Ansel Adams Zone System chart

Ansel Easton Adams (February 20, 1902 - April 22, 1984) was an American photographer and environmentalist. His black-and-white landscape photographs of the American West, especially Yosemite National Park, have been widely reproduced on calendars, posters, and books.With Fred Archer, Adams developed the Zone System as a way to determine proper exposure and adjust the contrast of the final print The Ansel Adam Zone System (AAZ System) has, for many years, been one of those concepts that photographers liken to Marmite. You either love it or you don't. For those that don't love it, an adversity to the AAZ System seems more to do with understanding exactly what it is and how it can be successfully applied to photography work It may interest math geeks, but it is unnecessary for understanding the Zone system. The charts for gamma = 2.2 and 1.8 came out closer than I expected. The major differences are in the lower zones. The zones below closely resemble those in my 1959 edition of Ansel Adams' The Negative The Zone System and Digital Photography The Zone System is a precise and powerful method for controlling not only exposure, but also to control the final appearance of a photographic print. The Zone System was introduced to a larger audience in 1948, when Ansel Adams (1902-1984) published the second volume of his Photography Series, titled the Th The Zone System is a technique that was formulated by Ansel Adams and Fred Archer back in the 1930's. It is an approach to a standardized way of working that guarantees a correct exposure in every situation, even in the trickiest lighting conditions such as back lighting, extreme difference between light and shadow areas of a scene, and many similar conditions that are most likely going to.

Astrology birth chart for Ansel Adam

  1. The zone-system of Ansel Adams divides the photo into eleven zones; nine shades of gray, together with pure black and pure white. You could assume that a normal photo does not contain pure black.
  2. About Zone 5 in the chart below. The zone system was developed by Ansel Adams to overcome this problem. Basically his solution was, when taking a photograph, we have to carefully study what we're photographing and also visualise the final product
  3. Ansel Adams wrote a deeply descriptive book detailing the Zone System called The Negative, which can be found on Amazon. It takes the reader on an in-depth journey into the Zone System. For our purposes, I have made up a basic diagram, followed by a synopsis of his narrative concerning the zones
  4. ing exposure for making prints

The Zone System is a photographic technique for determining optimal film exposure and development, formulated by Ansel Adams and Fred Archer. Adams described the Zone System as [...] not an invention of mine; it is a codification of the principles of sensitometry, worked out by Fred Archer and myself at the Art Center School in Los Angeles, around 1939-40 The zone system was formulated by Ansel Adams and Fred Archer. Take into account that it's used for taking a picture and making a positive copies in the dark room (where the numbers are reversed when working with negatives) When Ansel Adams developed the Zone System with Fred Archer in 1940, he gave photographers a tool great for controlling their images—but only with black-and-white film, and only with view cameras, where sheets of film could be processed individually. Today, any photographer with a digital camera can have even more control, whether working. Download The Zone System - Ansel Adams. Type: PDF. Date: December 2019. Size: 95.9KB. Author: Vincent Wong. This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA The Zone System applies as much to color, digital and video as it does to black-and-white. Ansel Adams even shows us in The Negative how to use it with point and shoot cameras! Ansel Adams chose to divide the range between white and black into about ten zones. Each is an f/stop apart

The Ansel Adam Zone System - Institute of Photograph

  1. The Zone System. Most of the charts on the internet depicting the Ansel Adams Zone System are completely wrong. They were produced in the wrong color space. The Zone System is a perceptual method of reproducing real-world tones in a target image. It was conceived for use in black and white photography, but the concepts still hold true for.
  2. e the correct image values of a photo. The image values of a photo are related to the light and dark values within the image. Adams originally formulated the method in black and white photography.
  3. The 11 zones in Ansel Adams's system represent the gradation of the different tonal values in a black and white print. Zone 5 is middle gray, zone 0 is pure black (with no detail), and zone 10 is pure white (with no detail). Theoretically, each zone represents one f-stop in exposure. You'll also notice there is then an 11-stop difference.
  4. If your subject is in zone IV, you would set exposure at 1 stop under 0 because zone IV is one stop under zone V. You can see 11 zones in the guide above (from 0 to 10). Ansel Adams formulated the descriptions for each zone. Each zone is one stop of light different from the zones before and after it - just like stops of light on your camera
  5. This is a chart of the Zone System which I found on a website called 'Push Processed'. This is a picture taken from the internet showing how you can apply Ansel Adams' Zone System The theories and work of Ansel Adams are integral to the advancement and success of my own photography, therefore it was a an easy decision which photographer I.
  6. The resulting Zone Scale will have value steps that progress from zero through 100% brightness in 10% increments. A 50% middle gray step will be placed in the middle of the scale. This corresponds to the traditional Zone V in Ansel Adams Zone System and, as it turns out, this value is what all light meters are calibrated to
  7. Ansel Adams developed his famous Zone System along with Fred Archer at the Art Center School in Los Angeles in the 1940s. The roots of their system were based on the experiments of John Davenport, who demonstrated that the same density on a negative could be achieved with different amounts of exposure by changing the amount of development

Jun 23, 2009 Alan Ansel Adams, Zone System and Metering Ever since I was back at Ansel's in the late '70's, I had been faithfully calibrating my high values at Zone VIII, targeting a density of about 1.25 above filmbase-fog http://theartofphotography.tv/episodes/episode-60-zone-system/In this episode we'll look at Ansel Adams' Zone System and how it was traditionally developed t.. The Zone System. The Zone System was developed by Ansel Adams with Fred Archer way back in 1940. It is a system to map the various tonal regions or luminance of objects in any given scene to enable the photographer to reach the optimal exposure during the capture of the image, and the developing and printing of the negative

A simplified zone system for making good exposure

The Zone System is the best, fastest and most logical way to get to gain technical facility in pho- It is important to note that this system was conceived by Ansel Adams and some of his pals; guys at the chart below, it is significant to note that each pairing of aperture and shutter speed (the. In Ansel Adams' full zone system, you would expose to maintain shadow detail, then develop to place highlights in zones of your choosing. For example, in the scene above you would meter the shaded. Adjust the lightness of an image using Ansel Adams' zone system. The lightness of the image (the L channel in Lab color space) is divided into a number of zones ranging from pure black to pure white. These zones are displayed in a zonebar beneath a preview image. The number of zones can be changed by mouse-scrolling on that bar (default 10 zones) Ansel Adams developed the Zone System. His technique was to carefully study a scene, visualise the final print, then determine the correspondence between portions of the scene and tones in the print. He would then meter, expose and develop the negative accordingly The higher up you go on that zone chart, the more time you need to develop, and the more movable the zones are. In effect, you're just scrunching up the higher zones like so: Ta-da. In reality, the Zone system is a lot of work. Every film with every developer gives a slightly different result/effective speed

Understanding & Using Ansel Adam's Zone Syste

  1. Ansel Adams photographed America's national parks extensively. Yet again, we see multiple zones in this image. Many other photographers have tried to match Ansel Adam's creative use of the zone system over the years, and it wouldn't be too dramatic to state that not many have come close to his masterful technique
  3. What may sound funny and flippant is meant very serious: I believe Ansel Adams' Zone System, the holy grail of traditional B&W photography, is fundamentally flawed. The great news is that you can forget about it now (in case you didn't ever completely understand or like it anyway), because there's a much easier and more reliable way to.
  4. Digizone chart Digizone Acrobat PDF(44K) Digizone is the Zone System applied to digital images. For those that are familiar with Ansel Adams, the chart which is linked to at the top of the page should seem very familiar
  5. For those photographers who didn't struggle through Ansel Adams' exquisite explanation of this approach to B&W photography, this is a brief, lucid, and excellent introduction. For those already familiar with the Zone System, this is an excellent refresher. Easy going, clear writing, good teaching technique. Worth the price and the time

The Zone System 101 To use the Zone System effectively in the digital world, you need to understand a few of its basic principles. The ZS was originally conceived by Ansel Adams and fellow photo instructor Fred Archer as a tool to give photographers working with black-and-white negative film (no digital back then!) the ability to plan and. The zone system was invented by Ansel Adams, one of the most famous photographers ever. He was a master of technique, and had an eye for light that few are blessed with. His photographs were the result of a happy combination of comprehensive technique and the knack of taking a picture when the light was at its best Ansel Adams Zone System Explained Started Mar 22, 2006 | Discussions thread Forum: Parent: First: Previous: Next: Flat view This chart? ISHMAIL. Mar 25, 2006 Re: Ansel Adams Zone System Explained . Ross. Mar 23, 2006 Re: Ansel Adams Zone System Explained.

When I first started this post, I said that Ansel Adams created the Zone System as a way to control both exposure AND development. When the shadows and highlights are not perfectly spaced apart, this is where your developing technique comes in Excellent use of charts and references throughout. The Practical Zone System is a great starting point for photographers of all types to get a worthy introduction to one of Ansel Adams' key theories on photography I use the Ansel Adams zone system to discover the zones and handle the zones if necessary individually. I tell the lab to expose a small version, some times an important crop of the photo to paper, maybe in two versions: without the automatic optimization of the lab's systems but also, if I am unsure, a lab-processed copy Actually, the Zone System is very applicable to color photography and can be employed whether your are shooting with film or digital technologies. Remember, Ansel Adams lived to 1984 and though his most renowned images are B&W, he did apply the Zone System when shooting color. Originally Posted by oldgreygary The Ansel Adams Zone System. Making Zone-Based Adjustments. Customizing Zones Using the Zone Panel. Resetting Color and Zone Adjustments. Curves & Histogram. RGB Mixer. Introduction to the Color Warper. Using the Grid Controls to Manipulate Color. Hue — Saturation Controls. Chroma — Luma Controls. HSL & LUM Qualifier. 3D & RGB Qualifier.

In case you're wondering what N is, it's normal development as per Ansel Adams' Zone System. You can expect a future article covering my take on this pervasive metering and development system in due course but if you're serious about making the most out of your own photographic process in the meantime, I would strongly. How to Use the Art Adams (as opposed to the Ansel Adams) Zone System I shot this image with an F55 in SGamut3.cine/SLog3 while doing some color science tests for Sony: The shadowy part of the building looked to be about 18% gray in reflectance, so I took a spot meter reading and set that on the lens

How to Meter Using the Zone System — Alan Brock Images

For those of you that are not familiar with Ansel Adams's Zone System. Created to have to total control of exposure when out on the field. Zone 1 is Black and Zone 9 is White. To get best result you may want to go for Zone 3 (Shadows with Maximum Detal and Zone 7 (Highlights with Maximum Detal) So let imagine that your shooting at 1/25 These images are following the Zone System devised by famous photographer, Ansel Adams. The problem today for people new to photography they do not get taught about the 'Zone System'. I teach my photography students about this very early on in the course Apr 9, 2013 - A lesson on how to use the Zone System to obtain perfect exposure. Apr 9, 2013 - A lesson on how to use the Zone System to obtain perfect exposure. Pinterest. Today. Explore. When the auto-complete results are available, use the up and down arrows to review and Enter to select. Touch device users can explore by touch or with swipe. Zone System Digital Reference Chart.jpg In Ansel Adams words, 18% is mid grey on a geometric scale of black to white, We know that he was primarily concerned with printing and that Grey cards are all about proper exposure I have been using the Ansel Adams Zone System for more than 50 years, starting with B&W large format and also with 35mm film photography, yet have drifted away from such precision in metering since the advent of auto-exposure and then digital photography and the reliance on mushy auto-everything pushed on us by the camera manufacturers

In fact, this is the one Ansel Adams himself recommended for those learning the zone system. It has a long shelf life and it's cheap to use as one-shot. It's not great for pushing, but we're. The Asahi Pentax Spotmeter V (1°) The Spotmeter that Ansel Adams used creating the zone system. The Asahi Pentax Spotmeter V advertisement is a light meter for spot-metering, build by the Japanese brand Asahi Pentax. It became famous, due to the fact that Ansel Adams used it to create his famous zone system The Zeiss Ikonta B (523/16) is a close relative to one of Adams' favorites (the Super Ikonta B). This is a later model (1953) and shoots the same 2 ¼ x 2 ¼ format. A couple of cameras in this format that were used regularly by Adams: Another type of camera that shoots the 6×6 frame is this Super Ricohflex In about 1939, Ansel Adams and Fred Archer formulated a technique for determining optimal film exposure and development. They called this technique the Zone System. Ansel Adams believed that the perfect print, derived from the combination of proper exposure when shooting a scene and the subsequent development of the negative in the. The zone system of light metering. The zone system was first used by Ansel Adams in 1941 to help set exposure correctly. I use the zone system to help set the proper exposure and tonality on wildflowers. The color tone will not always come out correct if you go by your meter reading alone. Most camera meters will try to set the camera to medium.

Video: How to Use the Ansel Adams Zone System in the Digital

Ansel Adam's Law

I do have a working understanding of the Zone system and do use an abbreviated method to determine film speed and development times like so: But now I would like to make a chart, just to be in the sensitometry film club. Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2. Apr 22,. The ZONE SYSTEM. Devised by Ansel Adams and colleague Fred Archer in 1939, the 'Zone System' is a grey scale chart which can help to determine correct exposure, both in black and white photography for which it was originally intended, and more recently can be adapted for use in colour photography Zone System Archives - jbhphoto.com Blog. This is where we will share our knowledge of the wet darkroom, what we have learned about traditional B&W film photography and what we are currently doing. Ansel Adams Photography Royal Photography Photography Filters Black And White Photography Editorial Photography Photography Basics Wedding.

Zone system - Ansel Adams

One thing that's worth getting familiar with is the famous 'Zone System,' developed by Ansel Adams (arguably the greatest black and white landscape photographer of all time). To summarize, Adams worked out a chart that runs from zone 1 to zone 9. Zone 1 is pure black, while zone 9 is pure white This can cause headaches with SFR measurements. But it's not a bad idea generally; it's quite similar to the development adjustments (N-1, N, N+1, etc.) in Ansel Adams' zone system. For this reason it's not a bad idea to place a Q-13 or Q-14 chart near the slanted edges Ansel Adams and Fred Archer developed the Zone System. Adams in particular was very interested in the way he visualised the scene as a part of making the photograph. He made his images with a clear picture in his mind of what he wanted the outcome to look like. This visualisation technique is used in a wide range of sports and business situations I performed a 10 exposure test of a middle tone well textured tree bark including an 18% gray card in the picture as well just for reference. I performed this test according to what I understood of Ansel Adams' Zone System , I started by exposing the tree at the camera's exposure to place it in Zone V. then manually modified the exposure by 1 stop every time until I hit zone 0 , and same thing.

Aug 24, 2017 - Explore CJ's board Ansel Adams on Pinterest. See more ideas about ansel adams, ansel adams zone system, ansel adams photography The Zone System developed around 1939-40 by Fred Archer and Ansel Adams uses a logarithmic scale in order to work well with the analogue photographic process; middle gray is known as Zone V in the scale of 11 zones from Zone 0 (black) to Zone X (white)

Authorized by the Ansel Adams Publishing Rights Trust, this collection ranges in price from from $129 to $1,499 depending on size and framing. Join us in celebrating a full range of some of Ansel's finest work, featuring America's wild places, its national parks, and its great mountain ranges Ed's adaptation of Ansel Adam's Zone System to the digital world is a game changer. For any disciple of photography, Ansel Adams' stunning and iconic landscapes underscore the paramount need for precise exposure control in the creation of indelible images THE ZONE SYSTEM OF PLANNED PHOTOGRAPHY Minor White The Zone System of planned photography grew out of Ansel Adams' search for controls by which he could make prints that possessed the utmost illusion of substance and reality regardless of lighting conditions. In this way alone could his love of things as they appea

Ansel Adams and Fred Archer developed a zone system to control every levelfrom lightto dark in a photograph through both exposure and the paper that the image was printed on. The zone system isdesigned to make sure that you get correct exposures when taking a picture.The system begins with a tonal chart with nine zones that range from dark blackt I included, on the lens focus testing chat, Ansel Adams`s gray scale, called as the Zone System. It helps a lot to post process black & white photos, by giving you a reference of gray color range, were particular elements of photo, should be. Click here to find out more about Zone System. Click on the picture, view full size, than right click. However, even though I learned a great deal from the three books of the New Ansel Adams Photography Series and they are treated as critical reading for any photographer I must admit that I have found a far more comprehensive, albeit dense, explanation of ZS in Phil Davis' Beyond the Zone System. After guiding the reader through sensitometric.

Zone System and The Ansel Adams' Project

Ansel Adams' Zone System is now easily replicated in Photoshop thanks to Blake Rudis. Blake runs F64 Academy and teaches Photoshop to hundreds of photographers on a regular basis. For years now Blake has offered products called Digital Zone System, which relied on Photoshop Actions The Zone System was formulated by Ansel Adams and Fred Archer (Graves, 1997; Koren, 2013) in 1939-40 for the purpose of making accurate exposures, rich in tonality. The formula was developed for the use of black & white film photography; however the system has since evolved for use in the digital era. The simplified Zone System as prescribed b The zone system was developed by Ansel Adams. He was a great photographer, but a master wizard in the darkroom. His prints are a reflection of his mastery at printing. Grab one his books on the zone system. Sent from my iPad using Tapatalk Pr

The Zone System Really Right Stuff Blo

In my last post (many many months ago) I explained my own education about Zone System and how this empowered my visualization skills and technical control to achieve a desired image quality. Being a Zone System practitioner many years in the analog medium, however, makes for translating the same co Yes, it is not a true Zone System in the Ansel Adams sense, but it is what you are looking for if you are shooting transparency film. Check his website. If you want to read a good description of the system stroll down to your local bookstore (or order from Amazon.com) his book called The Backpacker's Photography Handbook To use the Ansel Adams zone system, follow these steps: Choose the scene area where you want to meter the light (the key tone), the one you want to be correctly exposed (or want to expose according to your taste). In the zone diagram, identify the tone area you want a specific area to have in the photo and keep the zone number

As the film had a 9 stop range from black to white when printed on grade #2 paper the Zone system ended up with 10 tones. The standard Zone system densities and tones were an average found by Ansel Adams through his experimentation. These densities have become standards so that everyone agrees on what a particular zone represents Ansel Adams was known for his black and white landscape photographs and Fred Archer was a portrait photographer of Hollywood and between them, they developed a method to improve photography known as The Zone System Get this from a library! The practical zone system : for film and digital photography. [Chris Johnson] -- The Practical Zone System: for Film and Digital Photography 4th edition is an updated version of what has become the classic book on the technique developed by Ansel Adams in the 1940's. The zone. Then in the 1930s, Ansel Adams developed his popular Zone System about controlling photographic grayscale tonal values. The 18% card already existed, and was called middle gray, and Ansel declared the 18% card was Zone V at the middle of his system, eleven tone levels, 0 (zero, black) to X (10, white), even if the Romans had no number for 0 Using a small stop only increases depth; beyond a certain point definition is actually impaired Ansel Adams, June 3, 1937, from page 244 of Ansel's autobiography. My article below will help you determine this point and get the sharpest possible images out of larger format cameras

The Definitive Guide To Always Expose Your Photos

Ansel often carried a viewing filter (typically a Wratten #90) to help visualize the response of black and white film. The ZoneView is an all in one solution and thin enough to carry in a shirt pocket; always at the ready. The filter provides a spectral response similar to the #90 and the cutout matches the height:width ratio of 4x5 sheet. Ansel Adams had the Zone System... I'm working on the points system. First I points it here, and then I points it there... Expose for the shadows and develop for the highlights, is one of the most recognizable mantra of modern photography. These words are from the wisdom and experience of American photographer Ansel Adams

How to Use the Old Zone System for Digital Photograph

Ansel Adams created a zone system for photo prints, but today we can look towards Adobe, who defines the exposures zones as follows: Blacks, Shadows, Primary Exposure, Highlights, Whites. Exposure is tricky to gauge underwater since our LCD screen is so bright and the ambient light is relatively dark The Zone System is a method of dividing the gray values between and including black and white into eleven levels. Black is Zone 0, White is Zone 10. Zone 1 is dark gray without detail, Zone 9 is light gray without detail. Zone 5 is medium Gray. It was invented by the great photographer Ansell Adams and is very popular with photographers In both cases if you were to trustingly use even the most sophisticated multi-zone matrix metering system you would end up with very badly underexposed and overexposed negatives or transparencies. The reason, of course, is that the meter sees the black cat and coal, or the white cat and snow as being 13% gray

Zone System - Wikipedi

Feb 17, 2017 6:25pm. Ansel Adams. Monolith, the Face of Half Dome, Yosemite National Park, 1927. Jackson Fine Art. Portrait of Ansel Adams by J. Malcolm Greany. Image via Wikimedia Commons. On April 10, 1927, Ansel Adams. clambered through Yosemite's LeConte Gully trail with four of his friends in tow The Ansel Adams Zone System. Making Zone-Based Adjustments. Customizing Zones Using the Zone Panel. Resetting Color and Zone Adjustments. Curves, Histogram & Image Density. RGB Mixer. Introduction to the Color Warper. Using the Grid Controls to Manipulate Color. Hue — Saturation Controls. Chroma — Luma Controls. HSL & LUM Qualifier. 3D. Hello. I think that having a huge peak brightness capability doesn't mean that the rest of the grey values should be remapped to it. The standard, say, 99% white (Slight tone without texture as per Ansel Adams' zone system) at 35 fl, should remain the same even if the TV can handle a hundred times more

Zone System: The Basics - Click it Up a Notc

The zone system is not super common for digital photographers, but it's a tool I use to help my brain understand how the camera sees the world. As you could probably tell from me confusing the numbers last night, I don't qualify light as zone 2 or zone 4 instead, what I do, is I think what tones in this scene are 18% grey—so for. About HC-110 Kodak HC-110 is a liquid-concentrate film developer introduced in 1962 and widely used ever since, particularly in photojournalism and fine-art photography.. It is recommended by Ansel Adams in his book, The Negative, and is a favorite of Zone System enthusiasts. The official Kodak data sheet contains recommended developing times for practically all Kodak black-and-white films Along with Fred Archer, Adams created a technique used to standardise a way of working which resulted in correct exposure every time, despite the lighting conditions, they names the technique the Zone System. This is a system that splits the image into 11 zones, each zone being 1 stop brighter than the one before

Zone System for Landscape Photography - Outdoor Photographe

Transcript and Presenter's Notes. Title: ANSEL ADAMS. 1. ANSEL ADAMS. Master of Black and White Photography. 2. A Long Life. Adams was born in 1902 in San Francisco, CA. Click the picture to link to a website about ANSEL ADAMS 1902-1984 His love of the natural world began early and became the most potent influence on his art. At the age of 12, Ansel taught himself to play the - PowerPoint PPT presentation. Number of Views: 451. Avg rating:3.0/5.0 I'm not a video expert but am learning a lot about the most recent technologies and how as a professional photographer you have to think differently. The importance of understanding the subject scene, in terms of the amount of shadow and highlights in the scene and setting ISO accordingly (somewhat the same as Ansel Adams Zone system) It's the digital post-processing equivalent of the legendary Ansel Adams' & Fred Archers' photographic Zone System. • This is Part 2 of what will be a multi-part series of blogposts on Layer Masks. E ach post will be short and sweet, and focused on just one aspect of Layer Masks - given in bite-size pieces, if you will As a well known protègè of Ansel Adams to whom he was later to become a consultant to, John Sexton is a well know photographer, master print maker and influential workshop instructor. His now-familiar black and white images of the natural environment have been described as luminously quiet

Ansel Adams, Zone System e a fotografia | Dicas de FotografiaZone System: The Basics - Click it Up a Notch

Ansel Adams' latest book features a sequence of photographs that he selected before his death but are being published in this sequence in book form for the first time. The book includes a foreword. Ansel Adams Lesson Plan. Instructor: Dana Dance-Schissel. Show bio. Dana teaches social sciences at the college level and English and psychology at the high school level. She has master's degrees. The Zone System (the seminal reference is probably THE NEGATIVE by Ansel Adams) is fairly straightforward, and some authors hash is to death and try to make it more complicated than it is. I thought this book was another make something simple more complicated books like that, but it's not 2. Kodak HC-110. Next up is the first developer I became enamored with, and one of the classic solutions you'll see mentioned in some classic technical photography texts from the likes of Ansel Adams—Kodak HC-110.This viscous liquid concentrate is a favorite of Zone System practitioners due to its ability to yield full shadow detail, a wide tonal scale, and full film speed Zone system → Zone System — Ansel Adams (to the extent of my research) capitalized both words in his publications referring to this system—Zone System, not Zone system as the page is currently titled. WP:CAPS says that For multiword page titles, one should leave the second and subsequent words in lowercase unless the title phrase is a proper noun that would always occur capitalized. Use a chart derived from our sharpest aperture article to figure out which aperture best balances depth of field and diffraction. As an aside, this method - spot metering to expose the brightest tone of your scene optimally - reminds me a lot of Ansel Adams's zone system, just a bit more digital..