Originally posted by ankit So what is the difference between the K-, A-, and M- mount lenses (lenses that will mount without an adapter, but dont give AF if I understand correctly). Is there a database of these lenses somewhere?
Hold on! There are only "K" mount lenses. All lenses are K-mount, letters indicate variations and upgrades in functionality. All Pentax lenses have compatible "K" mount and ANY Pentax K-mount lens can be mounted on any Pentax K-mount camera. What functionality certain lens-body combination will offer is what differentiate between them. Here is the best resource:
Pentax K-Mount Lenses and Lens Accessories
Let me give you a brief summary: In 1975 Pentax introduced "K" mount lenses. The name engraved on those lenses was simply
SMC PENTAX. We refer to those lenses as "K" to avoid confusion (for example take SMC PENTAX 1:1.4/50: there is no "K" in the name itself which indicated the very first K-mount generation but we would call this lens K50/1.4 anyway). Here is the example:
K 50/1.4). All following generations do have additional letters after Pentax to indicate family as follows:
smc PENTAX-M: redesigned optics to provide same focal length and aperture in smaller mechanical package. Sometimes optics remained the same if original design was compact enough. "smc" lettering is lowercase, original was "SMC" uppercase. Example:
M 50/1.4 smc PENTAX-A: added "A" position to the aperture ring to "surrender" control of the aperture to the body, and electrical contacts on the mount so that camera body can know aperture range. Example:
A 50/1.4 smc PENTAX-F: added auto focus, first generation. Example:
F 50/1.4 smc PENTAX-FA: second generation auto focus, mechanically compatible with "F" series. I believe there are some changes in the communications protocol, otherwise "F" and "FA" are functionally the same. Example:
FA 50/1.4 smc PENTAX-FA J: no primes ever made in "FAJ" series only zooms. This is the first series without aperture ring: they operate the same way A, F and FA lenses do with aperture ring in "A" position where body controls aperture. Made in an attempt to reduce price and survive on the market. I believe FAJ series made Pentax look bad and actually loosing to other brands. Lenses in "FAJ" series are of very poor mechanical construction and not so good optically and even designed poorly (like toys) and are in general not recommended. Example:
FAJ 28-80/3.5-5.6 AL smc PENTAX-D FA: coating of the rear lens element optimized to reduce flare from the sensor, otherwise functionally the same as "FA" series. Only two were designed, both macro (DFA50/2.8 MACRO and DFA100/2.8 MACRO). Example:
D FA 50/2.8 Macro smc PENTAX-DA: designed for digital. No aperture ring and some lenses have reduced image circle to fit APS-C sensor and are not suitable for film bodies. "DA" lenses can be used with film bodies that support A, F, FA, FA J and D FA lenses with aperture ring in "A" position. Very old mechanical bodies can not control aperture on "DA" lenses although you can mount them. Example:
DA 40/2.8 AL Limited
There are also "Limited" lenses, but apart from exceptional mechanical construction and optical qualities FA Limiteds are functionally identical to other FA lenses and DA Limiteds are functionally identical to other DA lenses.
So with your digital bodies
you can use all lenses but here is what you will get:
K, M: no auto focus, limited shooting modes, limited metering modes, no P-TTL flash support.
A: no auto focus, all shooting modes, all metering modes, P-TTL flash support.
F, FA, FA J, D FA, DA: auto focus, all shooting modes, all metering modes, P-TTL flash support.
Easy! :-)
Quote: hmm, the DA 40mm/2.8 looks very attractive with the $50 rebate. Maybe I'll just get that and the K100D for now!?
That is a good idea! Consider FA 50/1.4 as well if you like 50mm on digital bodies.