How to have auto-exposure take advantage of SR?

MarkJerling · 11-24-2019, 04:09 PM

Originally posted by photoptimist

The current P mode and Av mode refuse to pick a shutter speed slower than 1/F or change the aperture even if the lighting conditions require ISO 204800.

That's not correct, sorry. The current P mode and AV mode is certainly happy to pick a slower shutter speed than 1/F on my K-1II. My experience is that by how much varies depending on the lens mounted, and not because the lens "tells" the camera anything by means of it's electronic contacts, but simply because of different lenses varying light gathering abilities at different focal lengths.

MarkJerling · 11-24-2019, 04:15 PM

Originally posted by photoptimist

That's strange because I can reproduce it easily.

The only issue is that the behavior does vary with the Program line mode choice:
Auto: speed limit is about 0.25/F
Normal: speed limit is about 1/F
Speed: speed limit is 1/1000 (not a function of F)
Deep DoF: speed limit is about 0.25/F
Shallow DoF: speed limit is about 0.25/F
MTF: speed changes with F but more slowly and depends on the lens: Sigma12-24 DG (1/30@12mm -> 1/45@24mm); Pentax FA28-80 (1/90@28mm -> 1/125@80mm); Pentax FA100-300 (1/125@100mm -> 1/350@300mm).

Only the "Speed" mode ignore focal length.

P.S. It is true that the SR setting does not change the shutter speed -- that's what we want to change.

Evidently you have contradicted your earlier post (copied with my previous post) in this reply. There you said 1/F, now it's "about" 0.25/F etc.

What I believe is happening is that we're reaching different conclusions from the same observations. It's clear from your post that, in most instances, the camera will happily go to well less than 1/F, which contradicts the OP's original's contention. And further, the fact that you're saying "about". That proves the point that there are other factors at play here. What I believe the camera is doing, is mainly using it's light meter to make it's decisions - simple as that, as evidenced by the same behaviour with lenses without any electronic componentry. Any program input from lenses that have a seventh contact is either minimal or non-existent.

biz-engineer · 11-25-2019, 02:16 AM

Originally posted by MarkJerling

The current P mode and AV mode is certainly happy to pick a slower shutter speed than 1/F on my K-1II.

The reason why shutter speed isn't exactly 1/F is because the exposure setting steps aren't smaller than 0.3ev and the lens F readount is not continuous either.

So you'll have plus or minus 30% shutter speed around the step values of the lens FL readout, that's why you feel like shutter speed isn't consistent with lens FL, but in any case the shutter speed changes when you change the lens focal lens with everything else remaining constant.

MarkJerling · 11-25-2019, 03:43 AM

Originally posted by biz-engineer

The reason why shutter speed isn't exactly 1/F is because the exposure setting steps aren't smaller than 0.3ev and the lens F readount is not continuous either.

So you'll have plus or minus 30% shutter speed around the step values of the lens FL readout, that's why you feel like shutter speed isn't consistent with lens FL, but in any case the shutter speed changes when you change the lens focal lens with everything else remaining constant.

Yeah, nah, as we say in New Zealand.

FA 28-80: P mode (Auto), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5"
FA 28-80: P mode (Normal), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5"
FA 28-80: P mode (Action), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5"
FA 28-80: P mode (MTF), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5"
FA 28-80: P mode (DOF Deep), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5"
FA 28-80: P mode (DOF Shallow), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5"

FA 28-80: P mode (Auto), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60
FA 28-80: P mode (Normal), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60
FA 28-80: P mode (Action), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60
FA 28-80: P mode (MTF), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60
FA 28-80: P mode (DOF Deep), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60
FA 28-80: P mode (DOF Shallow), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60

Results identical with Sigma zooms, Pentax auto primes, manual primes and Pentax manual zooms. Tell me what I'm missing please.

Last edited by MarkJerling; 11-25-2019 at 03:56 AM.

biz-engineer · 11-25-2019, 03:59 AM

Originally posted by MarkJerling

FA 28-80: P mode (Auto), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5"

That's because you reached the max of the ISO range, so the camera can't set the shutter speed proportional to the lens focal length.

MarkJerling · 11-25-2019, 04:05 AM

Originally posted by biz-engineer

That's because you reached the max of the ISO range, so the camera can't set the shutter speed proportional to the lens focal length.

Ok, so what would you like me to set as the maximum ISO value?

And, why do I get the same values, no matter whether I'm mounting a 28-80, 35-70, 50mm, 28mm, 70-300mm or 24mm lens?

biz-engineer · 11-25-2019, 04:18 AM

Originally posted by MarkJerling

Ok, so what would you like me to set as the maximum ISO value?

Doesn't matter, because that method to fix the max ISO doesn't reach the goal of including SR capability for having slower shutter speed in general.
I use the min and max ISO limits with TAv (auto-ISO), so when the max ISO is reach the shutter speed automatically drops to a lower value. But as long as the ISO value doesn't hit the max value I set, the shutter-speed + Aperture + ISO value will still be set without taking advantage of SR, the ISO value won't be lower than what it could be when SR is enabled. IMO, a number of poster in this thread understood the concept, while others didn't get it yet.

MarkJerling · 11-25-2019, 04:27 AM

Originally posted by biz-engineer

Doesn't matter, because that method to fix the max ISO doesn't reach the goal of including SR capability for having slower shutter speed in general.
I use the min and max ISO limits with TAv (auto-ISO), so when the max ISO is reach the shutter speed automatically drops to a lower value. But as long as the ISO value doesn't hit the max value I set, the shutter-speed + Aperture + ISO value will still be set without taking advantage of SR, the ISO value won't be lower than what it could be when SR is enabled. IMO, a number of poster in this thread understood the concept, while others didn't get it yet.

Sorry, you're not making sense. I'm not seeing the focal length relationship with any lens. As noted, I can't reproduce your results.

biz-engineer · 11-25-2019, 05:04 AM

Originally posted by MarkJerling

Sorry, you're not making sense. I'm not seeing the focal length relationship with any lens. As noted, I can't reproduce your results.

It's possible that your camera or lens is defective. Have you considered sending it for repair?

MarkJerling · 11-25-2019, 05:11 AM

Originally posted by biz-engineer

It's possible that your camera or lens is defective. Have you considered sending it for repair?

The K-1II functions perfectly, in every mode, with any lens. There is no fault with the camera or any lens. I cannot, of course rule out operator error, but, tests have been performed with a variety of primes and zooms as stated. As noted prior, I believe you're seeing a relationship of focal length to shutter speed that does not exist.

Alternatively, if you'd like to post your (full) settings, or if you can show what I'm doing wrong with my tests, I can try again.

**Lowell Goudge** · 11-25-2019, 05:50 AM

Originally posted by MarkJerling

The K-1II functions perfectly, in every mode, with any lens. There is no fault with the camera or any lens. I cannot, of course rule out operator error, but, tests have been performed with a variety of primes and zooms as stated. As noted prior, I believe you're seeing a relationship of focal length to shutter speed that does not exist.

Alternatively, if you'd like to post your (full) settings, or if you can show what I'm doing wrong with my tests, I can try again.

Although I disagree with the idea of having the camera provide a function for exposure considering shake reduction, I have to agree here with biz-engineer.

The camera in some of its modes, has program lines that follow the “golden rule” of keeping shutter speed above 1/fl.

This does not mean there is anything wrong with the camera, it is just the way it is.

For example, set it inactive mode with auto isu. Go into a low light situation and it will at some point, Start changing iso when the light falls below enough to satisfy 1/fl plus aperture.

The programmers assumed this relationship. That is all.

**fs999** · 11-25-2019, 06:22 AM

It would be better to have an AUTO ISO mode "with SR" to go below the 1/FL but you can do it already manually in Av mode, choosing the speed you want...
If you set the e-dial layout front dial = Aperture, back dial = Speed or front dial = Speed and back dial = Aperture...

Penview52 · 11-25-2019, 06:37 AM

biz_engineer is occupied with a notion hard to believe, can you post a sample to probe the worth what you are saying?

photoptimist · 11-25-2019, 08:09 AM

Originally posted by MarkJerling

Yeah, nah, as we say in New Zealand.

FA 28-80: P mode (Auto), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5"
FA 28-80: P mode (Normal), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5"
FA 28-80: P mode (Action), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5"
FA 28-80: P mode (MTF), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5"
FA 28-80: P mode (DOF Deep), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5"
FA 28-80: P mode (DOF Shallow), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5"

FA 28-80: P mode (Auto), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60
FA 28-80: P mode (Normal), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60
FA 28-80: P mode (Action), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60
FA 28-80: P mode (MTF), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60
FA 28-80: P mode (DOF Deep), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60
FA 28-80: P mode (DOF Shallow), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60

Results identical with Sigma zooms, Pentax auto primes, manual primes and Pentax manual zooms. Tell me what I'm missing please.

Hmmm..... I think we are talking about two differ definitions of "slowest it will go." Your's looks like "the slowest it will ever go" and ours is the "slowest it will go before increasing the ISO above the baseline."

If you take the camera from full sun into progressively dimmer scenes, the AE system first picks slower and slower shutter speeds whilst keeping ISO at the baseline value (e.g., 100 or 200 if you have highlight protection). At some "speed limit" shutter speed, the AE system switches to holding shutter speed constant and raising ISO until ISO hits its max value.

Thus a series of AE settings in progressively dimmer scenes might look like this:

t=1/500, ISO=100
t=1/250, ISO=100
t=1/125, ISO=100
t=1/60, ISO=100 <-"speed limit" where the camera switches from slower shutter to higher ISO
t=1/60, ISO=200 -- speed stops changing, ISO increases
t=1/60, ISO=400
t=1/60, ISO=800
t=1/60, ISO=1600
t=1/60, ISO=3200 <-Max ISO limit where camera switches back to slower shutter
t=1/30, ISO=3200 -- ISO stops changing, shutter time increases
t=1/15, ISO= 3200
t=1/8, ISO= 3200
t=1/4, ISO= 3200
t=1/2, ISO=3200
t=1, ISO=3200
BLINKING t=1, ISO=3200 -- the AE system has reached its sensitivity limit

In my K-1 the "speed limit" is a function of F and the chosen program mode.

**Lowell Goudge** · 11-25-2019, 11:47 AM - **2 Likes**

Originally posted by fs999

It would be better to have an AUTO ISO mode "with SR" to go below the 1/FL but you can do it already manually in Av mode, choosing the speed you want...
If you set the e-dial layout front dial = Aperture, back dial = Speed or front dial = Speed and back dial = Aperture...

You can actually do it by setting Tav mode also, but the OP wants it all automatic with out thinking. Hmmmmm... let me think about this a minute

Ok I’ve thought about it, the problem with auto modes is they stop you from thinking, this is usually where mistakes happen

11-24-2019, 04:15 PM	#92
MarkJerling Moderator Site Supporter Join Date: May 2012 Location: Wairarapa, New Zealand Photos: Gallery \| Albums Posts: 20,406	Originally posted by photoptimist That's strange because I can reproduce it easily. The only issue is that the behavior does vary with the Program line mode choice: Auto: speed limit is about 0.25/F Normal: speed limit is about 1/F Speed: speed limit is 1/1000 (not a function of F) Deep DoF: speed limit is about 0.25/F Shallow DoF: speed limit is about 0.25/F MTF: speed changes with F but more slowly and depends on the lens: Sigma12-24 DG (1/30@12mm -> 1/45@24mm); Pentax FA28-80 (1/90@28mm -> 1/125@80mm); Pentax FA100-300 (1/125@100mm -> 1/350@300mm). Only the "Speed" mode ignore focal length. P.S. It is true that the SR setting does not change the shutter speed -- that's what we want to change. Evidently you have contradicted your earlier post (copied with my previous post) in this reply. There you said 1/F, now it's "about" 0.25/F etc. What I believe is happening is that we're reaching different conclusions from the same observations. It's clear from your post that, in most instances, the camera will happily go to well less than 1/F, which contradicts the OP's original's contention. And further, the fact that you're saying "about". That proves the point that there are other factors at play here. What I believe the camera is doing, is mainly using it's light meter to make it's decisions - simple as that, as evidenced by the same behaviour with lenses without any electronic componentry. Any program input from lenses that have a seventh contact is either minimal or non-existent. Last edited by MarkJerling; 11-24-2019 at 07:48 PM.

11-25-2019, 04:05 AM	#96
MarkJerling Moderator Site Supporter Join Date: May 2012 Location: Wairarapa, New Zealand Photos: Gallery \| Albums Posts: 20,406	Originally posted by biz-engineer That's because you reached the max of the ISO range, so the camera can't set the shutter speed proportional to the lens focal length. Ok, so what would you like me to set as the maximum ISO value? And, why do I get the same values, no matter whether I'm mounting a 28-80, 35-70, 50mm, 28mm, 70-300mm or 24mm lens? Last edited by MarkJerling; 11-25-2019 at 04:15 AM.

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11-24-2019, 04:09 PM	#91
MarkJerling Moderator Site Supporter Join Date: May 2012 Location: Wairarapa, New Zealand Photos: Gallery \| Albums Posts: 20,406	Originally posted by photoptimist The current P mode and Av mode refuse to pick a shutter speed slower than 1/F or change the aperture even if the lighting conditions require ISO 204800. That's not correct, sorry. The current P mode and AV mode is certainly happy to pick a slower shutter speed than 1/F on my K-1II. My experience is that by how much varies depending on the lens mounted, and not because the lens "tells" the camera anything by means of it's electronic contacts, but simply because of different lenses varying light gathering abilities at different focal lengths.

11-25-2019, 02:16 AM	#93
biz-engineer Pentaxian Join Date: Feb 2015 Photos: Gallery Posts: 12,232 Original Poster	Originally posted by MarkJerling The current P mode and AV mode is certainly happy to pick a slower shutter speed than 1/F on my K-1II. The reason why shutter speed isn't exactly 1/F is because the exposure setting steps aren't smaller than 0.3ev and the lens F readount is not continuous either. So you'll have plus or minus 30% shutter speed around the step values of the lens FL readout, that's why you feel like shutter speed isn't consistent with lens FL, but in any case the shutter speed changes when you change the lens focal lens with everything else remaining constant.

11-25-2019, 03:43 AM	#94
MarkJerling Moderator Site Supporter Join Date: May 2012 Location: Wairarapa, New Zealand Photos: Gallery \| Albums Posts: 20,406	Originally posted by biz-engineer The reason why shutter speed isn't exactly 1/F is because the exposure setting steps aren't smaller than 0.3ev and the lens F readount is not continuous either. So you'll have plus or minus 30% shutter speed around the step values of the lens FL readout, that's why you feel like shutter speed isn't consistent with lens FL, but in any case the shutter speed changes when you change the lens focal lens with everything else remaining constant. Yeah, nah, as we say in New Zealand. FA 28-80: P mode (Auto), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5" FA 28-80: P mode (Normal), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5" FA 28-80: P mode (Action), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5" FA 28-80: P mode (MTF), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5" FA 28-80: P mode (DOF Deep), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5" FA 28-80: P mode (DOF Shallow), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5" FA 28-80: P mode (Auto), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60 FA 28-80: P mode (Normal), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60 FA 28-80: P mode (Action), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60 FA 28-80: P mode (MTF), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60 FA 28-80: P mode (DOF Deep), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60 FA 28-80: P mode (DOF Shallow), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60 Results identical with Sigma zooms, Pentax auto primes, manual primes and Pentax manual zooms. Tell me what I'm missing please. Last edited by MarkJerling; 11-25-2019 at 03:56 AM.

11-25-2019, 03:59 AM	#95
biz-engineer Pentaxian Join Date: Feb 2015 Photos: Gallery Posts: 12,232 Original Poster	Originally posted by MarkJerling FA 28-80: P mode (Auto), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5" That's because you reached the max of the ISO range, so the camera can't set the shutter speed proportional to the lens focal length.

11-25-2019, 04:18 AM	#97
biz-engineer Pentaxian Join Date: Feb 2015 Photos: Gallery Posts: 12,232 Original Poster	Originally posted by MarkJerling Ok, so what would you like me to set as the maximum ISO value? Doesn't matter, because that method to fix the max ISO doesn't reach the goal of including SR capability for having slower shutter speed in general. I use the min and max ISO limits with TAv (auto-ISO), so when the max ISO is reach the shutter speed automatically drops to a lower value. But as long as the ISO value doesn't hit the max value I set, the shutter-speed + Aperture + ISO value will still be set without taking advantage of SR, the ISO value won't be lower than what it could be when SR is enabled. IMO, a number of poster in this thread understood the concept, while others didn't get it yet.

11-25-2019, 04:27 AM	#98
MarkJerling Moderator Site Supporter Join Date: May 2012 Location: Wairarapa, New Zealand Photos: Gallery \| Albums Posts: 20,406	Originally posted by biz-engineer Doesn't matter, because that method to fix the max ISO doesn't reach the goal of including SR capability for having slower shutter speed in general. I use the min and max ISO limits with TAv (auto-ISO), so when the max ISO is reach the shutter speed automatically drops to a lower value. But as long as the ISO value doesn't hit the max value I set, the shutter-speed + Aperture + ISO value will still be set without taking advantage of SR, the ISO value won't be lower than what it could be when SR is enabled. IMO, a number of poster in this thread understood the concept, while others didn't get it yet. Sorry, you're not making sense. I'm not seeing the focal length relationship with any lens. As noted, I can't reproduce your results.

11-25-2019, 05:04 AM	#99
biz-engineer Pentaxian Join Date: Feb 2015 Photos: Gallery Posts: 12,232 Original Poster	Originally posted by MarkJerling Sorry, you're not making sense. I'm not seeing the focal length relationship with any lens. As noted, I can't reproduce your results. It's possible that your camera or lens is defective. Have you considered sending it for repair?

11-25-2019, 05:11 AM	#100
MarkJerling Moderator Site Supporter Join Date: May 2012 Location: Wairarapa, New Zealand Photos: Gallery \| Albums Posts: 20,406	Originally posted by biz-engineer It's possible that your camera or lens is defective. Have you considered sending it for repair? The K-1II functions perfectly, in every mode, with any lens. There is no fault with the camera or any lens. I cannot, of course rule out operator error, but, tests have been performed with a variety of primes and zooms as stated. As noted prior, I believe you're seeing a relationship of focal length to shutter speed that does not exist. Alternatively, if you'd like to post your (full) settings, or if you can show what I'm doing wrong with my tests, I can try again.

11-25-2019, 05:50 AM	#101
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,888	Originally posted by MarkJerling The K-1II functions perfectly, in every mode, with any lens. There is no fault with the camera or any lens. I cannot, of course rule out operator error, but, tests have been performed with a variety of primes and zooms as stated. As noted prior, I believe you're seeing a relationship of focal length to shutter speed that does not exist. Alternatively, if you'd like to post your (full) settings, or if you can show what I'm doing wrong with my tests, I can try again. Although I disagree with the idea of having the camera provide a function for exposure considering shake reduction, I have to agree here with biz-engineer. The camera in some of its modes, has program lines that follow the “golden rule” of keeping shutter speed above 1/fl. This does not mean there is anything wrong with the camera, it is just the way it is. For example, set it inactive mode with auto isu. Go into a low light situation and it will at some point, Start changing iso when the light falls below enough to satisfy 1/fl plus aperture. The programmers assumed this relationship. That is all.

11-25-2019, 06:22 AM	#102
fs999 Loyal Site Supporter Join Date: Jul 2008 Location: Luxembourg Photos: Gallery Posts: 8,639	It would be better to have an AUTO ISO mode "with SR" to go below the 1/FL but you can do it already manually in Av mode, choosing the speed you want... If you set the e-dial layout front dial = Aperture, back dial = Speed or front dial = Speed and back dial = Aperture...

11-25-2019, 06:37 AM	#103
Penview52 Veteran Member Join Date: Apr 2017 Photos: Albums Posts: 327	biz_engineer is occupied with a notion hard to believe, can you post a sample to probe the worth what you are saying?

11-25-2019, 08:09 AM	#104
photoptimist Pentaxian Join Date: Jul 2016 Photos: Albums Posts: 5,125	Originally posted by MarkJerling Yeah, nah, as we say in New Zealand. FA 28-80: P mode (Auto), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5" FA 28-80: P mode (Normal), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5" FA 28-80: P mode (Action), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5" FA 28-80: P mode (MTF), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5" FA 28-80: P mode (DOF Deep), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5" FA 28-80: P mode (DOF Shallow), ISO Auto (with max set to 3200): Slowest it will go at 28mm is 0.5", at 80mm 0.5" FA 28-80: P mode (Auto), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60 FA 28-80: P mode (Normal), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60 FA 28-80: P mode (Action), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60 FA 28-80: P mode (MTF), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60 FA 28-80: P mode (DOF Deep), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60 FA 28-80: P mode (DOF Shallow), ISO Auto (with max set to 204800): Slowest it will go at 28mm is 1/60, at 80mm 1/60 Results identical with Sigma zooms, Pentax auto primes, manual primes and Pentax manual zooms. Tell me what I'm missing please. Hmmm..... I think we are talking about two differ definitions of "slowest it will go." Your's looks like "the slowest it will ever go" and ours is the "slowest it will go before increasing the ISO above the baseline." If you take the camera from full sun into progressively dimmer scenes, the AE system first picks slower and slower shutter speeds whilst keeping ISO at the baseline value (e.g., 100 or 200 if you have highlight protection). At some "speed limit" shutter speed, the AE system switches to holding shutter speed constant and raising ISO until ISO hits its max value. Thus a series of AE settings in progressively dimmer scenes might look like this: t=1/500, ISO=100 t=1/250, ISO=100 t=1/125, ISO=100 t=1/60, ISO=100 <-"speed limit" where the camera switches from slower shutter to higher ISO t=1/60, ISO=200 -- speed stops changing, ISO increases t=1/60, ISO=400 t=1/60, ISO=800 t=1/60, ISO=1600 t=1/60, ISO=3200 <-Max ISO limit where camera switches back to slower shutter t=1/30, ISO=3200 -- ISO stops changing, shutter time increases t=1/15, ISO= 3200 t=1/8, ISO= 3200 t=1/4, ISO= 3200 t=1/2, ISO=3200 t=1, ISO=3200 BLINKING t=1, ISO=3200 -- the AE system has reached its sensitivity limit In my K-1 the "speed limit" is a function of F and the chosen program mode.

11-25-2019, 11:47 AM - 2 Likes	#105
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,888	Originally posted by fs999 It would be better to have an AUTO ISO mode "with SR" to go below the 1/FL but you can do it already manually in Av mode, choosing the speed you want... If you set the e-dial layout front dial = Aperture, back dial = Speed or front dial = Speed and back dial = Aperture... You can actually do it by setting Tav mode also, but the OP wants it all automatic with out thinking. Hmmmmm... let me think about this a minute Ok I’ve thought about it, the problem with auto modes is they stop you from thinking, this is usually where mistakes happen