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04-03-2008, 08:06 PM   #1
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I'm not understanding why...

Hi everybody, I'm a newbie in the DSLR world and I'm doing my first steps (never owned an SLR but played around often with a bridge camera).

So, the other evening I was in a pub taking pictures (and drinking beer of course!) the room was under dim light (AF was sometime hunting... :-|). I was shooting in aperture priority with a K100D + Pentax-F 50mm f1.7 (most of the time wide open or step down to f2).
Once at home I checked the pictures, some of them were very good, some others very blurry.
In some blurry picture the Exif was saying: Aperture f1.7, Shutter Speed 1.5secs (or even 2secs) and ISO 200!!!! Now my ISO setting was in automatic in the range of 200-800. So why the camera chose to pick a shutter speed of 1.5 secs and keeping the ISO at 200 when it could have been better to have ISO800 and shutter speed of 0.3"? Am I doing anything wrong?
Thank you very much for any advice....

04-03-2008, 08:21 PM   #2
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QuoteOriginally posted by soalle Quote
Once at home I checked the pictures, some of them were very good, some others very blurry.
In some blurry picture the Exif was saying: Aperture f1.7, Shutter Speed 1.5secs (or even 2secs) and ISO 200!!!! Now my ISO setting was in automatic in the range of 200-800. So why the camera chose to pick a shutter speed of 1.5 secs and keeping the ISO at 200 when it could have been better to have ISO800 and shutter speed of 0.3"? Am I doing anything wrong?
Thank you very much for any advice....
Did you apply exposure compensation for the blurry shots?
04-03-2008, 08:24 PM   #3
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Yes, how do you know??!!!!
I set a -1.0 EV with the only aim of taking pictures with a faster speed. So do you think this affected the ISO choice? If yes, why?
04-03-2008, 08:27 PM   #4
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Ouch... I just checked the exif of all the photos, and the ISO dropped from 800 to 200 as soon as I set EV to -1.0... so I guess this is the reason, but I'm still not getting why...

04-03-2008, 08:49 PM   #5
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QuoteOriginally posted by soalle Quote
Ouch... I just checked the exif of all the photos, and the ISO dropped from 800 to 200 as soon as I set EV to -1.0... so I guess this is the reason, but I'm still not getting why...
I think the issue is when you set overrides like exposure compensation the camera assumes youo no longer want auto modes. I am guessing a bit on this because I never use auto ISO. In fact in low light, I generally keep the camera metering in manual mode, and I decide whether I want to over or under expose the image.

Also, you asked if you are doing something wrong. you want a good exposure at 0.3 seconds? with virtually any lens you will have shake even with SR on, and that does not count the times your subject moves, because although SR can get rid of camera shake, it does nothing to freeze the subject, that is achieved by shutter speed alone.

If you got shots that turned out at 1.5 seconds you must have a good technique, because I wouldn't expect many
04-04-2008, 01:28 AM   #6
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In all Pentax cameras up to K10D Auto ISO and EV compensation wasn't working together. As soon as you dial in EV compensation, Auto ISO is turned off and ISO set to lowest value. Very nasty "feature".

Unfortunately Pentax decided not to fix it (it is extremely easy firmware fix IMHO).

I am Auto ISO user and this issue was very annoying to me and was the main reason why I did upgrade my *ist DS to K10D as soon as K10D became available.
04-04-2008, 05:06 AM   #7
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Don't rely on the camera to think for you! You should ALWAYS be aware of
1)What the ISO is set to
2)The aperture (should be easy if you're in Av)
3)The shutter speeds you're getting

I would have noticed a 1.5 second exposure before the picture was taken. Not to mention it should be pretty easy to see that the shot is blurry on the LCD before you get home

In summary, don't use AutoISO, and always be aware of your three exposure settings.
04-04-2008, 05:12 AM   #8
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QuoteOriginally posted by egordon99 Quote
In summary, don't use AutoISO, and always be aware of your three exposure settings.
I completely disagree with you. Auto ISO implementation on K10D and later Pentax DSLRs is very nice and makes Auto ISO very useful feature. ISO is upped only when you really need it.

04-04-2008, 08:04 AM   #9
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QuoteOriginally posted by Edvinas Quote
I completely disagree with you. Auto ISO implementation on K10D and later Pentax DSLRs is very nice and makes Auto ISO very useful feature. ISO is upped only when you really need it.
this is not quite true, if you are in flash mode, auto ISO bumps the ISO up to the max limit first, in an attempt to get a no flash photo. As a result, you may be wanting full flash, but you get a super grainy high ISO witl fill flash only.

As others have stated, you really should not rely on auto functions, yes the work up to a point, but they do not always do what you are intending.

Unfortunately since the onset of the computer era, one critical function has always been missing, the program should be called MINDREAD.EXE. Until then, it is the user's responsibility to tell the camera what it should do explicitly
04-04-2008, 08:08 AM   #10
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this is why you dont trust the camera, and pick stuff yourself.
04-04-2008, 10:02 AM   #11
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QuoteOriginally posted by soalle Quote
Ouch... I just checked the exif of all the photos, and the ISO dropped from 800 to 200 as soon as I set EV to -1.0... so I guess this is the reason, but I'm still not getting why...
Its the Auto ISO problem on the K100D.
Auto ISO works fine if you don't set Exposure compensation

Whenever you set Exposure compensation while you are on Auto ISO, it automatically defaults back to ISO200, regardless of lighting condition.
Page 121 - 122 of the K100D manual. Annoying, but that's what the manual says...

The workaround is to set the ISO manually and not rely on AutoISO.

The K10D and the new models do not have such a problem.
04-04-2008, 11:50 AM   #12
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thank you very much for all your answers!
I actually tested also Auto ISO with Manual mode. Also there once you set aperture and speed the camera automatically choose ISO200... too bad. It could have been nice to have this fix in the next firmware release...
04-04-2008, 12:40 PM   #13
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QuoteOriginally posted by Lowell Goudge Quote
this is not quite true, if you are in flash mode, auto ISO bumps the ISO up to the max limit first, in an attempt to get a no flash photo. As a result, you may be wanting full flash, but you get a super grainy high ISO witl fill flash only.
There are other oddities with the program modes in AutoISO. High Speed Sync won't work, for example. Plus, there's a huge difference in what it decides to do with the aperture below or at and above ISO 400. (ISO 400 and up, it prefers to give you around f/8. ISO 320 or down, it jumps to wide open or close to it.) So while I use AutoISO generally, I have USER configured to give me ISO 400 by default (and then of course I adjust as appropriate.)


(This is for the K10D -- not sure exactly what the K100D does since I never used its flash when I had one.)
04-04-2008, 01:10 PM   #14
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QuoteOriginally posted by Edvinas Quote
I completely disagree with you. Auto ISO implementation on K10D and later Pentax DSLRs is very nice and makes Auto ISO very useful feature. ISO is upped only when you really need it.

I think egordon99 is absoluely correct. While that Auto ISO can be a wonderful tool under the right circumstances it essentially gives the camera control ofver too many aspects of photography while allowing the phtographer to use the camera as nothing more than a P&S.

While that may not be a bad thing at times it is not what one generally buys a DSLR for. To use a DSLR correctly generally requires that the photographer learn how to handle the reciprocal functions of light vs ISO, or ISO and aperture, F-stop selection under varioius lighting conditions. Understanding these relationships is what helps create a photographer vs being a picture taker. Knowing these formulas will allow you to handle virtually all the complex situations that you may find yourself in at one time or another.

Stephen
04-04-2008, 07:59 PM   #15
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QuoteOriginally posted by SCGushue Quote
I think egordon99 is absoluely correct. While that Auto ISO can be a wonderful tool under the right circumstances it essentially gives the camera control ofver too many aspects of photography while allowing the phtographer to use the camera as nothing more than a P&S.

While that may not be a bad thing at times it is not what one generally buys a DSLR for. To use a DSLR correctly generally requires that the photographer learn how to handle the reciprocal functions of light vs ISO, or ISO and aperture, F-stop selection under varioius lighting conditions. Understanding these relationships is what helps create a photographer vs being a picture taker. Knowing these formulas will allow you to handle virtually all the complex situations that you may find yourself in at one time or another.

Stephen
Stephen

I guess the broader issue is that these features are provided with the intent of attracting new users, not all of who have learned about exposure, ISO, shutter speeds and Fstops, but who want to get reasonable photos right out of the box.

I go back to my first photos, which were by coincidence, taken with an SLR, and I made the same mistakes also. BUT I learned as everyone else will. I have the present advantage of more than 25 years of shooting, 5 cameras between then and now, and a collection of great lenses.

The best advise for any new shooter is go out and buy a book. Read it, take some photos, and then re-read it!

That is much faster than learing by trial and error, and the only thing DSLRs make easy is the speed at which you can make errors. To try and figure out what the camera is doing by trial and error in each mode is a complete waste of time and hard disk space. But let's face it, the auto everything features are here to stay. I'm just glad that pentax has limited it to a relitively small number on the K10D and K20D. My cameras generally have lived in manual mode, and that includes an *istD and PZ-1 along with my K10D

As I said in my post, the only thing missing is the MINDREAD button.
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