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Thread: Camera grossly over-exposing images in Av mode - Need help understanding why

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    Camera grossly over-exposing images in Av mode - Need help understanding why

    I took some pictures in the park of my daughter. The first few pictures show some nice green grass. Then the colors changed, I think I changed from the portrait setting to aperature priority trying to get a more shallow depth of filed. I have two questions. First, what can I do in-camera to prevent this in the future and second, how can I fix it in PP?

    Camera grossly over-exposing images in Av mode - Need help understanding why

    Camera grossly over-exposing images in Av mode - Need help understanding why

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    re: Camera grossly over-exposing images in Av mode - Need help understanding why

    Well I think Mr Oops crept in here.
    The first shot has been taken at 1/500 f4 and the second shot was taken at 1/200 f5. So the exposures are consistent, and considering the second shot is closer the step up to f5 is justified. What I can't understand is why THE FLASH FIRED IN COMPULSORY MODE. This has caused overexposure and the consequent loss of your contrast. Had the flash not fired you would have had the shot you wanted.
    Last edited by Colin Southern; 24th May 2009 at 03:58 AM.

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    Camera grossly over-exposing images taken in Av mode - Need help understanding why

    Quote Originally Posted by heather4279 View Post
    I took some pictures in the park of my daughter. The first few pictures show some nice green grass. Then the colors changed, I think I changed from the portrait setting to aperature priority trying to get a more shallow depth of filed. I have two questions. First, what can I do in-camera to prevent this in the future and second, how can I fix it in PP?
    Hi Heather,

    I've just checked the exif data attached to the image: the first was shot at 1/500th @ F4 @ ISO100 whilst the 2nd was shot at 1/200th @ F5 @ ISO400 - that an increase of over 3EV - which is why the image appears to be massively over-exposed.

    Big question is, why did it get it so wrong?

    Here's my theory ...

    In Portrait mode the camera takes care of shutter speed - aperture - AND ISO - and gave you a good exposure.

    In Av mode the camera runs with the selected aperture (F5 in your case), and varies the shutterspeed to suit - TAKING ISO INTO ACCOUNT. For some reason it looks like your camera is set to ISO = 400 which would mean that the shutterspeed should have been around 1/1600th, not 1/200th - BUT - it looks like you've had the flash popped up and it thinks that you want to use fill-flash. Problem is, it can't have a shutterspeed any higher than 1/200th if flash is to be used ...

    ... so the camera is between a rock and a hard place ... it's been told to use ISO 400 by the boss - it's been told to use F5 by the boss - and it's under strict instructions by the programmer not to use a shutterspeed of greater than 1/200th (even though it wants to go 5 times as high).

    OK - how to get around ...

    1. Set the ISO to 100 for starters on bright days when your using fairly wide apertures

    2. Don't use flash if you need a shutter speed above 1/200th

    3. Stop down your aperture until the shutterspeed drops to 1/200th or below.

    Also, if you take a look at the exposure meter in the viewfinder prior to taking the shot it should be centered - if it's off to one side then you've either dialed in come exposure compensation, or your asking it to do something that's not going to end well!

    To answer the other part of your question about what to do with these shots, I'd suggest shooting them again if you can. Bringing back the levels with a levels layer will make a BIG diference, but you've got significant areas of blown highlights, and no amount of post-processing is going to be able to recover them unfortunately.

    Does this help?
    Last edited by Colin Southern; 24th May 2009 at 04:00 AM.

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    re: Camera grossly over-exposing images in Av mode - Need help understanding why

    Thanks for such quick replies. Very new to all of this. So if the photo is overexposed, then I would increase the ev?

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    re: Camera grossly over-exposing images in Av mode - Need help understanding why

    Quote Originally Posted by Colin Southern View Post
    Does this help?
    It does help, even though some of it is in Chineese as far as I know. I'm trying to experiment and figure that it is a great way to learn. Only downside is that I like the picture and wish it did come out well.

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    re: Camera grossly over-exposing images in Av mode - Need help understanding why

    Quote Originally Posted by heather4279 View Post
    Thanks for such quick replies. Very new to all of this. So if the photo is overexposed, then I would increase the ev?
    Hi Heather,

    You'd dial in negative exposure compensation - but - I think your reply crossed with a major update to my first post -- you might like to re-read it as I think I've found the problem.

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    Re: Camera grossly over-exposing images in Av mode - Need help understanding why

    Hi Heather,
    Here's my version. Unlike film,the over exposed portion on digital pics looks pretty harsh. My trick is to soften it in PS using gaussian blur.
    If the skin tone still looks too much like a white kid, turn it into B&W. That's my last trick for exposure or WB mistakes.

    img_1644_1191_edited-1.jpg
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    Last edited by Colin Southern; 24th May 2009 at 04:58 AM. Reason: Insert Image Inline

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    Re: Camera grossly over-exposing images in Av mode - Need help understanding why

    Damn, missed the change in ISO.
    Last edited by Colin Southern; 24th May 2009 at 05:00 AM.

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    Re: Camera grossly over-exposing images in Av mode - Need help understanding why

    Quote Originally Posted by Bill44 View Post
    Damn, missed the change in ISO.
    Actually, I think that you still provided the missing puzzle-piece in that the exif info I was looking at didn't mention the flash ...

    ... when I saw you mention flash - the 1/200th suddenly made sense
    Last edited by Colin Southern; 24th May 2009 at 05:00 AM.

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    Re: Camera grossly over-exposing images in Av mode - Need help understanding why

    Quote Originally Posted by Raycer View Post
    Hi Heather,
    Here's my version. Unlike film,the over exposed portion on digital pics looks pretty harsh. My trick is to soften it in PS using gaussian blur.
    If the skin tone still looks too much like a white kid, turn it into B&W. That's my last trick for exposure or WB mistakes.
    Well, I have to say I'm pretty impressed with myself, not for the horrible picture, but because as the two of you were trying to help I was working with the photo. (Inserted the wrong pic at first.) without much knowledge I did exactly as you said. turned the pic b&w and then applied a gaussian blur.

    Camera grossly over-exposing images in Av mode - Need help understanding why

    Still want to try some things though, maybe working with the highlights?
    Last edited by Colin Southern; 24th May 2009 at 05:01 AM. Reason: Add closing quote tags

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    Re: Camera grossly over-exposing images in Av mode - Need help understanding why

    Hi Heather,

    Just to illustrate the point I was making with regards to the blown highlights, I've given the over-exposed image the "30-Second Photoshop treatment" (TM)

    As you can see, the blown highlight detail is gone for good - not possible to recover. When the remaining (non-blown) skin tones are returned to normal (as best possible; there are some VERY big shifts going on here) your still left with white areas on the upper nose, under the eyes, and in other areas.

    Camera grossly over-exposing images in Av mode - Need help understanding why
    Last edited by Colin Southern; 24th May 2009 at 05:01 AM.

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    Re: Camera grossly over-exposing images in Av mode - Need help understanding why

    Quote Originally Posted by Colin Southern View Post
    Hi Heather,

    Just to illustrate the point I was making with regards to the blown highlights, I've given the over-exposed image the "30-Second Photoshop treatment" (TM)

    As you can see, the blown highlight detail is gone for good - not possible to recover. When the remaining (non-blown) skin tones are returned to normal (as best possible; there are some VERY big shifts going on here) your still left with white areas on the upper nose, under the eyes, and in other areas.
    I see. Thank you for all of your time. It is much appreciated. Would you mind sharing with me the "30-second Photoshop treatment"? Can't believe the differnece, even if the picture is beyond repair.
    Last edited by Colin Southern; 24th May 2009 at 05:02 AM.

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    Re: Camera grossly over-exposing images in Av mode - Need help understanding why

    Quote Originally Posted by heather4279 View Post
    I see. Thank you for all of your time. It is much appreciated. Would you mind sharing with me the "30-second Photoshop treatment"? Can't believe the differnece, even if the picture is beyond repair.
    Of course

    1. Open the image in Photoshop

    2. Add a levels layer

    3. Move the mid-tone slider to the right until the skintones look about the right colour (about 0.25)

    4. Add an HSB (Hue-Saturation-Brightness) Layer and decrease the saturation about 25%.

    Job Done

    To be honest, it was so far out I was using the colour of the grass as more of a reference than your babies skin tones, although you'll no doubt have a better idea of how they should look that me.
    Last edited by Colin Southern; 24th May 2009 at 05:03 AM.

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    Re: Camera grossly over-exposing images in Av mode - Need help understanding why

    Quote Originally Posted by heather4279 View Post
    Well, I have to say I'm pretty impressed with myself, not for the horrible picture, but because as the two of you were trying to help I was working with the photo. (Inserted the wrong pic at first.) without much knowledge I did exactly as you said. turned the pic b&w and then applied a gaussian blur.



    Still want to try some things though, maybe working with the highlights?
    good job.
    Here are list of other things you can do:

    sharpen the front eye. selective soften the highlights - same technique as highlight glow. Also play with the curve to make the highlight shoulder softer.

    sorry, if you took the pic in jpg, you can't recover anything from the highlights. The best you can do is make the transition to 255,255,255 smoother.

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    Re: Camera grossly over-exposing images in Av mode - Need help understanding why

    All of you are very, very helpful.
    Raycer, I don't know how to do much of what you are advising but I greatly appreciate your help. It gives me something to manipulate and play around with.


    Looks like we are going to need another day at the park. Now just what to put on those toes to make sure she puts them back in her mouth.......?

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    Re: Camera grossly over-exposing images in Av mode - Need help understanding why

    how's this version?
    My girls just loves their toes too!
    cheers

    img_1644_1191_edited-1.jpg
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    Last edited by Colin Southern; 25th May 2009 at 06:33 AM. Reason: Insert Image Inline

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    Re: Camera grossly over-exposing images in Av mode - Need help understanding why

    Quote Originally Posted by heather4279 View Post
    how can I fix it in PP?
    Not going to go over one word that Colin has pronounced....but he is too gentlemanly to suggest cheating. In this case after getting back as near correct as poss using proper PP, pipette a bit of correct skin colour from the correct exposure pic and put a gentle wash of it over the whole partly-corrected one, then a bit more on the blown-highlight part, then minus it on the eyes
    Camera grossly over-exposing images in Av mode - Need help understanding why

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    Re: Camera grossly over-exposing images in Av mode - Need help understanding why

    If one were REALLY keen then I guess one could also use the very first photo as a source of "doner" skin for the one with blown highlights.

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    Re: Camera grossly over-exposing images in Av mode - Need help understanding why

    You are all too generous with your help.

    Raycer, I love how focused you have my daughter's eye. It looks beautiful. The rest of the picture looks a little too blurry for me. You are all very talented and I look forward to learning for each of you.

    Thanks again.

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    Re: Camera grossly over-exposing images in Av mode - Need help understanding why



    there's no blurry in my pics
    its soft focus :P

    cheers

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