Maybe Adam has been given too many of the latest Pentax lenses (for "reviewing" or whatsoever) so that he has almost forgotten how older Pentax manual lenses would behave on all the Pentax digital bodies. Nevermind, I think it's my take now! Below are two summaries that I compile to let all my readers here know (or got refreshed for the knowledge if already known) about the basic technical features or limitations of our Pentax lenses back to the 60s of the last century and what they could or could not do for us with our Pentax DSLR bodies! :-)
N.B. I don't think that you can find ALL of the information below in any of the Pentax DSLR/lens user/operation manuals! ;-D
Table 1: Lens Data/Function Availability with different Pentax Lenses
| Lens Data and/or Function | Provision Means | M42 | K/M | _A_ | _F_ | _FA_ | FAJ/ DA/ DAL | DFA (1st Gen.) | DFA (2nd Gen.) |
| Wide-opened Metering | Instant Return Aperture Coupler | - | Y | Y | Y | Y | Y | Y | Y |
| Number of Steps Stopped-down (via Aperture Ring) | Mechanical Position Indicator | - | Y | Y | Y | Y | - | Y | - |
| Maximum Aperture | Array of Electrical Contacts | - | - | Y | Y | Y | Y | Y | Y |
| Minimum Aperture | Array of Electrical Contacts | - | - | Y | Y | Y | Y | Y | Y |
| Focal Length | (Advanced/Serial) Electronic Communication | - | - | - | Y | Y | Y | Y | Y |
| Focus Distance | Electronic Communication | - | - | - | Y | Y | Y | Y | Y |
| Lens ID | Electronic Communication | - | - | - | Y | Y | Y | Y | Y |
| MTF Data | Electronic Communication | - | - | - | - | Y | Y | Y | Y |
| Powered/Auto Zoom | Electronic Communication and KAF2 Power Contacts | - | - | - | - | S* | - | - | - |
| In-lens AF (SDM or DC Motor) | Electronic Communication and KAF2 Power Contacts | - | - | - | - | - | S | - | - |
Legend: Y= Yes/Available; "-" = No/Not Available; S = Supported depending on Lens Model (if Feature is Available)
*Remark: Limited/Partial Function - Only Auto Zoom Retract and Powered Zoom are Supported.
Table 2: Pentax DSLR Camera Function Availability with different Pentax Lenses
| Body Function | M42 | K/M | _A_ | _F_ | _FA_ | FAJ/ DA/ DAL | DFA (1st Gen.) | DFA (2nd Gen.) | *Remark |
| Wide-opened Metering | - | -* | Y | Y | Y | Y | Y | Y | Stopped-down metering is available with a push of button. |
| Multi-segment Metering | - | - | Y* | Y | Y | Y | Y | Y | Not as accurate as subject distance information is Not available (and hence is not included in the calculation). |
| Off-the-film TTL Flash Auto (*ist D and DS/DS2 Only) | Y | Y | Y | Y | Y | Y | Y | Y | TTL flash sensor underneath mirror is installed; No Pre-flash is required. |
| Off-the-film TTL Flash Auto (All Others) | - | - | - | - | - | - | - | - | No TTL flash sensor underneath mirror; P-TTL is mandatory for Auto Flash. |
| P-TTL (where P stands for Pre-flash) | - | - | Y* | Y | Y | Y | Y | Y | Not as accurate as subject distance information is Not available. |
| AF | - | - | - | Y | Y | Y | Y | Y | - |
| Lens Correction on Image | - | - | - | - | -/Y* | Y | Y | Y | Only the three FA Limited are Supported. |
Legend: Y= Yes/Available; "-" = No/Not Available
Okay, is it and everything much clearer now? :-> And no need to make thanks to me, thank Adam instead! ;-p After all, I just won't make any reply over his premise to help others (and actually help him to make more money!) anymore (although Adam is really "kind" enough for not banning me!), as I decided and told two-and-a-half year ago! :-D
Further/Reference Read:-
K-Mount Metering and Exposure Bases - A Technical Brief
Related:-
Two Important Custom Functions for Proper Metering
Modding a Rikenon-P 50/1.7 Into an "A" Lens! :-o
Ten Things that I Want Ricoh to Do for Pentax
Hypocrites of the PentaxForums and Their Lies
Updating of my Blog Editing Direction