How to Correctly Expose K40

[perthskydiver]

Hello all..

In the final stages of preparing to film my Super 8 Short Film for a contest but I want to ask a simple question first...

Correct me if i'm wrong but is the following the correct way to get an accurate light reading & exposure setting for K40 super 8 film using an external handheld meter:

If shooting 24fps, you'd go 24 x 360/shutter angle (150 degrees on daylight setting on my 814XLS) which gives me 57.6th/second shutter speed, so on my handheld meter set it to 1/60th second (using a Minolta III). Since it's daylight shooting, expose at ISO 25. I've also heard to underexpose K40 by about half a stop to give best results. Do I need to compensate for the reflex viewfinder on the 814XLS?

Also on the K40 box it says expose at ISO 25 when using in daylight sun with an 85 filter. Is this filter built into the 814XLS when on the daylight setting?

If I have anything wrong or you have any other exposure tips please let me know...

[Maurizio Di Cintio]

Basically you are right almost on everything. The filter is built in your camera and is held in place when the switch on the right hand side of your canon points to a symbol of the sun. You cannot notice this in the viewfinder though, since the light heading to the VF follows a different path after going through a split image prism. For this reason you must not underexpose your aperture as opposed to the reading of your hand-held mightmater: you must overexpose by about half stop, since that prism subtracts light for the film.
But why do you want to use this system? The lightmeter inside the Canon is very accurate and sensitive, and you can do multiple readings as well, by using the zoom before the final framing of each scene.
Anyway I suggest you do some tests and bracketing with your external lightmeter before shooting the real stuff.

Cheers.

[mattias]

i usually shoot at the aperture the meter tells me and let the viewfinder steal just enough to get a slight underexposure.

/matt

[perthskydiver]

When using the light meter built in the camera, doesn't it give you varied readings when shooting different coloured surfaces? Would it be best to meter off a grey card?

Also, when using zoom to meter, does the meter read the whole frame in the fiewfinder or does it only meter off the centre split image circle?

[Maurizio Di Cintio]

Yes, because certain colours reflect more light than others. But it also depends from what lightmer you have: CdS based lightmeter tend to have a certain preference for red. Silicon photo cells are more neutral (BTW thats the kind of cell you have in the Canon).

As for the second question, it's hard to tell, as the area read by each camera could vary quite a bit. I've never heard of a camera featuring spot light reading though, and from the tests I did, I figured out that mostly cameras read an area which is about 20-25% smaller than the actual frame. But this is easy to assess for a specific camera: put it on a tripod, and frame a white rectangular (3:4 aspect ratio) put against a black surface a little prominent behind the white so that it is visible behind it as a sort of frame. Than look in the viewfinder while slowly panning and tilting back and forth, in order to leave the black part outside/include it in the frame and see how the aperture varies; you will notice you need a certain degree of variations to have the metering change when including/excluding the black area.

Hope this helps.

[Ian_]

from my experience,

I ditched my light meter in favour of the on board meter. I was told it was better to use that meter to learn what you camera actually does in regards to light, shutter angles and speeds...or something like that. As soon as I started doing that I started getting perfect exposures.

My technique was zoom in to brightest and darkest point of you scene, average them, and minus 1-2 stops depending where i was. (Mostly 2 because I was in snow).

Ian

[monobath]

My technique was zoom in to brightest and darkest point of you scene, average them, and minus 1-2 stops depending where i was. (Mostly 2 because I was in snow).

Ian

Ian, you have it backwards. You'd have to increase the exposure rather than decrease it for shooting in snow. Being a Texan, I have to admit that my familiarity with snow comes mainly from hearsay, pictures, and from TV and movies, but I know how reflective light meters work.

Most reflective light meters base calculations on an assumed reflectance of 18% gray (some people say camera meters are really calibrated to an assumed 13% reflectivity). When measuring a sunlit snow scene, which reflects far more than 13% or 18% of the light that hits it, the meter will calculate a shutter and aperture combination that results in less light striking the film than is required to properly expose the scene. In other words, it will calculate a smaller aperture or a faster speed than what is really needed for proper exposure of sunlit snow.

If you use the aperture and speed recommended by a reflected light meter on a sunlit snow scene, you will get underexposure. If you stop down 1 or 2 more stops, you'll get an even darker, less exposed, picture. You'd need to increase your exposure, not decrease it, to properly expose the snow scene. For example, suppose the meter reads 1/250th at f16, you'd probably really need something like 1/250th at f9.5 or f8 (i.e., 1.5 to 2 stops MORE exposure, not less) to compensate for the 13% reflective assumption. If you were to "minus 1-2 stops", you would be at risk of turning your snow scene into an almost featureless darkness.

Note: I am assuming a reflected light meter here, which is the type of all built-in camera light meters. If you have a handheld meter that can measure incident light, and you can meter in the scene that you are shooting along with the important objects that you want to be properly exposed, then you will get an accurate exposure reading, and you won't have to worry about exposure compensation.

[S8 Booster]

Hello all..

If I have anything wrong or you have any other exposure tips please let me know...

What do you plan to shoot?


The built in auto exposure control in your cam is the best in business. Unless you are filming extremely contrasty stuff - rely on the internal meter - see mattias post. will do.

Filming snow?
Depends if you want correct exposure of the snow or the other objects.

R

[MovieStuff]

Here is what I do when shooting Kodachrome outdoors under natural light:

I meter for the scene using the in-camera meter and then I hold out my hand and meter off the back of it, as well. I then set my exposure in between the two, IF there's a difference. I find this works really well because, if there is no difference, then everything generally comes out well anyway. If there IS a difference, then the split exposure tends to preserve the most it can in the way of skin tones and shadow detail. If shooting inside with artificial light that I have control of, I tend to meter for skin tone only because I know I can add fill light to the shadow areas to protect them and nothing looks worse that incorrectly exposed skin tones under artificial light on Kodachrome, IMHO.

Roger

[Ian_]

yes I ment to say I overexpose the film by 1-2 stops.

[Alex]

I think the overexpose underexpose issue has been somewhat oversimplified.

If an actor has dark features, wardrobe and hair, you slightly overexpose.

If the actor has lighter features, you probably do a regular exposure. Underexposure is done when one wants to make sure no highlights get blown out.

If you are doing a master shot, you really have to decide what part of the shot matters most to you, and set your exposure to what will optimize the part of the scene that matters most to you.

If it's a wide shot with an actor in it, decide which is more important, the actor or the environment.

If it's a sky versus ground issue, decide which is more important.

I guess I would say always keep in mind what is most important in the shot and remember your meter will be "fooled" on bright reflective spots (a white t-shirt) and dark spots (black clothing).
spots.