Camera-chosen Minimum Shutter Speed with Av Mode?

[lunaticitizen]

I usually use Av mode.

A long time ago I noticed when I use an on-camera flash for taking portraits, the minimum shutter speed my camera (Sony FF) would select is 1/60s even if I use my 20mm lens.

I just got a 14mm f/1.8 lens. I noticed that the minimum shutter speed is 1/40s instead of 1/15s.

Why do you think the camera would choose 1/40s?

I assume for the on-camera flash scenario, the algorithm chooses 1/60s to compensate for subject motion.

[Manfred M]

There is no understanding why camera makers make the decisions that they do.

In principle, camera makers will set the maximum shutter speed to the camera's sync speed. It looks like Canon is going a step further and setting it to a speed where one can expect sharp, handheld images.

The 1/focal length minimum shutter speed recommendation is rather out of date and applied to a standard (A4 / 8" x 10" print) held about 30 cm / 1 ft from the eyes for shooting with a film camera. It took a certain amount of knowledge and skill to do this. With people holding their cameras away from the body and using the screen on the back to shoot, rather than a good, tight shooting stance with arms against the chest and viewfinder pressed against the face.

[pschlute]

I assume for the on-camera flash scenario, the algorithm chooses 1/60s to compensate for subject motion.

With on-camera flash providing the main lighting, subject motion will not be an issue. Flash operates in the speed of 1,000 seconds plus so any subject movement will not affect the image irrespective of shutter speed.

Of course your camera has no idea if you are using flash to provide all the light, or as a daylight fill, so it guesses according to how it has been programmed.

Most users of flash in portrait situations use Manual camera exposure together with manual flash output.... so they are setting the parameters, not the camera.

[DanK]

My usual starting point for candid portraits is manual, 1/60 or a little faster, f4.5, flash set to E-TTL. The reason I sometimes go faster is that if the ambient light is bright enough, even indoors, 1/60 with E-TTL can produce blurred eyelids. Not an issue if flash overpowers the ambient light.


Sent from my iPhone using Tapatalk

[revi]

1/60 is flash sync speed. Nothing to do with freezing motion (the flash should take care of that), it's the fastest shutter speed that uncovers the whole sensor at once.

[William W]

Precise answers are impossible without details of the: Camera, Flash, Lenses, and likely also the: ISO setting, Metering Mode and Ambient Light EV of the Scene.

However,

I usually use Av mode.
A long time ago I noticed when I use an on-camera flash for taking portraits, the minimum shutter speed my camera (Sony FF) would select is 1/60s even if I use my 20mm lens.
I just got a 14mm f/1.8 lens. I noticed that the minimum shutter speed is 1/40s instead of 1/15s.
Why do you think the camera would choose 1/40s?

Don't understand why 1/15th sec is now mentioned? - however, there are a few reasons why in Av Mode a Sony Camera might select 1/40th sec: all of the reasons would be predicated on the Ambient Light Value of the Scene and the Metering Mode used, and - IF the Camera recognizes an Active Flash on the Camera and IF that Flash is a dedicated Sony Flash, or not.

***

I assume for the on-camera flash scenario, the algorithm chooses 1/60s to compensate for subject motion.

Maybe, maybe not: again mainly depending upon IF the camera recognizes an active Flash on the hotshoe - AND - the value of the Ambient Light.

*

(My best guess as to what is happening) - it is likely the camera does recognize an active Flash - AND - the Flash is not a Sony dedicated Flash so therefore the camera defaults to a safe slower than Maximum Flash Sync Speed of the Camera, which on many Sony Digital Cameras, is faster than 1/60th sec.

***

In any case, (usually) one main reason for using Flash for Portraiture, is to arrest Subject Motion: i.e. in the majority of situations, when Flash is used correctly, as the Main or Key Light, it is the Flash which freezes the Subject Motion, not the Shutter Speed.

WW

[lunaticitizen]

With on-camera flash providing the main lighting, subject motion will not be an issue. Flash operates in the speed of 1,000 seconds plus so any subject movement will not affect the image irrespective of shutter speed.

Of course your camera has no idea if you are using flash to provide all the light, or as a daylight fill, so it guesses according to how it has been programmed.

Most users of flash in portrait situations use Manual camera exposure together with manual flash output.... so they are setting the parameters, not the camera.

You're right about flash' operation. I forgot about that.

However, what I want to understand is why the camera chooses 1/60s even when the lens is a 20mm.

Yes, only the manufacturer knows exactly why, but educated guesses are also welcome.

[lunaticitizen]

1/60 is flash sync speed. Nothing to do with freezing motion (the flash should take care of that), it's the fastest shutter speed that uncovers the whole sensor at once.

My camera's flash sync speed is 1/200s with its electronic shutter. Shooting at shutter speed slower than that should be fine, though. Am I confused?

[lunaticitizen]

Precise answers are impossible without details of the: Camera, Flash, Lenses, and likely also the: ISO setting, Metering Mode and Ambient Light EV of the Scene.

However,


Don't understand why 1/15th sec is now mentioned? - however, there are a few reasons why in Av Mode a Sony Camera might select 1/40th sec: all of the reasons would be predicated on the Ambient Light Value of the Scene and the Metering Mode used, and - IF the Camera recognizes an Active Flash on the Camera and IF that Flash is a dedicated Sony Flash, or not.

***



Maybe, maybe not: again mainly depending upon IF the camera recognizes an active Flash on the hotshoe - AND - the value of the Ambient Light.

*

(My best guess as to what is happening) - it is likely the camera does recognize an active Flash - AND - the Flash is not a Sony dedicated Flash so therefore the camera defaults to a safe slower than Maximum Flash Sync Speed of the Camera, which on many Sony Digital Cameras, is faster than 1/60th sec.

***

In any case, (usually) one main reason for using Flash for Portraiture, is to arrest Subject Motion: i.e. in the majority of situations, when Flash is used correctly, as the Main or Key Light, it is the Flash which freezes the Subject Motion, not the Shutter Speed.

WW

OK my equipment:
- Camera: Sony FF camera with 1/200s flash sync speed with the electronic shutter. I only use this type of shutter. I've confirmed that my flash works as expected up to this shutter speed (1/200s) without using HSS.
- Lenses: Let's say for my questions I use a 20mm f/1.8 lens and a 14mm f/1.8 lens.
- Flash: Nissin i60A
- ISO: mostly Auto ISO
- Metering Mode: always multi-pattern which according to the manual: "Measures light on each area after dividing the total area into multiple areas and determines the proper exposure of the entire screen (Multi-pattern metering)."
- Ambient Light EV: I don't know But after hitting the minimum shutter speed chosen by the camera it also raises the ISO (i.e. not ISO 100 anymore)

There were 2 scenarios for my original question.

Scenario 1
20mm f/1.8 lens with the on-camera flash.

My expectation was that the camera should lower the shutter speed until 1/20s (i.e. 1 / focal length) before raising the ISO, which is what the camera does without any on-camera flash.

However, for this scenario the camera chooses 1/60s as the shutter speed before raising the ISO.


Scenario 2
14mm f/1.8 lens (no flash)

My expectation was that the camera should lower the shutter speed until 1/15s before raising the ISO.

However, for this scenario the camera chooses 1/40s before raising the ISO.


The question was, what do you think the algorithm Sony uses to choose the minimum shutter speed?


I only have this flash so I cannot do a comparison with Sony's own flashes..

[lunaticitizen]

There is no understanding why camera makers make the decisions that they do.

In principle, camera makers will set the maximum shutter speed to the camera's sync speed. It looks like Canon is going a step further and setting it to a speed where one can expect sharp, handheld images.

The 1/focal length minimum shutter speed recommendation is rather out of date and applied to a standard (A4 / 8" x 10" print) held about 30 cm / 1 ft from the eyes for shooting with a film camera. It took a certain amount of knowledge and skill to do this. With people holding their cameras away from the body and using the screen on the back to shoot, rather than a good, tight shooting stance with arms against the chest and viewfinder pressed against the face.

I remember with my Fuji X100F there were 2 choices for minimum shutter speed with Av mode: 1 / focal length and 1 / 4*focal length. I usually chose the former

[lunaticitizen]

My usual starting point for candid portraits is manual, 1/60 or a little faster, f4.5, flash set to E-TTL. The reason I sometimes go faster is that if the ambient light is bright enough, even indoors, 1/60 with E-TTL can produce blurred eyelids. Not an issue if flash overpowers the ambient light.


Sent from my iPhone using Tapatalk

What is this 1/60s and why did Sony also decide to use this particular value when using flash. Quick Googling didn't help me.

[William W]

OK my equipment: . . .
- Flash: Nissin i60A
- ISO: mostly Auto ISO
- Ambient Light EV: I don't know But after hitting the minimum shutter speed chosen by the camera it also raises the ISO (i.e. not ISO 100 anymore)

OK Thanks.

***

Scenario 1
20mm f/1.8 lens with the on-camera flash.

My expectation was that the camera should lower the shutter speed until 1/20s (i.e. 1 / focal length) before raising the ISO, which is what the camera does without any on-camera flash.

However, for this scenario the camera chooses 1/60s as the shutter speed before raising the ISO.

OK, thanks.
My educated guess: as I previously mentioned - the Camera detects the active flash, assumes the Flash will be the Key Light, knows that it is not a Sony dedicated Flash and defaults to a slower than the Maximum Sync Speed. The User Manual of many cameras mentions Max Flash Sync and then makes a note that with a third-party flash, the Max Sync Speed will be slower. Because you have the camera in an Automatic Mode whereby the Camera is selecting the Shutter Speed, the Camera will select a 'safe' shutter speed so that it is most likely to sync with the Flash without any black bars in the image. If the Camera's Max Flash Sync is 1/200, then I consider the Camera selecting 1/60s to be 'safe' for an unknown Flash.

The fact that the Ambient Light is unknown could effect a slightly different answer from me, in some Shooting Scenarios when making Portraits, but not many: suffice to say the above answer covers most of it.

???What really amazes me though is the fact that your Camera's algorithm when in Av Mode and Auto ISO will allow the Tv to drop to 1/20s: I think that is a really 'unsafe' Av / AUTO ISO algorithm.???

Or maybe I misunderstand the the meaning of your text? Were you stating that the Camera does drop the Tv to 1/20s when you have the 20mm lens on?

***

Scenario 2
14mm f/1.8 lens (no flash)

My expectation was that the camera should lower the shutter speed until 1/15s before raising the ISO.
However, for this scenario the camera chooses 1/40s before raising the ISO.
The question was, what do you think the algorithm Sony uses to choose the minimum shutter speed?
I only have this flash so I cannot do a comparison with Sony's own flashes..

OK, thanks.
My educated guess: The Camera again is selecting a 'safe' Shutter speed. The 1/Focal Length Rule is merely a guide based primarily upon the Field of View of the lens and guessometry of the 'typical' shooting distance to the Primary Subject. I think that many modern cameras, in Av Mode and Auto ISO would bottom out the Tv at around 1/60s ~ 1/50s, you indicate you Sony bottoms at 1/40s. I think that's an 'unsafe' algorithm: there are quite a few Shooting Scenarios where 1/40s would capture Motion Blur due to Camera Shake when using a 14mm lens.

***

The bottom line is - when one selects any Automatic Mode one is relying on the Camera to select something: my advice (and teaching practice) has always been that the Photographer should monitor closely the Exposure Element which is being selected by the Camera.

Note that in both scenarios above there are two Exposure Elements being selected by the Camera, not one.

Relevant: In all of the Wedding Photography Master Classes I taught during the 90's, 2000's and 2010's - one of the most prevalent single issue problems was the misunderstanding of the functionality and the subsequent error rate of images showing Motion Blur; this occurred when Photographers were using Av Mode, without Flash, and then plonked the Flash on - and did not monitor closely the Tv that the Camera was selecting.

WW

[lunaticitizen]

Bill, thank you for the detailed comment.

Yes, the camera indeed chooses 1/20s before raising the ISO for this particular lens (20mm f/1.8).

I checked with another lens, 24-105mm f/4.0 at 24mm. The camera chooses 1/30s before raising the ISO.
I think with newer cameras claiming 8-stop stabilization, they might even choose lower shutter speed?

I wonder if with my camera I can program the minimum shutter speed to 1 / (2 * focal length) etc.. Honestly I'm more a snapshooter (that's why I use Av mode) I don't like fiddling with lots of parameters (ISO, SS) during shooting. Let me check that manual again.

[William W]

Bill, thank you for the detailed comment.

You're welcome.

Yes, the camera indeed chooses 1/20s before raising the ISO for this particular lens (20mm f/1.8).

Thanks for clearing my understanding on that point.

I checked with another lens, 24-105mm f/4.0 at 24mm. The camera chooses 1/30s before raising the ISO.
I think with newer cameras claiming 8-stop stabilization, they might even choose lower shutter speed?

Unsolicited comment: The complete reason why I think an Automated Algorithm in Av Mode is 'unsafe' if we do not monitor the camera allowing such very low Tv, (based upon FL of the lens), is two fold:

The first I mentioned above, Image Blur due to Camera Shake, as you imply (and I agree) good quality Image Stabilization can (will in most situations) counter that problem: however, IS does not counter Subject Movement.

Let's consider two common scenarios; one a Candid (aka 'snapshooter') Portrait Scenario and the other a Candid (aka 'snapshooter') Travel Landscape Scene -

Lets say we have 24~105 loaded for both shots.

The first is a group of kids playing around swings and slippery-dips and the like at a park, its a cloudy/overcast day - two kids run a bit closer to us and we zoom out to 24mm, capture the two kids laughing in an "Environmental Portrait" with swings and other kids in the background . . . the two kids were running transverse to the camera axis - expect lots of Subject Motion blur if the Camera decided to drop the Tv at or below 1/250s

Similarly we have a fantastic Landscape Scene - and it is a bit cloudy and windy - let's say the Camera decides to drop the Tv at or below 1/250s - expect we might get blurry and unsharp tree branches and leaves.

***

I wonder if with my camera I can program the minimum shutter speed to 1 / (2 * focal length) etc.. Honestly I'm more a snapshooter (that's why I use Av mode) I don't like fiddling with lots of parameters (ISO, SS) during shooting. Let me check that manual again.

Understood re title "snapshooter". And for clarity, my commentary neither reflects nor comments on that in any way: merely just advising to keep an eye on what exactly the Camera is choosing for you - that's my message.

WW