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09-19-2017, 06:43 PM   #1
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Aperture Priority with Auto Iso?

So... I may be having a thicko day at the office, but earlier this morning I read an article about Aperture Priority mode (not Pentax specific) and a specific segment stood out, in the article it mentioned that if the camera has auto iso ability that then when in Av mode the shutter speed should not drop down below handheld capability, therefore the shutter speed might max out at say 1/50th (if say a 50mm lens is attached) and then the ISO would push up to compensate for correct exposure.

This I thought interesting, because up till now I have been using my K-1 in full Manual mode (for stationary static subject matters) and TAv for 'people'. The reason I haven't used Av much is because I can't figure out how to auto Iso in that mode. I get to control ISO and Aperture and then the shutter does its thing, if the shutter speed is too low, bump up the ISO. But this kinda strikes me as a roundabouts way of kinda TAv mode in a slightly different fashion.

Yesterday I was shooting a school event in very bright outdoor conditions, shooting wide open I was up to 1/8000th, but then as soon as you go into the classroom, then obviously I needed to adjust the shutter speed right down. It would have been really helpful if the camera could see that I have went indoors and thus dropped the shutter speed down to the lowest speed that I had perhaps specified somewhere (or that it itself deemed safe for handheld) and adjusted the ISO accordingly. In a way it's lazy photography but you could truly focus on just composition and DoF and leave the camera to do the rest.

For example;

A 50mm lens, Av mode, Auto ISO, don't drop below 1/50th, if you get to 1/50th (and it would rather go lower) then it starts bumping the ISO up to compensate.

A 100mm lens the same, but now perhaps 1/100th etc etc.

This is essentially what I do with TAv mode, but I am adjusting Shutter speed manually. I leave aperture where I want it, have Auto ISO on, and then if in dark lighting low the shutter speed to what I think is the safest speed I can still get a shot from (subject depending of course), but then when I step outside or the light changes dramatically I now need to pay attention to any warning lights and fire the shutter speed up till the camera stops blinking, it can just be 'too much' to do in the heat of the moment.

Can the K-1 do what I'm getting at?

Cheers,

Bruce

09-19-2017, 06:48 PM - 1 Like   #2
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You can combine the program line and auto iso curve to change the way the camera behaves with respect to the shutter speed chosen. There is no way to set hard limits, however.

To enable auto ISO simply press the green button together with the ISO button.

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09-19-2017, 07:19 PM   #3
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QuoteOriginally posted by Adam Quote
You can combine the program line and auto iso curve to change the way the camera behaves with respect to the shutter speed chosen. There is no way to set hard limits, however.

To enable auto ISO simply press the green button together with the ISO button.
Just after I typed this question I picked up the K-1 again and thought to myself 'there must be a way to do it!', and lo-behold I stumbled upon it (somewhat).

Believe it or not I have never really used the dedicated ISO button (near the shutter button), I forgot it was there! Instead I have most of the time had that other wheel set to ISO and used the other wheel near thumb to change the amount.

However, as you say you can set to Auto ISO if you first push ISO and then the Green Button afterwards.

So, what I noticed was this.

- With the FA50mm attached, setting to Auto ISO it didn't want to drop below 1/80th. My Program Line I set as the DoF icon (the one with the blurry background).

- I went and changed the Auto ISO settings from the middle to Slow, and it now didn't drop below 1/40th.

- Changing the Auto ISO to Fast settings and now it didn't want to drop below 1/160th.

Cool... so that's something at least, a choice of 1/40th, 1/80th and 1/160th with a FA50mm attached.

Now to see if it says anything different with a 100mm attached.

PS: Oh and I had SR off, tho when I toggled it on it didn't seem to make any difference to those values changing...

EDIT: And here are the values for using a 100mm lens, Normal = 1/125th, Slow = 1/60th and Fast = 1/250th

Now the question is... is there a shortcut way to set the Auto ISO Parameters to being more easily accessed than the Main Menu (such as pressing the Info button), I can only see options for actually setting the min and max ISO values being bindable but not the actual parameters (Slow, Normal, Fast etc).

Last edited by BruceBanner; 09-19-2017 at 07:33 PM.
09-19-2017, 09:26 PM   #4
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Din't you try use TAv mode? This mode gives you full control on Aperture and Shutter speed.

09-19-2017, 09:34 PM   #5
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QuoteOriginally posted by BruceBanner Quote
Now the question is... is there a shortcut way to set the Auto ISO Parameters to being more easily accessed than the Main Menu (such as pressing the Info button), I can only see options for actually setting the min and max ISO values being bindable but not the actual parameters (Slow, Normal, Fast etc).
Not AFAIK, but you should be able to create USER modes with different presets selected.

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09-19-2017, 09:49 PM   #6
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QuoteOriginally posted by Adam Quote
Not AFAIK, but you should be able to create USER modes with different presets selected.
That's exactly what I have done, I've labeled one 'kids' and one 'adults' hehe, I was just trying to conserve a User Mode for another task.

---------- Post added 09-20-17 at 02:52 PM ----------

QuoteOriginally posted by tregubovav Quote
Din't you try use TAv mode? This mode gives you full control on Aperture and Shutter speed.
I did yes, I start off by saying that I use either Manual or TAv mode exclusively (up until today when I started reading about Av mode a little more). I think setting up Av mode with Auto ISO is actually one step better (for certain scenarios) than TAv mode as it's one less thing I need to adjust, I can concentrate more on Aperture, composition etc and fiddle less knowing that in plenty of sunlight the shutter speed will take care of itself, and when not enough light is possible the shutter speed still won't drop down below a predetermined 'safety' level. I think this is fantastic.
09-24-2017, 02:56 PM   #7
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QuoteOriginally posted by BruceBanner Quote
Now the question is... is there a shortcut way to set the Auto ISO Parameters to being more easily accessed than the Main Menu (such as pressing the Info button), I can only see options for actually setting the min and max ISO values being bindable but not the actual parameters (Slow, Normal, Fast etc).
You can use the Customizable Control Panel.
Pentax K-1 Review - Highlights and New Features | PentaxForums.com Reviews

Press INFO once after powering the K-1 on.
Then press +/-, select the icon to change and confirm with ok.
Now you can scroll down the list to page 2 ISO AUTO MAX (point 1) and AUTO ISO MIN (point 2).


Or you just press ISO and scroll the rear e-dial left/right to set an fixed ISO value.
Pentax K-1 Review - Exposure Modes | PentaxForums.com Reviews

Or you use the K-1 function dial on the top. Setting it to ISO and switching the setting dial clockwise to decrase ISO and ccw to increase ISO.
Pentax K-1 Review - User Interface | PentaxForums.com Reviews

Program line diagrams are somtimes hidden somewhere, but not regarding to the focal length.
Pentax Green Button Guide - Articles and Tips | PentaxForums.com
09-24-2017, 07:45 PM   #8
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QuoteOriginally posted by angerdan Quote
You can use the Customizable Control Panel.
Pentax K-1 Review - Highlights and New Features | PentaxForums.com Reviews

Press INFO once after powering the K-1 on.
Then press +/-, select the icon to change and confirm with ok.
Now you can scroll down the list to page 2 ISO AUTO MAX (point 1) and AUTO ISO MIN (point 2).


Or you just press ISO and scroll the rear e-dial left/right to set an fixed ISO value.
Pentax K-1 Review - Exposure Modes | PentaxForums.com Reviews

Or you use the K-1 function dial on the top. Setting it to ISO and switching the setting dial clockwise to decrase ISO and ccw to increase ISO.
Pentax K-1 Review - User Interface | PentaxForums.com Reviews

Program line diagrams are somtimes hidden somewhere, but not regarding to the focal length.
Pentax Green Button Guide - Articles and Tips | PentaxForums.com
Thanks for that, but unless I have misunderstood this isn't quite the feature I am after. The bind I'm looking for (or quick shortcut) is to the Menu>Camera1>ISO Auto Setting>Auto ISO Parameters (bottom)> then choosing Slow, Normal or Fast.

When you have Auto ISO selected (and not a specific ISO but genuinely Automatic), and are in Av mode, what Slow, Normal and Fast do is actually change the lowest shutter speed values (and then the ISO would adjust automatically). For example;

- If you were using the K-1 with a 50mm lens attached, and chose 'Slow' then the lowest Shutter speed it would drop to would be 1/40th and no lower than that.
- If you selected 'Normal' it would drop to 1/80th but no lower
- And if you selected 'Fast' it would not drop below 1/125th.

Each scenario above the ISO would automatically adjust, so I just set the minimum to 100 and Maximum to 204800. Being able to adjust these values via the Info button doesn't help in this regard (I don't think). I use 'Slow' for shooting portraits of adults (as they are generally still subjects, if the adult is still enough 1/40th is fine. I use 'Fast' for when shooting kids, this means that even in less than ideal lighting the shutter speed would still be above 1/125th or higher (although in the same scene the ISO would be higher than that if shooting 'Slow' for adults, but I'd rather have in focus non blurry kids with more noise than cleaner blurry kid images.

09-25-2017, 12:03 AM   #9
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I would set up User modes for these three setups. Then it is just a spin of the wheel away.
09-25-2017, 12:14 AM   #10
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QuoteOriginally posted by jbinpg Quote
I would set up User modes for these three setups. Then it is just a spin of the wheel away.
That's what I've done
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