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Thread: Making Sharp Images

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    Workshop Member glenerrolrd's Avatar
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    Making Sharp Images

    As I am getting into some Landscape photography , I am learning about some of the trade offs in working with long exposures . Could use some insights from the experienced group here at GETdpi .

    Context ....Leica S kit , primarily seascapes at dawn ....challenges ...dynamic range ,diffraction and noise .

    With a large Gitzo and B55...having no problems with stability ..long exposures up to the practical limit on the Leica S of 60 second exposures (you can get around this but Leica had a point in limiting automatic exposures beyond 60 seconds ).

    With the Leica CCD sensor on the S ...you want to be at base ISO where the DR is at its best as you increase ISO you pay a heavy price in loss of DR (limitation of the Leica and most CCD sensors ). This is how I am taking on the challenge of needing maximum DR .

    Diffraction ....most of the tests show that diffraction with a Leica S kicks in starting at F8 ..but with proper sharpening can be mitigated up to about F13.5 (from diglloyds recent tests of the 30-90 S lens). At F16 ....you have lost “maybe” too much . I would like to be at F22 ..but can t get there without incurring a penalty someplace.

    Exposure ...from my tests clearly going beyond 60 sec exposures is adding too much noise to the images ....but I ve seen advice that indicates that beyond 20-40 seconds with a CCD sensor will result further degrading of sharpness to handle the noise trade off.

    First ...do I understand the trade offs correctly . Second ....how do you establish the BEST balance (obviously it depends on the requirements of a specific capture ) . But .....getting some perspective is my objective .

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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: Making Sharp Images

    One approach I've taken in the past is to consider what you want to shoot with extended exposure (sky, sea etc) and the rest of the subject matter that will leverage the sharpness and resolution of the system. Take two shots, one with a short exposure for the main subject matter to create a low noise image and then another long exposure for the movement component. Blending the shots allows you to apply any required noise reduction to the longer exposure without necessarily degrading the main subject matter.

    Just a thought - it doesn't work in all scenarios / subjects and is a post processing extra step but it can make up for the image degradation from long shots.
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    Senior Member danlindberg's Avatar
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    Re: Making Sharp Images

    +1
    That's exactly what I do, when the scene allows for it.
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    Re: Making Sharp Images

    Focus stacking can work for some subjects, since it allows a larger aperture and proportionally shorter exposures.

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    Workshop Member glenerrolrd's Avatar
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    Re: Making Sharp Images

    Thanks for the insight ....do I understand this correctly . You are recommending focus stacking. One exposure keeps the ISO low,the aperture small and lets the exposure go to whatever is needed . Lets assume this might be ISO100(base) ,F13.5 (max before degrading due to diffraction beyond what can be repaired in post) and an exposure of 60 sec .this is the desired exposure with good depth of field .

    The 2nd exposure would be still base 100 , but now the aperture is closer to wide open say F4 so that the exposure would 8 sec . Not ideal but producing less noise . Focus would have to be on the primary areas where sharpness is desired ?

    If you had to compromise further ...would you increase the ISO in order to push down the exposure ? The ISO loses both DR and creates noise ....the exposure just creates noise . Is that correct?

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    Senior Member danlindberg's Avatar
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    Re: Making Sharp Images

    When I use this technique it is usually in ok light. I use ND filters to reach desired exposure length and can therefore unscrew the filter and remain with same aperture (and ISO) for second faster exposure. The trick here is to just screw on the filter very loosely so that you can unscrew it easy to not disturb the cam.

    As I am working with a tech cam I have the bonus to be able to introduce forward tilt for larger DOF and still use a moderate aperture.

    Photographing in dim, low light then this does not work and I guess it is more a question of trial and error to find the best balance with your sensor/lens combo.
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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: Making Sharp Images

    One thing that would help would be to know whether you WANT long exposures and their effects or whether you find yourself having to take a long exposure due to the light levels.

    As Dan described, using an ND filter for long exposures and then removing and reshooting a shorter shot without the ND (using the same aperture) can give you the two shots for blending if you want the long exposure effect.

    If you are forced into the long exposures, then it's a different problem to solve with respect to exposure time/aperture/ISO and noise. I would do some tests with the S to compare longer exposures vs higher ISO noise to see what is the best trade off with your system.

    Btw, another approach if the subject is static but you want a long exposure look is to shoot multiple images and then stack them in Photoshop using mean/average and weighting the layers from the bottom up 100%, 50%, 33%, 25%. 20% etc.
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    Administrator, Instructor Guy Mancuso's Avatar
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    Re: Making Sharp Images

    Don't rule out painting with light both with flash or even flashlights which I use flashlights a lot sometimes. Not as primary techniques per say but some additional help.
    Photography is all about experimentation and without it you will never learn art.

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    Re: Making Sharp Images

    Quote Originally Posted by glenerrolrd View Post
    Thanks for the insight ....do I understand this correctly . You are recommending focus stacking. One exposure keeps the ISO low,the aperture small and lets the exposure go to whatever is needed . Lets assume this might be ISO100(base) ,F13.5 (max before degrading due to diffraction beyond what can be repaired in post) and an exposure of 60 sec .this is the desired exposure with good depth of field .

    The 2nd exposure would be still base 100 , but now the aperture is closer to wide open say F4 so that the exposure would 8 sec . Not ideal but producing less noise . Focus would have to be on the primary areas where sharpness is desired ?

    If you had to compromise further ...would you increase the ISO in order to push down the exposure ? The ISO loses both DR and creates noise ....the exposure just creates noise . Is that correct?
    My suggestion applies to certain situations which I can illustrate with an example: Conditions require f/16 for DOF and an exposure of 120 s. You wish to avoid the long exposure, higher ISO and diffraction. So 3-4 separately focused shots at f/5.6 and 15 s could be focus stacked avoiding all the negatives and giving sufficient DOF. If you want long exposures for blur, then Dan's, Graham's or your interpretation may be more appropriate. My 645D has a similar Kodak sensor and I almost never used it above ISO 400 and that only rarely - too noisy.

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    Re: Making Sharp Images

    It might sound dismissive but it may be that you aren't using the right tool for the job and as a result, you won't get the images you want. I'm a massive fan of the S, it has replaced almost every camera I own and I use it now for 95% of my work, personal and commercial but despite it's absolute brilliance, it doesn't work for everything.

    I have done a lot of experimentation with long exposures, it's just not designed for what say a D810 would take in its stride when it comes to long exposures. For me, once off base ISO the shot length is dramatically reduced, 8 seconds at ISO 800 is at the absolute limit for me and I wouldn't print that. To be honest, if it's not doable at ISO100 then I reach for the Nikon for anything over 30 seconds.

    I am also not that worried about the affect on DR and also diffraction, I can only comment on my experience but I have printed 48" long images shot at f22 and seeing nothing at all that would indicate a significant loss in quality at those sizes, I haven't printed bigger so can't comment further. I have no problem with using the aperture I require for the shot, I just don't find it a problem when I'm shooting landscapes, I'll take an image at f22 any day over a shot at f11 which doesn't include what I want in focus. As far as focus stacking goes, I have shot plenty with the background as a single exposure at say f11 and the foreground as a second shot but I'm not sure how that would help you for the type of sunrise scenes you are talking about, too much has happened within a minute anyway, especially with the dark frame doubling that time.

    My advice for what it's worth, use the S for what it's amazing for, use something else for what it isn't.
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    Re: Making Sharp Images

    But if the scene luminance range is less than the sensor DR, you can shoot at a higher ISO without losing tonal values. You do get noise. I am not sure what that is like on an S.

    Diffraction is overstated on 6um sensors. I routinely use f/16 and make very sharp images with a bit of sharpening. I will use f/22 as well with no complaint.

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    Workshop Member glenerrolrd's Avatar
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    Re: Making Sharp Images

    This has been quite helpful . Just to level set ......living in Florida near a Fishing Pier ...(10minutes) ..its easy to go down to the pier a dawn and check out the clouds . Predawn in the blue period always seems to provide the best light . To shoot at small apertures ....I am struggling with maintaining base ISO and exposures under 20 seconds ....not enough light .

    Since this must be a common problem ...assumed that I could learn something about managing the trade offs ...

    1. Increase the ISO .

    2. Increase the exposure time .

    3. Opening up the aperture .

    I am not trying manage “blur” in the water or clouds ....this is pretty easy in light this low. Ultimately I will ,of course, gain enough experience to arrive at my own “best practice”. But I appreciate the insights gained from others.

    This scenic is very common and to my eye I favor the aesthetic produced by medium format CCD sensors ..I want the fine tonal grades in the mid tones and the clean bright highlights . Again many ways to achieve a good outcome .

    And yes I could use my D810 and the Zeiss lenses to make it easier to manage the tradeoffs .

    Next time I will include a photo ....but I am packing down the Florida home for the season .

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    Senior Member dchew's Avatar
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    Re: Making Sharp Images

    Roger,
    Given the goals above, I would stick at base ISO, go to the longest exposure time you know you will be happy with, then open up the aperture and focus stack. Depending on the composition you might get away with only two images. One for the pier and one for the sky.

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    Senior Member ErikKaffehr's Avatar
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    Re: Making Sharp Images

    Hi,

    I don't know about the noise thing. ISO may be just fake, same thing as underexposure.

    Regarding diffraction, I would say that you can go beyond f/13.5. Very clearly, you will start loosing sharpness, but you can probably recover a lot of it. You need to increase sharpening radius from say 0.8 to 1.3, tough.

    Anyway, that is for pixel peeping, for prints you could sharpen with a larger radius. Personally, I would advocate a two step sharpening.

    • Stage 1: sharpen with a high amount and small radius (in my case 0.8 and 45 in LR)
    • Stage 2: sharpen with say radius 2 and a small amount (say 15-25% in PS)


    Stage one fixes microcontrast while stage two pushes contrast at low frequencies which dominate perceived sharpness.

    Best regards
    Erik


    Quote Originally Posted by glenerrolrd View Post
    Thanks for the insight ....do I understand this correctly . You are recommending focus stacking. One exposure keeps the ISO low,the aperture small and lets the exposure go to whatever is needed . Lets assume this might be ISO100(base) ,F13.5 (max before degrading due to diffraction beyond what can be repaired in post) and an exposure of 60 sec .this is the desired exposure with good depth of field .

    The 2nd exposure would be still base 100 , but now the aperture is closer to wide open say F4 so that the exposure would 8 sec . Not ideal but producing less noise . Focus would have to be on the primary areas where sharpness is desired ?

    If you had to compromise further ...would you increase the ISO in order to push down the exposure ? The ISO loses both DR and creates noise ....the exposure just creates noise . Is that correct?

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