Diffraction affects your image sharpness by limiting Depth of Field and useful Resolution. See how our camera and lens choices influence these limits.

To increase Depth of Field we simply decrease aperture (larger f-stop). However, we cannot get infinite Depth of Field by decreasing our aperture infinitely. Diffraction establishes the upper limit to Depth of Field.

The subject may seem very technical, but the solution is far from being difficult. To understand this tutorial better, consider reading my Correct Exposure Series of Tutorials and my previous tutorial on Hyperfocal Distance, which explains the relationship of aperture and Depth of Field.

Diffraction is an optical effect limits the resolution / sharpness of our photograph. Since it is an optical effect, higher resolution sensors will not improve resolution further. Higher resolution cameras are thus more demanding on our optics and eventually will yield little to no improvement in total resolution. Diffraction plagues landscape photographers who are striving for a large depth of field and high-resolution images. Many of us are not even aware of this, blindly selecting a small aperture according to our calculators and charts.

Determining the "correct" exposure for an image can be a challenging task. We could choose to simply let our camera decide for us, and use the fully automatic settings that are quite sophisticated and often do a reasonably good job. However, this also means to give away part of the creative process to your camera. I am writing this tutorial with the beginning photographer in mind. The principles outlined in this article should become a second nature to you. I encourage you to practice and to ask questions. In many ways, this is like riding a bike. Once you learned how, you can focus your attention on your surroundings.

I am not advocating using the manual settings of your camera at all times. Instead, I am a big fan of the creative zone settings such as Aperture Priority Mode, Shutter Priority Mode and Program mode. I use these automatic modes 95% of the time and I rarely resort to Manual Mode.

Aperture settings determine the Depth of Field (how much of your scene is in focus). Landscape photographers often strive for a very large Depth of Field while Portraits often require a shallow Depth of Field. Being in control of the aperture, the photographer can direct attention and guide the viewer through the image.

Shutter speed controls how motion of the subject or your camera will look like in your pictures. A slow shutter will blur fast moving subjects and a fast shutter will freeze them.

Learn what it takes to take perfect photos in winter.

Extreme weather conditions are challenging to photograph. High contrast scenes and bright snow throw off your auto exposure. Cold weather and condensation can damage your equipment and batteries drain faster.
Whether you are trying to capture the beauty of icy winter landscapes or your children’s fun on the slopes, the challenges of winter photography require preparation. In this short essay, I am going to give you advice to help you coping with those situations.

Someone sitting on the curb

Learn how to optimize pictures for websites without sacrificing quality.

The benefit of small pictures is immediately obvious. Requiring less bandwidth will reduce your cost and the cost to your visitors (time or volume charges). People will not remember your site as being slow and come back again (although slowness might happen for other reasons).
I also reduce the size of personal images I send via email to friends and family.
It is thoughtful not to waste other people's time and mailbox space.
The image on the left is only 13.8kB and can be loaded, even through a dialup connection, in a fraction of a second (the text on this page is bigger). Further optimization could reduce the size of this image to about 10kB without too much loss of quality. To save time, I have automated my workflow (including the final compression), leaving some room for further improvements.
I will demonstrate how to optimize your images with Photoshop, but you should be able to reproduce these steps with just about any Photo Editor

Preserve the Colors of your Images Recently Ron sent me an email and hinted me towards the fact that I missed the last mile on my workflow tutorials.
I was asked to give some more insight into the process of preparing images for web viewing and/or printing.
In this tutorial I am going to cover some of the basics of color profiling and in the next tutorial I am going to talk a bit about resizing and compression of images. After all you want your images to look good without annoying your viewers (and your wallet) by large data transfers. As you can see this site has a reasonable amount of graphics, but (hopefully) still loads fairly quickly. Part of the reason (besides a good host) is that I optimize my images for online viewing. Since I have automated the process, I forgot to cover this subject. You can use the same technique to send your pictures via email.

Color Profiles and Management

I am by no means an expert in color profiling, nor do I understand all of it. But I can give you some tips on what worked for me without drifting too much into technical jargon.
Color Management should be part of your digital workflow and it is tightly interwoven with all the applications.
Since different devices use different technology (an LCD uses light and color filters to render pixels while an inkjet puts ink onto a paper), you need color management to make the picture look the same on either of them. You want the picture to be printed the same way it looks on your screen. Today's consumer grade LCD screens are often too bright and too cold (blue/green tint). I guess the reason behind this is that manufacturers want them to look brighter in the show room. Unfortunately, this really messes up your color management, so if you are serious about getting the best quality from your pictures, check out my short article on LCD Color Calibration.

Color Proofing

Even after you calibrated your monitor, you still need an application like Photoshop that supports color management. As far as I understand the process, the monitor profile consists of two parts. One part is loaded in the operating system (the one that converts a standard color space to the color space of your monitor) and another part is used by the application.
All you need to worry about is that your application supports color management. On some LCDs (like my laptop screen) I can see a visible difference between an image that I open in Photoshop on the calibrated monitor and one I open with the Windows picture viewer.
In order to color proof your image for your printing service, you need an ICC Profile. Since EZPrints offers good prices and a color profile (EZPrints Profile), I am going to use them as an example. Simply download the profile and right click on the file. Select "Install Profile" and start (or restart) Photoshop.
In Photoshop open the picture you wish to color proof.
Go to View -> Proof Setup -> Custom
Under Device to Simulate select ezprints.icc (or whatever printer you want to use) and leave the rendering intent on Relative Colorimetric.
Now you can do two things:
1) You can go to View -> Gamut Warning and let Photoshop highlight the areas in your picture that are out of Gamut (that have levels of saturation your printer cannot reproduce). If you have a lot of those areas and if the color range is wide, you will see posterization effects. That usually happens when you try to boost the saturation too much.
2) Or you can go to View -> Proof Colors. Provided your Monitor is calibrated and able to reproduce the entire color range (that's usually the case, as a monitor has a wider color space than prints), you will be able to preview exactly how the final print colors will look like. Don't even try this with an uncalibrated screen.
I have also set up Photoshop to use ProPhoto RGB as my working color space (Edit -> Color Settings). For some reason, Photoshop only lets you select ProPhoto RGB after clicking the "More Options Tab" (which cost me quite some time to find out).

Color Spaces

Ron asked: "The instructors for Photoshop at the UC ext. courses there in Cupertino always said to use Adobe RGB color space. Now I see that people say sRGB might be better."

4th of July Fireworks in Seattle
The photo was shot from across the bay (Harbor Avenue) with a long lens. It's almost 4th of July again. Millions will watch the fireworks displays all across the country and many of us will want to photograph the fireworks.
Photographing fireworks is actually easier than it sounds.
Two years ago I found myself in Seattle on July the 4th and I decided to give it a go and see what would happen.  
Fireworks photos are almost guaranteed to be spectacular and with a little preparation are really easy. In this article I am going to outline the process of researching locations, preparing, and taking the actual photographs.
Surprisingly, most of the effort goes into a good preparation. Once you are set up, you won't have to do much more then pressing the shutter. 

Let's start with the basic research you should do before going on a fireworks shootout.

Researching Location

Key to good photographs is often proper research. I arrived in Seattle during the early afternoon of July 4th and didn't have a lot of time to research locations.
A while ago I wrote a Tutorial on finding Photo Opportunities with Google Earth and using a GPS receiver to home in on those.
You don't really need a GPS device, but using Google Earth to find spots for taking photos is a really good idea. It has measuring tools, 3D views of Skylines and a whole lot of other tools that can help you find a good location.
I recommend that you check out this tutorial, since it has a lot more valuable information (e.g., how to export a track to your GPS from within Google Earth).


I took the photographs of the fireworks from Harbor Avenue Across the bay. In the image above you can see how I measured the approximate distance (2 miles) for the shots. I would recommend not going much above 2 miles, since this would require a really long lens.
I positioned myself across the bay from the fireworks, hoping to be able to capture the fireworks with the Seattle skyline in the background.


I actually found two or three potential places, so I decided to drive by each of them before making my final decision. I took my equipment and went for a drive early in the afternoon. Much to my surprise, the area around my first choice was filling up with spectators already and parking was almost impossible. When I finally found a parking spot, I decided to simply wait until nightfall for the fireworks. Unfortunately, I had left all my comfort items (warm clothes, water, and food) in my hotel room. Don't make the same mistake I did, plan ahead!

On the other hand, I was at my location early enough to secure a good position.  After what seemed like an endless wait and with still a couple of hours to go, I set up my tripod as  the place was filling up quickly with like-minded shutterbugs. I found a guard-rail and I set up against it to avoid awed spectators stumbling into my scene.

Preparing for the Photos

El Capitan photographed while focusing on the Hyperfocal distance
(Very large Depth of Field) In this article I am going go outline some basic concepts of Depth of Field and Hyperfocal Distance. As a little extra you can download my Hyperfocal Distance Calculator to create your own tables for use in the field and for experimentation.

Depth of Field is defined as the range in front and behind the focus point that is still in focus and sharp. Since perceived sharpness depends on print size, viewing distance and lighting conditions as well as your eyesight.
Therefore I will use quantifiers like shallow to describe the Depth of Field.

Focusing and Depth of Field

In Landscape Photography I often try to achieve a maximum Depth of Field (picture of El Capitan). Getting such a deep DOF requires planning.
You need to set a very small aperture (large f-stop number). I therefore use Aperture Priority Mode (Av on most Cameras) and place the camera on a tripod, since a small aperture usually results in a long exposure time.
Since I want to keep the foreground and the background in focus, I usually use manual focusing and set my focus distance to the Hyperfocal Distance (see below).
Some lenses (usually prime lenses) offer a Depth of Field Scale. This scale will show you how far the range of the DOF extends at a certain aperture. Although this is a good reference, it is normed. Since perceived Depth of Field also depends on print size and viewing distance, those values are not always accurate in all situations.
Digital SLR usually have a Depth of Field Preview Button that is located somewhere near the lens. Unfortunately most Digital SLR with crop factor have a relatively small viewfinder, limiting the usefulness of this preview. Since my Eyesight isn't what it used to be anymore, I don't use this very much and I rather depend on experience or a cheat sheet I created.
An easy rule to remember is the 1/3 - 2/3 rule: For any f-stop, the depth of field extends about twice as far behind the focal plane then in front. Therefore the saying: Focus 1/3 of the way into your image.
Example: If your DOF is 30 meters and you want to have everything between 20m and 50m in focus, you need to focus at about 30m (1/3 of the distance between 20m and 50m). Depending on your nearest point, you can replace infinity with approx. 50m to 300m (if you focus close, use 50m).
When you focus on a subject at close range (macro) this rule doesn't hold true anymore (the distances become approx. equal).

Web Server Traffic from Digg during day 1, outlining some important events Last Sunday I casually wrote a post about the most common pitfalls in photography.
I had written the post a long time ago, but I never put it on this site.

The story ended up on the front page of Digg, stayed there for nearly 12 hours and was picked up by a bunch of secondary sources, resulting in 100,000 Visitors within a day (most of them within the first 12 hours). Trying to keep my server up and alive, I learned a lot about what it takes to keep the server alive, hence I decided to slide a non photography related post in, hopefully giving everyone who finds themselves in a similar situation some points to consider.

On Sunday Usproblogger (Digital Photography Blog) submitted the story to Digg (probably using the button that my blog software puts below each post).
Initially I wasn't aware of what had happened and while I was watching a movie the post must have hit the front page of Digg.

My site is hosted on a Virtual Private Server (VPS) with 256MB guaranteed RAM and 1GB burstable RAM. I have tweaked my VPS significantly, turning off all non-essential demons and keeping only the things that are required for hosting. This article is not about tweaking a VPS machine; I assume you have already done it.

This website is powered by a dynamic content management software. Among the many benefits (visitors can comment, I can maintain a site with over 2000 pages easily), it has one major drawback. The web content is stored in a database. Each time someone views a page; a program is executed (php). That program gets the information from the database (MySQL), and literally builds the page for each and every visitor (enough of the basics, I am going to assume you know all this if you are having the same problem that I had).

With such limited resources and the amount of traffic Digg can send, my Server quickly ran out of breath and was unable to handle the traffic.
The server recovered somewhat, probably because the traffic dropped momentarily.
By the time I noticed what was happening, i was completely locked out of my system and had to reboot in order to regain control and do something about the situation.

What I did to keep the Server up