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09-29-2020, 11:57 AM - 1 Like   #16
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QuoteOriginally posted by ehrwien Quote
I have a use for that when I have minimum or fixed requirements for aperture and shutterspeed and want to influence the automatic metering in a certain direction which is faster than switching to M and figuring out exactly what the ISO should be
I use TAv mode a lot, mainly for action shots. EC will change the ISO, but will also change the exposure. I think you understand this, but I wanted to make it clear to the OP that using EC in TAv mode has its consequences.

---------- Post added 09-29-20 at 08:12 PM ----------

This thread seems to have gone off at a tangent.

To the OP..... when in TAv mode you cannot change the ISO by using EC unless you also want to change the exposure. I don't think this is what you want to do, but tell me if I am wrong.

AUto ISO has its uses for some (in modes other thatn TAv), but I never use It.

Last edited by pschlute; 09-29-2020 at 12:12 PM.
09-29-2020, 12:34 PM   #17
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Perhaps as a final disclaimer from me for the way I described using exposure compensation in TAv with AutoISO: it applies an offset that will still only work inside the ISO range that was specified, say 100 - 6400. When you have dialed in your aperture and shutterspeed and the camera chooses ISO 125 and say you want it to be two stops darker than the metering would choose, exposure compensation would not do anything because the ISO is already right at the edge of the range (and the picture will be exposed the way the camera wants it to according to the chosen metering mode, not the way you want it to be exposed). You would have to close the aperture and/or reduce the shutterspeed to allow for your interference into metering to be possible in that way.

Last edited by ehrwien; 09-29-2020 at 01:00 PM.
09-29-2020, 12:34 PM   #18
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QuoteOriginally posted by normhead Quote
It's pretty simple, set your camera to AV. I depress the ISO button and turn the main dial to change ISO's. (80% of the time my camera is set to 100 ISO, and if that doesn't work for some reason, I crank it up. I also set my aperture, and that's absolutely critical for controlling depth of field. The exposure is the only variable I'm willing to leave to the camera. And I only change my ISO when the exposure time is too long to create the image I want.

My final adjustment is the EV button, which is usually set to -.7 EV. But there are many situations where that must be changed. A scene with deep shadows where you want to capture detail must be shot at 0 or +1 EV, sometimes +2 for backlit details.

This is what works for me.

For me this is what gives me the most control over what most affects noise and depth of field. Two things that most affect how your final image looks. Shutter speed , shooting stills on a tripod is often irrelevant.

I use TaV only for birds in flight, when shutter speed is important to neutralize subject motion.
Thank you, Norm. That is very helpful.
09-29-2020, 12:54 PM - 1 Like   #19
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QuoteOriginally posted by TerryL Quote
Thank you, Norm. That is very helpful.
Any time, I'd also add, for times like this, where I'm shooting in low light, I had to increase the ISO to 400 to get to 1/25s and I shot four exposures in burst. I don't want motion blur, from which the SR might save me, but I also want multiple exposures in case SR fails, and I move too much for it to compensate. Since I'm often pretzeled into very uncomfortable positions my control of motion can be even more compromised. I don't have the steadiest hands. I will go as low a a 1/6 second exposure with multiple exposures to keep from having to go over 400 ISO. I find after 400 ISO even on my K-1 results can be unpredictable. On my K-3 they can be quite noisy. Especially if shooting at -.7 EV. -.7 EV increases contrast and saturation, but it can negatively affect noise.

09-29-2020, 02:25 PM   #20

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I use TAV mode exclusively when Manual may not be a choice to keep up with the action. It will give you auto ISO per the Aperture and Shutter Speed settings you are using. Also, which has been said, when using TAV mode you can use the Exposure Value EV setting to minus the light being used or plus the light being used, which effects the Auto ISO (minus EV lower ISO, higher EV higher ISO.

Of course in Manual mode you will have complete control over all settings (ISO, Aperture, and Shutter Speed).

It is quite simple after you have used it (TAV) for awhile and see how it operates.

Auto ISO does not have to be engaged in other modes such as AV and TV.

Below are a shortcut to a chart showing functions available and not available when using different modes and a definition list of some of the modes (K-1 online manual). Note that "Sensitivity" is ISO.

Sv ("Sensitivity value" mode): This is an exclusive Pentax exposure mode. The user sets the ISO with the rear e-dial and the camera will set shutter speed and aperture to match.

Tv ("Time value"): Shutter speed priority, the user sets the shutter speed with the front e-dial. The camera sets a matching aperture (and ISO if auto-ISO is engaged).

Av ("Aperture value"): Aperture priority mode, the user sets the aperture with the rear e-dial, the camera sets a shutter speed to match (and ISO if auto-ISO is engaged).

TAv ("Time and Aperture value"): This is another Pentax special. The user sets the shutter speed with the front e-dial and the aperture with the rear e-dial, and the camera adjusts the ISO to match. Think of it as M mode with auto ISO.

M: Metered manual exposure mode. The user sets shutter speed and aperture, the camera meter is active and indicates how much the exposure is off the metered value. ISO cannot be set to auto in this mode.

B ("Bulb"): Aperture is set with the rear e-dial. The shutter stays open for as long the shutter button is held down. What we particularly like is that a custom function can change this behavior so that the first press of the shutter release opens the shutter and the next press closes the shutter. The same behavior can be obtained when using the infrared remote control. This makes for much more convenient night shooting.

X ("X-sync"): This setting is handy when using third party flash guns or when a flash is connected to the X-sync terminal rather than the hot shoe: The shutter is set to the flash sync speed and the aperture can be adjusted with the rear e-dial. The flash sync speed can be adjusted in custom function no. 7 in steps from 1/90 s to 1/200s.

Read more at:

Last edited by C_Jones; 09-29-2020 at 03:10 PM.
09-29-2020, 03:32 PM   #21
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I am late to this party, but will put my two-cents in anyway. I am quite famously not a fan of auto-ISO, partially because it often results in unpredictable behavior and difficult help requests on this site and partially because I prefer to not leave something that affects image quality as much as ISO up to the whims of the automated exposure system.*

That said, it is easy to switch your camera to manual ISO and leave it that way. Simply use the ISO button to manually select the ISO you want. As long as you don't have a user mode set to use auto-ISO, it will stay in manual mode until you press the ISO and green button at the same time.

(...Of course, there are a million ways to do things on a K-1, but the above is straightforward...)


* Auto-ISO does not ramp by EV steps except for the special case of EV mode. As a result, its behavior can be frustrating. I believe auto-ISO to be an invention of the dark forces and an instrument of evil.
09-29-2020, 09:23 PM - 1 Like   #22
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I pretty much have the "function dial" (see p.19 in the K-1 manual) set to "ISO", so that by rotating the "setting dial" I can change it manually and conveniently. (These are the two large circular knobs on the top-right adjacent to the LCD screen.) Though in TAv drive mode, you can't change the sensitivity manually. I have the five custom function settings defined in different ways depending in part on whether I want to control the ISO or not; for those in which I do want such control, I use the M drive mode. Then, switching is performed by means of the drive mode knob.
09-30-2020, 03:51 AM - 1 Like   #23
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QuoteOriginally posted by TerryL Quote
Hello folks,
Back when I got my K1, I set the ISO to be automatic with a range. Although that works well for most things that I do, I would like to be able to set it manually. Iíve checked the manual, but itís just not clear. Your help would be appreciated.
You guys have been so helpful, and Iíve learned a lot. Thanks to all.


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