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09-29-2014, 07:47 AM   #16
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QuoteOriginally posted by Andi Lo Quote
I guess the lesson of this thread is not to use PTTL if you want consistency
..from the K-01.

09-29-2014, 08:19 AM   #17
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QuoteOriginally posted by Andi Lo Quote
I guess the lesson of this thread is not to use PTTL if you want consistency, or you're sure that the particular combination you're using works.
Probably correct, and that's why I'm returning the Pentax AF160FC. My old Sunpak DX8R ringflash must be used in manual mode because the old TTL module doesn't function on a modern digital camera, and that flash has more EV steps than the Pentax unit (Pentax: full, 1/4, and 1/16; Sunpak: full, 1/2, 1/4, 1/8, and 1/16). ALso, the battery door on the Sunpak is vastly better. The battery cover on the Pentax AF160FC is held on by hopelessly tiny plastic tabs. I doubt they would last a year in my hands*. I've also been using and pleased with a Cactus manual-only flash that has an excellent wireless system and EV steps down to 1/128 in increments as small as 1/10 EV (pointless, as it is only marginally possible to see a difference of 1/3 EV step, and PP can easily correct/adjust to finer levels than that). However, the point of PTTL with macro in the field are insects that may not await an exposure adjust following a test shot.

*Battery doors/covers have become a peeve. The original AF360 had a dismally weak battery cover. Back in the LX era I was obliged to glue on a home-made locking device to one of my 280T's. On the other hand, I have a heavily-used Braun manual-only two AA flash purchased back in the 1960's, and its slide-on battery door, as well as the flash itself, still works. I also have cheapy manual-only four AA and one AA cell slave-or-manual flash units from the 1990's, and their slide-on tongue-in-groove battery doors are as tight and secure as when they were new - simple, reliable, durable design. The preoccupation with having a battery door that is attached to the flash unit so it cannot be dropped/lost has been pursued at the expense of security and durability. It was not, IMHO, a satisfactory trade-off. Are battery doors more easily lost when taken off than a memory card when it is removed? or harder to locate if dropped? If hard to see dropped into tall grass, then make the battery doors brightly colored, white, red. Must the vast majority of flash units be black? Should safety tethers be developed for memory cards, clipping them to a camera or shoulder strap? A battery cover that stays in place and won't wear out or break easily is better than one that's trying to circumvent improbable carelessness.
09-29-2014, 09:48 AM   #18
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QuoteOriginally posted by WPRESTO Quote
Back in the LX era I was obliged to glue on a home-made locking device to one of my 280T's.
Ha! Ha! I have a AF-280T and consider it a miracle of sorts that the door is still intact after all the years since it was made. I am glad I have it though, since it looks like it will be my good option for A-series lenses on the K-3


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09-29-2014, 10:08 AM   #19
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QuoteOriginally posted by stevebrot Quote
Ha! Ha! I have a AF-280T and consider it a miracle of sorts that the door is still intact after all the years since it was made. I am glad I have it though, since it looks like it will be my good option for A-series lenses on the K-3


Steve
A second 280T I had (with all the wires and grips for a two-flash set up with the LX) had a good battery door, but that unit was sold when I switched to digital. The home made battery-door-latch mechanism on other 280T did and does work, as does the flash itself, but there is too little control in manual mode, and I doubt the thyristor sensor would provide satisfactory or consistent exposure. So that flash has been dormant for many years. I have other 4AA manual flash units that are more compact. Unfortunately my Sunpak 444D, which was a real workhorse and for which I have a variety of accessories, has gone dead. The capacitor will no longer take a charge. I sometimes consider purchasing a used 444D on EBAY, but they would be equally old with a capacitor equally close to failure.

10-01-2014, 10:04 AM   #20
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QuoteOriginally posted by WPRESTO Quote
NEITHER THE K5 NOR THE K3 WITH PRESENT FIRMWARE WILL PROVIDE PTTL EXPOSURE WITH AN "A" SERIES LENS.
I contacted Ricoh this morning regarding this issue and am waiting for a reply.

It occurred to me afterward that my camera differs from a stock K-3 in one key way. I have an aftermarket focus screen with a center split-image focus aid. It is well-known that the split-image will pretty much hose spot metering. Might it also be possible that it could throw off P-TTL as well? I would expect that all series lenses would be affected the same way, though perhaps not.

I also determined this morning that the flash is NOT firing at full power. It is just not being properly controlled. My understanding is that there is a subtle difference in how P-TTL is managed depending whether the lens has the data contact. I may be wrong (happens frequently), but I believe that if the data contact is present on the lens, the body transmits details of the lens state to the flash and the flash controls both the pre-flash and main flash intensity and duration. If the data contact is not present (all manual focus lenses) both pre-flash and main flash duration are determined by the body with only limited control over flash intensity.

Put another way, with A-series lenses P-TTL exposure is controlled by flash duration only. With AF lenses both duration and intensity are leveraged with the flash controlling itself based on data* passed by the body. I used the word "limited" in the following paragraph because it is possible to signal the flash to operate at 1/2 or 1/4 intensity by using the flash compensation setting on the body.


Steve

* Focal length, focus distance, ISO, and pre-flash light reading
10-01-2014, 11:23 AM   #21
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QuoteOriginally posted by stevebrot Quote
I contacted Ricoh this morning regarding this issue and am waiting for a reply.

It occurred to me afterward that my camera differs from a stock K-3 in one key way. I have an aftermarket focus screen with a center split-image focus aid. It is well-known that the split-image will pretty much hose spot metering. Might it also be possible that it could throw off P-TTL as well? I would expect that all series lenses would be affected the same way, though perhaps not.

I also determined this morning that the flash is NOT firing at full power. It is just not being properly controlled. My understanding is that there is a subtle difference in how P-TTL is managed depending whether the lens has the data contact. I may be wrong (happens frequently), but I believe that if the data contact is present on the lens, the body transmits details of the lens state to the flash and the flash controls both the pre-flash and main flash intensity and duration. If the data contact is not present (all manual focus lenses) both pre-flash and main flash duration are determined by the body with only limited control over flash intensity.

Put another way, with A-series lenses P-TTL exposure is controlled by flash duration only. With AF lenses both duration and intensity are leveraged with the flash controlling itself based on data* passed by the body. I used the word "limited" in the following paragraph because it is possible to signal the flash to operate at 1/2 or 1/4 intensity by using the flash compensation setting on the body.

Steve

* Focal length, focus distance, ISO, and pre-flash light reading
V-A-V my K5 & K3. The K5 has an aftermarket split image + microprism ring screen, the K3 has the stock screen. The K5 is now used almost exclusively indoors, in the "studio," primarily for close-up/macro shots, and the screen was replaced to aid manual focusing which is now used almost exclusively on both the K5 and older K20. The screen does indeed ruin spot metering. Actually, I would have preferred an all microprism screen which is what I used going back to, I believe, an H1a, certainly the original Spotmatic, and obtained for the LX. With the K5 & K3 the flash is not simply being triggered incorrectly, both the AF160 and the AF360 are unambiguously firing at full blast every time regardless of f-stop. A few quick tests with the K3 indicate that the pop-up flash is doing the same. BUT, any flash plus any A-series lens on the K20 provides correct PTTL, and any DA lens on the K5 or K3 provides correct PTTL. It's only the combination of an A-series lens on a K5 or K3 that fails to provide PTTL. The instruction manuals for all three cameras explicitly indicate that PTTL should work with an A-series lens.
10-01-2014, 07:00 PM   #22
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QuoteOriginally posted by WPRESTO Quote
With the K5 & K3 the flash is not simply being triggered incorrectly, both the AF160 and the AF360 are unambiguously firing at full blast every time regardless of f-stop. A few quick tests with the K3 indicate that the pop-up flash is doing the same.
Then apparently we are having similar, but significantly different symptoms. I get about 2 stops overexposure at 6 foot distance with the onboard flash on the K-3 with the A 50/1.7 @ f/5.6. The same flash in manual mode (no P-TTL), full strength, at same distance and aperture, is a total white-out.


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10-24-2014, 03:13 PM   #23
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It took two tries with "live chat" at Ricoh-Pentax support, but their final answer is this: The instruction manual for the AF360 flash says that it only provides PTTL with an autofocus lens, end of story. They did not attempt to explain to me why 1) the K20 DOES provide PTTL with an A-series manual focus lens combined with the AF360; 2) the K5 and K3 instruction manuals have identical flash-function charts that indicate ALL Pentax-made PTTL flash units including the AF360 will provide PTTL with an A-series lens. BTW, the flash-function chart in the K20 manual is almost identical to that in the K5/K3 manuals, except it does not list the AF160 ring flash presumably because it was not in production at that time.
From the Ricoh-Pentax point of view, they've answered my question, end of interest, but from my point of view, they have not really addressed the issue. Either there is something amiss with the K5/K3 firmware, or the instruction manual is in error and misleading.

10-24-2014, 06:40 PM   #24
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The thing I don't understand is that I haven't had any problems using P-TTL with A series lenses with the AF160FC.

QuoteOriginally posted by stevebrot Quote
I get about 2 stops overexposure at 6 foot distance with the onboard flash on the K-3 with the A 50/1.7 @ f/5.6.
I attempted to replicate this with the same lens on my K5IIs - exposure was about 0.5 stops underexposed considering the white subject, but usable.

Last edited by Digitalis; 10-24-2014 at 06:46 PM.
10-24-2014, 07:48 PM   #25
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Perhaps the K5IIs has different firmware compared to K5 & K3. Perhaps it is something akin to K20 firmware, which as noted, does provide PTTL with A-series lenses. That is the issue I put to Ricoh-Pentax, but clearly they claim the AF360, and by extension I presume all other Pentax flash units, will only provide PTTL with autofocus lenses. I do not accept that. The problem resides in body firmware not providing the functions that the manual claims otherwise why would a K20 and a K5IIs work as specified?.
10-24-2014, 08:31 PM   #26
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QuoteOriginally posted by WPRESTO Quote
Perhaps the K5IIs has different firmware compared to K5 & K3.
I don't think so, the Pentax K5IIs is basically identical to a K5, the differences that do exist between them are rather minor.
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