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09-02-2015, 10:09 AM   #16
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I'm now the happy owner of a new Pentax AF-540 FGZII WR flash! I've had a bit of a play and its really a very good unit with plenty of things to justify its premium over the older models I think. I'll post in another thread some first impressions, but I'm now going to be able to develop the Flash Guide with much more on this latest flash, including images plus better descriptions of the differences between it and the older model. Where possible I'll try and include side by side references to the features as implemented on both the older and newest Pentax flashguns.

For now, in relation to this thread on P-TTL ..... firstly, the new flash manual is quite direct and specific about one thing ..... (page 29 within the P-TTL mode operating steps) - 'The correct flash output is obtained in P-TTL mode only when the flash is used with autofocus lenses'.

So there we have it. Certainly it agrees with my own experiences ... so that is what I'll go with and A series lenses will clearly continue to be excluded from P-TTL operations.

I haven't yet had time enough with the flash to put the various lenses through my entire P-TTL checklist, but certainly the DA 18-55 AL II WR performed faultlessly with P-TTL exposures. I actually found this newer flash to be more consistent than the previous model, producing identical flash exposures with many different apertures. The flash compensations were very good as well, as were exposures in HSS mode. Bounce was consistent also.

However, not the case with the F35-70 ..... once again with this new flash I was unable to get any reliable P-TTL flash exposures. In fact many flash compensations with this F series lens had no effect at all, even compensations of 2 stops and more! This is consistent with my experiences with this F lens and the older flash also.

So ..... I still need some more user reports on F series P-TTL performance to be able to commit more firmly for the next version of the guide. At present I have decided to re-write the references to mounts to remove the KAF2 designation and use KAF only .... but at present I am still forced to draw the line between F and FA series lenses. I just wish I knew more about why this seems to be necessary .....


Last edited by mcgregni; 09-02-2015 at 10:25 AM.
09-02-2015, 02:54 PM   #17
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QuoteOriginally posted by mcgregni Quote
I'm now the happy owner of a new Pentax AF-540 FGZII WR flash! I've had a bit of a play and its really a very good unit with plenty of things to justify its premium over the older models I think. I'll post in another thread some first impressions, but I'm now going to be able to develop the Flash Guide with much more on this latest flash, including images plus better descriptions of the differences between it and the older model. Where possible I'll try and include side by side references to the features as implemented on both the older and newest Pentax flashguns.

For now, in relation to this thread on P-TTL ..... firstly, the new flash manual is quite direct and specific about one thing ..... (page 29 within the P-TTL mode operating steps) - 'The correct flash output is obtained in P-TTL mode only when the flash is used with autofocus lenses'.

So there we have it. Certainly it agrees with my own experiences ... so that is what I'll go with and A series lenses will clearly continue to be excluded from P-TTL operations.

I haven't yet had time enough with the flash to put the various lenses through my entire P-TTL checklist, but certainly the DA 18-55 AL II WR performed faultlessly with P-TTL exposures. I actually found this newer flash to be more consistent than the previous model, producing identical flash exposures with many different apertures. The flash compensations were very good as well, as were exposures in HSS mode. Bounce was consistent also.

However, not the case with the F35-70 ..... once again with this new flash I was unable to get any reliable P-TTL flash exposures. In fact many flash compensations with this F series lens had no effect at all, even compensations of 2 stops and more! This is consistent with my experiences with this F lens and the older flash also.

So ..... I still need some more user reports on F series P-TTL performance to be able to commit more firmly for the next version of the guide. At present I have decided to re-write the references to mounts to remove the KAF2 designation and use KAF only .... but at present I am still forced to draw the line between F and FA series lenses. I just wish I knew more about why this seems to be necessary .....
I've found that the documentation on support for P-TTL with non-autofocus lenses is inconsistent in the Pentax user manuals. While the AF540FGZ II manual has the restriction you quoted, the K-3 manual on page 81 in section Functions Available with Various Lenses explicitly lists P-TTL auto flash as supported with A-series lenses, when using the built-in flash, the AF540FGZ II flash, and others. The same information is also on page 84 in section Functions when Using an External Flash.

Do you suppose the status of P-TTL support with non-autofocus lenses depends on which camera body is being used?

I've been having some success using P-TTL with the AF540FGZ II flash, the K-3, and the SMC Pentax-A 70-210mm zoom lens (aperture ring in A position), at least in basic scenarios. But I've been concerned that there may be problems I haven't encountered yet, so I am happy to have found your thread on this very subject! I plan to try your detailed list of test scenarios with this combination, and see what I can learn...
09-02-2015, 03:46 PM   #18
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Lo I'd be very grateful for all test information .... Especially at this stage the F series autofocus lenses, which I fully accept in theory should function correctly. ..... It's just that mine won't! Is it just mine? The quote above from the latest flash manual would seem to be the most up to date pronouncement from Pentax, and it is all encompassing .....ie not camera body dependent.

I have seen web resources that list focal length and focus points as parts of the P-TTL equation, which makes sense. You can't determine distance from a focal length alone, it depends on the position of the subject in the frame as well. I just can't figure out whether this extra information was added through the data contact at some point .... And whether that coordinated with any particular lens releases. It could be of course that only SOME f series lenses have issues ..... ?

Thanks, I'm looking forward to seeing your test results !
09-08-2015, 09:00 AM   #19
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QuoteOriginally posted by Sherman Quote
've found that the documentation on support for P-TTL with non-autofocus lenses is inconsistent in the Pentax user manuals. While the AF540FGZ II manual has the restriction you quoted, the K-3 manual on page 81 in section Functions Available with Various Lenses explicitly lists P-TTL auto flash as supported with A-series lenses, when using the built-in flash, the AF540FGZ II flash, and others. The same information is also on page 84 in section Functions when Using an External Flash.
The inconsistency in the user manuals is troubling. Until this latest generation of flash, support for A-series lenses has been explicit for both bodies and flash.

QuoteOriginally posted by Sherman Quote
Do you suppose the status of P-TTL support with non-autofocus lenses depends on which camera body is being used?
I think that is a safe assumption. Ultimately, the body controls the flash, though the nature of the control interface seems to be evolving.

QuoteOriginally posted by Sherman Quote
I've been having some success using P-TTL with the AF540FGZ II flash, the K-3, and the SMC Pentax-A 70-210mm zoom lens (aperture ring in A position), at least in basic scenarios.
That is good to know.


Steve

09-08-2015, 09:55 AM   #20
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My issue as the writer of a 'Guide' is that I need the certainty to be sure the resource is definitive ... That is a kind of responsibility. I have to consider the impact on beginners and people trying Pentax flash for the first time. The last thing you want is things not working the way 'its supposed to' .... This can kill off any new found confidence .....


That's why I played safe for the first edition without any further evidence.
09-08-2015, 12:15 PM   #21
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I’ve gone through the P-TTL Lens Compatibility Test with the following configuration:
- Pentax K-3 body
- AF540FGZ II flash
- SMC Pentax-A 70-210mm F4 (a non-autofocus lens), with aperture ring in ‘A’ position.

I checked all 11 scenarios and all were successful, with the following exceptions and caveats:

2) Check that the Auto Zoom is working on the flash head zoom …
The auto zoom feature does not work with non-autofocus lenses, the flash coverage angle must be set manually. This is to be expected, as this is a documented restriction in the AF540FGZ II user manual.

11) Back to normal mode and M exposure mode, try a few bounced shots …
Bounce flash worked, but there is no effective flash range indicator displayed on the screen when the flash head is set at an angle of other than 0 or -10 degrees. This is also a documented restriction in the user manual.

Overall in these tests the flash exposures were all decent, but some were not optimal (especially in some of the more extreme cases). However, a modest amount of flash exposure compensation would suffice.

In item 6) Change the focus distance, by moving your subject or focusing on something else …
I initially counted the results as a success, but to investigate more deeply I refined the test as follows:
- Set up a scene with two subjects, one near and one far.
- Set camera exposure mode to ‘M’, meter for the ambient light and underexpose substantially, so that the flash exposure dominates.
- Place the subjects in the scene so that the near subject is close to the minimum effective flash range, and the far subject is close to the maximum effective range.
- Focus on the near subject and take a P-TTL flash exposure.
- Re-focus on the far subject (keeping all other variables fixed) and take a second exposure.
- Compare the two histograms, and see if the focus distance change has resulted in a change to the exposure value from the P-TTL system.

Sure enough, with the non-autofocus lens the two histograms were essentially the same.
I then repeated the test with a current technology KAF3-mount autofocus lens (HD Pentax-DA 20-40mm F2.8-4). With this lens the histogram shifted to the right for the exposure focused on on the far subject, which seems to show that the focus distance had been a factor in the exposure calculation. It wasn’t a huge shift, but enough to make a visible difference in the image.

I’m still learning about the Pentax flash system, but my initial conclusion is that it is too soon to dismiss P-TTL as only working with autofocus lenses. (Further tests with additional configurations would be valuable…) It appears that there are many inputs to the P-TTL algorithm, some essential and some not essential. When a non-essential input is not available, the results may be less accurate (flash exposure compensation is more likely to be required). But the results can still be quite usable.

Consider also the following scenarios:
- P-TTL bounce flash
- P-TTL off-camera wireless flash, triggered optically by the on-board flash in CONTROL mode.
In neither of these cases does flash-to-subject distance have any relationship to the focus distance, correct? So if focus distance information from the AF system was essential for P-TTL, neither of these cases could work. But both are clearly documented in the user manuals as supported.

We still have the puzzle of the contradictory information in the K-3 and the AF540FGZ II user manuals. Perhaps there is a translation issue, and the key restriction in the flash manual should really be something like:
“The most accurate flash output is obtained in P-TTL mode only when the flash is used with autofocus lenses.”
Maybe we could find a Pentaxian that is fluent in Japanese and would translate for us page 29, section P-TTL Auto Flash, in the AF540FGZ II user manual...

Finally, one suggestion you might find useful when further researching the AF540FGZ II user manual, while working on the next revision of your excellent Pentax Flash Guide. I discovered that on the Ricoh UK web site, there is an English-only version of the flash manual. I’ve found that one somewhat easier to read than the bilingual version that comes with the flash.
09-08-2015, 12:45 PM   #22
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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.

09-08-2015, 01:10 PM   #23
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Oh no, it IS a mess! Perhaps I should never have asked!?!

Sherman and Steve, thanks very much indeed for your detailed input and testing results (and welcome Sherman ) ...
There's a lot to digest but we are moving closer to an acceptable compromise between fact and likelihoods.

Not sure about Japanese translations, but these new flashes are the first to be designed by Pentax in a long time. Perhaps something HAS changed with the recent bodies, and when the new design team started testing they found the same things we are now .... Perhaps they freaked out and took the same conservative approach to their new manual as I felt I had to take with the Guide, and they just wrote off manual focus lenses altogether ... Hence the new but contradictory guidance in the latest flash manual ..... ?
09-08-2015, 11:06 PM   #24
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I really need to read this all properly.

I had an *istDS and have never really been happy with the results I get from my Sigma EF530dgst.
When i use the Sigma 18-50 kit lens it's ok, but i'm limited by the lens.


But when i use any of my decent lenses (all Manual focus A series) it's inconstant and rubbish.

I've had my best results with A series lenses using old flashes like the Pentax AF160, or an old Sunpak Auto321 (both use the old fashioned "magic eye" thing on the front of the flash)



Flash photography is really a dark art, especially since there are so many combinations that can cause things to not work right.
09-09-2015, 03:14 AM   #25
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I need to read it all properly as well! There's been an amazing response and a great meeting of minds here to try and solve this mystery. It seems as soon as one question is answered something else raises it's head.

Its good to hear those experiences .... Your descriptions of A-series lens performance with P-TTL match my own, ie no performance at all. It is puzzling that others who have had much longer term use have reported successful working with older cameras. In any case, it's clearly not a consistent picture ... Certainly for the purposes of the flash guide there's nothing come through that could cause me to include A-series lenses within the compatible category.

There's no reason of course why people can't experiment and find individual ways that they get some consistency. F series is going to be the tricky one. ....I suspect I may have to include it within the compatible category, with a note that due to unknown developments of the mount and data transmitted throughout the 1990s there may be variables in performance with different lens and camera combinations .... Not ideal, but the idea here is to lay out the true picture.
09-09-2015, 04:43 AM   #26
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QuoteOriginally posted by Sherman Quote
I've found that the documentation on support for P-TTL with non-autofocus lenses is inconsistent in the Pentax user manuals. While the AF540FGZ II manual has the restriction you quoted, the K-3 manual on page 81 in section Functions Available with Various Lenses explicitly lists P-TTL auto flash as supported with A-series lenses, when using the built-in flash, the AF540FGZ II flash, and others. The same information is also on page 84 in section Functions when Using an External Flash.

Do you suppose the status of P-TTL support with non-autofocus lenses depends on which camera body is being used?

I've been having some success using P-TTL with the AF540FGZ II flash, the K-3, and the SMC Pentax-A 70-210mm zoom lens (aperture ring in A position), at least in basic scenarios. But I've been concerned that there may be problems I haven't encountered yet, so I am happy to have found your thread on this very subject! I plan to try your detailed list of test scenarios with this combination, and see what I can learn...
Its not that complicated

P-ttl requires the 'A' pin for matrix metering therefore to engage P-ttl flash mode you a 'A' lens or above.

To get an accurate exposure under P-ttl the camera requires distance data this is only provided with 'F' lens and above i.e autofocus

So both statement are true

For P-ttl functionality you need an 'A' lens or better (otherwise the camera fire full power flash)
For accurate P-ttl flash you need an auto-focus lens.

To add a fly in the ointment
1 some focal length 'A' lens will appear to work fine (lucky)
2 Some 3rd party lens don't provide correct distance data hence inaccurate flash (tamron 18-50 is a known culprit)
09-09-2015, 05:13 AM   #27
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Yes, most of that summary will probably be carried through to the new edition of the guide. It's obviously going to be necessary to draw attention to these variables and inconsistencies. As we approach the FA lens series then we are expecting increasingly reliable working.

Regarding the A series ... There's not a lot of point to an auto exposure flash system that is not accurate and reliable with all lenses of a particular type, so as the writer of a guide that's intended for a wide range of users, then I'm compelled now to go with Pentax's latest pronouncement on the matter, which is the guidance in the latest flash manual requiring autofocus lenses for P-TTL operations.
09-09-2015, 06:20 AM   #28
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Agreed whilst technically correct being able to activate P-ttl is bxgger all use if its automation wont help you attain a consistent exposure.

I wonder if it only become a lot more noticeable now as prior to the k3 all top flight bodies had flash consistency issues

K10d underexposure
k20-k7 highlight confusion (reflection would throw exposure)
K5-k5ii - hardware fault causing flash inconsistency especially when bounce on camera (Pentax admitted this one)

Whereas both the k3 and k3ii besides the silly delay before the pre-flash are deadly accurate under P-ttl so any discrepancies are glaringly obvious

My favorite consistency check is/was to fire 10 shots under flash without moving the camera and check exposure levels , Till the k3 there was are least 1.5 stop variance across a series the k3 is less than a 1/3 out
09-09-2015, 08:36 AM   #29
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It's encouraging that the K3 seems to have resolved these matters. I wonder about the other recent cameras like the K50 and K-S2? I was disappointed to see wireless triggering with the pop-up removed from the K-S2 ....but it gained the 2-step manual flash exposure mode from the K3 !


Seems odd. ... After all they are both sort of 'advanced' user type of things. Why would such a user of built -in flash only want the manual option and not care about wireless? Perhaps they are just trying to sell more flashguns!
09-09-2015, 10:30 AM   #30
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QuoteOriginally posted by mcgregni Quote
Your descriptions of A-series lens performance with P-TTL match my own, ie no performance at all. It is puzzling that others who have had much longer term use have reported successful working with older cameras.
A-series lens P-TTL on bodies prior to about mid-2013 was essentially the same as with AF lenses. I suspect that someone slipped a hack into the body firmware with unintended consequence and Pentax is finally updating the documentation to match.


Steve
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