Light metering for film

[robert32]

Hi there,

I'm getting into the use of both vintage cameras and shooting on expired film, further to a long standing interest in digitally restoring old film. Unfortunately, I'm having a bit of a problem with light metering at the moment.

I recently shot a roll of brand new Kodak Colorplus 200 on an EOS 30 using and a roll of brand new CineStill 800T on a Zenit 11. For both, I set the ISO, aperture and shutter speed manually, referencing a free app on my iPhone entitled "Lux". In every case the results were significantly underexposed. In many cases I had to set the exposure to +3.0 when scanning with a SilverFast driven OpticFilm 8200. I understand this is the equivalent to 3 f-stops. Ultimately, many results were still too dark or grainy to be of any real use.

I have performed the following tests this evening by comparing the recommendations of three light meters:

1. Inbuilt light meter on Canon EOS 30 (film)
2. Inbuilt light meter on Canon 650 D (digital)
3. Lux light meter on iPhone.

I get the following shutter speed recommendations by using the same lens for both canons, and a consistent aperture (4.0) and ISO (200) for all 3 devices when photographing the same vase of flowers at a consistent light intensity and physical distance:

1. Canon EOS 30 - 1/15
2. Canon 650 D - 1/4
3. Lux/iPhone - 1/8

The following results were observed when applying each of these shutter speeds to the 650 D:

1. f4.0 ISO200 1/15 = underexposed
2. f4.0 ISO200 1/4 = overexposed
3. f4.0 ISO200 1/8 = correct exposure

So why were my results underexposed by 3 stops when using the Lux in combination with the EOS 30 and Zenit 11?

To add more confusion, I have also tried using the automatic settings on the EOS 30, which has set the exposure perfectly, so why is it advising a shorter shutter speeed to what works on the 650D?

Anyway... the immediate reason I am posting is because I am about to start using a Yashicamat 124g and would like to be able to have confidence in getting some appropriately exposed pictures.

What shall I do? Stick with the iPhone app, but compensate by 2 stops? Obviously, I will record the aperture and shutter speeds for each photo (together with the light meter recommendation), so I can review the results afterwards.



Thanks,

R.

 

[TCampbell]

I’d be suspicious of any app on a smartphone that claims to be a light meter.

I have incident meters and few different cameras. When I check them, the camera metering and indepdent metering tend to agree ... typically within 1/10th of a stop.

Keep in mind that the meter built into a camera is a “reflected” meter and the cameras let you set the metering area. If you were to choose center or spot metering modes on a camera, then you’d have to be careful to target the same bit of your subject and with identical light to get consistent readings. In “evaluative” metering mode, the camera samples a fairly broad area of the frame ... but a difference in lens or focal length will alter the meter reading.

You may want to pick up a dedicated meter if you are using a camera that doesn’t have one.

On a budget, you can get a Sekonic L-208 incident meter ($126 as I check B&H Photo prices). There are more sophisticated meters ... so if you need to meter for flash ... or want more features... but this one handles the basic needs.

 

[Derrel]

I’d be suspicious of any app on a smartphone that claims to be a light meter.

There are some good ones. Pocket Light Meter for iPhone is very accurate across a wide range of light levels, and also allows the user to snap a photo which records exposure data, and which shows the metering area in a red bracket, and also snaps a photo of the actual scene...these small photos can be used as a form of reference, which might be useful for those new to photographing and using a hand-held light meter.

Reflected light meters are highly influenced by the color (white/black/gray) of the scene or object being metered, and in-camera light meters depend upon the lens and its angle of view to arrive at the reading. Different lens focal lengths on different cameras can cause variation in the meter readings; also, and this is something some people miss, "some" cameras read a fair amount of light that enters from the camera's eyepiece when there is no person's eye/face blocking external light from entering the eyepiece. Some cameras can be fooled when used tripod-mounted and or when a lot of light cones in through the rear eyepiece.

 

[mrca]

When I shoot MF film, it's $ 3 a click. You can be sure I take the time to use a hand held meter and the zone system to nail exposure I want and the do a test shot on digital. I think if you learn to use a meter, I use sekonics, you will save money on not having to bracket and have confidence when you push the shutter release. I work in studio with up to 5 or 6 light/reflectors and an incident meter allows me to quickly dial in for fine tuning on my tethered, calibrated monitor. Recently had clients have to leave before I was able to get "my shot" after the things they wanted were in the can. A meter got me set up before they could pack up and I nailed the shot. I like the sekonic to have reflective metering as it allows me to nail the tone of the bg or hue/saturation of gels instantly by the difference between subject incident camera setting and reflective of bg reading taken from my stool. I can control bg lights from my stool so just spot around subject and adjust bg light power from my stool til I hit the desired delta. Get a dedicated meter, it will last you for years. I have a sekonic L558 that is both incident and reflective in excellent condition forsale at $325. How many bracketed shots does it take to pay for it and you have a meter for doing spot metering for zone landscape work as well. Take the 1 degree spot reading of the brightest area you want detail eg, clouds, giving you a reading of 18% gray for that area, zone 5 and increase exposure 3 stops to zone 8 and you have the exposure pushed to the right retaining detail in important highlights but at the same time have moved the shadows as far to the right as possible requiring the least manipulation to get detail there, hence the best shadows possible in that shot without using lights or a split nd filter.

 

[Vtec44]

Assuming you rated your film at box speed. Film in general like to be over exposed. Where and how did you meter will have a big difference.

 

[robert32]

Thanks for the insight guys. Dedicated light meter definitely seems the way to go

Assuming you rated your film at box speed. Film in general like to be over exposed. Where and how did you meter will have a big difference.

In terms of an interim solution... is it fair to say that overexposure is better than underexposure? What is the best way of doing this? Reducing the ISO by one stop (e.g. from 200 to 100)?



Thanks,

Rob.

 

[jcdeboever]

I have no use for android base, light meter apps. I typically just use the sunny 16 rule when shooting a film camera without a light meter. I've had very little issues with that. As mentioned for color, I guess what the exposure should be and add a stop of light. They come out fantastic. I will use a light meter if it is challenging light scenarios. I wish I had one this past weekend as the day started out with thick fog, cleared, rolled in again, cleared, rolled in again, cleared, partly sunny, overcast, and around 1:00 all sun no clouds. If I would have grabbed my F3, I would have been golden. If you are not comfortable with that, then the above lightmeter should work, one more thing to carry.

 

[JBPhotog]

For staters the CineStill 800T and the Kodak Colorplus 200 are colour negative films and should never be used to determine light meter accuracy, their inherent wider latitude offers poor data. If one is looking for accurate results choose colour reversal film which has a very narrow latitude compared to colour negative film. Unless you have a densitometer this will only be an estimate to see how accurate your light meters are. Using a colour chart and an 18% grey card is far more accurate than a scene with various items in them. Anyway, calibrating meters is quite involved and there is a right way to do it.

 

[Vtec44]

In terms of an interim solution... is it fair to say that overexposure is better than underexposure? What is the best way of doing this? Reducing the ISO by one stop (e.g. from 200 to 100)?

Thanks,

Rob.

With film it's almost always better to over expose. How much to over expose depending on the film stock. I shoot almost exclusively Portra 400, and about 2 stops with this film stock is perfect for my personal preference. One way to do this is that you can rate it at box speed in camera and meter, but meter for the shadows (darkest area in the scene). This would give you about 1.5 stops over exposure. Other people do it differently. but the idea is still the same: over expose.

 

[Tim Tucker 2]

In terms of an interim solution... is it fair to say that overexposure is better than underexposure? What is the best way of doing this? Reducing the ISO by one stop (e.g. from 200 to 100)?

Thanks,

Rob.

With film it's almost always better to over expose. How much to over expose depending on the film stock. I shoot almost exclusively Portra 400, and about 2 stops with this film stock is perfect for my personal preference. One way to do this is that you can rate it at box speed in camera and meter, but meter for the shadows (darkest area in the scene). This would give you about 1.5 stops over exposure. Other people do it differently. but the idea is still the same: over expose.

Absolutely totally agree. When I used to stick a roll of colour film for a few holiday snaps in the camera I always halved the rated speed, if 200ASA I exposed at 100ASA, and I never said a word to the lab, just got them to process as normal.

The difference is staggering.

 

[john.margetts]

First, your EOS 30: this camera reads the film speed off the cassette so I would not set the film speed manually. One less thing to get wrong. To test the onboard meter in the camera, let the camera determine the exposure and then look at the negatives. If the negatives have a good density (no completely opaque black, no completely clear areas) then the meter is good. Comparing the settings produced by Canon's onboard meter with a mobile phone just tells you that they are different - the Canon is likely to be more right.

Secondly, your 650D: to compare this to the film EOS 30 you need to ensure that you have the same metering mode on both and the same metering point. There will still be differences due to many years of development in metering technology. Then, the digital camera is not using film.

As to what you should do, buy a proper handheld meter from eBay or somewhere similar. I have several and they all agree with each other and are very reliable (and cheap!).

 

[greybeard]

In terms of an interim solution... is it fair to say that overexposure is better than underexposure? What is the best way of doing this? Reducing the ISO by one stop (e.g. from 200 to 100)?
Thanks,

Rob.

With film it's almost always better to over expose. How much to over expose depending on the film stock. I shoot almost exclusively Portra 400, and about 2 stops with this film stock is perfect for my personal preference. One way to do this is that you can rate it at box speed in camera and meter, but meter for the shadows (darkest area in the scene). This would give you about 1.5 stops over exposure. Other people do it differently. but the idea is still the same: over expose.

Expose for the shadows and print for the highlights.

 

[ac12]

To validly compare the meters, you need to meter an even color/tone surface, like a wall or gray card. The surface has to cover the entire field of view of the camera/lens/meter. And keep the angle of the surface to the meter the same.

Only if the solid surface comparison is the same would I then move to objects.

The "sunny 16" rule is my standard method to check any light meter, in the field.
In fact before I could afford a light meter, I used the paper in the Kodak film box, which gave a generally recommended exposure for different lighting conditions, which was really the sunny 16 rule. And that worked just fine for years.

 

[AlanKlein]

For staters the CineStill 800T and the Kodak Colorplus 200 are colour negative films and should never be used to determine light meter accuracy, their inherent wider latitude offers poor data. If one is looking for accurate results choose colour reversal film which has a very narrow latitude compared to colour negative film. Unless you have a densitometer this will only be an estimate to see how accurate your light meters are. Using a colour chart and an 18% grey card is far more accurate than a scene with various items in them. Anyway, calibrating meters is quite involved and there is a right way to do it.

What's the right way to calibrate?

 

[JBPhotog]

For staters the CineStill 800T and the Kodak Colorplus 200 are colour negative films and should never be used to determine light meter accuracy, their inherent wider latitude offers poor data. If one is looking for accurate results choose colour reversal film which has a very narrow latitude compared to colour negative film. Unless you have a densitometer this will only be an estimate to see how accurate your light meters are. Using a colour chart and an 18% grey card is far more accurate than a scene with various items in them. Anyway, calibrating meters is quite involved and there is a right way to do it.

What's the right way to calibrate?

For starters use colour reversal film.
- an 18% grey card
- sunny 16 rule
- tripod
- leave the lens at infinity, fill the frame with the card and do not focus on the card.

A series of exposures starting with the sunny 16 rule using these exposures using shutter speed:
-3, -2 2/3, -2 1/3, -2, -1 2/3, -1 1/3, -1, -2/3, -1/3, 0, +1/3, +2/3, +1, +1 1/3, +1 2/3, +2, +2 1/3, +2 2/3.

Take notes of exposure settings by frame number, you will need these to view the results.

Then a series using the cameras meter, should be close to sunny 16 settings, using the above exposure series. That should take care of a 36 exposure roll.

Get it processed and do not get them cut and mounted so you can cut the film into the card and camera meter series into two strips and compare exposures side by side and compare the value of the 18% grey target. If you did it right, the two sets should match frame to frame with 1/3 difference. This will give you a visual of where you meter is.