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09-09-2015, 10:40 AM   #31
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QuoteOriginally posted by awaldram Quote
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
Historically, only the first was true. I have done many accurate P-TTL exposures with A-series glass on the K10D and there is ample documentation from users on this site with bodies up through the K-5II. It was only recently that the bodies have been unable to properly control the pre-flash/flash with non-AF lenses. I say properly control because there is an obvious attempt by my K-3 to attenuate the flash, but the behavior indicates that something other than the older algorithms is being used.


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09-09-2015, 10:46 AM   #32
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QuoteOriginally posted by mcgregni Quote
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!
I have a sneaking suspicion that Ricoh/Pentax will be giving the flash system a general overhaul shortly after the FF body is released. After AF performance, the P-TTL flashes have been the main tech shortfall for the Pentax line. Nikon really shines in this area showing it can be done using similar tech.


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09-09-2015, 08:32 PM   #33
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QuoteOriginally posted by stevebrot Quote
I have a sneaking suspicion that Ricoh/Pentax will be giving the flash system a general overhaul shortly after the FF body is released. After AF performance, the P-TTL flashes have been the main tech shortfall for the Pentax line. Nikon really shines in this area showing it can be done using similar tech.


Steve
The p-ttl delay is probably the biggest shortcoming now. Exposure seems to be right on with all the p-ttl flash units I've used on the K-3. The multiple flash system needs work as well.

I suspect the p-ttl delay fix will also fix some of the auto focus latency as well. All the subsystems talking at the same time seems to saturate the processor.
09-10-2015, 05:41 AM   #34
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It would be great to see some real technology developments with our dedicated flash system. I still appreciate having the 'legacy' 'Auto-Flash' mode which makes things easy with non-coupled lenses. Its my choice for A series types as well un-surprisingly. But at the same time I like the newer features that we've got on the MKII flash models now.

As you may have seen I have opened up the discussion for the 2nd Flash Guide development topic on another thread, so I'm looking to draw final conclusions here regarding the P-TTL and lens compatibility.

This is a quick overview of what I'm thinking of for the next edition of the Guide .....

1) Change the references to the KAF2 mount and use the 'Autofocus / Manual Focus' distinction as the main defining criteria for the various functions available

2) Maintain the A-series as within the 'manual lens' category and therefore not P-TTL compatible

3) Bring the F-Series into the 'autofocus' category and therefore P-TTL compatible

4) Add some notes that outline the confusing picture presented here on this thread .... ie: there are inconsistencies with user experiences with camera bodies and F and A series lenses. P-TTL functioning and reliability pre- FA type may be dependent on individual camera models or lenses. This is a frustrating aspect of the flash system we have, but then again it is compensated for by availability of 'Auto-Flash' and Manual flash modes for these older lens types .

Based on the superb range of information presented here in this thread, these conclusions to me seem to be the best compromise between keeping the guide as absolute and definitive but being honest about the real practical situation .....

09-10-2015, 09:41 AM   #35
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QuoteOriginally posted by mcgregni Quote
It would be great to see some real technology developments with our dedicated flash system. I still appreciate having the 'legacy' 'Auto-Flash' mode which makes things easy with non-coupled lenses. Its my choice for A series types as well un-surprisingly. But at the same time I like the newer features that we've got on the MKII flash models now.

As you may have seen I have opened up the discussion for the 2nd Flash Guide development topic on another thread, so I'm looking to draw final conclusions here regarding the P-TTL and lens compatibility.

This is a quick overview of what I'm thinking of for the next edition of the Guide .....

1) Change the references to the KAF2 mount and use the 'Autofocus / Manual Focus' distinction as the main defining criteria for the various functions available

2) Maintain the A-series as within the 'manual lens' category and therefore not P-TTL compatible

3) Bring the F-Series into the 'autofocus' category and therefore P-TTL compatible

4) Add some notes that outline the confusing picture presented here on this thread .... ie: there are inconsistencies with user experiences with camera bodies and F and A series lenses. P-TTL functioning and reliability pre- FA type may be dependent on individual camera models or lenses. This is a frustrating aspect of the flash system we have, but then again it is compensated for by availability of 'Auto-Flash' and Manual flash modes for these older lens types .

Based on the superb range of information presented here in this thread, these conclusions to me seem to be the best compromise between keeping the guide as absolute and definitive but being honest about the real practical situation .....
I'm finally back home and will run the A, F, FA comparative tests this week-end per the procedure you have defined a while back.
09-10-2015, 09:47 AM   #36
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Hi Ole, good to see you back and thanks very much for the testing offer. There's been some superb input here and I am very grateful to you all. It would still be helpful to have some data on F series types performance especially as I still feel this is borderline. My decisions as above are purely evidence and probability based according to all the information that has been presented. I look forward to hearing your results, and I hope the test regime is enjoyable ..... well, its a good excuse to give the flash and lenses a good workout
09-12-2015, 09:56 PM   #37
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PTTL consistency across lenses

I have completed the FA/F/A tests and documented the findings here.

Reduced size test images can be browsed or downloaded on said page.
09-12-2015, 10:58 PM   #38
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FWIW, in poking about the EU Patents database, there are quite a lot of Pentax flash patents with what may be useful information - eg patent US2002061192 (A1) - Flash photography system, which has some diagrams which reveal some of the P-TTL logic.



There is a lot more in that patent, and the others, if someone has the time (and expertise in electronics) to interpret the documents.

09-13-2015, 05:06 AM   #39
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QuoteOriginally posted by Ole Quote
I have completed the FA/F/A tests and documented the findings here.

Reduced size test images can be browsed or downloaded on said page.

A big thanks to Ole and the Team for providing the thorough P-TTL practical testing results. There's a lot to look through, but I really appreciate the time and care taken to help with this on-going question. It seems like this P-TTL conundrum has been around for a long time, and I am hoping that the Flash Guide will become an accurate and definitive guide to the best information available .... and now I feel it can become that!

Thanks to all who have helped and input, and I appreciate all the information that has been assembled here. The latest detailed tests with example photos will serve as a great reference. There seems to be reasonable consistency with the autofocus lenses. I'll take a detailed look soon and then lets try and agree the best guidance to help Pentax users of all experiences.


rawr, thanks also for the links to that patent data ..... wow, thats an impressive flowchart .... clearly something going on then! A lot of things to happen in a very short time.
09-14-2015, 06:38 PM   #40
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QuoteOriginally posted by rawr Quote
FWIW, in poking about the EU Patents database, there are quite a lot of Pentax flash patents with what may be useful information - eg patent US2002061192 (A1) - Flash photography system, which has some diagrams which reveal some of the P-TTL logic.



There is a lot more in that patent, and the others, if someone has the time (and expertise in electronics) to interpret the documents.
Well, that is interesting and explains some of what I was seeing...at least I think it might.


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09-14-2015, 07:04 PM   #41
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QuoteOriginally posted by Ole Quote
I have completed the FA/F/A tests and documented the findings here.

Reduced size test images can be browsed or downloaded on said page.
QuoteOriginally posted by mcgregni Quote
A big thanks to Ole and the Team for providing the thorough P-TTL practical testing results. There's a lot to look through, but I really appreciate the time and care taken to help with this on-going question...
Yes, many thanks to Ole and company, though I would caution that much depends on the flash and/or body mounted. A good example would be HSS with A-series lenses. Ole's tests indicated no support with the AF 360 FGZII. The photo below was taken using an A-series lens on the K-3 (firmware v1.11) with the Sigma AF-610 DG Super.


Pentax K-3, Sigma AF-610 DG Super, 1/320s, F/1.7, ISO 100

Exif should be intact. I don't know whether this is due to the flash or the K-3 firmware version. (Later firmware included compatibility routines for the newest flashes.)


Steve

Last edited by stevebrot; 09-14-2015 at 07:15 PM.
09-15-2015, 06:53 PM   #42
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Thanks for the sample, Steve.

That made me try High Speed Sync again with two A-series lenses and the AF360FGZ II. The other day the HSS mode indication just flashed briefly on the LCD screen and then went away, but today the flash happily remained in HSS mode and I was able to shoot in that mode with the two lenses I tried, the A 35mm F2 and the A 50mm F1.4.

I have updated my write-up accordingly.

K-3, A50mm F1.4 at F5.6, 1/1500s, ISO 100:
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PENTAX K-3  Photo 
09-16-2015, 06:37 AM   #43
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There is a note in the current guide that P-TTL exposures in HS mode with manual focus lenses 'can be quite successful' .... This is based on my own successful testing. I did not find any consistent P-TTL with manual lenses in normal mode, only HSS. I assumed this to be a factor of the additional shutter time value information being included for HSS mode, and this adding weight to the calculations able to be performed. So I am not surprized to see your good HSS results there Steve.
09-21-2015, 05:38 PM   #44
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In conclusion now, having looked through the tests in detail, I am happy that my earlier conclusions are well supported by this new evidence. There seems to be enough consistency with all auto-focus types to confidently include them in the same category, so I will bring the F series back into the fold. The rather variable bounce performance is a worry .... I'd have hoped for better than that. The A series remains very much out as I don't see any reliable exposure performance demonstrated, so P-TTL is an autofocus only mode now.

I will make summary comments as well explaining that there will be some variations on older lens performance and that some users may find they can get good results with their particular lens/camera combinations. I am already revising the guide for its 2nd edition and I am removing the KAF2 designation and making the P-TTL functioning distinction between AF & Manual lens types.

Finally, thanks again to all here who have helped so much in delving deeper into this issue and improving the guidance in the Flash Guide. I am hoping to be able to issue the new edition next month, which as well as these P-TTL matters will also correct a number of small errors, include some points on radio triggered alternative systems, add photos of the AF540II WR flash throughout, plus descriptions of the LED functions on this new model, and a fuller coverage of wireless P-TTL control and contrast sync.
06-28-2020, 01:20 PM   #45
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Hi,
I am a bit late to this discussion, but shortly after I bought my K5 (2011?), I contacted the (dutch) pentax service with a wireless p-ttl problem when using A type lenses.
Camera at AV, popup as control, 360fgz as slave, short object distance:
50mm 1.7 A lens very dark
50mm 1.7 F lens right exposure.

And later I found out that I could get the same dark exposure by focussing the F lens manual to infinity.
So somehow the camera uses the object distance in its flash calculation, and A lenses who do not communicate object distance are probably considered at infinity.
I cannot remember I had these problems with my K10D.

Never got a decent solution from pentax, and now I rarely use P-TTL anymore, just manual and make some test exposures to get it right.
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