The world’s first and only expert system dedicated to photographic lenses

How it all began

lens-db.com was founded on July 6th, 2012 by Evgenii Artemov and was originally created as a regular photographic lens database. Over time, its creator developed an understanding that it is not enough just to provide visitors with general information - it is necessary to help choose the most suitable lenses for certain genres of photography and explain why it is advisable to opt for them. In addition, it is necessary to simplify the selection process as much as possible, without the need for the visitor to manually go through tens or even hundreds of lens models in the database. And, of course, it became clear that the extensive database formed over the years of the website's existence, along with expert experience, allows not only providing users with comprehensive information, but also giving advice on the choice and effective use of lenses, compare and evaluate them according to certain rules, without shifting this task to the visitors themselves.

This is how our website evolved into the expert system.

What is an expert system?

An expert system is a computer program that uses artificial-intelligence methods to solve problems within a specialized domain that ordinarily requires human expertise. Structurally, the expert system consists of a knowledge base, an inference engine and an user interface. A knowledge base is an organized collection of facts about the system's domain. Facts for a knowledge base come from human experts and are usually presented in the form of "if - then" rules that can be applied to known facts to generate new facts. The inference engine interprets and evaluates facts in the knowledge base to provide an answer. Expert systems do not replace human experts, but serve as additional aids.

Some statistics

Thanks to the hard systematic work, the database contains photos, model history, camera compatibility information, specifications and descriptions for 5757 autofocus and popular manual focus interchangeable lenses designed for SLR, rangefinder and mirrorless cameras: from APS-C to medium format 6x7cm, from fisheye to super telephoto lenses, from Asahi/Pentax to ZEISS.

It is not our goal to record as many lenses as possible in order to make the database the largest in the world. In our opinion, quality, uniformity and accuracy of information, as well as conclusions based on it, are much more important than quantity of information.

Unfortunately, being guided by this principle, we cannot entrust the users of our website to modify the database. The data come from the extensive collection of documents from manufacturers and dealers: 8400+ booklets, catalogs, ads, instruction manuals and datasheets occupying 61.2 GB of storage, while the facts in the knowledge base come from the experts with an extensive level of knowledge and many years of experience in the use of photographic equipment. All this makes our data/knowledge base the world's largest credible.

Note: since the website is an expert system and not a test lab, we don't have lens tests and reviews here.

Website features

The website's inference engine solves the following tasks:

• finds the pros and cons of lenses,
• determines if the lens belongs to professional models,
• determines which genres of photography the lens suits best,
• finds alternatives for a particular lens,
• compares lens specifications,
• allows you to choose a suitable lens by the genre of photography and a camera you plan to shoot with,
• evaluates the completeness of lens lineups for enthusiast and professional photography, finds similar lens lineups.

All these tasks are solved using a set of heuristic rules, or "rules of thumb", and not simply based on focal length and speed of lenses.

Other useful features include:

• The database contains a complete list of lenses ever produced by system camera manufacturers. At the same time, manufacturer websites usually list only those models that are currently available for purchase, and information on discontinued models may be scarce or even absent.
• The website automatically decodes abbreviations used by manufacturers in the lens names, so you don’t need to consult various "lens abbreviation tables" available online or remember specific abbreviations by yourself.
• Thanks to the website’s built-in help system, when viewing the lens specification you don’t need to google what are the advantages of Lead-screw type Stepping Motor, what does "MO" stand for in the Sigma [AF - MO - MF] focus mode selector name, and how Mode 1 of the optical image stabilizer differs from Mode 3. And of course, the possibilities of the website’s help system are not limited to the mentioned above examples.

Thus, as you can see, our website has no competitors: on the one hand, there are ordinary databases dedicated to photographic lenses, and on the other hand, there is lens-db.com.

Who is the target audience?

The website is intended for a wide range of visitors, whether they are beginner photographers or honored masters, amateur photographers or professionals.

The website is an independent non-commercial project: we are not affiliated with any photographic equipment manufacturers or commercial organizations and work out of love for art, not for money.

The website is absolutely free to use. The registration is not required.

How you can help

As a visitor, you may:

• leave your feedback on lenses you used in the past or use now,
• inform us about errors in specifications, lens descriptions or website engine,
• donate money for maintaining the website.

Also, feel free to share links to our website on social media, if you believe that our website is really useful and deserves that as many people as possible should use it.

Our ongoing tasks

• Maintain the website until the photographic technologies to which the website is dedicated remain relevant and users are interested in receiving information about them;
• Improve the data/knowledge base: find and fix errors (if any), add descriptions and missing information, add new lenses announced by manufacturers;
• Improve website design and presentation of information from the data/knowledge base.