What a mess!
A few weeks ago I agreed to test my lenses/flashes against my K-3 and I figured, no big deal. I had worked this all out in the past. Well, that was then and this is now.
A few quick notes:
- I do very little flash work outside of covering the occasional event or using flash for product shots
- My experience with Pentax-brand P-TTL flash is limited to the built-in flash on the K10D and K-3
- I own a Sigma EF-610 DG Super (purchased Dec 2013) which has the reputation of being a stable and complete third-party Pentax P-TTL implementation.
- When I purchased the Sigma flash, I extensively tested it on the K10D (did not own the K-3 yet) with all of the lenses on my shelf and found no significant incompatibility.
- When I purchased the K-3, I did a bit of flash testing with both the Sigma and built-in flash, but found no significant problems except for a tendency to overexpose with my A-series lenses at other than low ISO or at relatively close distance.
- I no longer own the K10D
- The K-3 is currently running firmware v1.11
Running through the test criteria listed on the previous
POST, I found a mixed bag of P-TTL compatibility.
General findings:- Ability of the camera to properly attenuate the flash depends strongly on the lens mounted
- Both FA and DA lenses provided full feature support
- Exposure consistency in decreasing order: Pentax-DA (recent) >> Pentax-DA (older, no power contacts) >> Pentax-FA (and non-Pentax AF lenses) >> non-AF KA lenses
- Best results in general were with the camera in P mode, auto-ISO enabled
- Ability to attenuate the flash is ISO dependent with tendency to overexpose as ISO increases. With fixed ISO, 100 or 200 with a max of 400 seemed to work best with my lenses.
Non-AF KA lenses: (Pentax-A and similar)- Best results at low ISO
- Strong tendency to overexpose (sometimes grossly) at ~1.5m and closer
- Exposure accuracy is highly dependent on subject and background with overexposure (2+ stops) being the most likely failure result
- Flash exposure compensation via 4-way controller will generally work, though may not be adequate to quench the overexposure
- The body is definitely attempting flash attenuation, but control and interpretation of the pre-flash appears to be inappropriate with apparent fail-over to full power*.
- Bounce flash tends to work somewhat better that direct
- Flash range indicator (at least on the Sigma) does not respond with this class of lens regardless of mode
Note that I do not recall any particular issues with non-AF lenses on the K10D or my initial "new camera" check-out with the K-3. Whether this behavior came as a result of subsequent firmware updates is unknown to me, though I have my suspicions.
Trailing Curtain Sync
Works with both AF and non-AF lenses with exposure quirks as per above
High Speed Sync (HSS)
Works with both AF and non-AF lenses, though actual exposure with non-AF is different than the straight P-TTL behavior noted above.
Conclusions:
The short story is that P-TTL support for non-AF KA lenses is rather poor. Use at your own risk and expect poor results in many cases. This bad behavior is relatively recent (within the last two years) and is a disappointing turn of events.** P-TTL behaves fairly consistently with my FA-series lenses in a manner that is generally consistent with my DA glass.
Steve
* The pre-flash behavior is definitely different when an A-series lens is mounted with the camera. The light is more intense. It appears that when an appropriate exposure cannot be calculated, the fail-over is to full power.
** There are other reports on this site regarding poor behavior with A-series lenses, but only with fairly recent model bodies. (One of the best examples is the long, confusing, and nasty thread regarding the AF160C ringflash
HERE.) To the best of my knowledge, flagship models prior to the K-3 offer full backward support. I cannot say in regards to the K-30/K-50/K-500 or the K-S1/K-S2.