Makernotes usually store the lens type in some way. Sometime as a string, sometime as an numerical ID, or something else. There is not standard and it is mostly per vendor.

References

Nikon

• Nikkor Lens ID
• Nikkor Extended Lens ID

Pentax

• Pentax Lens ID

Canon

• Canon LensType from ExifTool Canon cameras do not have a reliable "?LensType" field. For example my 20D does not and put 0xffff, while some later Rebel model does.

So there are two ways: if you have a consistent ?CameraSettings.?LensType, use it.

If you don't (0xffff for example) you have other lens info that should allow to reduce the list to a bunch and require some user selection for the few last cases. For that there are a few fields in the makernotes:

First the ?FocalLength.?FocalType to see if it is a zoom or a prime.

Second ?CameraSettings.?LongFocal and ?ShortFocal, and ?MaxAperture + ?MinAperture.