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wstotler

To EV or not to EV?

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Hi, all. Please go easy on me in regard to this question--I'm just trying to cut through some confusion regarding setting an EV on my M8.

 

I've read in several places on the forum that it makes sense to dial back the EV to -1/3rd, -2/3rd, and -1 to keep highlights from blowing out.

 

The way I understand it is that dialing in a lower EV affects how the camera manages its meter readings. But I don't completely understand how this works.

 

I know the EV settings have grown out of the Zone System (I've read a bit about this online) but I'm not too interested in the Zone System right now--I might be in the future. I've read what the M8 manual says about EV, also. The lightbulb isn't going on here. Sorry.

 

Question 1:

Should I dial in -1/3rd, -2/3rd, etc. as a general precaution against blown highlights?

 

Question 2:

Does the EV - amount affect the DNG? (I presume it does.)

 

Thanks for any help you can give.

 

BTW, searching on EV in the forums is painful--I couldn't find a good thread on EV settings for the M8, pros, cons, and what it means. Doesn't mean it isn't there, just couldn't find a good one. . . .

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Here are some answers to your question...

 

First, I wish they had called it EC as in Exposure Compensation. But it's Exposure Value, and is consistent (sort of ) with most light meters.

 

So here is my take:

 

1). Try it and see. I did it --dialled in a -1/3 value--and didn't like it, so went back.

 

See, you need some general metering techniques to not be fooled by the auto-fool inside in the camera. The M8 metering is very good, and in soft, even light, you want to fully expose your shot with this camera, and the meter is bang on (at least mine is).

 

In hard light, you need to dial back and watch the histogram, because depending on where you point the meter, you will either underexpose or overexpose. BTW--underexposure is usually what you want here

 

So try it, but YMMV as they say.

 

If you can afford it, I *urge* you and all serious amateurs to go out and buy a good incident light meter like a Sekonic or Minolta and figure out how to use it.

 

You'd be surprised at how quickly you "see the exposure in your head" after doing this for awhile, and if you don't shoot enough to get there instinctively after awhile then the light meter pretty much guarantees better results and more fun, since with an incident meter you meter once till the light changes and just keep shooting.

 

IOW, you won't always be tied to a light meter, but you'll quickly learn how to shoot with the in-camera meter as if it's an incident meter...

 

2) Yes, the EV compensation affects the exposure, which affects the RAW file.

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Question 1) is a question of taste and working style, as well as where you work and what kinds of lighting conditions you usually have. I would say that if you find that you don't get enough detail in your highlights but are happy with the shadows, try -1/3.

 

The answer to question 2) is yes, but indirectly. The reason is that it changes the exposure that is used, and thus the image is recorded differently (darker, in the case of -1/3).

 

In general, I find that 0 works well, although I did try -1/3 for a while. The difference is small, but could be important at the limit.

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Exposing to the right means to shoot so that the histogram tapers off towards the right edge, but not crossing it. This means that you are overexposing in dark scenes and underexposing in bright scenes, so that the histogram's right tail is always anchored at the right side of the diagram.

 

The reason to do this is that most digital cameras record the brightness value linearly. Twice as many photons (light particles, loosely) means a value twice as large. Since one "stop" more in photography means twice as much light (doubling the exposure time, for example), you can see that this skews the numerical representation of the scene in favour of the bright areas. For example, the brightest stop of information in an 8-bit file is encoded with the values 128-256, whereas the second-brightest stop has only half that many values (64-128), the third-brightest stop a quarter (32-64), and so on. Given that the M8 can record about 10 stops of information, this would mean that the shadow areas would all be encoded in just a few values, leading to posterisation if you later brighten the image on the computer.

 

Exposing to the right generally maximises your usage of the limited representation values in a typical digital file, by shifting all the information as high up as possible. Another way of phrasing "expose to the right" is to record the image as brightly as possible without overexposing the highlights.

 

This concept is independent of using EV -1/3 to avoid blowing highlights. Using EV in this manner is more of a safe-guard for general automated metering. In fact, EV -1/3 means expose one-third stop to the left of where the meter reads!

 

The M8 has an unusual 8-bit encoding, as some threads have covered. It is not linear. In other words, the brightest stop of data is not stored in the values 128-156. Instead, the square root of the value is taken, and that is then stored instead. This moves some of the bits from the highlights to the shadows, but unfortunately, even with the shadows improved in this manner, 8 bits is really very tight for storing images, and the result is inferior to full 16-bit storage, at least in theory. The idea is that this isn't visible in practice, and as we all know, the M8 delivers beautiful results. However, it is possible that if we could compare with full 16-bit DNGs, we would see a small, but definite improvement, both in the highlights and in the shadows.

 

Personally, I would love to see a 16-bit format using Leica's scheme of taking the square root. That should give fantastic depth in the image compared to most 16-bit formats which are just linear, and still give the shadows the muddy end of the stick.

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Jaime and Carsten: Thanks for the info.

 

You'd think that with only three real things to keep track of (Focus, Speed, Aperture) it wouldn't be such an issue. But it is. Because (pretending for a moment that "post production" doesn't exist) those three things make the photo! Duh.

 

But the M6TTL beat me up until I got the hang of it and pointed out clearly that I was really relying too heavily on software in post to deal with less than perfect exposure issues and the M8. . . . All operator inflicted, for sure. (Some comments in the Film forum got me on track.) So I started to pay even more attention to the M8 when shooting to get better photos out of the camera before post--hence my question here.

 

Anyway--I'll experiment with the -1/3rd EV thing a bit to see.

 

Carsten: Thanks for the explanations and encouragement.

 

Jaime: Do you recommend a particular model of Sekonic that's currently available new through B&H? The 398A? I'll go get it and learn it as what you're saying makes complete sense. Concurrently, can you recommend a good textbook that really deals with issues surrounding exposure? (I think I have a handle on depth of field, working/handling style, lenses, digital RAW workflow, etc. Thanks are due to help I've gotten in the forum: I always apply what is said in one form or another.) The Osterloh text and a few other books I have (plus things I've read online) don't nail the exposure issue, really. I'm not a dummy but I'm missing something (or a few somethings). It's not the camera--it's the operator.

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"The Negative" by Ansel Adams is awesome, and doesn't only cover the zone system. He is very good at explaining things, even if he can be a little dry.

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You also could consider "Beyond the Zone System" by Phil Davis. Davis is a strong advocate of incident metering (Adams typically used reflective), and explains why quite clearly. The book is also pretty dry and technical at times, and like Adams' book, is focused on film, but the books discuss (at least somewhat) different approaches to exposure in detail.

 

I tried a little compensation, and quit. I get better exposure with zero compensation.

 

Until later,

 

--clyde

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If you tend to blow highlights, 1/3rd stop may not help much. It's OK for near average scenes, but could give you a false sense of security in more contrasty situations. 1/3rd stop won't make a dent in extreme highlights.

 

Better to follow Jamie's advice and analyze the scene carefully and use an incident meter. The M8 meter with exposure lock also work great once you grasp the middle gray concept and can identify it in scenes.

 

I use a Sekonic L-358, which is a fine meter and relatively small and affordable.

 

John

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I find that using the M8 as

a meter is a better workflow than dealing with a separate meter.

just shoot and then use the neat feature that the INFO histogram works with the zoom wheel to examine the image for both shadow and highlight issues

 

Re the zone system, I

believe that you can't use any light meter without a basic understanding - if you don't know where to "place" the metered object (e.g. Caution skin in Zone 6) how do you understand what the meter (which puts everything in Zone 5) is telling you?

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{snipped}

Jamie: Do you recommend a particular model of Sekonic that's currently available new through B&H? The 398A? I'll go get it and learn it as what you're saying makes complete sense. Concurrently, can you recommend a good textbook that really deals with issues surrounding exposure?

{snipped}

 

Hey Will--

 

I think even this one would be good to start:

 

Sekonic | L-208 Twin Mate Meter | 401208 | B&H Photo Video

 

under $100, but if you (like me) also hate to rely on batteries, then the 398A is a great meter, and the one I use (along with a studio strobe meter).

 

It's also good when I'm shooting an M3. But it's probably overkill too

If you do get the 398A, then make sure you don't put it next to your wallet (or hard drive) though, it's got a powerful permanent magnet in it!

 

The 358 is also a studio strobe meter as well as an incident (and spot, IIRC), a bit overkill and much larger.

 

The Gossen Digi6 I'm sure is fine too, and cheaper than either of the others and has a digital readout (I used a Lunasix for ever and a day before it finally gave out!)

 

Gossen | Digisix Ultra Compact Lightmeter | GO4006 | B&H Photo

 

As for a book, the Adams ones are fine, really, but for learning how to use an incident (and reflecting) meter the best one I've ever seen is called "The Exposure Meter Book":

 

Amazon.com: The Hand Exposure Meter Book: Books: Martin S. Silverman,Gerald Hisrchfeld,Bob Shell,Jim Zuckerman

 

But I see it's now worth $200 and up used!! Geez!! Don't you hate it when collectors get in the act!

See if you can find this through your local photography dealer.

 

Check through Amazon, too; I'm sure there are a number of other books out there.

 

The key points to using an incident meter:

  • The 3D dome attachment for the meter should be in place (unless you're in the studio and measuring ratios or shooting paper / fine art; then use the flat incident face. Ignore that if it didn't make sense to you )
  • You're measuring the light falling on a subject, not the light reflected off it. Unlike using a reflective meter (such as inside the M8) blacks will look black and whites will look white; not grey.
  • Go to where the subject is, point the dome towards the camera, then take the reading. Watch to make sure you're not putting the meter into a stray shadow or shaft of light.
  • As long as the light doesn't change, that's your reading--forget about what you're shooting and just shoot. Chimp if you like; you get to the point where you turn it off, though...

The key points for using a reflective meter (like the one inside the M8):

  • Remember you're measuring now the light reflected off a subject. Different subjects reflect light differently. But the meter is trying to make everything just about 18% (actually closer to 12%) grey.
  • If you meter something white, it will be grey (and other stuff less bright will be underexposed)
  • If you meter something black, it will be grey (and other brighter stuff will be overexposed)
  • If you meter something gray, at the right angle, you will have the average exposure. This is how all in-camera meters work; they just vary by field (wide to spot) and weighting (based on what the camera thinks it "sees").
  • If you have a grey card handy, this works very well when you can't get close to the subject and the light is different.

Obviously once you have an idea of incident and reflective ways of measuring light, then the zone system starts to make a lot more sense; gray values are where you place them, and metering carefully (with a reflective spot) helps you figure out where the tonal relationships lie in terms of gray values.

 

But it's pretty advanced, and is different with film and digital. So I'd begin with the incident meter and see how that goes. To my mind it's really the easiest way to start to nail exposures.

 

Hope this helps! Sorry for the long post.

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{Snipped}Re the zone system, I

believe that you can't use any light meter without a basic understanding - if you don't know where to "place" the metered object (e.g. Caution skin in Zone 6) how do you understand what the meter (which puts everything in Zone 5) is telling you?

 

No--this is the benefit of an incident meter, which essentially measures the light source and not the reflected light. In some ways, it's like carrrying around a corrected grey card with you all the time

 

It really is point and shoot, and very easy. What you do next is not easy, but if you want to place zones, you should have a spot reflective meter instead. Don't forget you need to post process too to get the digital zone system to work for you properly.

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Here are some answers to your question...

 

First, I wish they had called it EC as in Exposure Compensation. But it's Exposure Value, and is consistent (sort of ) with most light meters.

 

So here is my take:

 

1). Try it and see. I did it --dialled in a -1/3 value--and didn't like it, so went back.

 

See, you need some general metering techniques to not be fooled by the auto-fool inside in the camera. The M8 metering is very good, and in soft, even light, you want to fully expose your shot with this camera, and the meter is bang on (at least mine is).

 

In hard light, you need to dial back and watch the histogram, because depending on where you point the meter, you will either underexpose or overexpose. BTW--underexposure is usually what you want here

 

So try it, but YMMV as they say.

 

If you can afford it, I *urge* you and all serious amateurs to go out and buy a good incident light meter like a Sekonic or Minolta and figure out how to use it.

 

You'd be surprised at how quickly you "see the exposure in your head" after doing this for awhile, and if you don't shoot enough to get there instinctively after awhile then the light meter pretty much guarantees better results and more fun, since with an incident meter you meter once till the light changes and just keep shooting.

 

IOW, you won't always be tied to a light meter, but you'll quickly learn how to shoot with the in-camera meter as if it's an incident meter...

 

2) Yes, the EV compensation affects the exposure, which affects the RAW file.

 

Yes, Yes, Yes

 

Such good advice Jamie. If nothing else, it will lead to a full understanding of what is going on inside the camera's metering function and thus to more capable, properly exposed images. A wonderful meter such as the Sekonic (many options) is so cheap relative to what has already been spent on the M8, lenses et al that it is trivial. Go and learn. It will serve you well forever

 

Great advice Jamie

 

Woody Spedden

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No--this is the benefit of an incident meter, which essentially measures the light source and not the reflected light. In some ways, it's like carrrying around a corrected grey card with you all the time

 

It really is point and shoot, and very easy. What you do next is not easy, but if you want to place zones, you should have a spot reflective meter instead. Don't forget you need to post process too to get the digital zone system to work for you properly.

 

Great info! When you use an incident meter how do you set your ISO, meaning do you use 160,320 etc as in the camera or do you use 200,400 etc.

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Yes, Yes, Yes

 

Such good advice Jamie. If nothing else, it will lead to a full understanding of what is going on inside the camera's metering function and thus to more capable, properly exposed images. A wonderful meter such as the Sekonic (many options) is so cheap relative to what has already been spent on the M8, lenses et al that it is trivial. Go and learn. It will serve you well forever

 

Great advice Jamie

 

Woody Spedden

 

LOL, I'm accumulating a whole bag full of items that are cheap relative to the cost of the M8 !!!! handgrip, magnifier, white balance card, flash, milich adapters......

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Great info! When you use an incident meter how do you set your ISO, meaning do you use 160,320 etc as in the camera or do you use 200,400 etc.

 

This is an excellent question! With my personal Sekonic, I set it for the exact M8 ISO readings: 160, 320, etc...

 

Since the incident meter will take your highlights into speculars, you want to ensure you're not over-exposing here. From my own tests, I find the M8 corresponds exactly to the meter ISO setting.

 

Now, YMMV. It's absolutely worth "calibrating" your camera in this sense to the meter, and it's easy to be off by 1/3 stop. I know folks like Sean Reid, IIRC, have placed the M8's actual ISO sensitivity about 1/3 higher than marked, but all I can say is mine matches; if I move it up 1/3 stop (for ISO) then I get blown upper midtones.

 

With film cameras, it's even more crucial to check how the film's stated ISO reacts with your meter and camera, especially on older cameras where the actual higher shutter speeds can vary a lot as time goes on.

 

But with a digital, it's an easy check. Take a variety of shots with the incident meter; then chimp, and you'll soon see if you need to compensate or not.

 

FWIW, my Canons I own are all a little faster than indicated by the meter.

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Hey Will-- I think even this one would be good to start: <snip> The Gossen Digi6 I'm sure is fine too, and cheaper than either of the others and has a digital readout (I used a Lunasix for ever and a day before it finally gave out!) Gossen | Digisix Ultra Compact Lightmeter | GO4006 | B&H Photo

 

I bought the Digisix because the idea of the 398A as a hard-drive-wiping-strength permanent magnet in my work bag beside my M8 and laptop didn't seem like a good idea. Thanks for the warning and recommendation. Now I just need to remember to take it along AND learn it quick so I can make the transition (as said) from using it AND the M8 to just using the M8 with the absent Digisix being kept in mind.

 

 

As for a book, the Adams ones are fine, really, but for learning how to use an incident (and reflecting) meter the best one I've ever seen is called "The Exposure Meter Book" <snip> But I see it's now worth $200 and up used!! Geez!! Don't you hate it when collectors get in the act! See if you can find this through your local photography dealer.

 

I purchased it--found it for about $30 w/shipping. Circumventing the Web book-price speculators makes me happy.

Thanks Carsten and Jaime.

 

 

Hope this helps! Sorry for the long post.

 

I appreciate your comments--please don't apologize. Figure if I'm not getting the photos I expect with the M8/35/50 Summicron ASPH (Coded) combo then it's operator error and that needs to be corrected. Off to read and meter and shoot and read and meter and shoot and . . . .

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