Mylos longer articles

Introduction

This is a quick and semi-scientific comparison of three normal prime lenses for the Nikon system:

• 60mm f/2.8D AF Micro-Nikkor
• 50mm f/1.8 AF Nikkor
• 45mm f/2.8P Nikkor

Why these three lenses? Simply because I happened to have them on hand. The 45mm is the lens I use on my FM3A (see also my Epinions.com review), the 60mm macro is the lens I bought along with a D100 for my father, and the 50mm f/1.8 (non-D) is the normal lens I used to have on my old N6006, before I sold it off on eBay (and gave the lens away to a friend who lent it back to me for the purposes of this test).

Construction

The 45mm and the 60mm are both very well constructed in metal, to the same standard as old AI-S lenses. The 50mm is the cheapest lens in Nikon’s line, and it shows: the barrel is plasticky (and the silk-screened focal length has actually partly worn off).

The 45mm and 60mm both have well-damped manual-focus rings without play. The 50mm has a loose focus ring. The 45mm and 50mm are both quite light, the 60mm is a more substantial and heavier lens (but I think it balances better with the D100 body).

The 45mm is a Tessar, a lens design invented exactly one century ago by Paul Rudolph of Zeiss. It is supplied with a compact lens hood and a neutral filter to protect the lens. Interestingly, the “real thing”, a Contax 45mm f/2.8 Tessar T* by Zeiss is actually cheaper than the Nikon copy…

The 60mm has a deeply recessed front element that comes out as you crank the helical for close-up and macro shots. The concentric inner barrels rearrange their relative position as well, due to the internal focus design which allows the lens to be used both as a macro and a general standard lens. For general photography, no lens hood is needed as the lens body itself acts as one.

Sharpness

To test lens sharpness, I taped a page from the classified ads section of the Sunday paper to a wall, and lit it with a cheap Ikea halogen lamp. I then set up a Gitzo 2227 tripod with an Arca-Swiss B1 ballhead and shot the newspaper. I tried to use the same framing as much as possible to keep the shots comparable. Before running the tests, I applied a custom white balance using a standard 18% gray card. The shots were all taken with a 2s self-timer and the mirror vibration reduction function activated. The 50mm and 60mm were focused with AF, the 45mm was focused manually with the D100’s focus assist “electronic rangefinder”. The NEFs are “compressed NEFs”, around 4MB each.

You have to take this test with a grain of salt, as I had no way to make sure the camera axis was precisely perpendicular to the wall, whether the wall itself is flat and if the newspaper lay really flat against the wall. Furthermore, as I had to move the tripod to keep the framing identical across different focal lengths, I may have introduced subtle shifts in the tripod. To make this more usable, I am attaching below a table of 256×128 crops taken at the corners and center of the frame.

The differences between the lenses are subtle, and certainly within the error margin for the experiment, but all the lenses show excellent sharpness without fringe chromatic aberrations or the like.

Bokeh

Bokeh is the Japanese word to describe how out-of-focus highlights are rendered. It is principally controlled by the shape of the lens diaphragm. All three lenses have a seven-blade diaphragm, but only the 45mm’s blades are rounded.

At the largest aperture, the aperture is usually constrained by a circular portion of the lens barrel rather than by the diaphragm, which explains why the bokeh of the 50mm lens is significantly better at f/1.8 than f/2.8. The next table shows the incidence of aperture on the shape of out-of-focus highlights:

The 50mm’s out-of-focus highlights have a hard heptagonal shape beyond f/2.8, as do the 60mm beyond f/4. The 45mm clearly benefits from its rounded diaphragm blades.

Flare control

Not tested yet.

Barrel distortion

Not tested yet.

Real-world image tests

Summary

Conclusion

The 45mm f/2.8P Nikkor is clearly an excellent lens, and not just a retro head-turner. Unfortunately, it is rather expensive for what you get compared to the 60mm f/2.8D AF Micro-Nikkor (no AF, no macro capability). The 50mm f/1.8 AF Nikkor has less pleasant out-of-focus highlights than the other two, but it is remarkably sharp and one quarter the price. If the construction is an issue, the famous 50mm f/1.4D AF Nikkor (not tested as I don’t have one on hand) is also an excellent choice.

In any case, any of these lenses is an excellent performer that brings the best out of a Nikon camera, and no photographer’s camera bag should be without one.

Learning more

Here are a few good sites to learn more about Nikkor lenses:

Bjørn Rørslett is a nature photographer with reviews on quite a few Nikkor lenses.

Thom Hogan has a lot of instructive material on the Nikon system, including lens reviews.

Ken Rockwell has many opinionated reviews on Nikkor lenses (sometimes entertaining, sometimes infuriating). How he has the chutzpah to review lenses he has never held in his hands continues to elude me.

For French readers, Dominique Cesari has his take on Nikkor lenses.

The Nikon historical society in Japan has an interesting series, 1001 nights of Nikkor, with the back story on lens design.

Stephen Gandy’s CameraQuest website has reviews on some exotic Nikkor lenses on his Classic Camera Profiles page.

When you first start tinkering with digital imaging, you do things by the seat of the pants, and after a while you realize you need a more disciplined approach to have a manageable setup. The result is called a workflow.

Workflow phases

Each person’s workflow is slightly different, but the following rough steps are common to everyone:

1. Acquisition—getting the pictures in, whether from a flatbed scanner, a slide/negative scanner, PhotoCD or digital cameras. This also encompasses automated primary cleanup done from within a scanner driver, e.g. Digital ICE³.
2. Reviewing—deleting dud pictures, and if you have duplicates, selecting only the best one.
3. Asset management—cataloging your pictures in a database, with categories, captions and all. Professional organizations like photo agencies go to a very high level of detail as this is the key to their business, but this is also essential for anyone contemplating building an imae collection of more than 1000 pictures or so.
4. Editing—you can go hog-wild with Photoshop or the GIMP, although since this is a very labor-intensive process, it is usually done to a small minority of pictures
5. Output—getting prints made, but also publishing to the Web
6. Backup—backing up in case of hardware failure or catastrophe.

Acquisition

What hardware you use for acquisition controls the final quality of your results, so:

• Don’t skimp on a cheap scanner, use slide or negative scanners rather than flatbed scans from prints
• Use digital cameras like the Canon D60 or Nikon D100 that have larger sensors with less thermal noise rather than point and shoots.

Using a slide/negative scanner is a very slow and laborious process, and a preferable option in many cases is to have scans made by a photo lab. Avoid the low quality Kodak PictureCD and opt instead for PhotoCD Master, which has higher resolution and scans made more carefully.

Reviewing (editing)

Getting rid of the chaff early is a major step in improving your productivity, but it is difficult to be objective about one’s own photos. This process is sometimes also known as editing, although this term lends itself to confusion with digital imaging. Here is a good introductory article on the subject: Give That Cat The Boot: Editing 101.

Asset management

For most of the other phases, the choice of software does not matter very much and will indeed change over time. It is essential to get asset management right up-front, however. The solution you use must be

1. scalable to accommodate an expanding collection of photographs
2. open, you don’t want to be locked in a proprietary database format, at the very least you should have the ability to export the database to some kind of text format
3. flexible, allowing you to enter as much or as little metadata as you require for any given photo
4. Offer powerful retrieval capabilities: you should be able to run queries like “find all the photos of me and my grandma in front of the Golden Gate bridge”, or full-text caption search (if you use captions, not very common because of the amount of work involved)
5. standards compliant, the key standards being EXIF (picture metadata like aperture and exposure) and IPTC (the press photographers’ standard for captions)

The best program I’ve found so far is IMatch (Windows only, I’m afraid), mostly because of its incredibly flexible category system, that works like set theory with multiple inclusion relationships and boolean operators. I have posted a more detailed overview of how to use IMatch for image category management. As I have switched to the Mac, my current asset management program is Kavasoft Shoebox, which has the same power as IMatch and a much better user interface to boot, but is not scriptable.

Editing

The most comprehensive description of a Photoshop editing workflow is available here on Michael Reichmann’s Luminous Landscape site.

Output

As I’ve mentioned elsewhere, my preferred output method used to be prints made on a Fuji Frontier digital minilab system. Unfortunately, most labs are clueless about color management and cropping, and I now use an Epson R1800 archival pigment ink printer. People who want to print digital black & white prints may opt for the R2400 instead.

Backup

This is essential if you do not want all your hard work above to go in smoke in case of a hard drive failure.

Media failures are not the only kind of disaster that can destroy your digital images, fire, theft, flooding and earthquakes are also a consideration, depending on where you live. Most companies have a disaster recovery plan (at least on paper), most individuals should have a simplified one for their personal effects as well. I am not just talking about photos: scanning property titles, diplomas and other vital documents is an inexpensive precaution.

Sticking to a diet is hard. So is sticking to a backup plan, for human factors and process-related reasons, not technical ones. If your chosen backup method is so cumbersome you don’t apply it regularly, it is not going to do you much good. You should focus on developing a process that fits your risk sensitivity as well as your time and budget, and if your current approach is not sustainable, reexamine your backup requirements to fit within what you can do on a regular basis. A weekly or monthly backup schedule should not be too onerous for most people.

The backup process should also involve periodic verification of the backups, so that media failure can be detected and corrected immediately. This implies redundancy in the backup, as well as diversification (use media of different types, or different manufacturers, to avoid simultaneous failure from systemic causes). If you wait 5 years until you actually need the backup, Murphy’s law will inevitably strike.

CD-R and DVD-R media are the cheapest per megabyte, but I am not convinced of their archival characteristics (some published tests have shown CD-Rs can become unreadable in as little as 2 years). 70 or 80GB DLT tape cartridges (and other tape technologies like DAT DDS, 8mm, VXA or LTO) offer high capacity and are durable, but tape drives are very expensive, unreliable and usually available only in SCSI.

Just as the watched pot does not boil over, online data like that stored on external hard drives is harder to misplace than removable media. The solution I use is to make two backups onto two external 250GB firewire hard drives (under about $1 a gigabyte as of July 2005). I rotate them weekly between home and my office, so even if my apartment burns down, I will have lost at most a week’s worth of pictures.

If you prefer CD-R or DVD-R, be sure to use reliable brands like Mitsui Gold and follow the NIST guidelines for their care and handling (here is the PDF one-page summary).

For the backup software, I do not trust proprietary indexing formats and use a regular filesystem with incremental disk to disk copies using XXCOPY on Windows, LaCie’s free SilverKeeper utility on Mac OS X, and Rsync on UNIX.

Format obsolescence is a factor, although the magnitude of the risk is often overblown. While JPEG and TIFF are likely to be supported well into the future, manufacturers’ proprietary RAW image formats (for digital cameras) are less likely to. When a format becomes obsolete, it should be converted to a more durable one, obviously before the OS and drivers for it have become nonfunctional.

Finally, we are all mortal. If you were to disappear tomorrow, would your loved ones know how to retrieve your photos? Making prints of the best ones is a low-tech but robust way of ensuring their passage over time, possibly even skipping generations.

I have discussed digital imaging workflows elsewhere. In this article, I would like to focus on the asset management using IMatch.

Category management

The main reason why I selected IMatch is for its advanced category management. This masquerades as a hierarchical system, but it is actually a full-blown set theoretical system with:

1. Inclusion relationships: if a category is under a more general category, anytime you search for the more general category, the images under the more specific category will also appear, without having to assign them to the more general category explicitly as well.

2. Multiple inclusion (a category can belong to multiple larger categories.

3. Derived categories: you can have categories that are defined using boolean formulas of categories and file system folder location.

Category schema

To the left is a screenshot of the category window in IMatch.

It is very important to give some prior thought to how one’s categories will be organized, just as for librarians the choice of a catalog system like the Dewey decimal index is almost a matter of religion. A poorly designed category schema will almost inevitably entail at some point in time having to laboriously reassign categories.

The figure to the left shows my categories. I try and have a hierarchy where the most specific category (leaf categories in the tree) have a manageable number of images. If there are too many (more than a couple hundred), this means I have to break down the category into smaller, more specific subcategories.

Obviously, pictures of friends and family make a substantial proportion of my image catalog, so it is important to have a manageable approach to those.

For family, I use an inverted family tree: a family tree centered on myself, and then expanding on my father’s and mother’s side of the family, and so on, so that the path I take to get to the category for a relative. In the example on the left, I can get to the category for my cousin Hajera as follows:

1. My family

2. My mother’s side

3. My mother’s sister Yasmeen

4. Her daughter Hajera

This scheme is very simple and extensible, and avoids bunching all relatives together in a single disorganized mess.

In practice, however, I make some small adjustments that break this general approach. For instance, I have a separate category for my mother herself (“Naheed”, just under “Maman” – yes, I think in a mix of French and English), because otherwise whenever I would select the category for my mother, all her side of the family would appear as well, and the same thing for my grandmother. Andy Katayama describes a more systematic way to deal with these situations.

For friends, I use an approach where I organize them by how I met them (school, work, and so on). Sometimes, a single friend can belong to multiple categories, which is where IMatch’s multiple inclusion scheme comes in handy.

For instance, Bruno Chomel is an ex-colleague from three different companies, so I have link category to him in each of the three companies’ categories, as shown in the figure to the right.

I also have some special-purpose categories. “Concepts” is used for categories that encompass abstract concepts like humorous pictures. “Technical” is used for things like flagging pictures that are part of a panoramic set, or my best pictures.

Finally, I have a category “Places” that is used to indicate the geographic location for photos that have a distinguishing landmark in them, and this category is organized hierarchically by continent, then country, state, city and so on.

In addition to these categories I defined myself, I also use the standard “Universal” category schema supplied with IMatch for standard categories like “People & Relationships / Weddings” or “Culture & Communities / Holidays & Celebrations / Thanksgiving”.

Derived categories

As an example of a derived category, here is the property box for the “Uncategorized” category I use for all images that do not have any category assigned.

This formula means “all pictures that are not categorized under Fazal’s user-defined category schema or the Universal category schema supplied with IMatch, and that are not part of the Photodisc folder”. The expression for the Photodisc folder looks intimidating, but I actually entered it using the second button above, which allows me to enter a specific folder from a pop-up menu.

Assigning categories efficiently

For an asset management system to be viable, it shouldn’t take too much time. Systems that require you to enter captions are too burdensome for regular use, but categories strike the right balance, as long as they can be assigned to large numbers of images efficiently.

IMatch offers a number of time-saving features like splashers (a small drop-down menu that allows you to assign your most-frequently used categories to an image in two clicks), but in many cases this is not enough.

I import photos from my digital camera in batches of between 50 and 300, and I use the following algorithm to make assignments quickly. I have used this technique to categorize over a thousand images in less than an hour.

First, when importing the images (by clicking on the rescan button in the filesystem view of the database after importing the images), check the option to bookmark new images. Then go to the bookmarked images selection to view all of them.

Look at the first image, and pick a category among those that fit it. Control-click on all images that are also in that category, and then assign the category to all of them in one go using the category assignment dialog. Repeat if there are more categories to assign to the first image. Once all categories for the first image are exhausted, toggle the bookmark on it to make it disappear from the view. Usually, the next few images also have no categories remaining so you can take out a batch. You then repeat with the next image that has categories remaining to be assigned, and repeat the process until all categories have been assigned.

Typography

The optimal line length for readability is around 10-12 words (Source by Ruari McLean)

Telecoms, networking and IT

The ratio of peak load to average load in a service with diurnal activity variations is approximately 3 to 1. Source: my own empirical observation from Wanadoo access logs and France Telecom telephone call usage logs.

Probability of a Web page having X incoming links referring to it: P = X ^ -2.1 (Source)

When specifying computers, for balanced performance provision one gigabyte of RAM per gigahertz per core/thread.

Any standard making use of ASN.1 is a piece of junk.

You only get the benefits of statistical multiplexing or compression once, and it should only be done in one layer. Any other layers attempting to do the same only add cost, complexity, brittleness, overhead and latency.

When designing high-availability systems, fail-over is not the hard part, falling back is.

Photography

For most ordinary lenses, optimal sharpness is around f/8. For high-quality lenses, it is one or two stops below full aperture. Only the very best lenses are diffraction-limited and offer optimal performance at full aperture.

Camera light meters are calibrated for 12% gray. Common gray cards are 18% gray, so if you use one for metering, you should open up one half stop to compensate. (Source)

The human eye is a 6-7 megapixel sensor. The monocular field of view is 180 °, the binocular field of view is 120-140°, and the normal focus of attention spans a 45° field of view.

Avoid Kodak products like the plague. Those products they make that are actually decent (i.e. the engineers managed to sneak them past the bean counters) soon get adulterated (like Tri-X) or discontinued (like PhotoCD or their medium-format digital backs). Prefer Fuji, Agfa or Ilford.

Spam has become a global scourge in terms of the sheer volume of spam out there which is reducing the signal to noise ratio of email. While being careful with email addresses (using throwaway Yahoo or Hotmail accounts, for instance, when posting online) goes some way to minimizing the volume of spam, it doesn’t remove it altogether.

Bob Metcalfe, the inventor of Ethernet, postulated what is now known as Metcalfe’s law: the value of a network is proportional to the square of the number of users. The flaw in this law is that it does not take into account a law of diminishing returns: once all of your acquaintances are on the network, each additional user adds only very little value, whereas each additional bad apple destroys a constant value due to the time they waste, and thus, even if bad apples are a small minority, they will eventually drive the value of the network down in a sort of tragedy of the commons. So the value of an email network is going to be some constant times the number of your acquaintances minus the number of spammers. At some tipping point, the rising number of spammers will make this value negative.

What can be done?

Brightmail

Brightmail is a company that sells spam filtering services to ISPs and large corporations. They basically set up unused email addresses and spread them around where they can be picked up by spammers’ email address gathering robots: search engines, newsgroups. Any email that goes to such an address is bound to be spam. Brightmail monitors these mailboxes and whenver they find a new piece of spam, they create a filter specifically for it. If this is done sufficiently quickly, they can nip a mass emailing batch in the bud before it has had the time to hit too many mailboxes. The system is also very reliable and unlikely to cause false positives (a legitimate email being flagged as spam). Unfortunately, this is very labor intensive and thus costly, and will be limited to those with deep pockets.

A company called Cloudmark, founded by an ex-employee of Napster, offers what is essentially a peer-to-peer distributed version of Brightmail. It remains to be seen how resistant that system can be to denial of service attacks.

Legislation

Legislation against spam should be introduced, but is only a long-term solution as spammers will simply relocate to countries without anti-spam laws. Even common crimes like theft are not that well enforced across borders due to the cumbersome procedures involved with Interpol or international judiciary cooperation.

Pricing

The reason spammers can blast away hundreds of thousands or even million of emails is that the marginal cost to them is practically nil. Some people have advocated putting a per-email charge to make spamming economically no longer viable. I have been responsible for building large-scale billing systems at Wanadoo, France’s largest ISP, and I can tell you building a billing system on the scale of the whole Internet is simply not feasible from a project management point of view.

Even if it were, it would not be desirable because in many ways it would be throwing the baby with the bath water. Internet email is successful because it is so cheap, unlike the price-gouging of earlier messaging systems like EDI or X.400. Andrew Odlyzko has written a series of very persuasive papers that show how usage pricing stunts the development of networks and thus prevents society from realizing their full benefits: http://www.dtc.umn.edu/~odlyzko/doc/networks.html

Certification

The main problem with spammers is they are anonymous, and that Internet email with its limited support for cryptographically strong authentication makes it easy for them to hide. S/MIME or OpenPGP signatures are not very commonly deployed because they are cumbersome and this outweighs their advantages (national security agencies also dislike anything that makes crypto more commonplace, but that is another story).

Spammers, however, make digital signatures more attractive by increasing the cost of not using them. I believe when the tipping point I mentioned above is reached, people will only accept email that is signed by someone they already know (someone who is already in their address book) or by someone whose signature is certified by a trusted third party not to be a spammer (probably the same companies that sell SSL certificates that make electronic commerce possible, Verisign being the most commonly known of them).