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01-31-2016, 03:48 AM   #16
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It's a simple matter to measure the flash output with a flash meter. Unfortunately the flash function on my old Gossen Luna-Pro F is kaputt - a capacitor must have dried out. However I tested my K10D and with a MF "A" lens in manual mode. With the lens in "A" mode using the built-in flash the exposures are pretty much on the money until I set the f-stop past the GN for the flash and distance. With using the aperture ring to set f-stop works as expected if the flash were firing at full power all the time - exposures all vary with the f-stop. Using only a external flash in manual mode (full power all the time) exposures vary the same way dependent on f-stop regardless of whether "A" mode or aperture ring was used. I got the same results with the camera in X-sync mode.

I do notice a pre-flash when the lens is in "A" mode and no pre-flash when the aperture ring is used. Conclusion - camera uses P-TTL in manual/x-sync mode with lenses in "A" mode and full power for the flash for non-"A" mode lenses. Exactly as documented as pointed out by Clackers. This is expected behavior since P-TTL needs segmented metering which is not available with non-"A" mode lenses.

Note: Pre-flash is often not noticeable when looking through the viewfinder. I only noticed it when I stood to the side while taking a few shots.

01-31-2016, 04:08 AM   #17
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QuoteOriginally posted by clackers Quote
The flash is in auto mode while the lens aperture is set to A.



But you do. If you set it to f4 with the camera dial or the lens ring, it's f4.



I will try one last time, Cee Cee and then give up ... use the A setting, the P-TTL preflash sets the strobes off early. You say there is no pre-flash but you are wrong.

Don't use the A setting, there's no pre-flash, it fires once at full power and sets off the strobes at the same time.
so what you are saying is that the the camera fires a preflash (even in manual mode) makes calculations as to what the flash power should be then opens the shutter and fires the flash all so quickly that it all appears as one flash. I have no evdence to dispute that so I'm prepared to keep an open mind, although still a little sceptical, but while the mechanism by which this happens may be disputed the fact still remains that this behaviour is not documented in the manual and it should be, I shouldn't have to go to forums or websites to know how the camera works, that's the purpose of the manual
In simple terms
used the setup last year controlling the aperture from the lens ring -great results very happy
exact same setup this year only decided to control the aperture from the camera - results ... crap! I needed to know the behavior was different.

Perhaps we could meet over coffee some time, I think I could explain my points in person with camera in hand much better
cheers

ps. I'll devise a test for preflash and put it to the test
01-31-2016, 04:14 AM   #18
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QuoteOriginally posted by Cee Cee Quote
so what you are saying is that the the camera fires a preflash (even in manual mode) makes calculations as to what the flash power should be then opens the shutter and fires the flash all so quickly that it all appears as one flash.
That is what we have told you in this thread, and as documented by Pentax.

We cannot do anything if you continue not to believe this.
01-31-2016, 04:33 AM   #19
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QuoteOriginally posted by Not a Number Quote
It's a simple matter to measure the flash output with a flash meter. Unfortunately the flash function on my old Gossen Luna-Pro F is kaputt - a capacitor must have dried out. However I tested my K10D and with a MF "A" lens in manual mode. With the lens in "A" mode using the built-in flash the exposures are pretty much on the money until I set the f-stop past the GN for the flash and distance. With using the aperture ring to set f-stop works as expected if the flash were firing at full power all the time - exposures all vary with the f-stop. Using only a external flash in manual mode (full power all the time) exposures vary the same way dependent on f-stop regardless of whether "A" mode or aperture ring was used. I got the same results with the camera in X-sync mode.

I do notice a pre-flash when the lens is in "A" mode and no pre-flash when the aperture ring is used. Conclusion - camera uses P-TTL in manual/x-sync mode with lenses in "A" mode and full power for the flash for non-"A" mode lenses. Exactly as documented as pointed out by Clackers. This is expected behavior since P-TTL needs segmented metering which is not available with non-"A" mode lenses.

Note: Pre-flash is often not noticeable when looking through the viewfinder. I only noticed it when I stood to the side while taking a few shots.
thanks for your input and doing the test, the same results as I get, its been stated that the problem is pre flash triggering my stobes and they're firing before the exposure rather than after the exposure as I had concluded, I can test this with a simple test in my workshop using a photo diode and look for multiple output pulses. But as I said in another post this behavior needs to be in the owners manual, I got caught out by thinking manual mode is fully manual, not an unreasonable asumption I would have thought - but it isn't if you pop the flash up

01-31-2016, 04:36 AM   #20
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QuoteOriginally posted by Cee Cee Quote
I got caught out by thinking manual mode is fully manual, not an unreasonable asumption I would have thought - but it isn't if you pop the flash up
But, Colin, why did you think the popup flash was manual?

Where had you ever set it to fire at 1/8 power?
01-31-2016, 04:41 AM   #21
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QuoteOriginally posted by clackers Quote
That is what we have told you in this thread, and as documented by Pentax.

We cannot do anything if you continue not to believe this.

not documented in my owners manual

I am prepared to believe, but the reality is by whatever mechanism it is acheived ( and I may be wrong about how its acheived) the camera is adjusting the exposure automatically while I'm in manual mode and should have full manual control of the camera - which is not documanted in my owners manual, I shouldn't have to go to a forum or website to learn how my camera functions, - or stuff up 150 shots and find out the hard way - It should be in the manual !

---------- Post added 01-31-16 at 11:00 PM ----------

QuoteOriginally posted by clackers Quote
But, Colin, why did you think the popup flash was manual?

Where had you ever set it to fire at 1/8 power?
because I set the mode dial to manual and asumed the flash would fire at full strenth - the owners manual didn't tell me any different, it fires at full power when I set the aperture with the ring so why would I assume it to be different when controlling the lens aperture through the camera, that's why I was using manual mode to have full control of the camera.
I don't do a lot of flash photography and must admit my understanding of the different flash modes is not great - which is why I went "Manual" to have full control without the camera doing anything unexpected, It worked well for me last time, the only difference this time was controllng the aperature by the camera, which I did because when I started the shoot there was a lot of ambient light and it was going to get dark thoughout the shoot, I just thought it might be easier to adjust aperture though the camera controls, after all its the same thing isn't it ! No Wrong !!!

Last edited by Cee Cee; 01-31-2016 at 05:06 AM.
01-31-2016, 05:11 AM   #22
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QuoteOriginally posted by Cee Cee Quote
but the reality is by whatever mechanism it is acheived ( and I may be wrong about how its acheived) the camera is adjusting the exposure automatically while I'm in manual mode and should have full manual control of the camera !
It is not adjusting your exposure!

In fact, it can't use P-TTL when you turn the lens ring off A because you just took away its ability to do the pre-flash wide open. Lacking the info it requires to calculate what's needed, it fires at full power putting the onus on the photographer to stop up or down to adjust.

Manuals from any brand don't give you that reasoning I just provided, supplementary materials, personal experience and the advice of others do, none of which it appears you want to listen to.

Good night! ☺

Last edited by clackers; 01-31-2016 at 05:28 AM.
01-31-2016, 05:35 AM   #23
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QuoteOriginally posted by clackers Quote
It is not adjusting your exposure!

In fact, it can't use P-TTL when you turn the lens ring off A because you've taken away its ability to do the pre-flash wide open. Instead, it fires at full power letting the photographer stop up or down to adjust.

Manuals from any brand don't give you that reasoning I just provided, supplementary materials, personal experience and the advice of others do, none of which it appears you want to listen to.

Good night! ☺
It's adjusting the flash strength which is altering the exposure is it not -

well I certainly have the personal experience now - just a pitty it cost me so much

Owners manuals should fully explain the operation of the camera, I don't care which brand.

You shouldn't assume that I don't want to listen to advise.

surely you would conceed that a camera in manual mode should be in manual mode without the camera modifing the settings the photogrpher selects, including adjusting the flash intensity to correct the exposure.

cheers
its bin night, I've got to go and put the bins out

01-31-2016, 06:06 AM   #24
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QuoteOriginally posted by Cee Cee Quote
It's adjusting the flash strength which is altering the exposure is it not -
No, it's changing the amount of light generated by the flash. The exposure is based on the shutter speed / aperture / ISO settings.

QuoteOriginally posted by Cee Cee Quote
surely you would conceed that a camera in manual mode should be in manual mode without the camera modifing the settings the photogrpher selects
I have always thought that "M" manual mode referred to the exposure-related settings only - not necessarily *every* element of the camera being manual (otherwise, how could we have auto-focus capability in manual mode?). It's worth reading Nigel McGregor's flash guide posted here on PentaxForums if you haven't already. I think you'd find it helpful.

EDIT: Just checked my K3 manual and, in fact, it describes "M" as "Manual Exposure" mode - and not a "Manual Camera" mode, so I think this may be your confusion.

Last edited by BigMackCam; 01-31-2016 at 06:31 AM.
01-31-2016, 06:41 AM   #25
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QuoteOriginally posted by BigMackCam Quote
No, it's changing the amount of light generated by the flash. The exposure is based on the shutter speed / aperture / ISO settings.




I have always thought that "M" manual mode referred to the exposure-related settings only - not necessarily *every* element of the camera being manual (otherwise, how could we have auto-focus capability in manual mode?). It's worth reading Nigel McGregor's flash guide posted here on PentaxForums if you haven't already. I think you'd find it helpful.

I understand this, but by changing the flash intensity it's affecting the exposure is it not - in common terms you would say a picture is underexposed if it were too dark or over exposed if too light. By varying the flash strength it is making the picture darker or lighter - changing the exposure. you say the exposure is based on speed / aperture / ISO but also the amount of light affects the exposure surely, thats why we have the controls to adjust the exposure based on the amount of light that is being collected by the lens.


I think flash strength is an exposure related settng, what else would it be ?
I've read his guide, it is good but I don't think I recall this behavior being described, maybe it is and I missed it. In any event I shouldn't have to go to a 3rd party publication to learn how the camera functions. Its not all that hard really, perhaps something like...
"If the onboard flash is used with a "A" type lens with the camera set to "M" (manual) mode the camera will automaticlly adjust the exposure by varying the flash intensity."
not exactly hard is it.
cheers
CC.

Last edited by Cee Cee; 01-31-2016 at 06:56 AM.
01-31-2016, 06:50 AM   #26
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QuoteOriginally posted by Cee Cee Quote
I think flash strenth is an exposure related settng, what else would it be ?
That's not the way I've thought of it. I have a certain amount of light - the aperture and shutter speed will allow a variable amount of that light to hit the sensor, and depending on how sensitive it is, I'll get a shot of certain brightness. If the light source changes - the sun comes out, there's a flash of lightning, or a speedlight triggers, that's a variance in the amount of light being generated prior to the exposure taking place. So, in my understanding, only shutter speed, aperture and ISO sensitivity control exposure. Maybe I'm wrong, but that's how I understand it.

QuoteOriginally posted by Cee Cee Quote
I've read his guide, it is good but I don't think I recall this behavior being described, maybe it is and I missed it. In any event I shouldn't have to go to a 3rd party publication for to learn how the camera functions. Its not all that hard really perhaps something like...
"If the onboard flash is used with a "A" type lens with the camera set to "M" (manual) mode the camera will automaticlly adjust the exposure by varying the flash intensity."
not exactly hard is it.
cheers
CC.
I know where you're coming from, but I think this is a problem with all manufacturers of all complicated electronic equipment. I have KORG synthesizers where the manuals are virtually useless... a ham radio transceiver where the manual explains the settings in every menu option, but not what the effect of the settings will be... A breadmaker that tells me what to do, which settings to use, but not "why" those settings work. I'd be amazed if the manuals for the other camera manufacturers are vastly better than Pentax's. You're right, the manual should be a detailed book on how to use the camera fully - but in this day and age, I rarely see a manual for any item that matches up to this.
01-31-2016, 07:50 AM   #27
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QuoteOriginally posted by BigMackCam Quote
the manual explains the settings in every menu option, but not what the effect of the settings will be
I've been frustrated by this for 15 years, specifically as it relates to connecting and using the myriad components of audio and video systems. The various types of cables and connections used between them, the sequence of connecting them, and the various settings possible on each individual component have various limiting effects on the next component down the line and on the system overall, but you don't know that other than by trial and error and experience. I am similarly frustrated by camera manuals - they don't tell us HOW, only WHAT.

When I read the User Guide for a camera (I read every User Guide cover-to-cover twice right after I get the camera) I'm fully aware it will not tell me HOW to use the camera to achieve an effect; it will only tell me what each button and menu setting controls. It frustrates me, but I no longer expect it. I intuitively know they're not documenting everything, because they can't do it.

As it is, the K-3 manual pushes 300 (1/2 sized) pages just to label the settings. I can't imagine how big it would be if there was a call-out for each possible combination of settings and states (OBF used vs. OBF not used, with and without slaves, for each type of lens, for instance).

There are two problems for the manual writers: levels of detail; and (assuming the logic that the level of detail should be consistently applied across the entire manual) how many levels of detail deep to go.

Think of it as a pyramid. The deeper you go, the larger the manual gets, in orders of magnitude. If they make a Call Out note for the single circumstance of remote and OB flash operating changes using the pop-up flash as a controller, using an auto lens on lens aperture control versus using an auto lens on camera aperture control, wherein P-TTL is disabled versus enabled (which I believe is a quite 'deep' level of detail) how big would the manual be if every other feature and sub-system was explained to that same level? There would be orders of magnitude more use-case call-outs than there would be straight text.

I'm going to hazard a guess that somewhere in the K-30 manual a single entry in a table states that for M lenses (or A lenses using manual aperture) P-TTL is disabled and the OBF operates at 100% power. What's missing is the connection to the effect that design limitation has on situational use of OBF with remote slave flashes. If I were writing the manual I might decide to leave that detail to the slave flash manuals (assuming the slaves are Pentax flashes). The manual writer likely believes the OBF use is fully documented at the level of detail determined suitable for the entire manual.

The frustrating thing is they can't get in each user's head and know only the use cases that interest each user. From CeeCee's perspective the call out for this use case seems at a higher level - thus worthy of a call-out in the manual - than other detailed settings are. It's frustrating, but it's an understandable omission.

I suppose we need a Herbert Keppler for the 21st century.

Last edited by monochrome; 01-31-2016 at 07:57 AM.
01-31-2016, 07:50 AM   #28
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QuoteOriginally posted by Cee Cee Quote
surely you would conceed that a camera in manual mode should be in manual mode without the camera modifing the settings the photogrpher selects, including adjusting the flash intensity to correct the exposure.
You've added a p-TTL auto flash to the mix, it's no longer fully manual. A bit of info about the pre-flash is on the Ricoh website:

P-TTL pre-flash | Ricoh Imaging Support

This pre-flash is how P/I/E/?-TTL flashes from all manufacturers have worked since they were introduced afaik (this isn't the older TTL that had no pre-flashes!). You won't find every little camera nuance in the manual, there's just not enough room. And certainly not enough room to detail behavior with every expected combination of gear, like your strobes with 'dumb' optical slaves. I won't pretend the manuals are grand, but in the k-30 manual it lists the modes for the built-in flash (page 239). None of them indicate you'd have full manual controls, nor does anything under the 'flash' section of Ricoh's description of the k-30 SLR Pentax K-30 - RICOH IMAGING UK LTD.

If you want to argue that the built-in flash should have full manual controls like a user-controlled power output, then I'd fully agree. It can't be a complicated thing to include, my canon P&S from 11 years ago had a few manual flash power options. They've added this to the k3, and I hope it filters down to all future models.

For what it's worth, you can get optical slaves with a 'delay' mode for use with these fancy p-TTL type flashes. They'll sense the pre-flash then wait a smidgen before firing. A few flashes with built in slave modes include a delay option (Nikon SB-26 for example). Or you can get the cheapest hot-shoe flash with manual controls and stick it in your hotshoe. Use this to trigger your 'dumb' slaves. This would be a better option as you don't really want an on camera flash adjusting it's output and influencing the exposure, even if the off-camera strobes are syncing correctly. Another option is to get radio triggers to do the triggering and skip the optical triggers entirely.

Last edited by BrianR; 01-31-2016 at 08:00 AM.
01-31-2016, 07:52 AM   #29
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Some lenses will lock the flash sync shutter speed as 180th regardless if you are in M mode according to my K10D manual.

P-TTL is available in manual mode as long as you have an A type lens attached (and in A mode). There's nothing in the documentation that says otherwise. Indeed some of the flash function charts show that P-TTL is available in manual mode. If you were meant to full manual control of the flash there would be a menu to adjust the power settings of the flash other than EV compensation. If you want control of the flash use an external flash.

This is no different then on TTL cameras. TTL worked in manual mode as well. If you wanted control of the flash use an external with manual settings.

And it's no different than using an auto-flash in auto mode on a manual camera other than the flash doing the decision making through the auto-sensor. Put the flash in manual mode if you want control.
01-31-2016, 07:57 AM   #30
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QuoteOriginally posted by BigMackCam Quote
That's not the way I've thought of it. I have a certain amount of light - the aperture and shutter speed will allow a variable amount of that light to hit the sensor, and depending on how sensitive it is, I'll get a shot of certain brightness. If the light source changes - the sun comes out, there's a flash of lightning, or a speedlight triggers, that's a variance in the amount of light being generated prior to the exposure taking place. So, in my understanding, only shutter speed, aperture and ISO sensitivity control exposure. Maybe I'm wrong, but that's how I understand it.



I know where you're coming from, but I think this is a problem with all manufacturers of all complicated electronic equipment. I have KORG synthesizers where the manuals are virtually useless... a ham radio transceiver where the manual explains the settings in every menu option, but not what the effect of the settings will be... A breadmaker that tells me what to do, which settings to use, but not "why" those settings work. I'd be amazed if the manuals for the other camera manufacturers are vastly better than Pentax's. You're right, the manual should be a detailed book on how to use the camera fully - but in this day and age, I rarely see a manual for any item that matches up to this.
fully agree here,... hey, I repair Korg Syhths (along with a whole lot of other complicated electronics) I usually have to refer to the manual for each different model I'm working on, drives me crazy. some are as thick as a telephone book, and all you want to do is find basic operation to confirm the clients fault description, and then we get to the "service manuals" ... don't get me started


Regarding exposre, what you say is valid in terms of controlling exposure, but consider if the sun comes out unexpectedly and ruins your shot, you would say the picture is over exposed would you not, a unexpected variation in the light changed the exposure. To me exposure refers to the whole process not just what controls are available to adjust it.
In film days (as I under stand it) A standard film formulation would require a standard amount of light to expose the film correctly hence the ISO rating of the film would determine how much light was required for correct exposure, the aperture & shutter are just the mechanisms to acheive or control this.
cheers
2.14 am here in Australia, I'm going to bed.

Last edited by Cee Cee; 01-31-2016 at 08:13 AM.
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