Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
02-08-2010, 01:56 PM   #1
New Member




Join Date: Feb 2010
Location: East
Posts: 8
Why does EV comp not work in K-x?

Hi all.
It,s been awhile now since i got my new K-x for Christmas. I am trying to get more control of the photos. When i try a photo in Av mode, the EV adjust shows a hugh improvement in the preview histogram. However, after taking photo and reviewing there is absolutely NO difference whatever in taken photo. I repeated this several times and can't make EV comp show any difference. My technique is:
Take a photo with EV comp @ 0.0.
Retake photo with EV comp set to 3.0.
The preview histogram show big difference, but, both photos are identical.
Am i missing something?
Any help, suggestions, condolences?

02-08-2010, 02:10 PM   #2
Forum Member




Join Date: Jul 2008
Location: Netherlands
Photos: Gallery
Posts: 61
not sure how you do that but EV comp certainly works on my K-x.
maybe you could explain your setup? lens, camera setting etc.

sounds like a user error to me. Metering is one of the most basic things in a DSLR...
With more info on what is going on we might exclude user error though.

Last edited by jan rinze; 02-08-2010 at 02:21 PM.
02-08-2010, 02:30 PM   #3
Inactive Account




Join Date: Jan 2010
Location: Brooklyn, NY
Posts: 144
Check the EXIF data of your two images. Check the property called "Exposure bias value." It should be 3 if you have EV Compensation set to +3.

I just tried it with Live View and it works fine and the image looks over-exposed. Could you somehow be pressing the Green Button while EV Compensation is selected? That would reset the compensation to 0.
02-08-2010, 02:41 PM   #4
New Member




Join Date: Feb 2010
Location: East
Posts: 8
Original Poster
Here is some more info. Lense came with K-x kit, 18-55mm.
Reference photo 1, Mode Av, F#13, ISO=800, EV=0, H/L=0, Custom image = Natural, Dr = on, shadow = middle.
Reference photo 2, Mode Av, F#13, ISO=800, EV=+3.0, H/L=0, Custom image = Natural, Dr = on, shadow = middle.
All parameters are verified as correctly recorded in EXIF data for photo as displayed by Pentax Utility supplied with camera to view PEF images.
Specifically, I mean the recorded exif for reference photo 2 show EV is now +3.0 and NOT 0.0!!! Yet the images are identical!!!
So, the taken photos record the data i entered, BUT, the images are identical, including recorded histograms.
This is NOT TRUE if i adjust H/L to say +4 instead of 0.0. The taken photos then are obviously brighter as I expect.
I am some what lost.
What U think??
Need yet more info???

02-08-2010, 02:46 PM   #5
Veteran Member
GoremanX's Avatar

Join Date: Dec 2009
Location: Georgia, VT
Photos: Albums
Posts: 1,653
pictures, pictures, pictures! How can we comment on anything without examples?
02-08-2010, 02:56 PM   #6
Inactive Account




Join Date: Jan 2010
Location: Brooklyn, NY
Posts: 144
QuoteOriginally posted by MichaelA Quote
Need yet more info???
Yes. What was the shutter speed of the two images?
02-08-2010, 03:41 PM   #7
New Member




Join Date: Feb 2010
Location: East
Posts: 8
Original Poster
OK,
Here are the 2 images I use for reference. Please keep in mind, these were for gaining experience in controls only. I simply wanted a reference so that I could see the improvement. I included the actual exif data from the Pentax Utility so that you can see it.
83.jpg is the original reference. 88.jpg, I expected to see the actual improvement.
When using AV mode the camera decides the shutter speed. It decided 1/25th for both.
Attached Images
   
02-08-2010, 04:05 PM   #8
Inactive Account




Join Date: Jan 2010
Location: Brooklyn, NY
Posts: 144
QuoteOriginally posted by MichaelA Quote
OK,
Here are the 2 images I use for reference. Please keep in mind, these were for gaining experience in controls only. I simply wanted a reference so that I could see the improvement. I included the actual exif data from the Pentax Utility so that you can see it.
83.jpg is the original reference. 88.jpg, I expected to see the actual improvement.
When using AV mode the camera decides the shutter speed. It decided 1/25th for both.
You used the flash in both images, you had set Custom 3, #17 "Flash in Wireless Mode" to #2 (Off), and you have your flash set to Wireless Mode. Set your flash back to Manual to fix this problem.

Otherwise, send your camera to Pentax 'cause it's broken.

Wait. Before you do that, go to Custom 4 and select Reset, and go to Setup 3, and select Reset again. If that doesn't work, THEN send the camera back to Pentax.

02-08-2010, 04:23 PM   #9
Veteran Member
GoremanX's Avatar

Join Date: Dec 2009
Location: Georgia, VT
Photos: Albums
Posts: 1,653
QuoteOriginally posted by Graystar Quote
Otherwise, send your camera to Pentax 'cause it's broken.
it's not broken, it's working perfectly fine.

When using the flash, the camera is limited to a specific shutter speed based on the focal length of the lens. All exposure compensation in this case is done by making the flash brighter or dimmer. What's happening here is you've reached the limit of what your flash can do.

edit: try the same experiment without using the flash, you'll see a dramatic difference when you use EV comp then.
02-08-2010, 07:35 PM   #10
Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 26,635
QuoteOriginally posted by GoremanX Quote
it's not broken, it's working perfectly fine.

When using the flash, the camera is limited to a specific shutter speed based on the focal length of the lens. All exposure compensation in this case is done by making the flash brighter or dimmer. What's happening here is you've reached the limit of what your flash can do.

edit: try the same experiment without using the flash, you'll see a dramatic difference when you use EV comp then.
Good catch GoremanX and Graystar!

Exposure comp only applies when not using the flash.

Steve
02-08-2010, 07:53 PM   #11
New Member




Join Date: Feb 2010
Location: East
Posts: 8
Original Poster
I checked Custom Menu 3 #17. It was set to #1 = ON = Fires built-in-flash as master in the wirelss mode.
I also checked the flash setting. It was set to Manual Flash discharge.

I will try the Custom 4 reset and Setup 3 reset tomorrow and let you know the results.

I will also try tomorrow repeating the experiment without flash as suggested.

However, the reason for this setup was to find a common usable mode that I could control with predictable results.
I was concerned @ Christmas when several photos did/did-not use flash unpredictably. Of course at that time I was using Auto mode until I got more familiar with the controls. Small unpredictable movements of people caused unanticipated blurs. That defeats the purpose of a camera like this.
I am trying to find common setups to control depth of in focus, flash = yes/no, and minimize blurs due to people moving unexpectedly.

I want to also point out that dramatic improvements were observed on the LV display and histogram prior to taking picture. It is very confusing to observe apparent dramatic improvements, yet they don't show up in the picture.
It kind of defeats the purpose of the LV preview.
Anyway, I will perform all these suggestions and return tomorrow with results.
All suggestions received are very much appreciated.
02-08-2010, 08:16 PM   #12
Veteran Member
GoremanX's Avatar

Join Date: Dec 2009
Location: Georgia, VT
Photos: Albums
Posts: 1,653
QuoteOriginally posted by MichaelA Quote
I checked Custom Menu 3 #17. It was set to #1 = ON = Fires built-in-flash as master in the wirelss mode.
I also checked the flash setting. It was set to Manual Flash discharge.

I will try the Custom 4 reset and Setup 3 reset tomorrow and let you know the results.
None of that matters one bit. If you're using the flash, exposure comp can only do so much. Especially at distances greater than 6 feet away from you. The camera can only make the flash go so bright.

QuoteOriginally posted by MichaelA Quote
I will also try tomorrow repeating the experiment without flash as suggested.
If you're not using the flash, then the camera is free to select whatever shutter speed it needs to get the exposure you want. You'll see a dramatic difference, but if there's not enough light, you'll also end up with shutter speeds that are so slow that camera shake will become a problem. This is especially true with the kit lens, which has a pretty small maximum aperture size.

QuoteOriginally posted by MichaelA Quote
However, the reason for this setup was to find a common usable mode that I could control with predictable results.
I was concerned @ Christmas when several photos did/did-not use flash unpredictably. Of course at that time I was using Auto mode until I got more familiar with the controls. Small unpredictable movements of people caused unanticipated blurs. That defeats the purpose of a camera like this.
In this case, the user's (you) unfamiliarity with camera systems is the problem, not the camera. Please don't take that as an insult, it's not meant as one. To get the most out of the camera, you're going to need to learn how the exposure triad relate to each other and how best to take advantage of them. The fact that you're trying to learn how to take advantage of Av mode is a huge step in the right direction.

QuoteOriginally posted by MichaelA Quote
I want to also point out that dramatic improvements were observed on the LV display and histogram prior to taking picture. It is very confusing to observe apparent dramatic improvements, yet they don't show up in the picture.
It kind of defeats the purpose of the LV preview.
Live View is not a very good way to judge how the picture will turn out. Live View is not a very good shooting tool most of the time, I only use it when I'm using an angle that prevents me from using the viewfinder comfortably. Remember, Live View is only trying to show you how the camera THINKS the picture will turn out. If it had the flash power to do what you're asking it to, that IS how the picture would look. But the built-in flash doesn't have that kind of output.
02-08-2010, 09:06 PM   #13
Inactive Account




Join Date: Jan 2010
Location: Brooklyn, NY
Posts: 144
QuoteOriginally posted by stevebrot Quote
Exposure comp only applies when not using the flash.
Actually, on the K-x it does brighten the image by making the flash more powerful. And this is regular EC I'm referring to...not flash EC. Dunno if this is something different that the K-x is doing.
02-08-2010, 09:10 PM   #14
Inactive Account




Join Date: Jan 2010
Location: Brooklyn, NY
Posts: 144
QuoteOriginally posted by MichaelA Quote
I checked Custom Menu 3 #17. It was set to #1 = ON = Fires built-in-flash as master in the wirelss mode.
Then GoremanX is probably right...the flash was maxed out to begin with in the first image and just couldn't get any brighter in the second.

Test this using a much smaller scene...shoot the items on a bookshelf or desktop. The flash will start at a low power and have room to increase power as you increase the EV Compensation.
02-08-2010, 09:29 PM   #15
Senior Member




Join Date: Jul 2009
Location: BC, Canada
Photos: Gallery
Posts: 174
QuoteOriginally posted by MichaelA Quote
I want to also point out that dramatic improvements were observed on the LV display and histogram prior to taking picture. It is very confusing to observe apparent dramatic improvements, yet they don't show up in the picture.
It kind of defeats the purpose of the LV preview.
Anyway, I will perform all these suggestions and return tomorrow with results.
All suggestions received are very much appreciated.
Please note that the LV display (and its histogram) was taken without the flash. That's why it is called "Live View". It is showing you what the sensor is seeing live, using available light, given the current ISO, aperture, shutter speed, EV compensation, etc.

When you enabled the flash, you were no longer taking the picture under the exact lighting conditions as the LV one.

If you want exactly what you are seeing in LV, then take the picture without enabling the flash.

Conversely, if you intend to take the picture with the flash, then you can not rely on LV to give you an idea exactly how the picture will turn out. You will actually have to take the picture with flash and then review image afterward.

Last edited by ma318; 02-08-2010 at 10:01 PM.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, comp, dslr, ev, ev comp, histogram, photo, photography, photos, preview
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
P5 Exposure Comp. Halco Pentax Film SLR Discussion 0 10-27-2009 07:08 PM
K7 users - exposure comp? nostatic Pentax DSLR Discussion 24 08-06-2009 08:14 AM
EV Comp in Manual Mode NeverSatisfied Photographic Technique 26 01-29-2009 08:21 AM
Exposure Comp. Question JohnV3 Troubleshooting and Beginner Help 27 06-08-2007 10:47 PM



All times are GMT -7. The time now is 07:11 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top