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Thread: Super long exposures with MF Digital Backs

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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Super long exposures with MF Digital Backs

    Given that most digital backs are limited to <60 or <32 seconds for exposure, ignoring obviously the P45+, what techniques or recommendations do folks have for super long exposures that extend beyond a minute?

    I've looked at some of the star trail info out there that use 3rd party tools for combining collections of exposures but I was wondering if folks had some practical techniques for situations where you might want to combine shots for different situations such as flowing water such as waves or removing people from static landscapes? It seems to me that star trails are additive exposures vs landscapes or cityscapes where I want to average out elements.

    I have NDs for the exposure side of things but my Leaf & Phase One backs have limited maximum exposure.

    Thoughts or pointers to techniques or info out there that maybe I've missed?

    Thanks
    Remember: adventure before dementia!

    As Oscar Wilde said, "my tastes are simple, I only like the best"

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    Re: Super long exposures with MF Digital Backs

    I'm very interested in this too. I get 256 seconds from the H4D but would like to find a software solution for long exposures so that I can do star trails.
    Cheers,
    Jeff
    www.jeff-grant.com

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    Re: Super long exposures with MF Digital Backs

    I was never able to disable the dark frame capture with my P65+, so there was always a 30-second delay after the initial 30-second exposure. I see this as the biggest obstacle in making star trail stacks, as rather large gaps in the trails occur due to the dark frame captures.

    If you're able to disable the dark frame capture, then you can stack images pretty easily with Photoshop. Otherwise, a free utility called, "Startrails.exe" works perfectly for these purposes.

    Utility can be downloaded here: http://www.startrails.de/html/software.html

    The effectiveness is entirely dependent upon the ability to disable the "long exposure noise reduction" of the backs.

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    Re: Super long exposures with MF Digital Backs

    Thanks, the H4D doesn't need the dark frame capture so that isn't an issue. I'll look at Startrails.
    Cheers,
    Jeff
    www.jeff-grant.com

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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: Super long exposures with MF Digital Backs

    I guess I should clarify - I'm actually NOT looking for star trail solutions. What I'm looking for is a solution that would allow me to shoot a multi-minute or hour composite during daylight that would produce the same result as using a 10 stop or stronger ND filter.

    My particular use cases are seascapes or removal of people/vehicles from cityscapes without leaving behind trails. My thoughts are that averaging the brightness of each pixel of an image stack would produce the desired result which is a different technique to that required for star trails where you want to record the brightest level for each pixel in a stack.

    (Btw, for a Mac this looks interesting & worth checking: Keith Wiley's keithsImageStacker)
    Remember: adventure before dementia!

    As Oscar Wilde said, "my tastes are simple, I only like the best"

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    Re: Super long exposures with MF Digital Backs

    Thanks Graham, my apologies for highjacking your thread.
    Cheers,
    Jeff
    www.jeff-grant.com

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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: Super long exposures with MF Digital Backs

    Jeff, no problems just trying to find a non-star trail solution
    Remember: adventure before dementia!

    As Oscar Wilde said, "my tastes are simple, I only like the best"

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    Re: Super long exposures with MF Digital Backs

    Would the KG Multi-Shot/Long Exposure box work for you? http://www.kapturegroup.com/phase/phase.html#4x4one_a

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    Re: Super long exposures with MF Digital Backs

    Shooting long exposures in daylight leaves car and people trails that look like a fog. I haven’t tried that but what if you were to increase the contrast on the picture and apply the contrast on the foggy area using a mask. Would that work? I assume the contrast could help remove the fog effect, wouldn’t it?

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    Re: Super long exposures with MF Digital Backs

    Quote Originally Posted by Laurent View Post
    Shooting long exposures in daylight leaves car and people trails that look like a fog.
    In my experience, as with most things, it all depends upon the specific circumstances. Catherine Opie, for instance, had great success with her American Cities project using long exposures during daylight to eliminate the traces of peoples presence in public places (although she was shooting film), as you can see here: http://www.themorningnews.org/archiv...erican_cities/

    Back to the specific question at hand, I wonder if the sort of "averaging" process Graham is seeking couldn't be accomplished manually in Photoshop by stacking the individual photos as separate layers and blending them together using the various modes available?

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    Re: Super long exposures with MF Digital Backs

    you can also use the "statistics" script in photoshop CS3/4/5:

    http://buzz.shutterstock.com/photoshop-remove-people

    best,

    geb

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    Re: Super long exposures with MF Digital Backs

    Sometimes those "foggy" people can make for pretty cool photos: http://www.alexeytitarenko.com/index.html

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    Re: Super long exposures with MF Digital Backs

    stephen: those are very nice!

    would be good to have the control over the long exposure and play around with this

    i think blad is the only back that does not use a darkframe though

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    Re: Super long exposures with MF Digital Backs

    Quote Originally Posted by GrahamWelland View Post
    I guess I should clarify - I'm actually NOT looking for star trail solutions. What I'm looking for is a solution that would allow me to shoot a multi-minute or hour composite during daylight that would produce the same result as using a 10 stop or stronger ND filter.

    My particular use cases are seascapes or removal of people/vehicles from cityscapes without leaving behind trails. My thoughts are that averaging the brightness of each pixel of an image stack would produce the desired result which is a different technique to that required for star trails where you want to record the brightest level for each pixel in a stack.

    (Btw, for a Mac this looks interesting & worth checking: Keith Wiley's keithsImageStacker)
    You might actually be able to get by just fine with using the same program (Startrails.exe) for your purposes. Throw a few sequential 30+ second exposures into the program and try the different blending/stacking options. Being that you're not shooting anything that will show gaps, it will probably turn out close to what you're hoping for.

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    Re: Super long exposures with MF Digital Backs

    To remove people and vehicles you should use median stacking option. You do not have to use long exposures, but shoot many frames. If you use photoshops stacking you can manually remove areas causing problems (because there is a high concentration of items in that area)
    If you wan't to do landscapes use average stacking option

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    Senior Member ondebanks's Avatar
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    Re: Super long exposures with MF Digital Backs

    Graham,

    You should use DeepSkyStacker - despite its name, it is not only suitable for astronomy. It would suit your purposes, because you can choose any combination algorithm you please - not just "maximum" which is what most star trails software uses. Averaging, median, weighted averaging, sigma clipping...it's all there.

    And it's free.

    http://deepskystacker.free.fr/english/index.html


    And on the subject of backs that can or can't disable dark frame subtraction: I'm glad to hear that the H4D is in the stable that can disable it. Add that to the Pentax 645D, Mamiya ZD, the old Kodak 645 backs, and maybe some others. Now Phase One need to do it as well!

    Change your bloody firmware, Phase One!


    Ray

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    Re: Super long exposures with MF Digital Backs

    Quote Originally Posted by ondebanks View Post
    You should use DeepSkyStacker - despite its name, it is not only suitable for astronomy. It would suit your purposes, because you can choose any combination algorithm you please - not just "maximum" which is what most star trails software uses. Averaging, median, weighted averaging, sigma clipping...it's all there.
    So, assuming Phase One did let you disable the dark-frame subtraction, am I correct in assuming that you could effectively accomplish almost the same thing with this software by capturing a dark-frame at a more convenient time (say, after you have made a couple of exposures) and stacking them post-exposure?

    I know that, ideally, the dark-frame image should be made under identical conditions, but I wonder how close close-enough would get you? Being able to capture the dark-frame during downtime (say, when moving the camera to a new position or new location) certainly would be a lot more convenient, even if the results might not be quite as good as they are using the present methodology...

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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: Super long exposures with MF Digital Backs

    Thanks folks for the feedback. I'll give the average/median algorithms a try on some street scenes I have with me.

    Graham
    Remember: adventure before dementia!

    As Oscar Wilde said, "my tastes are simple, I only like the best"

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    Re: Super long exposures with MF Digital Backs

    Quote Originally Posted by ondebanks View Post
    Graham,

    You should use DeepSkyStacker - despite its name, it is not only suitable for astronomy. It would suit your purposes, because you can choose any combination algorithm you please - not just "maximum" which is what most star trails software uses. Averaging, median, weighted averaging, sigma clipping...it's all there.

    And it's free.

    http://deepskystacker.free.fr/english/index.html


    And on the subject of backs that can or can't disable dark frame subtraction: I'm glad to hear that the H4D is in the stable that can disable it. Add that to the Pentax 645D, Mamiya ZD, the old Kodak 645 backs, and maybe some others. Now Phase One need to do it as well!

    Change your bloody firmware, Phase One!


    Ray
    Just checked this program out -- looks much, much more featured than the one I suggested.

    Thanks!

  20. #20
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    Re: Super long exposures with MF Digital Backs

    There's a tourist remover built into Photoshop via Smart Object stacks!

    This is also a great trick for reducing noise by averaging multiple exposures.

    http://photoshopnews.com/2007/03/27/...-cs3-extended/

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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: Super long exposures with MF Digital Backs

    Be sure to read the fine print ... that's only with Photoshop CS Extended Edition which is a $350 upgrade from CS5.

    I remember seeing this and contemplated whether the upgrade was worth it. Well, I guess that the image stack features might well push me over the edge although I think I'll give it a whirl with the eval version first.
    Remember: adventure before dementia!

    As Oscar Wilde said, "my tastes are simple, I only like the best"

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    Re: Super long exposures with MF Digital Backs

    The median filter in PS is not only good for removing random moving objects -- it also can virtually eliminate random noise artifacts by stacking multiple exposures. Try averaging (medianing) 8 short high ISO shots vs one long low ISO shot with dark frame exposure.

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    Senior Member ondebanks's Avatar
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    Re: Super long exposures with MF Digital Backs

    Quote Originally Posted by Audii-Dudii View Post
    So, assuming Phase One did let you disable the dark-frame subtraction, am I correct in assuming that you could effectively accomplish almost the same thing with this software by capturing a dark-frame at a more convenient time (say, after you have made a couple of exposures) and stacking them post-exposure?
    Yes, exactly. This is what astrophotographers do. The last thing we want to be doing on a clear starry night is losing 50% of our long exposure opportunity time to the enforced taking of long dark frames.

    Quote Originally Posted by Audii-Dudii View Post
    I know that, ideally, the dark-frame image should be made under identical conditions, but I wonder how close close-enough would get you? Being able to capture the dark-frame during downtime (say, when moving the camera to a new position or new location) certainly would be a lot more convenient, even if the results might not be quite as good as they are using the present methodology...
    There is some leeway (several degrees) in the temperature matching; DSS for example has an option to try to scale dark frames to the observed intensity distribution of hot pixels in the scene frame. Also, many astrophotographers simply shoot a "library" of dark frames at different temperatures and choose the nearest match.

    Ray

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