[Prakticant]

Guys, I simply wanted to know upfront which ISO uses my K-3 in TAv mode with flash on, i.e. after I press green button. No way. After you switch on your flash, you get only 'Auto' ISO reading. That's my complain to Pentax/Ricoh.
Hello Pentax/Ricoh, please get a fix in K-3 firmware to allow ISO reading in TAv mode with flash open/attached, i.e. after your valuable prosumer presses camera green button.

[stevebrot]

That is actually opposite to what happens. In TAv mode, you MUST use auto ISO. The shooter sets shutter speed and aperture, the camera uses Auto ISO to set the exposure. If you specify an ISO range that is too low or too high to make a correct exposure, the camera will under or overexpose. It will not change aperture or shutter speed.

The settings referred to...

Menu > ISO AUTO Setting > AUTO ISO Parameters > Slow/Normal/Fast


Steve

[stevebrot]

Guys, I simply wanted to know upfront which ISO uses my K-3 in TAv mode with flash on, i.e. after I press green button. No way. After you switch on your flash, you get only 'Auto' ISO reading. That's my complain to Pentax/Ricoh.

After green button press it uses "camera will find out on pre-flash", the same as if green button is not pressed.

The answer is that the camera does not know before the pre-flash and if it displayed something, it might be lying. The behavior is the same for all modes where ISO is ramped and P-TTL flash is being used. If the camera knew, it would tell you. In case it was not obvious in the three pages of discussion so far...

If one expects the camera to choose the ISO be prepared for the ISO to not be to one's liking.

The above is true regardless of whether flash is in use. If you need the ISO to be moderate, take control of ISO. In the case of the original post, the question that goes begging is what would have been done differently had the camera displayed an ISO of 11,000. How far could it have been brought it down by changing the set EV in TAv mode...1600? Would there have had adequate DOF and ghost prevention at that EV? Would "auto" mode on the flash been a reasonable option? If ISO were important, why would one push the button if the display said "auto" rather than a usable value.

You may want to go into a store and ask to be shown the Nikon flash on a D7200. Configure the camera to the Nikon equivalent of TAv mode (M mode with auto-iso) and see how it behaves.* (Be surprised to find out that ISO is not part of the default viewfinder or top LCD display...apparently not important to Nikon users.) Be sure to compare the ISO in the display with the actual in the EXIF. Move on to a Canon 7D II and repeat. Buy the camera that behaves "properly" and which would have prevented the disastrous results mentioned at the thread start.


Steve

* I did a little Google work and it appears that Nikon iTTL works similar to Pentax P-TTL, though there seems to be a bit of confusion in Nikonland on the auto-iso + flash question. The user manuals are not much help. See: Inconsistent exposure in auto-ISO with flash | NIKON D7000 CLUB | Flickr

[Prakticant]

If you specify an ISO range that is too low or too high to make a correct exposure, the camera will under or overexpose.

That's interesting and questionable with the upper ('too low') range - as camera has the flash to further lit the scene.


-----

After green button press it uses "camera will find out on pre-flash", the same as if green button is not pressed.

I have nothing against doing strobe pre-flash (which is relatively weak and do not distracts your subject as far as actual trial pre-shot) after I press K-3 green button...

Or ISO value blinking saying "Pentax/Ricoh did their best to measure ambient light EV (ISO with TAv) without pre-flash".

Hello Ricoh/Pentax, please fix the above in new K-3 firmware

---

Last edited by Prakticant; 07-17-2017 at 02:37 AM.

[TheOneAndOnlyJH]

I have nothing against doing strobe pre-flash (which is relatively weak and do not distracts your subject as far as actual trial pre-shot) after I press K-3 green button...

I think this sounds like a neat idea but more in line with people who want so much control they end up in manual mode anyway. Once you're in manual mode, you may as well just take a test shot to see the exposure and net effect of all your settings. The advantage of other modes is that they take care of some or all of the thinking in changing environments so the user doesn't have to, but since the metering might change between every shot so you would have to do do this extra pre-flash quite often. Even though pre-flash is weak, it would still be distracting for many people.

Or ISO value blinking saying "Pentax/Ricoh did their best to measure ambient light EV (ISO with TAv) without pre-flash".

Hello Ricoh/Pentax, please fix the above in new K-3 firmware

Measuring ambient light without pre-flash and guessing ISO needed with flash is like guessing how much snow is falling without looking out the window*. There is no way to tell without a reference to compare against, so any guesses are just guesses and not really worth reporting. If they reported the 'best guess' ISO, people would be complaining that it doesn't always match the actual ISO when they take a picture. That aside, blinking is used to show when something has hit a limit and exposure will not be optimal, or when you have a card error or something else is wrong. I would be quite annoyed if ISO was constantly flashing to say it's just guessing. In my case, your 'fix' would be a nuisance.

This is not to say that your ideas aren't valid, and I can even see how useful they would be in certain scenarios, I just think they are too specific to be implemented. Pentax designed the camera for a wide range of users, so they settled on settings and behaviors they think most people would prefer. (Though I know many of us wouldn't mind if they updated the P-TTL system to get rid of the delay!)


* Assuming you're not looking at the weather channel. That would be cheating!

[stevebrot]

Hello Ricoh/Pentax, please fix the above in new K-3 firmware

Ricoh/Pentax does not monitor posts to the Pentax Forums. There is a specific forum for feature requests where the suggestions magically make their way to someone at Ricoh, but that is as far as it goes.

Product Suggestions and Feedback - PentaxForums.com


Steve

[stevebrot]

I think this sounds like a neat idea but more in line with people who want so much control they end up in manual mode anyway.

Yep...it would be a neat idea except that it addresses a corner use case with easy workarounds.


Steve

[stevebrot]

If they reported the 'best guess' ISO, people would be complaining that it doesn't always match the actual ISO when they take a picture.

From the searching I did, what your describe is the Nikon approach. Not having on of their cameras handy it appears that the camera displays the appropriate ambient light ISO and then does what it pleases on the actual exposure. I know that sounds dumb, but Pentax and Nikon just made different choices on how to deal with a difficult use case.

The Nikon approach may have spared the OP much harm if the high ISO had been noticed before shooting a bunch of photos that were disappointing.


Steve

[Prakticant]

Guys, if you say 'manual' flash mode, please be precise, as there are at least three different flash manual modes with Pentax K-3 and Pentax flash:

* on_the_flash manual mode (from 1/1 down to 1/64 flash power);
** camera program manual mode (Av, TAv, M = manual, B, X, ...);
*** camera menu Manual Flash Discharge mode (the one you find under down four-way joystick controller) from 1/1 down to 1/128 flash power.

Some of the above modes override the others, some influence other camera settings (mostly allowed shutter speeds, i.e. 1/180 or 1/90 as the shortest sync time, with the latter not feasible for long focus/tele lenses).
Actually, I doubt there is any manual mode with HSS or with trailing (second) curtain sync.

To mess things up, it looks there is some incompatibility between at least Pentax K-3 body and Pentax AF-540FGZ (ver. I) flash unit, as even with on-flash selector set to last fourth HSS setting, camera quite often disallows shutter speeds shorter than 1/180 sec. - or I do not know how to operate it to get into HSS mode whenever I want (which I doubt - as solved by switching-off both units, separating them, taking-off both batteries, than assembling again, then HSS mode (shutter times shorter than 1/200 sec.) comes back as accessible

Good news:
In the meantime I found out some workaround how to learn an ISO when in TAv mode.
Press 'MODE' on your Pentax AF-540FGZ strobe as to get into flash 'SB' (Spot Beam) mode, than 'Auto' (ISO) reading on your K-3 dissapears and you see an ISO value which K-3 chooses for the ambient light.
Pressing the on-strobe MODE button is much simpler than switching-off that flash.


-----

a typical outdoors set up for me is ambient exposure -0.7 stops, flash exposure +1.0 stop.

You go strange way as my (and other people I know) flash exposure compensation always goes minus (-0.3 down to -5.0 with very close distances), but may depend on the strobe unit (i.e. Sigma tends more to overexpose than Pentax).


-----

(by not setting a tighter AUTO-ISO range)

Too simple answer.
Might be the camera menu 6. Auto EV Compensation 'On'?

[stevebrot]

Might be the camera menu 6. Auto EV Compensation 'On'?

Not recommended...a significant number of help requests have had their root in that feature.


Steve

[mcgregni]

Originally posted by mcgregni Quote: 'a typical outdoors set up for me is ambient exposure -0.7 stops, flash exposure +1.0 stop'.

You go strange way as my (and other people I know) flash exposure compensation always goes minus (-0.3 down to -5.0 with very close distances), but may depend on the strobe unit (i.e. Sigma tends more to overexpose than Pentax).

No, this is not a 'strange way'. Plus or minus Flash Compensations are both a normal and required response to reflected light readings with the TTL metering. They are also normal and required to achieve the desired balance of flash exposure with ambient exposure. The user needs to respond with plus or minus FC settings as demanded by the metering results and their own creative needs for each shot.

If overexposure is occuring with a 0 FC setting, then there is a problem with the Flash to Subject distance and exposure settings ..... eg the ISO might be too high for the power of that particular flash, the aperture setting and the distance involved. The best response to that is to adjust one of those factors ... eg set a lower ISO, a smaller aperture, or increase the distance. Flash Compensation is intended as a user 'fine tuning' tool .... it cannot make up for incorrect configurations or situations that are outside the bounds of the technical limitations.

Regarding Flash metering generally ..... for portraits we should find that the more of the frame that is taken up with the subject (eg if you zoom in to fill the frame with a face) then this requires plus compensations ... eg +1.0 , +1.5 stops. Note this is not the same as walking closer to the face with the flash .... that reduces the flash to subject distance and can lead to exposure problems. Zooming (or any change to focal length) does not change the Flash to Subject distance, but it alters the lighting balance in the image, and so is likely to need FC adjustments.

[FilmORbitz]

Since I didn't see one, I'LL say "thank you" to everyone who provided a lot of useful information -- you know who you are

[audiobomber]

If you specify an ISO range that is too low or too high to make a correct exposure, the camera will under or overexpose. It will not change aperture or shutter speed.

That's interesting and questionable with the upper ('too low') range - as camera has the flash to further lit the scene.

Nothing questionable about it. A flash has limited power and may not have enough output to illuminate the scene if the exposure settings are off, especially when using bounce, in dim conditions or trying to light a large area.

[ffking]

elieve me or not, my Canon 300TL + Canon T90 was much superior than Pentax AF540FGZ + K-3 when it came to flash

I would have thought that that was good corroboration for those suggesting fixing the ISO?