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Thread: Building up multiple exposures...

  1. #1

    Default Building up multiple exposures...

    ok...got a basic question here about photoshop...

    how do i build up multiple exposures from digital images in photoshop? (want to achieve the equivalent in traditional film cameras...where multiple exposures on the same frame are made by exposing the film several times without advancing the film itself.)

    *not referring to simply putting layers on top of one another and adjusting the opacity*

    im sure there is a simple answer to this simple question...just that i have not figured out how it can be done. thanks for any tips in advance!

  2. #2

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    any tips and hints, guys?

  3. #3

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    i could tell u how to do it out of photoshop...

    strobe firing at regular intervals....else the only way i know of in photoshop is using the overlay...

  4. #4
    Senior Member sammy888's Avatar
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    Quote Originally Posted by imaginevisuals
    any tips and hints, guys?

    Like what Witness said.... YOu can do this outside of Photoshop. You do it all by using your camera. ANd yes you might be thinking..there is no multi-firing single frame feature like on some of the 35mm cameras in the DSLR. I did my first multi-strobe effect when I was using my Nikon FG in bulb mode. The strobe is not perfect as I hand fired it on my SB15 flash. Also note...you can't use your BUILT-IN flash to do this. You need a flash unit with which allows you to fire off multiple times. Most of the modern flash from Nikon does that more easily now and can even calculate the distance for you sow it to you on LED screen. But here is how I did it back during the Caveman days of early 80s heheh....

    I would set up the shot by calculating the flash power ratio to the distance I need to illuminate the shot. And you have to also factor in how many shots can be fired off per trial shot. That means you can not fire the flash at 100% flash power output. You have to set it at about 1/20 output flash power or there about...depending on how many strobe shot you want to fire in one frame of slide or negative. The easiest way to try this and get pretty good first time result would be to do this in the open. I did my at the beach at night where there is no background to reflect back stray light to my camera. I even added using those sparklers firework stick to "write" or "draw" images. Anyway, once I have my calculation all done up and with my friend as a model...and almost in the dark, go through a set of action he/she would do. Then I set the camera to bulb or in the case of modern SLR or DSLR set the exposure time to about anything from 10 secs to 20secs. Then trigger the shutter to open and tell your model to go through the actions and then you manually (holding the flash) press the manual flashing button in quick succession at your model. I got very good results even from my first time doing it. These days if you do this with your DSLR you get instant results to make adjustment..back then I have to wait a day to see if I got it right or wrong from the prints Also take note of your DOF to make sure the action takes place along the same focal length and there is also the need to have AF switch off and focused manually to the right distance.

    You can do this in Photoshop but it is not as simple as just doing layers. You have to work each image first to get the right transparency effect for both subject and background at the right exposure ( keep back ground simple or it would mean alot more hand work to clean up all the images) then there is the layering work to finish it all off. This is the only way to go if you want very controlled effect and working at varying distance and the actions are difficult at each stage of the exposure.

    I would recommend the manual way of doing it and not use Photoshop..which is really very hard work. I am a designer and I don;t even want to think about doing it on the PS unless you pay me heheh. Besides the photo shooting is where yo uhave the most fun figuring it all out.

    But if you want very controlled and well timed strobe shots....well unless you have a big wallet of $$$...buying a real strobe flash is not cheap. I recall Nikon having one but it is in the 5 figure dollar range You can do some basic strobe timing with your Speedflash...I have done that with my old SB26 and 28 ( my last few non DSLR era before I switch over) Also with a dark background and one where little to none busy background would help alot too and help make exposure more predictation. But that is a good place to start you on your way to more dramatic and complex strobe shots.

    Anyway..that was how I went about it with my strobe fetish photo experiments
    Last edited by sammy888; 5th November 2004 at 10:42 AM.

  5. #5

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    http://forums.clubsnap.org/showthread.php?t=2739

    In Photoshop, you paste the new picture over the old one as a new layer. Then you create a layer mask (specifying Hide All). Then you use the brush and "paint" in only those areas you want to include.
    Last edited by StreetShooter; 5th November 2004 at 11:22 AM.

  6. #6

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    thanks for the info guys, including the very exhaustive and informative manual written by sammy888 on "painting with light" with flash strobes. lovely picture you have there streetshooter!

    ok..let me clarify the purpose of asking such a question. let me simulate a shooting scenario, in order to put the question into context.

    let's say i have a tall sculpture, over 1.8 metre tall, and one flash strobe. in order to capture the art piece in its entirety, i would probably need to light it from several different angles (side, back, top, bottom etc.) to bring out its form, shape and texture. obviously 1 flash exposure won't do the trick, and setting the camera on long exposure and 'paint' the sculpture with flashes from the strobe as sammy888 described presents a few problems for me.

    1) during the entire exposure, any movement within the frame would be captured. hence, i can't move around the subject lighting it from different angles, unless i move really really fast.

    2) painting it with light this way is unpredictable as i won't be able to see the effects beforehand...how the light falls, any stray shadows, unwanted flare, strength of flash etc.

    it will be good if i want to do an experimental picture with unpredictable results. in this hypothetical scenario however, i would like WYSIWYG and a carefully choreographed lighting situation.

    with a traditional 35mm film camera, careful calculations can be made before each exposure on the same frame. set up lighting -> open shutter, flash -> close shutter -> repeat step 1 as needed.

    with a DSLR, the benefits are immediately obvious. the effects of each flash exposure can be reviewed and changes made accordingly. i can appear in the picture holding the flash, but i can be easily erased out later, as described by Streetshooter.

    however, this is the part where i got stumped. how i do combine the several images i have into one coherent picture? certain light rays will overlap each other, in essence, naturally adding on exposure to the previous (aka 'brighter'). simply adjusting the opacity of layers on top of another won't achieve that effect, nor erasing away layers. i know some software that comes with digital backs can achieve that automatically, but obviously i don't have access to that.

    i am sure photoshop can achieve that same effect of "building up" exposures, albeit a bit more manually. and i'm quite confident it's a matter of adjusting layer modes etc...but i haven't figure that out yet.

  7. #7

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    I painted this with a torchlight and a few minutes exposure time:

    http://forums.clubsnap.org/showthread.php?t=45622

    Is this what you had in mind? f22 ISO 100 i think.

  8. #8

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    maybe...is it a series of multiple exposures combined in photoshop? mind sharing your workflow? thanks!!

  9. #9

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    No, it is a single exposure (about 5 mins) at f22 ISO 100.

    I used a torchlight to illuminate the subject from many different angles. I shone the light for a longer duration on those areas I wanted to highlight.

  10. #10

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    ok..then it's not it then. it's similar to what sammy888 had written on, light painting... the quest continues!

    thanks for all the info anyway, it has been useful!

  11. #11

    Default tada...

    ok ... finally found the time to do a little experimentation today. as mentioned, what i wanted to achieve is similar to light painting, except the flash exposures i make come in separate, individual frames.

    to cut a long story short, the question is how to make the individual frames blend together 'naturally' to produce a correctly-exposed picture (i.e. each consecutive frame must add on to the exposure, i.e. make it brighter)

    EXPERIMENT
    *pardon for the quality of pictures to be shown below...nothing asethetic about them, just to serve to illustrate my point*
    picture is of my cd collection shelf.


    first, i exposed the bottom half of the shelf with a flash exposure at f/11, 1 second.





    the second exposure is for the top half...





    back in photoshop, i layered the top half on top of the picture of the bottom half. then it was a matter of finding which layer blending options to apply. i discovered 'linear dodge' works best. here is the result...


  12. #12
    Senior Member sammy888's Avatar
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    Well there you go.... There is nothing you can't do with a bit more time spent thinking about it.. knowing where the strengths of your camera equipment are and also learning abit about post-picture production like Photoshop. Now you are moving into the realm that is my favorite..mixed media production. Your concept is something most graphic designers uses ever so often. Looks like you are on your way to more complex shooting now.

  13. #13
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    Hi, pardon my ignorance but what is the purpose of this exercise?

  14. #14

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    saberlancer> it will be useful if one need to capture a scene which require multiple flash lighting setup, and you have less than what you require.

    actually i learnt this trick from interior photographers who use this method when capturing a super wide view. why?
    1> big room, and you might not have enough lighting equipment at hand. hence, need to duplicate lighting setups

    2> big room, unable to hide all lighting equipment without appearing in the scene.

    of course, they have access to proprietary software that comes with the digital back to combine the various exposures easily and automatically (ie. can duplicate the effects of building up exposures on film). was trying to find a roundabout way to do it in photoshop

  15. #15
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    Quote Originally Posted by imaginevisuals
    i discovered 'linear dodge' works best. here is the result...
    OIC,so thats what this is for...
    Hmm,actually,'dodge' brightens/saturates up ur image but u may wanna try 'lighten' instead as it most closely matches ur original photos?

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