Now that you understand more about sensor size and choosing the appropriate lens, there's still more compatibility issues to consider.

Manufacturer lenses vs. lenses from an independent lens maker...

Independent:An example of an independent lens maker is Sigma, Tamron, & Tokina. The manufacturers of these lenses do have occasional compatibility issues. Part of the problem is that none of the independent lens manufacturers have complete access to the specifications of Canon, Nikon, Pentax, Olympus, etc. camera-body communication. An example of some compatibility issues with independent lenses and DSLR bodies are:
* Soft focus
* back or front focus
* error messages on the camera body
* intermittent focus

If you do choose to go with an independent lens maker , here's a brief summary of what to look for on several manufacturers...

Tokina- look for the Pro DX lenses. These are digital only and do not work on the full size sensors. Some of the ProD lenses will work on full size sensors.

Sigma- look for the DC format for their digital only line (24mm sensor). The DG line will work on the full size sensors.

Tamron- look for the Di-II line for digital only. The original Di series worked on both digital and film.

Manufacturer lenses:

* The EF-S lenses. As described before, EF-S lenses only mount on the APS-C cameras (20D, 30D and Digital Rebel series).

Nikon- Nikon has continued to use the F lens mount over the years. The different series lenses are broken down as follows:
* D-series lenses are for both film and digital cameras .
* G-series lenses cover 35mm and digital sensor formats but can only be used with cameras that have electronic aperture control.
* DX (digital only) series can be used on all current DSLR's
* AF-S lenses are compatible with most camera bodies, but some of the digital bodies, such as the D40, will only work with AF-S lenses.
* Lenses with VR may auto focus on older film cameras, but the VR function may not work.
* Some of our descriptions specifically say N90 and later. This means that this lens will only work on camera bodies that are newer than the N90 model (+ the N90 itself).
* If a lens is marked Pronea, this lens will only work on the Nikon Pronea bodies.

* DA-series lenses are the current line of digital only lenses. If someone used these lenses on their 35mm camera, there will be reduced image coverage.

Minolta Maxxum/Sony Alpha
When the 7D and 5D Konica Minolta was current, all of the Maxxum lenses would work correctly on those bodies. Since 2006, Konica Minolta sold their Maxxum digital SLR technology to Sony, naming it the Alpha System. So, if you have a digital Sony body, you can shop for lenses in the digital Minolta or in the Minolta auto focus sections. Even though the Maxxum lenses will work on the Alpha system however, I would take the same caution that was advised on the EOS system- if the lens was produced in the 80's, the technology may have some focus compatibility issues.

Olympus did not have an Auto Focus SLR lens system out on the market to make the change to digital. So, they created their own system called Four Thirds . This is a 4:3 aspect ratio of the sensors used by the Olympus DSLR system. This sensor is larger than most point and shoot camera's but smaller than the 24mm sensor of other DSLR's. Olympus also now has a Micro Four Thirds system (ex. Pen). The distinction between a Four Thirds and a Micro Four Thirds lens will be an M. in the description. So for example, 17 F2.8 M. Zuiko lens is for the Micro Four Third models.

More on Four Thirds
Multiple brands have Four Third and Micro Four Third systems now. Usually, the lenses are interchangeable between brands for these systems (Digital 4/3: Olympus, Panasonic, and Leica).

* If you notice FO in one of our descriptions, that stands for film only, and that lens marked FO will not work on any digital camera body.

Yes, there's a lot to know and a lot to remember, and we know it can sometimes be overwhelming. If you're unsure, then double check your owners manual, or call one of our sales representatives. They will be happy to help you choose a compatible lens for your body! Also, stay tuned for tomorrows post where we'll explain how to navigate our website to find the right lens for your digital SLR.