[C_Jones]

The flash is going to decide what it wants to do with the settings present on the camera before the shutter is pressed if the flash is set to P-TTL. If you are in AV mode and the camera is choosing/registering an F8 parameter, the flash is going to shoot according to that parameter. If you are in Manual mode and you choose the parameters yourself, including the aperture, the flash is going to shoot according to those exact parameters and they (the parameters) are not going to change until you change them yourself.

[BruceBanner]

Have a look at Nigel's flash guides which give a detailed description of camera behaviour in each mode.

Slow speed sync is a flash mode you can only use in P or Av (and I think Sv). Normally in those modes when using flash the camera will choose a shutter speed with a limitation of 1/30 or 1/60 as the slowest depending on FL. It will try and balance the ambient and flash output to the scene, but wont go below the minimum shutter speed to avoid blur from elements in your picture lit by ambient light.. If you enable slow speed sync it will choose a slower shutter speed if the ambient light requires it.

Regarding your lensbaby, any lens that does not communicate its aperture and focus distance to the camera can lead to unexpected results when trying to use an auto mode like Av. if you add auto-ISO into the mix you are confusing things further.

There is a reason many flash users prefer Manual exposure mode when using a flash in P-TTL and that is it gives the greatest control and most consistent results.

Thanks for that. I just had a play with Slow Sync, interesting. I threw my handsome tooties up onto the computer desk as a test, and placed the camera in Av mode and had the flash on. Using 40mm and f4 in Auto ISO (without any Flash ev comp) it gave the image a 3200 ISO and 1/60th shutter speed. If using the Slow Sync I Could get the same exposure with 100 ISO (still in Av mode) but now suffer a 0.6 shutter speed (far too slow, motion blur even where the flash touched). However I was now free to adjust the shutter speed and could select 1/25 and now produced once again the same exposure with an ISO of 1600. This image was clean enough, no motion blur (but alas... it was just tootsies on the computer desk, real world shooting conditions not.

I did a few more shots and noticed 'that thing' happening again. Not in slow sync mode, I selected f4 and was in Auto ISO, it gave me 1/60 and when the shot was taken gave me ISO 3200. I now toggle slow sync on, adjusted the ISO (which therefore adjusts the shutter speed) and I select ISO 3200 it reads out a shutter speed of 1/20 when focus was confirmed and the shot was taken, however EXIF shows it was taken at 1/40. I repeated this a few more times, I got same kind of jumps prereadings of 1/25 with 3200 ISO and the EXIF shows 1/50. Ah... Av+Flash you do such weird and wonderful things

Still... that is interesting to know, because I couldn't figure out what was going on, I was given a shot at 1/60 with flash but was getting fairly high ISO (3200) selecting lower ISO didn't change the shutter speed at all, and this is what stumped me. You could of course adjust the ISO, lower it, shutter speed stays the same but the exposure balance between ambience and flash differed wildly. At least I know now if I am ever dumb enough to shoot in Av mode I can quickly toggle on Slow sync and drop that ISO and thus shutterspeed as well but at least keep the exposure balance the way I want. It really just depends on how far you can push it before motion blur behind the still flash starts to impact. I guess a lot of this has to do with also how you fire your flash. Ceiling vs directly at the subject, direct may freeze the person better and you can push those shutter speeds down lower, whereas off the ceiling less 'direct' flash is freezing them, you might start to get that thing where parts of the person are frozen quite well and other parts where the flash light struggled to hit suffers blur.

There is motion blur in your pictures. Look at the man behind the subject in the first picture and also the arms of the subject. Motion blur in both from the ambient part of your exposure, but the flash has frozen your subject as you would expect so you dont notice it.

Great pictures by the way.

Thanks, and yeah that was the intention of these party shots. I deliberately wiggled the camera after the flash fired to drive the motion blur harder.

I guess in this original context that sparked this thread of mine I was just curious about this fixed shutter speed in Av mode when flash was on is all, as it kinda flies in the face of Av mode generally speaking, or rather I accidentally found that shutter speed limit it wanted to compromise on (like an Auto-ISO Parameter for Av mode when coupled with Flash, but you awesomely showed me how to override that.
On the weekend I was covering a public speaking event and always take a group shot of the speakers with the founding members of the event, past examples;

FA77, f3.5, Av mode (I think), -1ev comp, 1/80 ISO 400


F28, f4.5, Av mode (I think), -1ev comp, 1/50, ISO 800


Both different environments but same venue, this past weekend I took another group shot (yet to edit/process) at yet again a different location (but same venue), and I think I had similar settings but perhaps they (the people) were furtherback... anyway I was getting ISO 3200 which I thought was a bit high for a shot using flash, and it stumped me why I couldn't back down from 1/50 to something lower in an effort to get lower ISO. I guess what I want to learn now is the shutter speed and ceiling flash bounce relation, just how far I can bump that shutter speed down before ambient motion blur really comes into play. A lot will have to do with me I suspect and how steady my hands are. I often shoot these events with a monopod (for Live View Manual Focusing so as to not be too annoying with the AF sound, I also just find it generally more accurate as well), perhaps I should do this group shot monopodded too, perhaps I can get the lowest ISO possible with quite a low shutter speed whilst maintaining that balance between ambient and flash that I am seeking. Fun times ahead!

Cool...I could not remember if you were part of that discussion way back when to hammer out the details of auto-ISO ramping.



Truly? I will have to look that up. That one sounds like a deep pit for a noob to fall into.
Edit: I just took a look at the manual and without a KP in hand, it looks to be a deep, deep, pit...


Steve

Too complicated. Especially when the next time you wander out with your camera you have forgotten you changed that setting.

Exposure is not rocket science. There are three parameters. There are enough modes to accommodate you as long as you understand exposure. Adding a shutter speed limit in Av ?.....really !!

Um, well it's something I noticed that was there, l haven't had to use it yet. You can still opt for the Slow, Normal & Fast thing. Just because an option is there doesn't mean you have to exploit it, and it really does involve a lot of menu diving to access it. Noobs will be noobs and they will stuff up with many other quickly accessed features than this pit I assure you. For example, the KP has been out how long... and since when have you heard of a noob asking for help and this issue is the culprit
Personally I can think of a few instances where this is a useful feature to have, imagine photographing a horse race or some other sport event whereby keeping a decent shutter speed is necessary. But the race is being held on one of our bright and sunny days, the dynamic light on the race course is severe! In the shade the shutter speeds drop to 1/200, in the sunshine they are 1/8000! But I like the exposure I am getting but 1/200 is not going to cut it for those shaded places, I'd quite happily take a bump up in ISO at the expense of lower shutter speeds, oh what is a person to do?! Don't worry! Pentax has your back, you can now leave the camera in Av mode, tell it to bump ISO up when you hit 1/1000 shutter speeds. Problem solved and the camera man can focus on aiming, composition and depth of field for his work.

Good stuff. KP has other treats the K-1 doesn't have, they don't seem to be hardware specific (like Dynamic PS on the K-1ii), I really wish they would release more firmware for the K-1 that has some of this stuff that the KP has...

[stevebrot]

Adding a shutter speed limit in Av ?.....really !!

I don't have the KP to explore the feature, but as he explained it, the setting is the base point for auto-ISO ramping such that ISO will ramp to secure a shutter speed no lower than the set value. Of course, it will only apply in P or Av modes. It is an interesting feature, but I would probably relegate usage to one of the "User" modes should I ever have a use case.


Steve

[BruceBanner]

I don't have the KP to explore the feature, but as he explained it, the setting is the base point for auto-ISO ramping such that ISO will ramp to secure a shutter speed no lower than the set value. Of course, it will only apply in P or Av modes. It is an interesting feature, but I would probably relegate usage to one of the "User" modes should I ever have a use case.


Steve

It's doing not a lot different than what we already get with changing Auto-ISO Parameters Fast, Normal and Slow, it's just letting us be a little more specific, what's not to like!

And FYI every User mode of mine is utilised, I want import/export User Mode abilities badly!

[pschlute]

If using the Slow Sync I Could get the same exposure with 100 ISO (still in Av mode) but now suffer a 0.6 shutter speed (far too slow, motion blur even where the flash touched). However I was now free to adjust the shutter speed and could select 1/25

That is because you are using auto ISO, not a good idea with flash.

it reads out a shutter speed of 1/20 when focus was confirmed and the shot was taken, however EXIF shows it was taken at 1/40.

When using flash P-TTL mode in any auto camera mode where the camera chooses the shutter speed you wont know what it will use until after the picture is taken. That is the nature of P-TTL. If you want certainty use M mode.

Personally I can think of a few instances where this is a useful feature to have, imagine photographing a horse race or some other sport event whereby keeping a decent shutter speed is necessary. But the race is being held on one of our bright and sunny days, the dynamic light on the race course is severe! In the shade the shutter speeds drop to 1/200, in the sunshine they are 1/8000! But I like the exposure I am getting but 1/200 is not going to cut it for those shaded places, I'd quite happily take a bump up in ISO at the expense of lower shutter speeds, oh what is a person to do?

That is what TAv mode is for

[morenjavi]

Hello,

I use M mode 99% of the time, but, about a month ago or so, I dediced to check the Av mode with my (Godox) flashes, just to see if I could use it with our without HSS, the ambient could be controlled... this kind of thinks.

Av mode was a bit pointless for me, at the beggining; I just couldn't understand why the speed was fixed at 1/focal length when you are in 'fast sync mode'. Fortunately, Nigel clarified a bit why.

So this is my understanding and what I tested about the Av mode with flash, that depends on the 'slow sync' camera mode.

SLOW SYNC MODE ON

So I think we all know what happens here: you set the Av, and then your camera sets the correct speed, depending on the ISO, etc. The flash contributes so you have a pic with a good mix of ambient and flash. If I'm not wrong, the speed is limited to 1/180-1/200, that is, you use always normal sync speeds.

SLOW SYNC MODE OFF

So, when you are in this mode, and you just turn your flash ON, you notice that your speed seems to be fixed at 1/focal length. So now you can face two situations: you have low ambient light or not.

If you have low ambient light, ISO fixed, Av fixed, and you fire your flash, you get a pic with really low ambient contribution and high flash contribution. From this point, you can control the ambient contribution by raising the ISO, so you get more ambient in the mix. Another option is just put auto-ISO, so you get a more or less good ambient/flash mix. If you set +-EV compensation, ambient and flash are compensated. The only way to change the flash/ambient contribution independently is to play with the ISO for the ambient, and FEC for the flash.

So now comes what was a nice surprise for me. If you have enought ambient light, suppose you are outside, you will notice that the speed go above 1/focal length value. The speed is not really fixed, it's just that the camera puts a lower limit. The speed can go above the sync speed, and you can use HSS with your flash. Again, you get a more or less good mix of ambient/flash light.

I don't remember exactly but I did the same tests with my AD200 in TTL mode and my PTTL Metz on camera, so you should reproduce my results without issue.

So the Av is more complex and useful that I thought at the beggining. I'm still using the M mode, that is my preferred mode, but it's good to know about other options.

Regards.

[BruceBanner]

Hello,

I use M mode 99% of the time, but, about a month ago or so, I dediced to check the Av mode with my (Godox) flashes, just to see if I could use it with our without HSS, the ambient could be controlled... this kind of thinks.

Av mode was a bit pointless for me, at the beggining; I just couldn't understand why the speed was fixed at 1/focal length when you are in 'fast sync mode'. Fortunately, Nigel clarified a bit why.

So this is my understanding and what I tested about the Av mode with flash, that depends on the 'slow sync' camera mode.

SLOW SYNC MODE ON

So I think we all know what happens here: you set the Av, and then your camera sets the correct speed, depending on the ISO, etc. The flash contributes so you have a pic with a good mix of ambient and flash. If I'm not wrong, the speed is limited to 1/180-1/200, that is, you use always normal sync speeds.

SLOW SYNC MODE OFF

So, when you are in this mode, and you just turn your flash ON, you notice that your speed seems to be fixed at 1/focal length. So now you can face two situations: you have low ambient light or not.

If you have low ambient light, ISO fixed, Av fixed, and you fire your flash, you get a pic with really low ambient contribution and high flash contribution. From this point, you can control the ambient contribution by raising the ISO, so you get more ambient in the mix. Another option is just put auto-ISO, so you get a more or less good ambient/flash mix. If you set +-EV compensation, ambient and flash are compensated. The only way to change the flash/ambient contribution independently is to play with the ISO for the ambient, and FEC for the flash.

So now comes what was a nice surprise for me. If you have enought ambient light, suppose you are outside, you will notice that the speed go above 1/focal length value. The speed is not really fixed, it's just that the camera puts a lower limit. The speed can go above the sync speed, and you can use HSS with your flash. Again, you get a more or less good mix of ambient/flash light.

I don't remember exactly but I did the same tests with my AD200 in TTL mode and my PTTL Metz on camera, so you should reproduce my results without issue.

So the Av is more complex and useful that I thought at the beggining. I'm still using the M mode, that is my preferred mode, but it's good to know about other options.

Regards.

Oh I use Av for outdoor flash all the time, typically I have my EV comp at -1 and that lowers the ambient light enough to get the flash to lift the shadows, somewhere between fill or key light depending on flash strength and distance to subject etc. I use it both in Manual power on the flash and P-TTL. Indoors its a bit of a different story, often I am in X mode as I can see things better due to the unique way X mode keeps the Live View screen always exposed correctly regardless of settings.

This thread was about that Av lower shutter speed limit, how it came to be that, why that amount, why not more, why not less etc (with flash on that is).

But really if you fix ISO in Av mode and EV compensate it can be a very quick and easy way to run and gun with flash. All of these shots were taken in Av mode and flash at 1/1 power (very bright day);

Ironfest 2019 | Flickr

[morenjavi]

Oh I use Av for outdoor flash all the time, typically I have my EV comp at -1 and that lowers the ambient light enough to get the flash to lift the shadows, somewhere between fill or key light depending on flash strength and distance to subject etc. I use it both in Manual power on the flash and P-TTL. Indoors its a bit of a different story, often I am in X mode as I can see things better due to the unique way X mode keeps the Live View screen always exposed correctly regardless of settings.

This thread was about that Av lower shutter speed limit, how it came to be that, why that amount, why not more, why not less etc (with flash on that is).

But really if you fix ISO in Av mode and EV compensate it can be a very quick and easy way to run and gun with flash. All of these shots were taken in Av mode and flash at 1/1 power (very bright day);

Ironfest 2019 | Flickr

What a nice results! It's clear that you master Av mode outside, with bright sun. Just your Cactus RF60 on camera ?
I'm still not comfortable with my setup with hard sun outside. I had a work last weekend and used my AD200 in TTL mode outside, under the sun and under the shade, but things didn't work as I expected. I had to switch to full manual mode finally. The k3-ii's rear LCD doesn't help with bright sun either, I need to be confident in PTTL or in my photometer, but the rear display is not my friend.

Regards.

[kaseki]

This discussion gave me an insight -- that as a historical film user I have been unconsciously maintaining a film photography viewpoint into the digital world, even though I was employed for 50 years engaged in activities that often dealt with various types of photodectors. With film, one can have (or could have had) various ISO graded films that traded light sensitivity for grain, which has the characteristic of noise. With a camera photodetector array, none of which as far as I know are designed around avalanche photodiodes, the sensitivity of the physical photodetector array does not change. The number of photoelectrons stored for a given number of photons that strike the photodetector is a constant. The ratio is the quantum efficiency, a number less than one.

What changes is the photographer's "message" to the camera about how much noise he is willing to tolerate, or equivalently, where he wants to set the camera's digitizer dynamic range with respect to the well storage dynamic range, and hence, what combination of aperture and shutter speed (or flash power) he will accept (if those are free parameters). This message is in the form of an ISO setting. Conversely, he may close the aperture and/or shorten the shutter time and force the camera to work lower in the detector well; in which case the camera reports this condition as a higher ISO value.

In a photodetector array with sufficiently deep photoelectron storage wells, the dynamic range can be quite high. If the detector and succeeding electronics have low "excess noise," the signal to noise achieved by a given photodetector (pixel) will be the square root of the number of photoelectrons collected in that detector's well, which depends on aperture and either shutter time or flash power. So in auto ISO, the camera has some program that says to itself: Self, is ISO = x a good balance between dynamic range, signal to noise, shutter speed, and aperture, or should I raise the ISO value to get a better balance? In manual and semi-manual modes, the photographer fixes one or more parameters and the camera chooses values from whichever remaining parameters are free using the designers' programmed-in view of optimal. The digital sampling of the amplified stored charge may in response to higher ISO move its LSB scaling to work over a lower range within the well depth.

If we consider (a guess here) that ISO 100 represents the same light irradiance that a film of the same ISO would be intended to work with, then the immense ISO values that cameras such as the 645Z can achieve represent noise values well below the grain levels achievable in fast films.

The aspect of this addressed by others above is that the camera has (usually) fine control over aperture, speed, and ISO, and is capable of dynamically adjusting them to values that are "odd" relative to the dial settings that were popularized by film cameras.

[stevebrot]

SLOW SYNC MODE ON

So I think we all know what happens here: you set the Av, and then your camera sets the correct speed, depending on the ISO, etc. The flash contributes so you have a pic with a good mix of ambient and flash. If I'm not wrong, the speed is limited to 1/180-1/200, that is, you use always normal sync speeds.

SLOW SYNC MODE OFF

So, when you are in this mode, and you just turn your flash ON, you notice that your speed seems to be fixed at 1/focal length.

Neither has been my experience, though it may depend on what flash is mounted, ambient light, aperture, and ISO setting. What I see with fixed ISO (just tested) has been that the shutter speed in Av mode will ramp for both cases as follows:

Slow Sync Off: Ramps within a limited range with the minimum being determined by ISO and set aperture, and that never going below 1/80s (at least on my K-3).

Slow Sync On: Ramps freely up to the X-sync speed.

Adding auto-ISO into the mix has the potential to complicate things considerably, of course. The observation that changing ISO provides the means to "tune" the behavior is quite true and part of the magic.


Steve

[BruceBanner]

What a nice results! It's clear that you master Av mode outside, with bright sun. Just your Cactus RF60 on camera ?
I'm still not comfortable with my setup with hard sun outside. I had a work last weekend and used my AD200 in TTL mode outside, under the sun and under the shade, but things didn't work as I expected. I had to switch to full manual mode finally. The k3-ii's rear LCD doesn't help with bright sun either, I need to be confident in PTTL or in my photometer, but the rear display is not my friend.

Regards.

This has been my running and gunning approach thus far;



Both parts are required to get a soft fill light for the subject.

Without the umbrella (just magbounce);



You get this kinda shot;



Still pretty good, but look at the shadow under her chin, it is still a hard line edge, even though it is softer.

Without the magbounce and just firing flash straight through umbrella you get similar results, like this shot here where I had to stand further back and even at 1/1 there wasn't enough light getting to the subject, something had to go so the magbounce was dropped and the flashhead aimed direct through umbrella;



Again look at the shadow under the little girls chin, hard line and harsh, yuck.

But the two together, with the right amount of HSS (1/1000 is a nice amount, golden hour stuff), you get a very decent shadow fall off;



The shadow lines under the chin are soft and pleasing.

It's probably not a set up I will run with much longer, it's too awkward to 'put down' whilst making a lens swap etc. I have a few more ideas to share in the future, something I'm keen to explore once I get out of post processing editing hell that I am currently in.

What's occurred to me however is this dilemma, I could switch to a AD200, it will solve the power issues and am sure to get pleasing outdoor shots firing through modifiers etc. The only issue is it is indeed quite a bit heavier, is it really going to be a comfortable 'running and gunning' solution? I saw 1-2 users using it on that event day naked, and I can kinda see why... to add modifiers to it and hold it one handed... ouch. Secondly, there is something nice about using a light speedlight, you can have it set to 1/1 power and then just pick a good distance from your subject, too much light? Back off, too little, come forward. You end up not messing around with power settings as much, it's more about picking a good lens that works with that combo (FA43 was perfect, FA77 required too much distance between subject and speedlight+modifier).

[morenjavi]

What's occurred to me however is this dilemma, I could switch to a AD200, it will solve the power issues and am sure to get pleasing outdoor shots firing through modifiers etc. The only issue is it is indeed quite a bit heavier, is it really going to be a comfortable 'running and gunning' solution? I saw 1-2 users using it on that event day naked, and I can kinda see why... to add modifiers to it and hold it one handed... ouch. Secondly, there is something nice about using a light speedlight, you can have it set to 1/1 power and then just pick a good distance from your subject, too much light? Back off, too little, come forward. You end up not messing around with power settings as much, it's more about picking a good lens that works with that combo (FA43 was perfect, FA77 required too much distance between subject and speedlight+modifier).

The AD200 can be a bit heavy to hold it with a hand + modifiers, etc, during a long time. But you can use the EC-200 extension cable. This cable allows you to detach the AD200's head from the body, so you can put the body on your belt, and just hold the head with your hand. You could put the small octa-softbox on the AD200's head, and this could be a good run & gun setup, with TTL. You need a trigger on your camera. Just an idea.

Regards.

[pschlute]

This has been my running and gunning approach thus far;

I have told you before....you will have someone's eye out with that

[BruceBanner]

The AD200 can be a bit heavy to hold it with a hand + modifiers, etc, during a long time. But you can use the EC-200 extension cable. This cable allows you to detach the AD200's head from the body, so you can put the body on your belt, and just hold the head with your hand. You could put the small octa-softbox on the AD200's head, and this could be a good run & gun setup, with TTL. You need a trigger on your camera. Just an idea.

Regards.

Yeah, that might be an option too. It just strikes me that a speedlight might be a good compromise for this kinda stuff simply because it's lighter, you just have to work around the pros and cons of both systems I guess. I'm still on my learning curve with it all, even that past cosplay event taught me a lot. If I am to handhold the ocf with one hand then I need a FA43 (or a FA31 which I don't yet have, so I make do with my F28 instead) because I can get in closer, this would be for those very bright HSS times such as midday. Towards the golden hour I think I could pop on the FA77 and now get some reach to the target with a few steps further back, so it's all about knowing the limit of a speedlight in HSS light and how that light varies in intensities throughout the day and can dictate the right lens for the job. Restrictive yes, but then you pro is not having to fork out more $$ for new lights and such and workaround issues surrounding heavier lights.
The other option is to utilise my portable light stand more, which I tried on the day but never got fully comfortable witht, it would allow me to use FA77 in brighter conditions and have the flash much closer to the subject. My issue on the day was wind and pegging the stand down into the ground, which is hard ground/grass in Australia, literally I thought I would need to start carrying a pegging mallet around with me as stomping on the pegs with my soft trainers wasn't cutting it. It isn't helped by the umbrella being a wind trap as well, but really even if it was a softbox up there I'd want it pegged down. I thought about carrying around a 5kg plate and anchoring that onto it but now we're getting a little ridiculous for running & gunning (more like crossfit & gunning!).

The AD200 (which I don't have, and would be around a $480AUD expense) is something I see me using for these kinda events, but that's a lot of coin for a light that I'm not sure would suit a lot of other kinds of shoots I wanna do. School photography is my long term goal and I think wired lights to a/c make a lot more sense than using stuff that is portable. I just don't see me doing the whole 'fashion shoot' outdoor thing any time soon with multiple AD200's and softboxes down urban alleyways, which is where I feel the AD200 is meant for. Just simply running & gunning event stuff is what I will be doing more of in the near future and I'm still not altogether giving up on speedlights, not just yet at least.

Anyway, I have a couple more ideas for set ups that I will try and share in time.

I have told you before....you will have someone's eye out with that

Yeah I have to be careful in crowds and when wind picked up made it harder to use/keep steady/be in control of.