Background Exposure

The Importance of On-Camera Flash

Brian White — Sun, 08 Apr 2012 18:45:04 +0000

I don’t think I’ll ever buy a camera that doesn’t include a flash on the body itself. It isn’t that I like flash photography; I abhor it, actually. On-camera flash photography makes for uneven lighting, weird color mixes, and generally bad images. However, having a flash built into the body means that I’ll never be without a fill flash and this is very important. Any time you’re photographing something, especially people, on a bright, sunny day, pop up the little thing and let the camera work its magic. It’s worth it.

Depth of Field

Brian White — Sun, 01 Apr 2012 06:10:31 +0000

It’s a long-standing “rule of thumb” that f/8 is the sharpest aperture. It’s important to remember, though, that there is exactly one distance from the focal plane that has “perfect sharpness” while distances near are simply “acceptably sharp”. There is no sharp boundary (if you’ll excuse the pun) between that is in focus and what is not but rather a gradual shift from one to the other.

(click for full-size version)

With the D800′s exceptional resolution, however, the definition of “near” becomes rather small. The above image is a hedge in bloom and that was approximately 2 meters (1 meter is equal enough to 1 yard for this comparison) away at its closest and 6 meters away at its farthest. It was shot at f/8 at 68mm and is a full-resolution crop from the center of the image. As you can see from the full-size image, even at f/8, the range of “acceptable sharpness” covered a depth of probably about a ¼ meter (call it 1 foot). Down-scaling by a factor of X will of course increase that range by a factor of X.

D800 or D800E

Brian White — Sat, 25 Feb 2012 10:31:30 +0000

There’s been a lot said about the new Nikon D800 and it’s twin, the D800E. There’s nothing but a single letter on the outside to tell them apart and not much on the inside, either, with only the anti-aliasing filter cancelled out.

What does an anti-aliasing filter do? It (nearly) eliminates the effect of “moire” patterns caused by fine, repeating detail. See the Wikipedia article for more information. The cost of such a filter is that the resolution is decreased somewhat because the light is “blurred” (high-frequency component is removed) so that it hits more than a single pixel.

What this means is that the D800E without the AA filter will be able to produce an image with more detail than it’s brother. However, any fine, repeating patterns will likely cause weird color artifacts. If you’re a nature photographer, such patterns are not common but if you’re going to be photographing anything man-made (including clothes), the lack of an AA filter is going to create problems, problems that are very difficult to remove in post-processing.

I’ve ordered a D800 (no-E) for myself because experience has taught me that too much stress on the best possible performance usually comes back to bite you in many other ways. Better to have something that works really well in all situations than something that works perfectly in only a few.

Lossy Compression of RAW

Brian White — Thu, 09 Feb 2012 07:55:14 +0000

There has been some discussion recently thanks to the huge pixel count of Nikon’s D800 regarding the size of the NEF (“raw”) files. They’re 75MB, 14-bit, uncompressed. Nikon offers a form of lossy-compressed NEF but a lot of people think this is a Bad Thing™ because they know that JPEG is “lossy” and everybody knows that is bad.

However, it’s not proper to compare the two. JPEG compression has quality problems because it loses information between pixels causing noise and artifacts around sharp edges (text being the best example), and because it loses some resolution (the number of bits worth of color detail) as well resulting in somewhat less than 8 bits of information per channel.

JPEG loses information you would not normally see. Nikon’s NEF compression loses information you cannot use. Let me explain…

First, you have to think how many bits you need on any single pixel. The dynamic range of the image is not relevant because the lossy-ness is only per-pixel and thus no odd artifacts around sharp edges.

Second, you can’t display or print with a resolution higher than 8 bits per channel.

Third, of all mathematical operations only subtraction loses significant bits. Note that clipping (i.e., increasing the brightness beyond maximum value) and contrast enhancements are a kind of subtraction.

With those in mind, you can keep only 9 bits of information for any pixel and still be able to create a full-detail image. A 9-bit number can hold values from 0-511. The value with 9 significant bits (i.e. has a 1 in the most significant bit) and the least amount of information is 256 and so still has full-detail when reduced to 8-bit (0-255) for display/print.

What is important is what 9 bits to keep. A 14-bit AtoD converter has 16384 output values. Ideally you want to encode this such that each pixel is stored in a way that it holds 9 bits of detail data (the mantissa) and where in the original 14 bits the 9 bits reside (the exponent). Yes, it’s effectively a floating-point number. It’s not too difficult to think how to store this efficiently.

Nikon doesn’t do it explicitly in this way but the non-linear encoding curve they use is close. Their 12-bit compression stores about 700 values (varies from camera to camera) and their 14-bit compression stores about 3000 values. The bottom line is that even compressing 12-bit/4096 values to 700 values keeps 7.75 bits of information and compressing 14-bit/16384 values to 3000 values has 9.3 bits of information. [source]

Therefore, given the 8-bit limits when it comes to printing and display, it seems to me that lossy-compressed 14-bit NEFs have all the information you could possibly use… though perhaps not all you could want.

Kids and Money

Brian White — Thu, 12 Jan 2012 15:56:14 +0000

I thought I’d take a break from Photography for a few minutes to talk about money. Specifically, about kids and money.

A study done (sorry, I can’t find the reference) in the USA showed that wealthy families are far more likely than middle-class or low-income families to teach their children about managing money. If you want your kids to be financially stable, or even outright successful, then we as parents need to teach them from a young age.

How? Start by giving them an allowance; $1 per year of age per week is a good starting point and it needs to be divided into categories such as “spending”, “savings”, “investment”, and “charity”. For proportions, 10% for the latter two is a good number and then divide the remainder equally between the first two. Round it nicely. (e.g. $8 => $3, $3, $1, $1) spending=”anything”; savings=”important things”; investment=”for retirement”; charity=”given to those less fortunate”

When? A child should start learning about money as soon as they are able to understand than a dime, though smaller, is worth more than a nickel. Physical spending money should come as soon as they can make change. My personal experience says that 7 years old seems the right time. 6 was a bit young.

Why? Because. It’s our responsibility as a parents to teach our kids and that’s what we’re doing here. I don’t personally believe in paying an allowance in exchange for chores around the house — in our family, doing chores is how you contribute back to the family; the kids don’t get paid for their chores any more than I get payed for cooking or doing dishes.

Once the child has money of their own, they need to be taught how to spend it wisely. They can divert “spending” into any of the other three categories or “savings” into “investment” but there’s no going the other way. If they want something for themselves, let them buy it, even if you think it’s wrong. Explain what something costs in terms of what else they could have instead (the “opportunity cost”) but in the end, abide by their decisions. It’s their money and they need to be allowed to make mistakes.

Encourage them to buy their own gifts for others on Christmas or birthdays rather than ride on the gifts from parents. I contribute 1/2 the cost when they’re buying for others. (…though gifts made by hand are still better, in my opinion.)

Make them pay if they break or lose something that then has to be replaced, like a windbreaker or winter gloves. I pay 1/2 of that, too, simply because it’s not practical for a $8 allowance, of which only $3 is available for reimbursement, to pay the full replacement cost.

If they’re short, be willing to loan them some money but set a strict repayment schedule and charge interest. 0.5%/month (6%/year) is an easy amount. That’s how the real world works so they might as well get used to it.

[comment]

I believe it’s a good thing to teach kids about investing from a young age. While I don’t expect a young child to grasp all the nuances of return-on-investment, present-value calculations, and price-earnings ratios, I do think they can start to pick up the basics ideas of investing and that the value of things bought can go up over the long term.

Investing for the future can be difficult which is why it’s so important for it to become a habit from the very beginning. If you take 10% of your gross income and invest it wisely (an S&P500 “index fund” outperforms most mutual funds largely because it has no “overhead” costs) then you should be able to retire and continue the same lifestyle you had at retirement. The earlier you start this, the earlier you can retire.

My parents told me this 10% rule but it was always in the context of when I got a real job after finishing university. Better would be from the first time I had any income at all — i.e. an allowance.

Also essential is that this 10% be moved from paycheck to investment account automatically. If you never see it, you’ll never miss it. If you look to invest from what is left over at the end of the month, then you’ll never have anything to invest. In doling out my son’s allowance, I divide it for him and tell him how much is going into each piggy bank (yes, he has four of them .

In the spirit of investing in what you know, I told my 7-year old son to talk to all his friends at school and find out what they were asking for as gifts at Christmas. There were a number of different items but Beyblades seemed a favorite so we found out the company that sells them (Hasbro) and bought one share in that company for $34.24. It’s in my name, of course, and I payed the brokerage fee but I’ve set it up a portfolio under Google Finance in his name so he can watch it. Last we checked he’d lost 6 cents. Losing a little at the front gave me reason to reinforce that investments are made for years, not months or days.

Incidentally, I don’t expect my kids to remember what I tell them. I expect to have to tell them many times in many different ways over many years before they fully understand. Typically though, I’m surprised at how much they pick up and right away. I’m also surprised by how much I learn while teaching.

[comment]

My son, being 7 years old, gets $7/week (or $1/day) as an allowance. There are parts of the world where the majority of the people live on less than this amount.

How much should you put aside for charity? I set the bar at 10% with my kids. I read in the Rockerfeller’s contract that he set the bar at 20% for his son. You can look at it as “investing” if you wish; you’re just investing in someone else’s future instead of your own. Or you could be like Warren Buffett who is notoriously thrifty despite being one of the richest men in the world but plans to leave the vast majority of his fortune to charity when he dies. He feels that the charities would rather have a lot more money tomorrow than some money today and, given his investing record, he’s probably correct.

Anyway… Today we dumped out my son’s “charity” piggy bank (which receives $1/week), counted it up, did various currency exchanges, and worked out that he had equivalent of about USD$55. We took $50 of it and transferred it to Kiva(.org) where he would be able to lend it out to people for causes he deemed worthwhile.

I chose Kiva for several reasons:

It’s interactive: You get to choose exactly where your donations go. Also, small donations like $25 or $50 have a measurable impact.
It’s personal: You get to see photos of and read profiles about the people requesting money. I can point directly at people and say, “That person makes less than you do and has to buy food, clothing, housing, and everything else with it.”
It’s a loan: This means he’ll get the money repaid and can lend it out again. This allows him to act more frequently and doubles as an education about lending money.

So my son is now a philanthropist and we’ll periodically check in to watch the loans get repaid and get status reports on how each recipient is doing. He’s really got a pretty opulent life and maybe one day he’ll even realize that.

[comment]

I’ve never been poor. The reason for this is not due to an abundance of money but rather always having the safety net of my parents. I always knew that if I hit rock-bottom, I could pick up a phone, call collect if necessary, say “I need help”, and help would be there.

I have, however, spent some months of my life with absolutely zero money. Those investments I had made? I cashed them in to fund a business I wanted to start with some friends. After a year or so, we hadn’t finished our product but were scraping by with some consulting work. It payed the rent but not any salaries.

Not only did I have no money in the bank, I had recently called Visa to ask for an increase in my limit… so I could take a cash advance to pay my rent. It was December in Canada and I was driving to work on tires so bald you could see the steel belts. My budget for Christmas was a whopping $25 of which $14 went to a box of cards. My most common gift was a bookmark and a note “Sorry I can’t buy you a book.”

A couple memories stick out. I remember an ad on the radio for some fancy necklace that was only $199.99; I figured if it were only $1.99 then I might be able to afford it. I also remember getting a $50 parking ticket while I was buying those bookmarks. I wasn’t going to be able to pay it for months.

But despite all this, I kept on with the plan because we were in the process of having the company bought to add our in-the-works product to the line-up of another company and we had to hold on just a few more months and there would be a reasonable pay-out. Not enough to make anyone rich, or probably even make up for the year’s salary we had done without, but enough to make us as individuals solvent again. Plus we’d get back to working on what we wanted.

This time of my life was an invaluable lesson. Money is a source of huge concern but also of huge pride to those who do not have it. Though I borrowed money that I would eventually pay back with interest, I wouldn’t accept a dime in the form of a gift (though I did accept new tires from my parents as a Christmas gift).

Really, having nothing is an experience everyone should have. It teaches you things that you can learn no other way. It makes you appreciate when you do have things. One of the problems I see with teaching my kids how to save & invest from a young age is that they may never gain this experience and I don’t know what could possibly serve as a substitute.

But even with this experience, I can only guess what it’s like to be poor.

[comment]

Today Tuesday

admin — Wed, 12 Oct 2011 13:30:09 +0000

In the interest of organization and my own sanity, I’ve moved all of the “Today Tuesday” pages to its own section of the blog, accessible from a link in the top-left corner of all pages. Thanks again to everyone who’s been contributing!

Go to TODAY TUESDAY

An Open Letter To Camera Manufacturers

admin — Mon, 18 Jul 2011 11:06:37 +0000

Silicon is found everywhere today. What used to be the domain of nitrocellulose, emulsion, and mechanical components is now light-reactive silicon, software algorithms, and computers. Inside even the simplest digital camera is much the same components you find in your desktop PC: a CPU, Input/Output, and Memory. (My CS-101 professor woud be so proud that I remember the basic building blocks of any computer.)

What I find personally frustrating is that I cannot use the computer inside my camera in any way other than what the manufacturer intended. Who today would be happy buying a home computer that could only run the software installed at the factory?

Why is my camera not programmable? Why can I not load new abilities onto it just as I do at my desk? Even my phone takes new programs!

What I want to see is a camera that has a language from which I can write programs to control its functions. This could be Python, Java, or even Pawn. It should be obvious from history that as soon as something is completely flexible, people start using it in ways that were never expected.

I like night photography, but the High Dynamic Range of such exceeds the capabilities of modern-day digital sensors. To compensate, I take multiple exposures with different shutter times and merge them using special “hdr” software.

The mixing is a fairly easy process with the exception of the alignment of the photos. Even with a tripod, touching the camera to change the shutter time moves the camera slightly and the resulting photos end up offset by a few pixels in some direction.

If the camera were programmable, I would have it take multiple exposures all by itself,
stopping automatically when it has all that are needed. I would write something like this:

function TakeHDR() {
    raise mirror        // do it once for all shots
    wait 5 seconds      // let mirror shake settle out
    let T = 30 seconds
    do {
        set shutter time to T
        take photo
        save photo
        let T = T / 4   // next at -2 stops exposure
        create histogram of photo
    } while (photo has any pixel's R,G,B at maximum value)
    lower mirror
    signal "all done"
}

With that simple program, I’d get a series of shots, each 2 stops faster in exposure, until there were no overexposed pixels. Because there was no need to touch the camera, all of the images would be perfectly aligned.

How important is this feature to me? I would actually consider switching my equipment from Nikon to another to get this.

The Deck

Brian White — Fri, 01 Jan 2010 04:00:12 +0000

As I mentioned previously, two of my many hobbies are construction and video editing. I finally found the time to finish the time-lapse video of the deck I built in the fall of 2006. Enjoy!

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Planet Sydney

Brian White — Sun, 06 Sep 2009 12:21:51 +0000

When a site with “little planet” images was first shown to me, I knew it was something I had to try. So during my recent visit to Sydney, I took the opportunity to capture the full sphere around me. I bought a 10.5mm (DX) fish-eye lens a couple years ago and this was the perfect application. Covering 180° corner-to-corner, or about 100° in one dimension and 75° in the other, you can capture the entire scene in as little as 12 images, including a little overlap for stitching.

You can, of course, use any type of lens but since a full sphere has an awful lot of angular area to cover, you really want to capture as much per image as possible. And since you’re going to be warping the images in weird & wonderful ways, there’s no advantage in starting with a rectilinear (i.e. “normal”) lens.

If you haven’t heard, there’s a very common problem with capturing multiple images for stitching. It’s called “parallax” and it’s what makes close-by things appear to move faster than far away ones when looking out the window of a moving car. This affects your images when you rotate the camera to capture an adjacent area. If your camera and lens are not pivoting on the optical center of the lens (the point at which light appears to be entering it) then close things will move faster that distant ones as you turn and the final stitched image will have odd discontinuities at image boundaries. A standard tripod will move around the focal plane (the film or CCD sensor) which is not the same thing.

You can spend hundreds of dollars for a nice, heavy “panoramic mount” that will make this problem go away… or you can cheat. The trade-off, of course, is time and accuracy. The trick to reducing parallax errors is to push them to places where it won’t be noticeable after blending. The sky is usually the best choice but anything without long, straight lines will usually work.

Before starting, set everything on the camera to “manual” so nothing changes between shots. This is supposed to look like a single exposure when all is said and done. Take some quick shots in all directions and adjust the exposure so that you’ll capture everything.

Start by capturing the entire scene. A level shot every 45° (vertical mount) or 90° (horizontal mount) plus a few of the sky and the ground will ensure that you have everything. This is important because it’s easy to miss sections in the next step but having this will allow you to fill in any gaps.

Parallax error is generally only noticable when there are long, strait lines because they tend to become “broken” when stitched. Since there is never any parallax error within a single image, you want to capture anything with continuous lines in a single shot along with some soft boundary area on the edges and at least some of the stuff on the other side of that boundary for joining. Later you can force the stitching seams to be in this boundary region where they will not be (overly) noticeable. You can make life easier for yourself by not having wide or tall things close by. For example, don’t set up next to a guard railing. These will almost certainly not fit in a single frame and yet have the biggest parallax errors.

Once the images are captured, they have to be warped and stitched. You can pay an obscene amount of money for PTgui or you can use the free Hugin software. There’s no question that PTgui is more robust and has a nicer user interface but there’s no difference in the final output quality. In fact, PTgui uses many of the same (free) back-end programs such as “nona” and “enblend” when creating the final image.

The most time-consuming part of the stitching process is defining the control points. Both programs mentioned above have built-in automated tools to create control points but don’t use them! You want to do this by hand and only add control points along or on either side of the intended seam. Placing control points elsewhere in the image is detrimental since the program will sacrifice some accuracy in the important points to try to satisfy these unimportant ones. You want these boundary regions to align after warping because that is where the seams will go and the closer the areas match between warped images, the less noticable the seam. What happens elsewhere, where there are no seams, isn’t important since we’re distorting the final image so much that any error won’t be noticeable.

To get the “tiny planet” effect, use a “stereographic” or “stereographic down” output with about 300° on both the horizontal and vertical. When you preview the output, you’ll likely find that it looks “wrong” but it’s just a matter of setting the center to where the tripod can be seen. Then you can push, pull, rotate, etc. the preview until you get the general result you want.

Now render the final result. If you’re supremely lucky, the blending program will automatically place the seams in the correct locations and you’ll be done.

However, if you’re not that person, it’s not going to be perfect and you’re going to have to adjust it by hand. To do this, render the output again but this time have it output all the individual images separately.

After loading the blended image into Gimp, Photoshop, or whatever, find the blending mistakes and load the appropriate image into a higher layer. You can then make transparent all of this new layer from the boundary areas outwards, effectively pushing the seam out to those areas. Rinse & Repeat until all seams have been fixed.

If the ground has lines, you’re going to find that the seams are noticeable. It’s going to take some work with Gimp or Photoshop to transform/warp various parts of the images to create something that doesn’t have noticeable errors. In the end, though… It’s all worth it!

About Face

Brian White — Thu, 30 Jul 2009 20:11:50 +0000

I’ve been using the “K2″ theme for WordPress from the beginning but decided I wanted to try something that will use a bit more of the available horizontal space on a typical browser. I’m quite impressed with the “Atahulpa” theme. It’s amazingly customizable even without knowing any HTML/CSS.

I’d be happy to hear what you think of the new layout compared to the old.