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01-15-2009, 08:58 AM   #1
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Confused by P-mode behavior

Okay, I've got a question on Program (P) mode. I'm an M or Av kind of guy, but I was messing around with P the other night on my K20D and it didn't behave the way I thought it should...

I had ISO on Auto (100-3200) and my Tam 17-50/2.8 mounted and could not get the shutter to go faster than 1/60s by turning the front e-dial. The only way I could get a faster shutter was to manually increase the ISO. I tried all 4 Program Line settings and it behaved the same way.

I was expecting that in P mode the camera would adjust ISO along with aperture or shutter (which ever one you're not setting manually). In other words I expected as I increased shutter speed that the camera would increase the aperture until it reached max open and then begin increasing ISO until I either ran out of shutter speed or it ran out of ISO. I'm guessing I'm wrong?

I would RTFM but haven't figured out which unpacked box from moving has my manual in it.

Thanks!

01-15-2009, 11:36 AM   #2
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Jim, the pentax site should have the pdf version of the manual for d'loading. Sorry don't have the 10 so can't help.
01-15-2009, 11:56 AM   #3
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first, which program is your program mode set to? you have 4 options, you can select it in the custom menu
01-15-2009, 02:27 PM   #4
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I have experienced the same with my cam (K10D) set to MTF program line.

Tends to behave in good sunlit conditions but in really overcast it rears its weirdness.

So say in this mode the best ap is F8 for the lens I should be able to shift the shutterspeed (If that's what I'm needing) to what I need and the cam should increase the ISO accordingly - which it doesn't.

d

01-15-2009, 02:37 PM   #5
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Program mode is an auto mode. Why fight the camera's programming? If you want to control shutter speed you should be in Sv mode.
01-15-2009, 03:37 PM   #6
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The camera is trying to tell you to use the flash.

Steve
01-15-2009, 11:40 PM   #7
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Original Poster
Thanks for the replies. Unfortunately I'm still baffled. Here's why...

Setup: K20D, DA*50-135/2.8, Normal Program Line, Auto ISO, opposite e-dials in Av & Tv modes set to EV+/-.

Starting at a base exposure of 1/60s, f/2.8, ISO 100 in Av mode, as I stop down the aperture, the ISO increases until it reaches its maximum (3200) and then the camera begins slowing the shutter speed.
Starting at a base exposure of 1/60s, f/8, ISO 100 in Tv mode as I speed up the shutter the aperture decreases until it reaches 2.8 and then the camera begins increasing the ISO.

What I am expecting the camera to do in P mode is mimic the behavior of Tv mode when I am moving the Tv e-dial and mimic Av mode when moving the Av e-dial. It doesn't.
Take this example of a base exp. of 1/60s, f/4, ISO 100 and increase shutter to 1/90 and then 1/125. Aperture changes to f/3.5 and f/2.8 respectively. The ISO will not increase from 100 however, and so the shutter can not increase past 1/125s. Now if I change the aperture back to f/4 the ISO will now increase to 200 and the shutter stays on 1/125. I can continue to push the ISO by stopping down the aperture until the ISO maxes out and the shutter will not budge off of 1/125. And if I try increasing the shutter dial again it runs home to mama and I'm back to 1/60, f/4, ISO 100.
And, If I start with an exposure with ISO mid-range and decrease shutter, once aperture hits 2.8 it will decrease ISO down to 100 (yay!). But it will not then let me increase shutter again (boo!).

So what in tarnation is that camera brain thinking? That's all I'm looking for here so I can understand and potentially make use of P mode.

Thanks again!
01-16-2009, 01:14 AM   #8
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QuoteOriginally posted by audiobomber Quote
Program mode is an auto mode. Why fight the camera's programming? If you want to control shutter speed you should be in Sv mode.
Sure - BUT the Pentax has Hyper Program Shift which should allow the user when in Program Mode (P) to shift between Av,Tv at will with Auto Iso taking care of correct exposure.

d

01-16-2009, 06:27 AM   #9
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Extract from the manual.

Hyper-program
To change the shutter speed
You can switch to Shutter Priority automatic exposure by turning the
front e-dial in e (Hyper-program) mode.
You can only set the shutter speed to a value that will give a correct
exposure with the aperture range of the lens being used.
If the brightness changes and the aperture value is outside the
relative range, the aperture value will blink in the viewfinder and on
the LCD panel.
Press the Green button to return to Hyper-program automatic
exposure.
To change the aperture
You can switch to Aperture Priority automatic exposure by turning the
rear e-dial in e (Hyper-program) mode.
You can only set the aperture to a value that will give a correct
exposure within the range of available shutter speeds.
If the brightness changes and the shutter speed is outside the relative
range, the shutter speed will blink in the viewfinder and on the LCD
panel.
Press the Green button to return to Hyper-program automatic
exposure.

This seems to imply that the ISO setting will be locked, but it says - later - that:-

You can set the sensitivity to ISO AUTO by pressing the Green button while
pressing the 4 button when the exposure mode is set to P (Hyperprogram),
TV (Shutter Priority), or AV (Aperture Priority).

Hope this helps.

Bill
01-16-2009, 10:34 AM   #10
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QuoteOriginally posted by Billgscott Quote
Extract from the manual.

Hyper-program
To change the shutter speed
You can switch to Shutter Priority automatic exposure by turning the
front e-dial in e (Hyper-program) mode.
You can only set the shutter speed to a value that will give a correct
exposure with the aperture range of the lens being used.
If the brightness changes and the aperture value is outside the
relative range, the aperture value will blink in the viewfinder and on
the LCD panel.
Press the Green button to return to Hyper-program automatic
exposure.
To change the aperture
You can switch to Aperture Priority automatic exposure by turning the
rear e-dial in e (Hyper-program) mode.
You can only set the aperture to a value that will give a correct
exposure within the range of available shutter speeds.
If the brightness changes and the shutter speed is outside the relative
range, the shutter speed will blink in the viewfinder and on the LCD
panel.
Press the Green button to return to Hyper-program automatic
exposure.

This seems to imply that the ISO setting will be locked, but it says - later - that:-

You can set the sensitivity to ISO AUTO by pressing the Green button while
pressing the 4 button when the exposure mode is set to P (Hyperprogram),
TV (Shutter Priority), or AV (Aperture Priority).

Hope this helps.

Bill
Sorry to sound dumb;

Which is the "4" button?

Cheers

D
01-16-2009, 02:05 PM   #11
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QuoteOriginally posted by dylansalt Quote

Which is the "4" button?

Cheers

D

I was thinking that to. It's the OK button. Try this:

1. Set ISO to 1600
2. Hold down OK and then press green button.

For me, the shutter speed dropped from 1/1500s to 1/90s and the ISO changed to AUTO (100-800). It's a permanent change. You will need to use the Fn key to access the menu and change it if you want to set a specific ISO again.

Dan

Last edited by dosdan; 01-16-2009 at 06:36 PM.
01-17-2009, 04:58 AM   #12
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Great - thanks

Will give it a try

Dylan
01-17-2009, 05:53 AM   #13
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QuoteOriginally posted by dosdan Quote
You will need to use the Fn key to access the menu and change it if you want to set a specific ISO again.

Dan
Or use the OK button and the front wheel.
01-17-2009, 06:35 AM   #14
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this is the k20d program mode glitch. all k20d's do it. hopefully it will be fixed with the next firmware update
01-17-2009, 08:21 AM   #15
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I could never get the ISO to operate the way I thought it should on my K10D, either. It always wanted to use 800 if it was in auto mode. So I always set the ISO to what I want. Sometimes you have to beat the camera.
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