Exposure, distortion and perspective ..

Discussion in 'Photography Beginners' Forum' started by redbourn, Dec 20, 2009.

  1. redbourn

    redbourn No longer a newbie, moving up!

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    Hi,

    Maybe I should have posted this on a PhotoShop forum and if "yes" then please just tell me.

    Some aspects of the photos may be of interest here though.

    I'm not a newbie at PS but am probably not yet at intermediate level either.

    I purposely chose this photo that I just shot in the desert because it has numerous problems.

    Perspective and/or len's distortion, and I'm not sure that I know exactly if this picture has just one, or both of them.

    Bland sky etc etc.

    pespective and distortion pictures by redbourn - Photobucket

    I still don't fully understand how much I should use exposure when working in RAW before I switch to brighten!

    I have looked at lots of tutorials about exposure but none of them explained how far to go before using 'brightness".

    Please take a look at the before and after pictures and tell me what I've made worse and what I've made better.

    Talking more about the technical aspect and not the artistic one.

    Thanks for your feedback,

    Michael
     
  2. IgsEMT

    IgsEMT No longer a newbie, moving up!

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    Michael,
    Photography as well as processing is really a subjective topic. I can show you my stuff and you might totally hate PP on it.
    I think it looks fine.
    you're retouch is nice - you brought the detail back to the sky.
    Generally, it's a combination of both factors. One person might have one workflow, another different.
    My first step is adjust WB (if needs be), then exposure. Buddy of mine will first recrop/recompose the image and will adjust color and exposure last.
    Its just a matter of preference what is more natural to you.
     
  3. KmH

    KmH Helping photographers learn to fish Supporting Member

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    Start by straightening the image so vertical lines, like the corners of the buildings, are indeed vertical before you attempt to evaluate the image for lens and perspective distortion. Where possible use vertical lines near the center of the image.

    One way to evaluate the amount of distortin is to drag guidelines out from the rulers. The guidelines are known to be straight so you can compare them to lines in the image that should be straight.

    As far as the Exposure and Brightness sliders in ACR: Exposure is just that and a change of 1 equals an exposure change of 1 stop. You can hold down the Alt key (PC) when you do the adjustment and the image will go completely black except the highlights in the image that are being clipped or at their maximum exposure values (255). If the image is completely black none of the highlights are being clipped. Not all color channels clip at the same time, so if you see red splotches only the red channel is being clipped. If you see yellow, both the red and blue channels are clipped. White means all 3 color channels are clipped. You can see that in the histogram too.

    An alternative is to activate the clipping indicators in the upper corners of the histogram. I prefer using the Alt key. The Alt key works similarly for the Blacks slider but the screen goes white rather than black.

    In ACR, the sliders are arranged in the order Adobe recommends they be used and that puts then Brightness slider down the list. The previous sliders have made tonal adjutments to the brightest and darkest areas of the image but may have altered the overall optimal brightness of the middle tones. The Brightness slider is like the Middle Tones slider in Levels and can be used to adjust the overall tonality of the image.
     
  4. redbourn

    redbourn No longer a newbie, moving up!

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    Thanks for the feedback. I'm a little concerned that there's some lens distortion down the left hand side, but it's obviously not terrible if it's not so readily apparent.

    I bought the camera used with 3 lenses and have hardly used the Nikkor 70-300 because I really need to use a tripod with it.

    Unless I've had about 5 beers of course :lmao:

    I'm still learning to use the camera properly and need to get some basics under my belt, and they're my main priorities right now.priority.

    Mike
     
  5. IgsEMT

    IgsEMT No longer a newbie, moving up!

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    Who said you need a tripod with that?
    It might be helpful but depends on what you're shooting.
     
  6. redbourn

    redbourn No longer a newbie, moving up!

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    Keith ...

    Start by straightening the image so vertical lines, like the corners of the buildings, are indeed vertical before you attempt to evaluate the image for lens and perspective distortion. Where possible use vertical lines near the center of the image.


    I tried straightening lines in this picture but when I straightened one side the other side of the picture got more slanted.

    As far as the Exposure and Brightness sliders in ACR: Exposure is just that and a change of 1 equals an exposure change of 1 stop. You can hold down the Alt key (PC) when you do the adjustment and the image will go completely black except the highlights in the image that are being clipped or at their maximum exposure values (255). If the image is completely black none of the highlights are being clipped. Not all color channels clip at the same time, so if you see red splotches only the red channel is being clipped. If you see yellow, both the red and blue channels are clipped. White means all 3 color channels are clipped. You can see that in the histogram too.

    An alternative is to activate the clipping indicators in the upper corners of the histogram. I prefer using the Alt key. The Alt key works similarly for the Blacks slider but the screen goes white rather than black.

    In ACR, the sliders are arranged in the order Adobe recommends they be used and that puts then Brightness slider down the list. The previous sliders have made tonal adjutments to the brightest and darkest areas of the image but may have altered the overall optimal brightness of the middle tones. The Brightness slider is like the Middle Tones slider in Levels and can be used to adjust the overall tonality of the image.


    Some excellent tips thank you.

    If I remember correctly, the original of this picture didn’t extend all the way to the right or to the left in the histogram, so I dragged the exposure sliders until both sides nearly reached the edges and then adjusted the brightness control, but that might well be a bad way of doing things.

    Seems like I should be adjusting channels separately but I’m not sure if that can be done in Camera Raw 5.2

    A picture speaks a thousand words so I just uploaded one ..

    pespective and distortion pictures by redbourn - Photobucket

    Called “under exposed?”.

    I assume it’s underexposed and my reaction would be to raise the exposure by .75 of a stop and to raise the blacks to 15.

    The trees are an example of what I meant by distortion.

    I have heard that the D70 under exposes so maybe I should change the default to +1

    Mike
     
    Last edited: Dec 20, 2009
  7. IgsEMT

    IgsEMT No longer a newbie, moving up!

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    Interesting. Didn't have that problem with that body.
     
  8. redbourn

    redbourn No longer a newbie, moving up!

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    When did you last have a body ;)

    Mike
     

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