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04-14-2010, 08:21 AM   #1
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K20d - I don't understand auto ISO

I know that this has probably been answered before - and many times - but I can't find it. Please forgive me.

I have a K20D. It's new and I'm inexperienced with DSLRs. My wondering is how to deal with the ISO. If I set it on automatic, it doesn't seem to change automatically when I'd expect it to. For example, in program mode in moderate light I get an indication that I need the flash - but it's because the ISO is staying rather low. When I set a higher ISO manually, it's fine.

So, the question is what to do about the ISO setting: Manual? Auto? Does it depend on what shooting mode I'm using?

Thanks!!!

Andy

04-14-2010, 08:28 AM   #2
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It's possible to set the ISO range that the camera will use while in auto-ISO mode. Are you sure that the full range has been selected?

To change this setting, when you go to select your ISO, make sure its on auto, then use the front and back e-dials to change the range.
04-14-2010, 08:34 AM   #3
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QuoteOriginally posted by Rev Andy Quote
I know that this has probably been answered before - and many times - but I can't find it. Please forgive me.

I have a K20D. It's new and I'm inexperienced with DSLRs. My wondering is how to deal with the ISO. If I set it on automatic, it doesn't seem to change automatically when I'd expect it to. For example, in program mode in moderate light I get an indication that I need the flash - but it's because the ISO is staying rather low. When I set a higher ISO manually, it's fine.

So, the question is what to do about the ISO setting: Manual? Auto? Does it depend on what shooting mode I'm using?

Thanks!!!

Andy
I shoot in full manual mode and it will not allow me to do auto ISO. If you shoot in any other mode other than full manual you should be able to use the auto ISO function (I have a Kx, but I think it is the same on both cameras). Try shooting in full manual. You will have to manually choose the ISO but that way you can train your photographers eye instead of letting the camera do all the work. Just my suggestion.
04-14-2010, 10:12 AM   #4
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Welcome to the forums Rev Andy!
You don't just set the auto ISO by just selecting "yes" or pushing it to activate.
You have to select what range you want the auto-ISO to work on too.
If your settings is low, then it will prevent the camera to select the high ISO's.
Letting the camera choose the ISO will get it to choose a continuous ISO (I think), instead of just the preset ones.
Check where you set the setting of the auto-ISO at.
I think, you also have to use the AUTO mode on the camera itself for it to work.
I never actually use the auto-ISO as I like setting the ISO itself to minimize the noise too as too high an ISO and you are begging for noise.

04-14-2010, 11:12 AM   #5
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@KxBlaze:
The K10D has TAv, and I think the K20D has it as well. That is a full manual mode (you can select aperture and shutterspeed) and the camera will adjust the ISO.

@Rev Andy
Sorry, don't know the answer why the camera is behaving like that; I don't use my K10D that way. Except that the above; check your manual.
04-14-2010, 07:35 PM   #6
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Just go in the iso settings and use the e dial to set the auto iso range to 100-800 or whatever you feel is appropriate.
04-15-2010, 03:55 AM   #7
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Basically, use the function key to go into iso and use the front dial to step one end of the iso range the rear dial to set the other end. I usually use 100-1600 as my range on the K20, although I know some avoid high iso more and would use 800 as the upper end.
04-15-2010, 04:13 AM   #8
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After setting your ISO range, you can override. In any mode, hold the OK button and twist the front dial to set any ISO. To go back to auto-ISO in any of the auto modes, hold the OK button and hit the Green button.

Something else that affects exposures when you're in Green or P(rogram) modes: Go to the Custom Menu entry for Program Line. Its options are Standard (default), Shutter priority, DOF priority, and MTF (best image per lens). Try these different options and see the results.

Personally, I'm in Av or M modes mostly. If I'm shooting landscapes or things where I want detail, I use the lowest ISO, a slow shutter, small aperture, and tripod. If I shoot people and action I use a fast shutter, whatever aperture, and let the ISO float upwards.

Any shot is a trade-off between focal length and focus, shutter and aperture and ISO, detail and grain or noise, tone and shape, angle and depth, what you frame and what you exclude. Photography is compromise. Bother.

04-15-2010, 01:15 PM   #9
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QuoteOriginally posted by sterretje Quote
@KxBlaze:
The K10D has TAv, and I think the K20D has it as well. That is a full manual mode (you can select aperture and shutterspeed) and the camera will adjust the ISO.
I'd nit pick this. If the camera is choosing the ISO, that means it is choosing the exposure, and that means it isn't full manual. That is, it will continuously change the exposure as the light changes - more light will result in lower ISO, less light higher ISO. The exposure will also change as the scene changes - ISO will go up when shooting a dark obejct, and down when shooting a light one. This to me is not "fully manual". In a fully manual mode, the exposure does not change until *you* tell it change. (whether by actually turning a dial, or by hitting the green button). TAV is an automatic mode just like Tv or Av are - it allows you to set two of the three parameters, but the camera retains control over the third, meaning exposures
"float" and are not manual.
04-15-2010, 09:38 PM   #10
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Marc, you're right. I never really played with it, but I think the one thing one can not do here is over/under expose. Must try it one day.
04-16-2010, 03:22 AM   #11
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Thank you all for your replies. I had already adjusted the ISO range for auto ISO adjust. That's why I'm particularly surprised that the camera obstinately refuses to adjust the ISO sufficiently to make a good exposure when aperture and speed setting changes are not enough.

While I'm inexperienced, I've read both the manual and the Magic Lantern book on this camera and neither says much about the how auto sensitivity works in any detail.

RioRico - your comment is particularly helpful. I did not pick up on that ISO override feature. Thanks!
04-16-2010, 03:32 AM   #12
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I don't know if Program lets you choose the type of metering, but when I use TAv I use matrix metering. I tend to use spot in manual, but auto-ISO and spot metering can give really weird results.
04-16-2010, 04:10 AM   #13
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Andy,

I know your problem as I noticed the same thing when I first bought my K10D. I had even selected high speed in the program line expecting that the camera would actively change the ISO to give a high shutter speed, but nooooooooo it didn't. Evidently the firmware is set up to give maybe 1-2 stops of shutter speed in high speed program line and to preserve a lower ISO setting as it's priority.

I noticed that the K7 allows the user to choose how actively the camera changes ISO. There are three settings; slow, normal, and fast. I suspect this was in response to your issue and mine.
04-16-2010, 12:16 PM   #14
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change the range

I am guessing you have the default 100-400 selected, and you can select the full range.....

Of course, in auto mode in the green mode, it acts more like a point and shoot, and calls for a flash if it can......
04-16-2010, 03:29 PM   #15
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Actually, I find auto ISO more of a bother than a help most of the time. It makes getting control of the exposure more of a whack-a-mole undertaking. I have had my auto range set to max out at 800 or even 1600, and had the camera stick with ISO 200 in conditions where it made no sense to me. To my eyes, the K20d is capable of excellent quality at ISO 400 and very good quality at ISO 800, but its program line is too reluctant to go there for my liking.
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