[Prakticant]

That's also my experience, so I started the thread.
My camera set-up ISO of 10000-12000, which I learned long after shots were done (and don't remind me one could check pixels 1:1 on 3'' LCD screen after every shot, that's not always feasible).
Might be the ISO 'climbing' mode (slow, standard, fast) do influence the results in TAv mode, so users forum is interesting place to share the thoughts (but nobody suggested that influence?).
Usefulness of Pentax/Ricoh DSLR technology: no sports (slow focussing), no children (slow focussing), no portraits/shallow DOF (front/back focussing), no usable flash (P-TTL), no weddings (1/3 sec shutter delay), no standard zoom (don't call 2.8/15-50mm a DA* lens - I got two different source equal rubbish).
Great system for sunny days, but why not to shoot Lomo then
OK, I'm frustrated
Actually I'd like to learn how it compares with Nikon/Canon/Sony fill-in low light flash photography?


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I don't know if it's due to poor calculations or differences in how the pre-flash and main flash illuminate the subject / room, but I find it often chooses very high ISO and greatly under-utilizes the flash power available when I would rather use higher flash power and lower ISO.

[mcgregni]

It appears that you need to learn more about DSLR operating techniques, and certainly flash control, before worrying about even more camera systems and how they compare with their auto flash program algorithms. Have you been reading the advice that's been given here about controlling ISO for flash photography ?

[stevebrot]

Might be the ISO 'climbing' mode (slow, standard, fast) do influence the results in TAv mode, so users forum is interesting place to share the thoughts (but nobody suggested that influence?).

That feature has a strange history on this site with at least one user (me) having a misconception based on various sources. The options are misnamed and documented incorrectly, but at the risk of not remembering right, I won't attempt to recall without finding the definitive thread on the topic. (I believe the settings influence the start point for the ramp and nothing else.)

Normally the auto-ISO settings don't come into play in TAv mode, though I believe they might when flash is attached. At least that is how it looked when I tested it this evening.

BTW...you must have been in a seriously dark room and/or impressive distance to have the ISO ramp above 10,000 with P-TTL flash in TAv mode.

Usefulness of Pentax/Ricoh DSLR technology: no sports (slow focussing), no children (slow focussing), no portraits/shallow DOF (front/back focussing), no usable flash (P-TTL), no weddings (1/3 sec shutter delay), no standard zoom (don't call 2.8/15-50mm a DA* lens - I got two different source equal rubbish).
Great system for sunny days, but why not to shoot Lomo then

Sounds like you are a good candidate to switch brands. My suggestion would be Nikon. They have superb flash system integration and top-tier AF. You will also be doing your part to save a struggling company. One caution however, even Nikon will not automatically do predictably consistent fine/selective focus for portraits.

OK, I'm frustrated
Actually I'd like to learn how it compares with Nikon/Canon/Sony fill-in low light flash photography?

All are P-TTL and the tech is very similar across brands. I would suggest addressing your "pain point" of low-ISO, low-light fill-flash* with a try at using manual or semi-automated technique with your Pentax before putting too much blame on the camera/flash system. Example:

• M-mode (chosen because P, Sv, and Av tend to keep shutter speed at 1/80s or higher making flash-as-fill difficult)
  Edit: @mgreni made the suggestion of using the Slow Sync feature. Doing so allows the camera to drop the shutter speed when using AE in low light conditions.
• Manual ISO 800
• LV 4 (moderately dimly lit room)
• 10ft
• P-TTL (-1 EC as fill)

Notice that I defined LV (Light Value) instead of aperture/shutter. That was intentional because I wish to test the ability of P-TTL to attenuate with both the on-board flash and my Sigma EF 610 DG Super.

• f/4.0, 1/8s both on-board and the Sigma attenuated beautifully
• f/2.0, 1/30s (same LV) on-board was fine, but the Sigma overexposed by at least two stops

We've got problems. Generally, 1/8s is too slow for flash shooting because of the risk of ghosts and in this case, 1/30s results in too wide an aperture for the more powerful flash to deal with at that distance. Solutions might include increasing the ISO to allow a narrower aperture and higher shutter speed or bounce the flash off the ceiling to spill some photons or a diffuser/filter or full manual flash (strobist technique) or any number of other tricks.


Good luck! FWIW, I am not a huge fan of P-TTL.


Steve

* In case anyone cares, true fill flash in low light is difficult, both from an aperture and shutter speed point of view. The ambient light exposure must be appropriate to the available light and the flash portion must be scaled down to allow the ambient light to dominate. The two requirements are at odds with each other.

[photoptimist]

* In case anyone cares, true fill flash in low light is difficult, both from an aperture and shutter speed point of view. The ambient light exposure must be appropriate to the available light and the flash portion must be scaled down to allow the ambient light to dominate. The two requirements are at odds with each other.

^^^ THIS

Unless the subject is right up against the wall so that the flash can uniformly illuminate the entire scene, the TAv with P-TTL setting will always use an ISO that's pretty close to the ambient light level to avoid a garish deer-in-the-headlights image of a brightly-lit person in a pitch black space.

In any case, the OP specifically told the camera that very high ISO was acceptable (by not setting a tighter AUTO-ISO range) but then complained that the camera picked a high ISO value.

[mcgregni]

There's been some very good detailed analysis here of the auto -program workings and flash/ambient balancing acts that the camera is expected to perform. It's interesting from a technology and academic point of view, but I honestly feel that the practical, real world value of auto-ISO and program modes for flash photography is limited. Certainly there needs to be a firm control over key aspects from the photographer to ensure consistent and reliable results, plus of course an ability to repeat what you have obtained.

The Slow Speed Sync mode is a key setting here ... In fact I always activate it when using Av mode and P-TTL flash. This camera mode ensures that the exposure time can increase for ambient conditions rather than the ISO having to shoot up, and allows the camera to create a good balance between flash and ambient exposures.

[stevebrot]

The Slow Speed Sync mode is a key setting here ... In fact I always activate it when using Av mode and P-TTL flash. This camera mode ensures that the exposure time can increase for ambient conditions rather than the ISO having to shoot up, and allows the camera to create a good balance between flash and ambient exposures.

Excellent suggestion. When I was fooling around yesterday, I also tried "green" mode on a whim. Dang! The system nailed a balanced exposure at a reasonable shutter speed and ISO. I tried the same settings in manual mode with P-TTL and did not get the same results. Ditto for P mode. There must be secret pixies working the "green" mode.


Steve

[stevebrot]

Certainly there needs to be a firm control over key aspects from the photographer to ensure consistent and reliable results, plus of course an ability to repeat what you have obtained.

That is why I have been experimenting with P-TTL in M-mode.* For many (most?) shooting situations, the ambient light is fairly consistent. It is the subjects that change. M-mode allows the photographer to expose for the ambient light with a high degree of control. Adding P-TTL provides the easy automation for subjects at various distances. Av with P-TTL using slow sync and manual ISO provides almost as good a control.


Steve

* For the longest time, I thought that M and X modes did not support P-TTL. Silly me.

[TheOneAndOnlyJH]

Unless the subject is right up against the wall so that the flash can uniformly illuminate the entire scene, the TAv with P-TTL setting will always use an ISO that's pretty close to the ambient light level to avoid a garish deer-in-the-headlights image of a brightly-lit person in a pitch black space.

Well that makes a lot of sense! I think that's exactly what I was running up against, since I noticed it was worse in darker settings.
I may revisit to play with it again just for curiosity, but I think I'll just stick to fixed ISO instead.

[mcgregni]

Be aware that the addition of P-TTL flash combined with an AE mode does not stop the camera from concerning itself with focal length and steadiness, even though the very addition of flash may make longer exposures quite manageable when they wouldnt be without. Without the Slow Speed Sync mode this is one of the program's priorities, and so if the auto ISO range permits it will instead allow far too high an ISO than the conditions demand ....in many cases the high ISO will also make the flash to subject distance far too small leading to flash overexposure.

All good reasons to use fixed ISO (or a very limited auto ISO range), and allow Slow Speed Sync mode with any applicable AE camera mode (i.e. P, Av, Green). Remember to set compensations for BOTH ambient and flash exposures (they are different and independent controls) .....a typical outdoors set up for me is ambient exposure -0.7 stops, flash exposure +1.0 stop.

[JimJohnson]

Excellent suggestion. When I was fooling around yesterday, I also tried "green" mode on a whim. Dang! The system nailed a balanced exposure at a reasonable shutter speed and ISO.
Steve

Why do so many of us deride Green (full auto) mode? I admit I don't use it regularly simply because it locks me out of all creative choices*, but I do use it and almost always get technically good images. In situations where subjects, lighting, perspective and so on are all changing more rapidly than I can think and tweak camera controls for what I consider aesthetically best for the image, it might mean the difference between a usable image and no image. Hey! it's just another tool in my kit. Like any tool, the trick is knowing when and where and how to use it.

*I can't tell you how many times I would have used Green mode if I could override just one thing... 'one thing' of course being different every time I wanted to use Green mode

[stevebrot]

Why do so many of us deride Green (full auto) mode?

We are all control freaks. We also don't like surprises.


Steve

[Prakticant]

It appears that you need to learn more about DSLR operating techniques, and certainly flash control

Might be good advice believe me or not, my Canon 300TL + Canon T90 was much superior than Pentax AF540FGZ + K-3 when it came to flash photography (besides wired vs. wireless sync), i.e. I could spot-measure whites ('highs') and blacks ('lows') with the flash before actually shooting the picture (30 years B.PTTL.)...

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a garish deer-in-the-headlights image of a brightly-lit person in a pitch black space.

More or less like in all-green-mode

the OP specifically told the camera that very high ISO was acceptable but then complained that the camera picked a high ISO value.

Tighter ISO range in TAv mode results in 'Auto' (ISO) blinking and AFAIR not telling you how many stops of underexposure.
Why do they advertise 51200, when 8000-10000 ISO is more or less useless?

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Actually, there is a lot of variables not covered in camera manuals (and even more with flash photography), so this kind of forum users' advice is very helpful, but please not be paternalistic.

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Slow Speed Sync is not_so_feasible with 50-135mm lens at long end and action shots, this is HSS which I try to use more often (than you have strobe range limited by 2x-3x with HSS). Also if one wants to use second (trailing) curtain sync with slow speed sync, K-3 limits shutter speed to just 1/90 (instead of 1/160-1/180) which is again not feasible with 50-135mm and/or action/children photography.

[photoptimist]

Why do they advertise 51200, when 8000-10000 ISO is more or less useless?

For the same reason they advertise shutter speeds slower that 1/30 (uselessly blurry moving objects) and apertures down to f/1.4 (uselessly narrow DoF).

Some of us do not find ISO 51200 useless. For some shots, it's more important to stop the motion or gain DoF even if it means accepting a lot more grain in the image. Moreover, modern post processing software has come a long way in extracting the signal from the noise (with perhaps some compromise on resolution). You can have a decent shutter speed, decent aperture, or decent ISO -- but you often only get to pick two of the three.

If a photographer has hard limits on acceptable ISO, shutter speed, aperture, etc. then it's up to them to enforce those limits (either manually or by setting restrictive AUTO ranges) and accept the consequences of the restrictions that some photos will be under- or over-exposed because the light levels are outside those defined by the parameter ranges.

The point is that photography is often a compromise and if one is not willing the compromise then there will be times one cannot take pictures.

[JimJohnson]

Sometimes you do what you have to do. ISO 51200, 1/4 second at f/4.5 (18-135 @ 36mm). This candid shot was inside a near total dark Disney ride and flash was naturally prohibited. (I've seen people asked to leave for violating this rule.) - no post processing of the jpeg other than size reduction.

Tons of color noise? Probably, but who could tell without pixel peeking given the stage lighting? Lots of grain? Yes. Blurry? Yes. But to parents and grandparents nothing beats the expression of rapture from their grandson celebrating his second birthday. There is more to photography than technically perfect exposure. We all strive for it, but what counts more is the emotional reaction of those viewing the image.

[audiobomber]

Normally the auto-ISO settings don't come into play in TAv mode, though I believe they might when flash is attached.

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.

Good luck! FWIW, I am not a huge fan of P-TTL.

P-TTL works very well, as long as you don't use auto ISO. P-TTL is most reliable if you use fixed ISO, which precludes the use of TAv. I suggest Av with fixed ISO for flash, or X-mode if you want to ensure a high shutter speed.