nut · Dec 20, 2010

hpulley said:
With automatic exposure you need EC so you can tell the computer you think the AE is wrong though in a way this is silly. If you know it is wrong then use a manual exposure.

While not detracting from the usefulness of manual exposure, using AE lock on an AE camera is often a very good solution.

hpulley · Dec 20, 2010

Rol_Lei Nut said:
While not detracting from the usefulness of manual exposure, using AE lock on an AE camera is often a very good solution.

AE lock has its own problems, having to hold it down while pressing the shutter to make the locked reading remain past one single shot; some cameras force you to turn the camera off if you decide not to use the locked value before you shoot the next frame; some other cameras let go of the lock if you don't use it after N seconds which can mean it lets go right before your exposure. I find manual exposure can be simpler, just "set it and forget it" though of course you can set it, forget about it and assume that it was changing the exposure too. It pays to look at the settings.

Cameras with multiple AF/spot metering points can be better. You just choose the spot you want and then you don't have to do focus/meter and recompose which has been a source of error for me in the past.

Vanishing Point Ent. · Dec 24, 2010

In Lieu of a Flash Exposure Compensation Dial.

There is One BIG Difference between changing the ISO setting
& using Exposure Compensation.

If you readjust the ISO setting, you change both the metered exposure
reading & the TTL flash system exposure reading.

If you adjust the Exposure Compensation Only, you change the metered
exposure reading, but do NOT change the TTL flash system exposure reading.

This is why Flash Exposure Compensation was invented.

Let me give you an example:

If I want the Flash TTL to give me -1 stop fill light exposure, I can either;

A. Set the Flash Exposure Comp to -1, or

B. Set the ISO to x2 the indicated ISO & then also
set the Exposure Comp to +1 stop.

By doing both for B. the normal exposure reading is normal,
but the TTL flash exposure, seeing only the ISO will give
1 stop less light.

In case you're wondering, the B. technique started with underwater
photographers using a Nikonos V & TTL flash.

eddym · Dec 25, 2010

MattKing said:
FWIW, I include "aperture priority" metering when I refer to "automatic" exposure, but of course I can remember when "aperture priority" metering was a recent innovation

I was going to say that I can remember that too... but my wife always says I can't remember anything. I just tell her my brain is full and there is no more disk space available.

The difference between Exposure comp and changing the ISO of the film???

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The difference between Exposure comp and changing the ISO of the film???

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