Is auto ISO fixed with fill flash?

Started 3 months ago | Questions
Jigal
Jigal Contributing Member • Posts: 588
Is auto ISO fixed with fill flash?

Currently I'm mainly shooting pups in our living room using a bounce flash. I set the A6400 in P mode, the Godox TT685s to TTL and noticed that the photos were quite dark. Exposure compensation on both the flash and the camera didn't make any difference. The histograms showed that non of the graphs (white, red, green, blue) got further to the right than about two thirds of the way.

Suddenly I noticed that all images had an ISO value of 200. I had set the auto ISO range to 100-400. Tonight I experimented a bit and each time the ISO was set to half the maximum value of that range (for all photos). I didn't change the lower limit, so maybe it sets a value half way between maximum and minimum.

I couldn't find anything in a manual about this but I'm really surprised by this. I kind of expected the camera to select the lowest possible ISO setting in the range that the light provided by the flash would allow.

Is this the behaviour of the camera? Or is it influenced by this particular flash? (Should I look for the HVL-F60RM?)

Are there settings to make it automatically select a value inside the range?

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Regards,
Jigal.

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ANSWER:
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Kev The Doc Senior Member • Posts: 2,216
Re: Is auto ISO fixed with fill flash?
1

Hi Jigal,

The camera doesn’t necessarily set the iso to half the max iso in your auto iso range, but it does tend to max out at half the iso of your max iso in your auto iso range, don’t ask me why though as it makes no sense to me. Max iso should be max iso right?

I use two different setups depending on the circumstances as follows:

1) When I’m shooting in a variable lighting environment i.e when I’m moving around a lot and each shot has different ambient lighting, I use auto iso but you have to have your max iso set high enough to cover the lowest lighting scenario. Typically indoors I have my max iso set to 6400. I personally shoot in manual mode with auto iso in this scenario so I can quickly adjust aperture and / or shutter speed as desired.

2) When shooting in a fixed environment I set the iso manually based on ambient light and the effect I’m looking for. The easiest way to do this is have a custom button programmed as “Shot Preview” which when held down shows you your ambient exposure because with a flash attached the brightness of the viewfinder / screen isn’t showing your live-view exposure.

My flash is set to TTL and I’m in fill flash mode on the camera for both of the above setups and they each work well for me. I’m typically using my A7Rii for this but the same principles apply to the other Sony cameras with these godox flashes (I have an A6500 also).

Let me know if any of this isn’t making sense? Here’s a few examples of fill flash always bouncing off a wall or ceiling.

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dbm61 Regular Member • Posts: 213
Re: Is auto ISO fixed with fill flash?
1

Jigal wrote:

Currently I'm mainly shooting pups in our living room using a bounce flash. I set the A6400 in P mode, the Godox TT685s to TTL and noticed that the photos were quite dark. Exposure compensation on both the flash and the camera didn't make any difference. The histograms showed that non of the graphs (white, red, green, blue) got further to the right than about two thirds of the way.

Suddenly I noticed that all images had an ISO value of 200. I had set the auto ISO range to 100-400. Tonight I experimented a bit and each time the ISO was set to half the maximum value of that range (for all photos). I didn't change the lower limit, so maybe it sets a value half way between maximum and minimum.

I couldn't find anything in a manual about this but I'm really surprised by this. I kind of expected the camera to select the lowest possible ISO setting in the range that the light provided by the flash would allow.

Is this the behaviour of the camera? Or is it influenced by this particular flash? (Should I look for the HVL-F60RM?)

Are there settings to make it automatically select a value inside the range?

Auto ISO and TTL are counter-intuitive. Auto ISO will try and boost the exposure  before the flash even fires. Then TTL tries to sense the needed flash to fill in the rest. And bouncing a flash loses power. So you're using the worse possible scenario for the flash.

Try setting the ISO fixed to be either 100 or 640 (Sorry, I don't know where the dual ISO kicks in on the A6400 for sure, but it's probably 640). Then use TTL and see where the exposure ends up. If bouncing still underexposes, increase the flash compensation to get the exposure you're looking for.

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Sympa Senior Member • Posts: 2,560
Re: Is auto ISO fixed with fill flash?

That Godox flash is quite big. Even when bounced it shouldn't lead to dark pictures. (At least in a normal room.)

But I agree auto ISO seems to be funny sometimes. I noticed on the A6500 it often sets ISO at 3200 (thanks for explaining it is one stop below the max of range...) as well.

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Bender79ita
Bender79ita Contributing Member • Posts: 963
Re: Is auto ISO fixed with fill flash?
1

Jigal wrote:

Currently I'm mainly shooting pups in our living room using a bounce flash. I set the A6400 in P mode, the Godox TT685s to TTL and noticed that the photos were quite dark. Exposure compensation on both the flash and the camera didn't make any difference. The histograms showed that non of the graphs (white, red, green, blue) got further to the right than about two thirds of the way.

There is no reason to use P mode when using a dedicated flash. ISO and flash will adjust exposure for you.

Suddenly I noticed that all images had an ISO value of 200. I had set the auto ISO range to 100-400. Tonight I experimented a bit and each time the ISO was set to half the maximum value of that range (for all photos). I didn't change the lower limit, so maybe it sets a value half way between maximum and minimum.

Don't try and make sense of it, it'll drive you crazy.

I couldn't find anything in a manual about this but I'm really surprised by this. I kind of expected the camera to select the lowest possible ISO setting in the range that the light provided by the flash would allow.

That would mean using the flash at full power, which is rarely desired. Give it a boost of exposure with iso (400 or any above).

Is this the behaviour of the camera? Or is it influenced by this particular flash? (Should I look for the HVL-F60RM?)

Most cameras work very weird with auto iso and flash. I used this setup on Nikon too a couple times, never again.

Are there settings to make it automatically select a value inside the range?

Select the value yourself. Shoot manual exposure; 1/100 or so, desired aperture, iso400, ttl flash.

If you think it's too much flash, increase ISO. If you want more flash, decrease ISO.

Once you set the shutter speed and aperture, that's pretty much the only thing you have to control.

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Kev The Doc Senior Member • Posts: 2,216
Re: Is auto ISO fixed with fill flash?

dbm61 wrote:

Jigal wrote:

Currently I'm mainly shooting pups in our living room using a bounce flash. I set the A6400 in P mode, the Godox TT685s to TTL and noticed that the photos were quite dark. Exposure compensation on both the flash and the camera didn't make any difference. The histograms showed that non of the graphs (white, red, green, blue) got further to the right than about two thirds of the way.

Suddenly I noticed that all images had an ISO value of 200. I had set the auto ISO range to 100-400. Tonight I experimented a bit and each time the ISO was set to half the maximum value of that range (for all photos). I didn't change the lower limit, so maybe it sets a value half way between maximum and minimum.

I couldn't find anything in a manual about this but I'm really surprised by this. I kind of expected the camera to select the lowest possible ISO setting in the range that the light provided by the flash would allow.

Is this the behaviour of the camera? Or is it influenced by this particular flash? (Should I look for the HVL-F60RM?)

Are there settings to make it automatically select a value inside the range?

Auto ISO and TTL are counter-intuitive. Auto ISO will try and boost the exposure before the flash even fires. Then TTL tries to sense the needed flash to fill in the rest. And bouncing a flash loses power. So you're using the worse possible scenario for the flash.

Try setting the ISO fixed to be either 100 or 640 (Sorry, I don't know where the dual ISO kicks in on the A6400 for sure, but it's probably 640). Then use TTL and see where the exposure ends up. If bouncing still underexposes, increase the flash compensation to get the exposure you're looking for.

I’m not sure how you’ve come to the conclusion that auto iso and TTL are counter intuitive? I’d say they work together to yield the correct exposure, but until you’re experienced and knowledgeable with flash shooting you might not always get the desired results. I had exactly the same problems as the OP when starting off, but now I realize I didn’t know what I was doing πŸ˜€.

I don’t disagree however that setting exposure manually (including iso) is one valid option, it gives the photographer more control on the outcome, the downside however being it’s a little slower if your in an ever changing lighting environment and needing to catch action as it happens. If you’re setting exposure manually and still getting underexposed shots then most likely your flash is putting out it’s max output but it’s still not enough (the flash tells you this on the screen for a few seconds right after the shot), so adjusting the flash comp won’t necessarily fix the problem, you may need to increase the ambient exposure on the camera.

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Jigal
OP Jigal Contributing Member • Posts: 588
Re: Is auto ISO fixed with fill flash?

Hi Kev The Doc,

Thanks for the hints. Raising the max auto ISO value considerably confirmed your observation that it uses half that value as the maximum ISO. The histogram showed a better distribution, however the high ISO values lead to more noise (ugly in black fur) and more influence of ambient light (moving puppies have some "ghosting" effect of motion blur combined with the flash exposure)

In short, the problem is: not enough light. Either the A77 solved this in a better way or the Metz 58 AF2 was more powerful than the Godox (despite the specs).

For the time being I'm experimenting with one of the old Metz flashes in slave mode. Maybe I'll see if there is a better way to let them work together but currently it seems to work fine just in the optical slave mode where it fires as soon as it detects a flash.
It looks like the Metz flashes at full power and the Godox adds whatever light is necessary for the scene.

Thanks for the clarification.

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Regards,
Jigal.

 Jigal's gear list:Jigal's gear list
Sony a6400 Sony E 18-200mm F3.5-6.3 OSS +1 more
Kev The Doc Senior Member • Posts: 2,216
Re: Is auto ISO fixed with fill flash?

Jigal wrote:

Hi Kev The Doc,

Thanks for the hints. Raising the max auto ISO value considerably confirmed your observation that it uses half that value as the maximum ISO. The histogram showed a better distribution, however the high ISO values lead to more noise (ugly in black fur) and more influence of ambient light (moving puppies have some "ghosting" effect of motion blur combined with the flash exposure)

In short, the problem is: not enough light. Either the A77 solved this in a better way or the Metz 58 AF2 was more powerful than the Godox (despite the specs).

For the time being I'm experimenting with one of the old Metz flashes in slave mode. Maybe I'll see if there is a better way to let them work together but currently it seems to work fine just in the optical slave mode where it fires as soon as it detects a flash.
It looks like the Metz flashes at full power and the Godox adds whatever light is necessary for the scene.

Thanks for the clarification.

Yeah the combination of indoor lighting with flash and high iso's on an APS-C sensor can lead to a lot of details loss / noise, which is one of the things I really love on FF is I can shoot indoors with 3200 ISO and still plenty of detail (or enough anyway).

On my A6500 I'd set my max ISO at 3200 and so it will shoot upto 1600 iso, and for moving subjects such as pets I'd set my SS to highest sync speed which is 1/160s on APS-C, and of course fast glass helps, so f2.8 or so depending how much you're will to trade off dof. If you're shooting in RAW with good noise removal software (I use DxO) shooting at 1600 iso should be ok.

You're not going to eliminate ambient light with one flash unit such as the 685s, hence setting your SS to the highest sync speed will help freeze movement caught by ambient light, but if you still think the flash could be outputting more than what your getting then try manually setting the flash power to full (instead of using TTL) and manually adjust camera exposure to suit.

For capturing faster moving action and knowing there isn't enough power in a single flash unit to kill ambient light consider using HSS and use the shutter speed to freeze the action, yeah we all know HSS greatly diminishes the flash power significantly and it's the enemy, but that second shot in my previous post was HSS (SS 1/640s) and the cats face was completely dark with no flash so there was still enough flash power to make the shot.

Of course my preferred way to capture action though is to get the strobes out and truly eliminate all ambient!

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sybersitizen Forum Pro • Posts: 21,074
Re: Is auto ISO fixed with fill flash?

Kev The Doc wrote:

dbm61 wrote:

Auto ISO and TTL are counter-intuitive. Auto ISO will try and boost the exposure before the flash even fires. Then TTL tries to sense the needed flash to fill in the rest. And bouncing a flash loses power. So you're using the worse possible scenario for the flash ...

I’m not sure how you’ve come to the conclusion that auto iso and TTL are counter intuitive? I’d say they work together to yield the correct exposure, but until you’re experienced and knowledgeable with flash shooting you might not always get the desired results.

If the discussion is about auto ISO in combination with TTL autoflash, Sony cameras have a pretty long history of generating some less than ideal results that way. (Maybe other brands as well, but my experience with those is limited.) I wouldn't use the term counter-intuitive, but I'd call it a less than ideal approach.

I had exactly the same problems as the OP when starting off, but now I realize I didn’t know what I was doing πŸ˜€.

Now that you know what you're doing, how do you make auto ISO with TTL autoflash produce ideal results every time? What do you do differently now?

As for the original question ... One possible reason for the auto ISO algorithm to choose a lower value than the designated maximum is that the camera knows a flash will be fired during the exposure, and there will be more light than is provided by the ambient source, so the ISO won't really need to be set as high as it would without it. But a potential sticking point is that the camera can't accurately predict how much light the flash will be able to contribute until the metering flash is fired and analyzed, when the ISO has probably already been set.

Kev The Doc Senior Member • Posts: 2,216
Re: Is auto ISO fixed with fill flash?

sybersitizen wrote:

Kev The Doc wrote:

dbm61 wrote:

Auto ISO and TTL are counter-intuitive. Auto ISO will try and boost the exposure before the flash even fires. Then TTL tries to sense the needed flash to fill in the rest. And bouncing a flash loses power. So you're using the worse possible scenario for the flash ...

I’m not sure how you’ve come to the conclusion that auto iso and TTL are counter intuitive? I’d say they work together to yield the correct exposure, but until you’re experienced and knowledgeable with flash shooting you might not always get the desired results.

If the discussion is about auto ISO in combination with TTL autoflash, Sony cameras have a pretty long history of generating some less than ideal results that way. (Maybe other brands as well, but my experience with those is limited.) I wouldn't use the term counter-intuitive, but I'd call it a less than ideal approach.

I had exactly the same problems as the OP when starting off, but now I realize I didn’t know what I was doing πŸ˜€.

Now that you know what you're doing, how do you make auto ISO with TTL autoflash produce ideal results every time? What do you do differently now?

This is a bit of a repeat of what I've already posted tbh, but the key learnings for me are:

1) Set the auto iso range wide enough so that ambient light plays a role in the exposure, understanding the camera will only go to half of the upper value. In the early days when I set this too tight and expected too much from the single flash unit I'd get inconsistent results i.e. lots of underexposed shots.

2) My bounce technique has improved to give better directional soft fill light, I think this also helps accomplish a more pleasing and consistent exposure.

3) Accept that ambient light will play a role and set your SS accordingly regarding motion.

4) Set a custom button to show "Shot Preview" to visualize ambient exposure through the EVF.

5) Use center zone exposure to ensure my subject is correctly exposed as the priority.

6) Know when to switch to manually setting iso for an additional level of control.

7) Don't be scared of using HSS when the circumstances require it, but understand it's limits in terms of flash power output degradation.

8) I have the TT350, the V860II, and the V1. Since getting the V1 I use that all the time and some people have commented that they think it gives more consistent TTL performance so could be an additional factor, but I wasn't having problems with the TT350 or V860II anyway.

Some people have reported problems when below f4 with the Sony / Godox combo, I personally haven't experienced any problems related to what F stop I'm using.

As for the original question ... One possible reason for the auto ISO algorithm to choose a lower value than the designated maximum is that the camera knows a flash will be fired during the exposure, and there will be more light than is provided by the ambient source, so the ISO won't really need to be set as high as it would without it. But a potential sticking point is that the camera can't accurately predict how much light the flash will be able to contribute until the metering flash is fired and analyzed, when the ISO has probably already been set.

The iso selected by the camera under auto iso shouldn't be based on being no more than half of the auto iso range as that auto iso range is just an arbitrary selection from the photographer based on their tolerance for things like noise and dynamic range. The camera should select the most appropriate iso within the range for the particular lighting condition. For example if I set max iso to 3200 and it uses 1600, why for the same shot should it use 3200 iso just because I change the max iso to 6400? Anyway, it is what it is and we just have to live with it, no big deal.

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sybersitizen Forum Pro • Posts: 21,074
Re: Is auto ISO fixed with fill flash?

Kev The Doc wrote:

sybersitizen wrote:

Kev The Doc wrote:

dbm61 wrote:

Auto ISO and TTL are counter-intuitive. Auto ISO will try and boost the exposure before the flash even fires. Then TTL tries to sense the needed flash to fill in the rest. And bouncing a flash loses power. So you're using the worse possible scenario for the flash ...

I’m not sure how you’ve come to the conclusion that auto iso and TTL are counter intuitive? I’d say they work together to yield the correct exposure, but until you’re experienced and knowledgeable with flash shooting you might not always get the desired results.

If the discussion is about auto ISO in combination with TTL autoflash, Sony cameras have a pretty long history of generating some less than ideal results that way. (Maybe other brands as well, but my experience with those is limited.) I wouldn't use the term counter-intuitive, but I'd call it a less than ideal approach.

I had exactly the same problems as the OP when starting off, but now I realize I didn’t know what I was doing πŸ˜€.

Now that you know what you're doing, how do you make auto ISO with TTL autoflash produce ideal results every time? What do you do differently now?

This is a bit of a repeat of what I've already posted tbh, but the key learnings for me are:

1) Set the auto iso range wide enough so that ambient light plays a role in the exposure, understanding the camera will only go to half of the upper value. In the early days when I set this too tight and expected too much from the single flash unit I'd get inconsistent results i.e. lots of underexposed shots.

2) My bounce technique has improved to give better directional soft fill light, I think this also helps accomplish a more pleasing and consistent exposure.

3) Accept that ambient light will play a role and set your SS accordingly regarding motion.

4) Set a custom button to show "Shot Preview" to visualize ambient exposure through the EVF.

5) Use center zone exposure to ensure my subject is correctly exposed as the priority.

6) Know when to switch to manually setting iso for an additional level of control.

7) Don't be scared of using HSS when the circumstances require it, but understand it's limits in terms of flash power output degradation.

8) I have the TT350, the V860II, and the V1. Since getting the V1 I use that all the time and some people have commented that they think it gives more consistent TTL performance so could be an additional factor, but I wasn't having problems with the TT350 or V860II anyway.

Some people have reported problems when below f4 with the Sony / Godox combo, I personally haven't experienced any problems related to what F stop I'm using.

Well, I'm glad you've gotten some improvement ... but I don't think any of that would help with the issues I've experienced over the years using auto ISO plus autoflash with my own Sonys. My solution has been to set ISO manually, which quickly solves the problems.

As for the original question ... One possible reason for the auto ISO algorithm to choose a lower value than the designated maximum is that the camera knows a flash will be fired during the exposure, and there will be more light than is provided by the ambient source, so the ISO won't really need to be set as high as it would without it. But a potential sticking point is that the camera can't accurately predict how much light the flash will be able to contribute until the metering flash is fired and analyzed, when the ISO has probably already been set.

The iso selected by the camera under auto iso shouldn't be based on being no more than half of the auto iso range as that auto iso range is just an arbitrary selection from the photographer based on their tolerance for things like noise and dynamic range. The camera should select the most appropriate iso within the range for the particular lighting condition. For example if I set max iso to 3200 and it uses 1600, why for the same shot should it use 3200 iso just because I change the max iso to 6400? Anyway, it is what it is and we just have to live with it, no big deal.

Should is a great word, but that last sentence says it all.

Kev The Doc Senior Member • Posts: 2,216
Re: Is auto ISO fixed with fill flash?

sybersitizen wrote:

Kev The Doc wrote:

sybersitizen wrote:

Kev The Doc wrote:

dbm61 wrote:

Auto ISO and TTL are counter-intuitive. Auto ISO will try and boost the exposure before the flash even fires. Then TTL tries to sense the needed flash to fill in the rest. And bouncing a flash loses power. So you're using the worse possible scenario for the flash ...

I’m not sure how you’ve come to the conclusion that auto iso and TTL are counter intuitive? I’d say they work together to yield the correct exposure, but until you’re experienced and knowledgeable with flash shooting you might not always get the desired results.

If the discussion is about auto ISO in combination with TTL autoflash, Sony cameras have a pretty long history of generating some less than ideal results that way. (Maybe other brands as well, but my experience with those is limited.) I wouldn't use the term counter-intuitive, but I'd call it a less than ideal approach.

I had exactly the same problems as the OP when starting off, but now I realize I didn’t know what I was doing πŸ˜€.

Now that you know what you're doing, how do you make auto ISO with TTL autoflash produce ideal results every time? What do you do differently now?

This is a bit of a repeat of what I've already posted tbh, but the key learnings for me are:

1) Set the auto iso range wide enough so that ambient light plays a role in the exposure, understanding the camera will only go to half of the upper value. In the early days when I set this too tight and expected too much from the single flash unit I'd get inconsistent results i.e. lots of underexposed shots.

2) My bounce technique has improved to give better directional soft fill light, I think this also helps accomplish a more pleasing and consistent exposure.

3) Accept that ambient light will play a role and set your SS accordingly regarding motion.

4) Set a custom button to show "Shot Preview" to visualize ambient exposure through the EVF.

5) Use center zone exposure to ensure my subject is correctly exposed as the priority.

6) Know when to switch to manually setting iso for an additional level of control.

7) Don't be scared of using HSS when the circumstances require it, but understand it's limits in terms of flash power output degradation.

8) I have the TT350, the V860II, and the V1. Since getting the V1 I use that all the time and some people have commented that they think it gives more consistent TTL performance so could be an additional factor, but I wasn't having problems with the TT350 or V860II anyway.

Some people have reported problems when below f4 with the Sony / Godox combo, I personally haven't experienced any problems related to what F stop I'm using.

Well, I'm glad you've gotten some improvement ... but I don't think any of that would help with the issues I've experienced over the years using auto ISO plus autoflash with my own Sonys. My solution has been to set ISO manually, which quickly solves the problems.

You say you don't "think" any of that would help, have you tried or have you simply given up beating the dead horse? It's certainly a quandary and you're certainly not the only one to report this, it's a common complaint. It's a pity because auto iso brings some benefits if you can get it to work which is why I'm trying to help here with my own experiences on this. Maybe it's even specific to certain camera model and flash model combo's with some firmware's being better than others, so maybe it's just pure luck it works for me in my setting?Β 

As for the original question ... One possible reason for the auto ISO algorithm to choose a lower value than the designated maximum is that the camera knows a flash will be fired during the exposure, and there will be more light than is provided by the ambient source, so the ISO won't really need to be set as high as it would without it. But a potential sticking point is that the camera can't accurately predict how much light the flash will be able to contribute until the metering flash is fired and analyzed, when the ISO has probably already been set.

The iso selected by the camera under auto iso shouldn't be based on being no more than half of the auto iso range as that auto iso range is just an arbitrary selection from the photographer based on their tolerance for things like noise and dynamic range. The camera should select the most appropriate iso within the range for the particular lighting condition. For example if I set max iso to 3200 and it uses 1600, why for the same shot should it use 3200 iso just because I change the max iso to 6400? Anyway, it is what it is and we just have to live with it, no big deal.

Should is a great word, but that last sentence says it all.

 Kev The Doc's gear list:Kev The Doc's gear list
DxO One Sony a7R II Sony a6500 Zeiss Loxia 21mm F2.8 Sony 1.4x Teleconverter (2016) +4 more
sybersitizen Forum Pro • Posts: 21,074
Re: Is auto ISO fixed with fill flash?

Kev The Doc wrote:

sybersitizen wrote:

Kev The Doc wrote:

sybersitizen wrote:

Kev The Doc wrote:

dbm61 wrote:

Auto ISO and TTL are counter-intuitive. Auto ISO will try and boost the exposure before the flash even fires. Then TTL tries to sense the needed flash to fill in the rest. And bouncing a flash loses power. So you're using the worse possible scenario for the flash ...

I’m not sure how you’ve come to the conclusion that auto iso and TTL are counter intuitive? I’d say they work together to yield the correct exposure, but until you’re experienced and knowledgeable with flash shooting you might not always get the desired results.

If the discussion is about auto ISO in combination with TTL autoflash, Sony cameras have a pretty long history of generating some less than ideal results that way. (Maybe other brands as well, but my experience with those is limited.) I wouldn't use the term counter-intuitive, but I'd call it a less than ideal approach.

I had exactly the same problems as the OP when starting off, but now I realize I didn’t know what I was doing πŸ˜€.

Now that you know what you're doing, how do you make auto ISO with TTL autoflash produce ideal results every time? What do you do differently now?

This is a bit of a repeat of what I've already posted tbh, but the key learnings for me are:

1) Set the auto iso range wide enough so that ambient light plays a role in the exposure, understanding the camera will only go to half of the upper value. In the early days when I set this too tight and expected too much from the single flash unit I'd get inconsistent results i.e. lots of underexposed shots.

2) My bounce technique has improved to give better directional soft fill light, I think this also helps accomplish a more pleasing and consistent exposure.

3) Accept that ambient light will play a role and set your SS accordingly regarding motion.

4) Set a custom button to show "Shot Preview" to visualize ambient exposure through the EVF.

5) Use center zone exposure to ensure my subject is correctly exposed as the priority.

6) Know when to switch to manually setting iso for an additional level of control.

7) Don't be scared of using HSS when the circumstances require it, but understand it's limits in terms of flash power output degradation.

8) I have the TT350, the V860II, and the V1. Since getting the V1 I use that all the time and some people have commented that they think it gives more consistent TTL performance so could be an additional factor, but I wasn't having problems with the TT350 or V860II anyway.

Some people have reported problems when below f4 with the Sony / Godox combo, I personally haven't experienced any problems related to what F stop I'm using.

Well, I'm glad you've gotten some improvement ... but I don't think any of that would help with the issues I've experienced over the years using auto ISO plus autoflash with my own Sonys. My solution has been to set ISO manually, which quickly solves the problems.

You say you don't "think" any of that would help, have you tried or have you simply given up beating the dead horse?

It was a vernacular expression to convey the idea that yes, I've done a great deal of personal experimentation with this issue, and have found setting ISO manually to be the solution I like. Also, some of the above is not relevant for me personally because it refers to gear I'll never own and doesn't cover some of the situations I've worked with. I don't doubt that other people might find it extremely helpful, though.

It's certainly a quandary and you're certainly not the only one to report this, it's a common complaint. It's a pity because auto iso brings some benefits if you can get it to work which is why I'm trying to help here with my own experiences on this. Maybe it's even specific to certain camera model and flash model combo's with some firmware's being better than others, so maybe it's just pure luck it works for me in my setting?

Neither of us can know if all Sony cameras suffer the same issues, or to the same degree. This is intended to be a casual discussion of different approaches. You have your experience with photography in general, and with some Sony cameras in particular, and I have mine. Do things your way, I'll do them mine, and others can do as they choose. Easy.

As for the original question ... One possible reason for the auto ISO algorithm to choose a lower value than the designated maximum is that the camera knows a flash will be fired during the exposure, and there will be more light than is provided by the ambient source, so the ISO won't really need to be set as high as it would without it. But a potential sticking point is that the camera can't accurately predict how much light the flash will be able to contribute until the metering flash is fired and analyzed, when the ISO has probably already been set.

The iso selected by the camera under auto iso shouldn't be based on being no more than half of the auto iso range as that auto iso range is just an arbitrary selection from the photographer based on their tolerance for things like noise and dynamic range. The camera should select the most appropriate iso within the range for the particular lighting condition. For example if I set max iso to 3200 and it uses 1600, why for the same shot should it use 3200 iso just because I change the max iso to 6400? Anyway, it is what it is and we just have to live with it, no big deal.

Should is a great word, but that last sentence says it all.

Jigal
OP Jigal Contributing Member • Posts: 588
Re: Is auto ISO fixed with fill flash?

Hi Kev The Doc,

Kev The Doc wrote:

If you’re setting exposure manually and still getting underexposed shots then most likely your flash is putting out it’s max output but it’s still not enough (the flash tells you this on the screen for a few seconds right after the shot),

I tried a few shots but nothing changed on the display of the TT685.

so adjusting the flash comp won’t necessarily fix the problem, you may need to increase the ambient exposure on the camera.

It probably depends on the type of subject if that is a solution. Moving (sometimes pretty fast moving) black and white pups really ask for faster shutter speeds or the situation that practically no ambient light is used and the short flash freezes the action.

For the lighting problems I experience I guess it's just a matter of "You're gonna need a bigger flash". Either that or the camera or flash is malfunctioning. From my memory the exposures were better some weeks ago; I'll have a look at earlier photos to see if the histograms support that memory.

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Regards,
Jigal.

 Jigal's gear list:Jigal's gear list
Sony a6400 Sony E 18-200mm F3.5-6.3 OSS +1 more
Kev The Doc Senior Member • Posts: 2,216
Re: Is auto ISO fixed with fill flash?

Jigal wrote:

Hi Kev The Doc,

Kev The Doc wrote:

If you’re setting exposure manually and still getting underexposed shots then most likely your flash is putting out it’s max output but it’s still not enough (the flash tells you this on the screen for a few seconds right after the shot),

I tried a few shots but nothing changed on the display of the TT685.

If you don’t see a message on the flash screen (I think the message is β€œHi”) then your flash hasn’t maxed out yet, so try manually setting the power to full.

so adjusting the flash comp won’t necessarily fix the problem, you may need to increase the ambient exposure on the camera.

It probably depends on the type of subject if that is a solution. Moving (sometimes pretty fast moving) black and white pups really ask for faster shutter speeds or the situation that practically no ambient light is used and the short flash freezes the action.

For the lighting problems I experience I guess it's just a matter of "You're gonna need a bigger flash". Either that or the camera or flash is malfunctioning. From my memory the exposures were better some weeks ago; I'll have a look at earlier photos to see if the histograms support that memory.

For more power the Godox AD200 is a very versatile little beast, almost three times the power of on camera flashes like the 685 but still quite portable (i have three πŸ˜€). You can use it off camera in combo with your 685!

 Kev The Doc's gear list:Kev The Doc's gear list
DxO One Sony a7R II Sony a6500 Zeiss Loxia 21mm F2.8 Sony 1.4x Teleconverter (2016) +4 more
Jigal
OP Jigal Contributing Member • Posts: 588
Re: Is auto ISO fixed with fill flash?

Kev The Doc wrote:

For more power the Godox AD200 is a very versatile little beast, almost three times the power of on camera flashes like the 685 but still quite portable (i have three πŸ˜€). You can use it off camera in combo with your 685!

Looks like a nice flash. If I read it correctly it has a rechargeable battery. As I use it exclusively at home I'll search for a nice deal on a studio flash that uses main power.

For the time being I still have three Metz flashes (1 48 AF-1 (Oly/Pan) and 2 58 AF-2 (Sony)) which do a wonderful job in Servo mode.

Thanks for all the help so far.

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Regards,
Jigal.

 Jigal's gear list:Jigal's gear list
Sony a6400 Sony E 18-200mm F3.5-6.3 OSS +1 more
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