Pentax K10D Hyper-Program and Auto ISO

artrasa · 08-01-2021, 12:13 PM

Hi

I have a question about how the Program mode works with Auto ISO in Pentax K10D. For some reason the Auto ISO seems to only work when in Aperture-priority AE. For example, if the normal Program selects 1/125s and f/6.3 at base ISO 100, it is possible to use the rear dial to adjust the aperture to, for example f/16 for getting a very wide depth of field. In this case, both shutter speed and ISO setting are automatically adjusted to 1/50s and ISO 320.

When the shutter speed is adjusted with the front dial, Auto ISO seems to always stay at ISO 100. Let's again consider the normal Program, which selects 1/160s, f/6.3 and ISO 100. It is possible to use the front dial to adjust the shutter speed up to 1/400s. In this case the aperture is adjusted to f/4, which is the largest for the lens I'm using (SMC F35-80). However the camera does not allow selecting any faster setting than 1/400s, even though Auto ISO is enabled.

Why does Auto ISO only work when the camera is in Aperture-priority AE mode but not in Shutter-priority AE mode? Is this the expected behaviour with this camera? I have been bitten by this functionality on several occasions, when I'm in Program mode and encountering some quickly moving subjects. Getting a decent shot in such situations require some extra fumbling, first manually incrementing the ISO and then selecting a faster shutter speed. Since then I have moved to TAv mode when taking pictures of any kind of moving subjects, because the auto ISO works reliably in this mode.

Here's a pic of the camera settings after pressing the INFO button.

Imgur: The magic of the Internet

I recorded a short video that shows the behaviour of the camera. Hope it's clear enough.

You Tube

Last edited by artrasa; 08-01-2021 at 12:27 PM.

stevebrot · 08-01-2021, 01:23 PM

Hyper-Program works the same on the K10D as with later cameras and it appears you are in auto-ISO mode in the first photo.

What are your set limits for auto-ISO? From the rear LCD, it appears the upper limit is set to 1600. Edit: Dumb question...It has been seven years since I sold my K10D.

Added: Note that other than in TAv mode, auto-ISO may not "ramp" as one might expect.* This is true for all Pentax dSLRs.

Steve

* Other than respecting auto-ISO range, TAv does not use the auto-ISO functionality. In other than TAv mode, auto-ISO generally adjusts as the solution of last resort and even then may not shift. TAv is the only mode that respects the so-called exposure triangle.

pschlute · 08-01-2021, 03:10 PM

What "Program line" have you set in the camera for P ?

**UncleVanya** · 08-01-2021, 05:27 PM

Is there a way to use the green button to change things?

Fogel70 · 08-01-2021, 08:19 PM

The auto ISO in K10D is a bit limited in Hyper-P. The camera in general only increase ISO if the shutter speed goes below what is possible to handhold without risking camera shake.
Put the lens cap on and you will see that auto-ISO works in Hyper-Tv.

AfterPentax Mark II · 08-02-2021, 05:11 AM

As Fogel70 explains it, the aim of program is to get the right handheld exposure. With auto iso you can go up and down with the aperture, the iso is changed to get a reasonable handheld exposure. If you try to change the shutter speed you will notice that: a) the aperture will change; b) the shutter speed only changes within the handheld combination of aperture and shutter speed and c) program tries to preserve the lowest iso and changes the aperture to have a good combination of shutter speed and low iso. Changing the aperture influences both the settings of shutter and iso. So what you see is normal behaviour of your camera, you can not influence it by changing the program line.

Not a Number · 08-02-2021, 08:10 AM

I'm not sure what you are trying to do.

I checked on my K10D and Auto ISO works in Av and Tv mode. You just can't see the ISO in the viewfinder or top LCD unless you press the "OK" button. If you want to control the ISO set a fixed ISO and program one of the eDials in Tv or Av to ISO. Or with a fixed ISO press the "OK" button and change the ISO with the front eDial then you can set what the shutter speed or f-stop to you liking.

pschlute · 08-02-2021, 09:04 AM

Well I just dug my old K10D out of cold storage and it behaves in Hyper P (Tv shift) mode exactly as the OP described.

Change it to the dedicated Tv mode however and the ISO will increase.

Not a Number · 08-02-2021, 09:25 AM

Doesn't the Hyper-P behavior depend on the program line setting and the lens being used?

artrasa · 08-02-2021, 10:25 AM

Originally posted by pschlute:

What "Program line" have you set in the camera for P ?

At that time I had the normal program line selected.

Originally posted by UncleVanya:

Is there a way to use the green button to change things?

Yeah, I use it often to reset back to the normal program line. It can also reset exposure compensation back to ±0. Very handy indeed.

Originally posted by Fogel70:

The auto ISO in K10D is a bit limited in Hyper-P. The camera in general only increase ISO if the shutter speed goes below what is possible to handhold without risking camera shake.
Put the lens cap on and you will see that auto-ISO works in Hyper-Tv.

Originally posted by AfterPentax Mark II:

As Fogel70 explains it, the aim of program is to get the right handheld exposure. ...

Thanks for explaining the logic behind the P mode and auto ISO. I finally start to understand why it works the way it does. I misunderstood its function.

Originally posted by Not a Number:

I'm not sure what you are trying to do.

I checked on my K10D and Auto ISO works in Av and Tv mode. You just can't see the ISO in the viewfinder or top LCD unless you press the "OK" button. If you want to control the ISO set a fixed ISO and program one of the eDials in Tv or Av to ISO. Or with a fixed ISO press the "OK" button and change the ISO with the front eDial then you can set what the shutter speed or f-stop to you liking.

I was just wondering about the logic behind the auto ISO function when shooting in P mode. When stopping down in Hyper-Av mode, the auto ISO function automatically increases the ISO to keep the shutter speed in range that's possible to handhold (1/50s with a 35mm lens). This definitely makes sense to me.

But if one is in Hyper-Tv mode and attempts to increase the shutter speed, the camera doesn't automatically ramp up the ISO when the lens reaches its max. aperture. This happens even when auto ISO function is enabled. E.g. if the normal program happens to select 1/250s and f/4 (max. aperture) with auto ISO enabled, attempting to increase shutter speed with the front dial is not possible as the ISO stays at 100. This didn't make sense to me. But thanks to Fogel's and AfterPentax Mark II's explanation, it became clear to me that the the auto ISO function in this camera (probably other Pentax' cameras too?) only ramps up the ISO to get handheld shots. 1/250s is already handholdable, so it doesn't attempt to automatically ramp up the ISO.

pschlute · 08-02-2021, 11:31 AM

I guess this is why I never use P mode

AfterPentax Mark II · 08-02-2021, 12:43 PM

Originally posted by artrasa

it became clear to me that the the auto ISO function in this camera (probably other Pentax' cameras too?) only ramps up the ISO to get handheld shots. 1/250s is already handholdable, so it doesn't attempt to automatically ramp up the ISO.

It is not the auto iso that does it, but the program line normal! The program line is set to make handheld shots and that is why auto iso behaves as it does, auto iso moves within the demands of the program line chosen.

08-01-2021, 01:23 PM	#2
stevebrot Otis Memorial Pentaxian Join Date: Mar 2007 Location: Vancouver (USA) Photos: Gallery \| Albums Posts: 42,007	Hyper-Program works the same on the K10D as with later cameras and it appears you are in auto-ISO mode in the first photo. What are your set limits for auto-ISO? From the rear LCD, it appears the upper limit is set to 1600. Edit: Dumb question...It has been seven years since I sold my K10D. Added: Note that other than in TAv mode, auto-ISO may not "ramp" as one might expect.* This is true for all Pentax dSLRs. Steve * Other than respecting auto-ISO range, TAv does not use the auto-ISO functionality. In other than TAv mode, auto-ISO generally adjusts as the solution of last resort and even then may not shift. TAv is the only mode that respects the so-called exposure triangle. Last edited by stevebrot; 08-01-2021 at 04:01 PM.

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08-01-2021, 03:10 PM	#3
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,198	What "Program line" have you set in the camera for P ?

08-01-2021, 05:27 PM	#4
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,400	Is there a way to use the green button to change things?

08-01-2021, 08:19 PM	#5
Fogel70 Pentaxian Join Date: Sep 2009 Location: Stockholm, Sweden Photos: Albums Posts: 3,062	The auto ISO in K10D is a bit limited in Hyper-P. The camera in general only increase ISO if the shutter speed goes below what is possible to handhold without risking camera shake. Put the lens cap on and you will see that auto-ISO works in Hyper-Tv.

08-02-2021, 05:11 AM	#6
AfterPentax Mark II Pentaxian Join Date: Mar 2021 Posts: 1,461	As Fogel70 explains it, the aim of program is to get the right handheld exposure. With auto iso you can go up and down with the aperture, the iso is changed to get a reasonable handheld exposure. If you try to change the shutter speed you will notice that: a) the aperture will change; b) the shutter speed only changes within the handheld combination of aperture and shutter speed and c) program tries to preserve the lowest iso and changes the aperture to have a good combination of shutter speed and low iso. Changing the aperture influences both the settings of shutter and iso. So what you see is normal behaviour of your camera, you can not influence it by changing the program line.

08-02-2021, 08:10 AM	#7
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	I'm not sure what you are trying to do. I checked on my K10D and Auto ISO works in Av and Tv mode. You just can't see the ISO in the viewfinder or top LCD unless you press the "OK" button. If you want to control the ISO set a fixed ISO and program one of the eDials in Tv or Av to ISO. Or with a fixed ISO press the "OK" button and change the ISO with the front eDial then you can set what the shutter speed or f-stop to you liking.

08-02-2021, 09:04 AM	#8
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,198	Well I just dug my old K10D out of cold storage and it behaves in Hyper P (Tv shift) mode exactly as the OP described. Change it to the dedicated Tv mode however and the ISO will increase.

08-02-2021, 09:25 AM	#9
Not a Number Moderator Join Date: Mar 2012 Location: Venice, CA Posts: 10,526	Doesn't the Hyper-P behavior depend on the program line setting and the lens being used?

08-02-2021, 10:25 AM	#10
artrasa Senior Member Join Date: May 2021 Photos: Gallery \| Albums Posts: 185 Original Poster	Originally posted by pschlute: What "Program line" have you set in the camera for P ? At that time I had the normal program line selected. Originally posted by UncleVanya: Is there a way to use the green button to change things? Yeah, I use it often to reset back to the normal program line. It can also reset exposure compensation back to ±0. Very handy indeed. Originally posted by Fogel70: The auto ISO in K10D is a bit limited in Hyper-P. The camera in general only increase ISO if the shutter speed goes below what is possible to handhold without risking camera shake. Put the lens cap on and you will see that auto-ISO works in Hyper-Tv. Originally posted by AfterPentax Mark II: As Fogel70 explains it, the aim of program is to get the right handheld exposure. ... Thanks for explaining the logic behind the P mode and auto ISO. I finally start to understand why it works the way it does. I misunderstood its function. Originally posted by Not a Number: I'm not sure what you are trying to do. I checked on my K10D and Auto ISO works in Av and Tv mode. You just can't see the ISO in the viewfinder or top LCD unless you press the "OK" button. If you want to control the ISO set a fixed ISO and program one of the eDials in Tv or Av to ISO. Or with a fixed ISO press the "OK" button and change the ISO with the front eDial then you can set what the shutter speed or f-stop to you liking. I was just wondering about the logic behind the auto ISO function when shooting in P mode. When stopping down in Hyper-Av mode, the auto ISO function automatically increases the ISO to keep the shutter speed in range that's possible to handhold (1/50s with a 35mm lens). This definitely makes sense to me. But if one is in Hyper-Tv mode and attempts to increase the shutter speed, the camera doesn't automatically ramp up the ISO when the lens reaches its max. aperture. This happens even when auto ISO function is enabled. E.g. if the normal program happens to select 1/250s and f/4 (max. aperture) with auto ISO enabled, attempting to increase shutter speed with the front dial is not possible as the ISO stays at 100. This didn't make sense to me. But thanks to Fogel's and AfterPentax Mark II's explanation, it became clear to me that the the auto ISO function in this camera (probably other Pentax' cameras too?) only ramps up the ISO to get handheld shots. 1/250s is already handholdable, so it doesn't attempt to automatically ramp up the ISO.

08-02-2021, 11:31 AM	#11
pschlute Moderator Loyal Site Supporter Join Date: Mar 2007 Location: Surrey, UK Photos: Gallery Posts: 8,198	I guess this is why I never use P mode

08-02-2021, 12:43 PM	#12
AfterPentax Mark II Pentaxian Join Date: Mar 2021 Posts: 1,461	Originally posted by artrasa it became clear to me that the the auto ISO function in this camera (probably other Pentax' cameras too?) only ramps up the ISO to get handheld shots. 1/250s is already handholdable, so it doesn't attempt to automatically ramp up the ISO. It is not the auto iso that does it, but the program line normal! The program line is set to make handheld shots and that is why auto iso behaves as it does, auto iso moves within the demands of the program line chosen.

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