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06-07-2018, 12:56 AM   #1
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Studio flash rear curtain K1

Hello K o(w)ners,

I'm quite new in this forum. I've been using Pentax all my live (from 21 to 61) I also have a Fuji XT-2, which is also great. Visited PentaxForums allready many times for the wonderful reviews but now I've a question/problem.
To control studio flash there should be a possibility in the menu....
For dance photography I need flash on the rear curtain. I don't understand why Pntax didnt enclose this in the menu of the K1. Answers from Pentax (France) don't help any further.

When I use the "Pentax way" by choosing rear curtain on my Pentax AF540-FGZ I then it works only with P-TTL, not with Manual-mode. Means pre-flash and that is not what I want!

Am I the only one with this problem??

If there is someone with a solution, I like to hear!

Wish you all happy shooting moments!

06-07-2018, 04:45 AM   #2
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Have you set shutter speed 1/90 or slower?
Are you using a lens with automatic aperture?
06-07-2018, 04:49 AM   #3
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For rear curtain sync with a Pentax accessory flash then you set that sync mode on the flash. It is only available in P-TTL mode. There is no setting on the K1 because the K1 has no built in flash for this setting to apply to.

The Cactus V6II offers 2nd curtain sync in both P-TTL and Manual flash modes with the Cactus RF60X flashes as slaves ......I do not know if you also get Manual Mode 2nd curtain sync when using other flashes with a V6II attached as receiver.
06-07-2018, 10:03 AM   #4
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QuoteOriginally posted by gijspossel Quote
When I use the "Pentax way" by choosing rear curtain on my Pentax AF540-FGZ I then it works only with P-TTL, not with Manual-mode. Means pre-flash and that is not what I want!
Strangely, 2nd curtain sync on current-model Pentax cameras is a flash feature, not a body feature and is limited to P-TTL. I say strangely, because it would seem easy enough to simply have the camera fire the sync when the second curtain begins its travel. The hard part is that such would limit the feature to manual flash only, or at best "auto" mode for flash supporting that feature*. Instead, Pentax erred on the side of providing TTL automation and having the flash manage the feature. Here are a few pertinent points:
  • Timing for second curtain flash is more difficult than it may seem. Discharge at second release may result in ghosting past the flash image if duration is short.
  • At optimum, the flash discharge should end at or just after the second curtain finishes its travel. This can only be done if the flash duration is calculated in advance, which in Pentaxland means P-TTL.
  • The signal for second curtain release is apparently sent through the data pin on the hot shoe and is assumed to always be sent, regardless of flash mode
  • It may be possible to spoof participation of non-P-TTL flash or strobes using optical triggering with an on-camera flash serving as trigger


Steve

* Meaning "auto" using an on-flash metering cell.

06-07-2018, 10:07 AM   #5
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@Stevebrot
I was thinking the same, but sure there must be a catch with getting precise timing... otherwise it would have been easy for the camera to just trigger the flash at the right moment, as you suggested in your first point if I got it right.

Moreover, flash duration is a function of power, so different brands (could) behave differently: it was discussed some time ago in a thread regarding bird pictures and flash duration. That brings us to the second point.

I think I tried using the pop-up as an optical trigger for second curtain a couple of years ago... I can't recall if it was the preflashes which spoiled the whole thing, or if the slave (a Yongnuo) just got confused and never flashed. Short story, it didn't work.
06-07-2018, 01:32 PM   #6
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QuoteOriginally posted by LensBeginner Quote
Have you set shutter speed 1/90 or slower?
Are you using a lens with automatic aperture?
shutterspeed about 1/8

---------- Post added 06-07-18 at 10:43 PM ----------

QuoteOriginally posted by mcgregni Quote
For rear curtain sync with a Pentax accessory flash then you set that sync mode on the flash. It is only available in P-TTL mode. There is no setting on the K1 because the K1 has no built in flash for this setting to apply to.

The Cactus V6II offers 2nd curtain sync in both P-TTL and Manual flash modes with the Cactus RF60X flashes as slaves ......I do not know if you also get Manual Mode 2nd curtain sync when using other flashes with a V6II attached as receiver.
QuoteOriginally posted by stevebrot Quote
I say strangely, because it would seem easy enough to simply have the camera fire the sync when the second curtain begins its travel.
Yes Steve, I agree. As mentioned before, I also have Fuji XT-2 and there you have 'rear curtain flash' in the menu. So...Fuji proved it can be done!

---------- Post added 06-07-18 at 10:55 PM ----------

QuoteOriginally posted by mcgregni Quote
There is no setting on the K1 because the K1 has no built in flash for this setting to apply to.
/ Mcgregni thanks for the effords, but... I don't think it has to do with a built in flash, my Fuji XT2 doesn't have build in flash, but it has 'rear curtain flash' in the menu. So I think Pentax has to try harder to fix this... It should be nice to have the possibility to shoot with studioflash on rear curtain.
06-07-2018, 02:13 PM   #7
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What specifically can you do with the 2nd curtain setting on the Fuji camera ? What effect does it have if using studio strobes? And do you need any particular type ot studio lights or flashes ?

You may need to find an alternative way to achieve the same with the K1, but it should be possible. The main point is you have to adapt to how the K1 operates .... There's no point expecting it to operate the same as the Fuji.
06-07-2018, 03:10 PM   #8
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QuoteOriginally posted by gijspossel Quote
So...Fuji proved it can be done!
Yes, it can be done and Fuji confirms it in the X-T2 manual for both M(anual) and TTL flash modes.* As noted in my comment above, Pentax could have gone this route, though at the risk of subject overrun.** The question is how well does the support offered for manual flash work? The test is to use a low flash duration (low power) and very low ambient light and see if there is blur beyond the subject. A good subject would be something fast moving with lights on the front so any subject overrun is obvious. This would not be a good place to post the results, though we do have the non-Pentax part of the site.


Steve

*In Fujiland, flash control is performed by the body, so this makes obvious sense. There are pros/cons to this approach since it requires fairly tight flash integration, but since firmware updates are frequent and model support long-running, this appears to work well. It should be noted that since there are no curtains (shutter is fully electronic), 2nd-curtain sync timing is emulated and not tied to any physical event.

**There is also a concern regarding flash wastage such that full power might have a lower guide number than with 1st-curtain sync. With some speedlights, duration at full strength may be fairly long. For example, my Yongnuo YN560III has a duration of 1/200s at full power. This is long enough to allow for spoofed (dark magic) HHS with my K-3.

06-07-2018, 03:18 PM   #9
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QuoteOriginally posted by mcgregni Quote
You may need to find an alternative way to achieve the same with the K1, but it should be possible. The main point is you have to adapt to how the K1 operates .... There's no point expecting it to operate the same as the Fuji.
The obvious method is to use a P-TTL flash configured for 2nd-curtain sync to optically trigger the studio flash/strobes. The P-TTL unit might be equipped with a IR filter to minimize its contribution. I am almost tempted to do this setup simply to prove that it can be done.


Steve
06-07-2018, 04:01 PM   #10
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QuoteOriginally posted by gijspossel Quote
Mcgregni thanks for the effords, but... I don't think it has to do with a built in flash, my Fuji XT2 doesn't have build in flash, but it has 'rear curtain flash' in the menu.
Flash control in the Fuji system resides mostly in the camera body. Pentax shares the responsibility with the body supplying shot setting and the flash coordinating the actual exposure. The Pentax approach allows broad backward camera compatibility such that your AF540FGZ is fully compatible with all supported flash features on all models back to the M-series film cameras (late-1970s).

QuoteOriginally posted by gijspossel Quote
So I think Pentax has to try harder to fix this... It should be nice to have the possibility to shoot with studioflash on rear curtain.
It is nice, possible, and also quite doable, though not in the way that Fuji does it. A P-TTL flash supporting 2nd-curtain sync must by attached to the camera to coordinate the sync. You may start a new product suggestion thread:

Product Suggestions and Feedback - PentaxForums.com

Suggestions are forwarded to Ricoh for consideration. Other suggestions in the past have been made for flash, so yours will be in good company. Take a look at the thread titles and you may notice a few features present in current model cameras. You may also notice a few than will likely never be supported.


Steve
06-25-2018, 07:47 PM   #11
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QuoteOriginally posted by stevebrot Quote
At optimum, the flash discharge should end at or just after the second curtain finishes its travel. This can only be done if the flash duration is calculated in advance, which in Pentaxland means P-TTL.
with a manual flash, finding which shutter speeds work optimally for trailing sync is something you'd only need to figure out once at a given power level, and it'd be the same, every single time, barring malfunction.
06-25-2018, 08:40 PM   #12
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QuoteOriginally posted by spinach Quote
with a manual flash, finding which shutter speeds work optimally for trailing sync is something you'd only need to figure out once at a given power level, and it'd be the same, every single time, barring malfunction.
Quite possibly, assuming one can find a body that will do second-curtain sync to a non-dedicated flash. This is a complicated subject and one that the more I think about it, the more convinced I am that many shots are done with manual trigger, timed trigger, or trapped trigger with the shutter operating in T-mode and the trigger also closing the shutter.*


Steve

* T is like B except that the shutter opens with one push of the shutter and closes with a second action. On Pentax dSLRs, T is enabled by a custom menu setting and the action to close the shutter is a second shutter push or impulse from a remote.

Last edited by stevebrot; 06-25-2018 at 08:54 PM.
06-25-2018, 09:00 PM   #13
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QuoteOriginally posted by stevebrot Quote
Quite possibly, assuming one can find a body that will do second-curtain sync to a non-dedicated flash. This is a complicated subject and one that the more I think about it, the more convinced I am that many shots are done with manual trigger, timed trigger, or trapped trigger with the shutter operating in T-mode.
doing it manually in T is a lot more complicated than the process i just described. the only T+flash shooting you'll see is light painting.
06-25-2018, 09:39 PM   #14
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QuoteOriginally posted by spinach Quote
doing it manually in T is a lot more complicated than the process i just described. the only T+flash shooting you'll see is light painting.
In the process you described, what body is being used to provide sync?


Steve
06-25-2018, 11:44 PM   #15
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QuoteOriginally posted by stevebrot Quote
In the process you described, what body is being used to provide sync?


Steve
whichever has a trailing sync pulse, or else you're making your own by putting a buffer inline between camera and flash to delay the firing signal.

---------- Post added 06-25-18 at 11:57 PM ----------

also here's a troubleshooting thread about the cactus v6ii wherein people having trouble with TTL second-curtain sync point out that manual second-curtain sync works fine so now we know that works.
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