Home  Donate  New  Search  Gallery  Reviews  How-To  Books  Links  Workshops  About  Contact

What are LV and EV
© 2005 ~ 2024 KenRockwell.com. All rights reserved.

Please help KenRockwell..com

This free website's biggest source of support is when you use those or any of these links when you get anything, regardless of the country in which you live — but I receive nothing for my efforts if you buy elsewhere. I'm not NPR; I get no government hand-outs and run no pledge drives to support my research, so please always use any of these links for the best prices and service whenever you get anything. Thanks for helping me help you! Ken.

 

January 2024, October 2013   Better Pictures   Nikon   Canon    Fuji    LEICA   All Reviews

 

Introduction         top

Adorama pays top dollar for your used gear.

B&H Photo - Video - Pro Audio
I use these stores. I can't vouch for ads below.

LV, Light Value and EV, Exposure Value, are terms used to allow easy discussion of exposure and light without the confusion of the many equivalent combinations shutter speeds and apertures.

LV refers to how bright the subject is. EV is the exposure setting on the camera.

You may have seen them if you like to read the fine print of camera specifications. They are used to specify ranges of light levels for metering and autofocus.

EV and LV follow an open-ended scale. Each one is one stop away from the next. In photography values of about 0 to 18 are commonly used. Negative values are perfectly valid, just very dark and only occur in night photography. LV 15 is full daylight, for example.

Each Exposure Value, or EV, represents any of many different but equivalent combinations of f/stop and shutter speed. For instance, 1/250 at f/8 is EV14, and so is 1/125 at f/11. 1/125 at f/8, one stop more exposure, is EV13, and 1/250 at f/11, one stop less exposure, is EV15. You don't need to remember these, they are on the dial of your exposure meter.

Understanding them will allow you to recognize common lighting values and guess correctly at exposures even without a meter.

This system is the correct way to discuss photographic light and exposure because it avoids all the confusion of f/stops and shutter speeds, if all you really want to discuss is light and exposure levels. it replaces the idiotic question I get all the time while shooting, "what f/stop are you using," which of course means nothing by itself.

 

LV, or Light Values

An LV, or Light Value, is a number that represents how bright a subject appears in absolute terms. It does not take film speeds or exposure into account. LVs are very handy photographic terms to use to describe lighting levels.

LVs measure light coming from a subject, or "luminance." They are not a measure of how much light is falling on a subject. In other words, the same light falling on a black object will have a lower LV than the same light falling on a white object.

Some light meters, especially spot meters like the wonderful Pentax Digital Spotmeter and analog Pentax Spotmeter V, read directly in LV. You transfer this number to a dial that, along with your film speed, reads out all the combinations of aperture and shutter speed that will give the correct exposure.

Some light meters use a similar scale, but shifted by a constant amount. For instance, the Gossen Luna-Pro uses a scale that reads 5 units higher, or reads 20 in full sun. It's still the same concept, and even those meters calculate the same Exposure Values, or EV, once you set your film speed. That brings us to:

Here's a table of common Light Values associated with common situations. If you use one of the Pentax meters you will quickly start to learn these without even needing the meter after a while. This is because the same number pops up for each subject each time. LVs eliminate the confusing issues of film speeds and f/stops that hide these simple truths when using SLRs or other light meters:

 

LV 18 (~ 700 kLux on an 18% gray card) and above: Bright reflection off a sunlit object, including reflections off the sea, Zone VIII.

LV 17 (~ 350 kLux on an 18% gray card) White object in direct sunlight; Zone VII.

LV 16 (~ 175 kLux on an 18% gray card) Light gray object or skin in full sunlight, Zone VI.

LV 15 (~ 88 kLux on an 18% gray card) full sunlight; typical exposure for ugly front-lit noon daylight photos; Zone V. On earth nothing is lit by more than about 88,000 Lux, which is strong noon sunlight. The reason there are brighter things above is that the subjects are lighter and reflect more of the incident light (measured in Lux) that's hitting them.

LV 14 (~44 kLux) Typical light level for side-lit daylight shots in good afternoon light.

LV 13 (~ 22 kLux) Typical shadow cast in a daylight scene; cloudy bright days.

LV 12 (~ 11 kLux) California bright overcast.

LV 11 (~ 5,500 Lux)

LV 10 (~2,800 Lux) Dark, dreary overcast day in Boston, London or Paris.

LV 9 (~ 1,400 Lux)

LV 8 (~ 700 Lux)

LV 7 (~ 350 Lux) Typical indoors; light outdoors about 10 minutes after sunset.

LV 6 (~ 175 Lux)

LV 5 (~ 88 Lux)

LV 4 (~ 44 Lux)

LV 3 (~22 Lux) Brightly lit night street scenes.

LV 2 (~ 11 Lux) Typical night street scenes.

LV 1 (~ 5.5 Lux) Dark scenes outdoors at night.

LV 0 LV Zero (~ 2.8 Lux) is defined as the light level that requires a 1 second exposure at f/1 with ISO/ASA100 speed film.

LV -1 (~ 1.4 Lux)

LV -2 (~ 0.7 Lux)

LV -3 (~0.35 Lux) Peak Supermoon brightness under unusually favorable conditons.

LV -4 (~ 0.175 Lux)

LV -5 (~ 0.088 Lux) Scene lit by a typical full moon.

LV -6 (~ 0.044 Lux)

LV -7 (~ 0.022 Lux)

LV -8 (~ 0.011 Lux) The Milky Way shot as the subject.

*

*

*

LV -15 (0.0088 Lux) Scene lit only by starligh and the Milky Way. I have loaded sheet film in light this dark, so don't expect to photograph it or meter it.

 

EV, or Exposure Value

Exposure Value, or EV, varies from LV, or Light Value, depending on your film speed.

EV = LV at ISO 100

With ISO/ASA 100 speed film you expose with an Exposure Value (EV) equal to the Light Value (LV).

Easy, eh? Your meter will do this for you, but you can do it in your head, too, if you forget your meter. Here's how:

If you shoot slower film you of course have to use more exposure (EV) for the same Light Value (LV), and vice-versa.

The EV is easy to calculate even if you forgot your meter, since each unit is one stop different than the next. For instance, with film a stop slower than ISO/ASA 100 (like 50 speed Velvia) you just subtract one from the LV to get the EV. This adds one stop of exposure.

For instance, if your subject is at LV14, expose at EV13 with ASA 50 film. EV13 gives one stop more exposure than EV14.

With ISO/ASA 400 speed film you add two to the LV to get the EV, which is the same as subtracting two stops of exposure. Therefore with an LV14 subject you expose at EV16.

Remember that the higher numbers refer to higher light values, and therefore less exposure. This is because the exposure values that correspond to those higher numbers give less exposure.

EVs are a great idea: by talking about an EV you are talking about any one of many different combinations of aperture and shutter speed that give the SAME exposure. Cameras started to use these numbers in the 1950s, but today only the Hasselblad retains them. With every other camera one needs to use the scales on light meters to determine the EV values. Some cameras can be adapted, as I did to my Plaubel Makina 67, which simplifies their use with spot meters.

Zero EV is defined as f/1.0 at one second. Therefore, EV0 is a pretty long exposure. This is the same exposure as f/1.4 at 2 seconds, f/2.0 at 4 seconds, f/2.8 at 8 seconds and so on. EV1 is one stop less: f/1.4 at 1 second. EV 2 is two stops less: f/2.0 at 1 second or equivalent EV is a camera setting. It was popular in the 1950s to couple camera controls together so that once one set an EV one could rotate locked f/stop and shutter speed rings to choose between different equivalent settings. Today only Hasselblad continues the tradition. It is much easier to remember typical light conditions as a single EV number than combinations of camera shutter and aperture settings.

So what's the correct exposure for Velvia (ASA/ISO 50) in side-lit daylight? That light is LV14. Since Velvia is one stop slower than 100 we need to give it one more stop exposure, or SUBTRACT one EV from the LV to get the EV. Therefore, LV14 - 1EV= EV13. EV13 is 1/125 at f/8 or 1/15 at f/22. Light meters that read in EV have scales on the side that show you all the equivalent camera settings for any EV.

What tricks does this tell us? Well, in nature nothing gets brighter than something lit by full sun, which is LV15. If you see LV17 in your meter you know that that must be a white object in daylight. Guess what: that's how evaluative and matrix meters know that, too!

 

Help me help you         top

I support my growing family through this website, as crazy as it might seem.

The biggest help is when you use any of these links when you get anything, regardless of the country in which you live. It costs you nothing, and is this site's, and thus my family's, biggest source of support. These places have the best prices and service, which is why I've used them since before this website existed. I recommend them all personally.

If you find this page as helpful as a book you might have had to buy or a workshop you may have had to take, feel free to help me continue helping everyone.

If you've gotten your gear through one of my links or helped otherwise, you're family. It's great people like you who allow me to keep adding to this site full-time. Thanks!

If you haven't helped yet, please do, and consider helping me with a gift of $5.00.

As this page is copyrighted and formally registered, it is unlawful to make copies, especially in the form of printouts for personal use. If you wish to make a printout for personal use, you are granted one-time permission only if you PayPal me $5.00 per printout or part thereof. Thank you!

 

Thanks for reading!

 

 

Mr. & Mrs. Ken Rockwell, Ryan and Katie.

 

Home  Donate  New  Search  Gallery  Reviews  How-To  Books  Links  Workshops  About  Contact

18 Jan 2024 add Lux values, Oct 2013, 2005 light yellow