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Thread: Focus Stacking & FoV change

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    Focus Stacking & FoV change

    I have been trying to use focus stacking for DoF using my 80LS. However, what I noticed is that the FoV changes slightly from near focus to infinity focus. The lens almost seems to zoom a little bit.

    Have others experienced it? And if so, are there any workarounds?

    Sorry for posting several of these newbie questions, this MF stuff is a whole new world to me

    Thanks for any help.

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    Subscriber & Workshop Member GrahamWelland's Avatar
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    Re: Focus Stacking & FoV change

    This is normal for any lens. Helicon Focus adjusts the image alignment and scaling to accomodate and adjust for this. You typically end up with a slight edge on the image that will be soft and you simply crop this off.
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    Re: Focus Stacking & FoV change

    Thanks Graham. I just looked at Helicon and looks like that's what I need rather than doing it manually. I think the time saving alone is worth it.

    BTW, all this is to stay off that nagging tech camera and T/S, and so far I'm still on the 12-step programme.

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    Re: Focus Stacking & FoV change

    No, you cannot change that--the image is getting larger the closer you focus. You will find internal focus (IF) lenses might do better as they change focal length to focus rather than image distance with more traditional designs.

    But as Graham states, programs like Helicon focus can deal with the registration problem where you are only losing the edges.

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    Re: Focus Stacking & FoV change

    Depending on the application you can move the subject rather than camera to keep constant the absolute size/magnification of the in-focus slice. That has it's own disadvantages too.

    Focus stacking is rarely easy. If you can get where you need to be using movements (e.g. a Cambo X-2 or tech camera with TS capabilities or bellows system) it's by far the better way to go.

    Of course at some point in any camera system (aperture/DOF/magnification/repro-size) you have no option but to stack.

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    Re: Focus Stacking & FoV change

    Quote Originally Posted by dougpetersonci View Post
    Depending on the application you can move the subject rather than camera to keep constant the absolute size/magnification of the in-focus slice. That has it's own disadvantages too.
    Doug Peterson (e-mail Me)
    Yes, Doug... there seems to be no perfect solution ¿unless someone has programmed a zoom lens to compensate for the change in magnification?

    If you move the lens-and-camera relative to the subject, the perspective (viewpoint) changes - (think about focus stacking your way down a long corridor).

    For Macro and close up you can avoid moving the view point by leaving the lens in position relative to the subject and moving the camera (back), as is normal for a bellows camera.

    I am booked in for a pacemaker on the 21st, and I hope I will be able to think straight (and do more photography) after that.

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    Re: Focus Stacking & FoV change

    Photoshop will also align the images to correct for the slight size variations and do a focus stack for you. Helicon does a better job and has more control, but for uncomplicated images Photoshop does a pretty good job.

    Here's a video shows how to do it in CS5.

    http://www.youtube.com/watch?v=intzev1gsbI
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    Re: Focus Stacking & FoV change

    Quote Originally Posted by Wayne Fox View Post
    Photoshop will also align the images to correct for the slight size variations and do a focus stack for you. Helicon does a better job and has more control, but for uncomplicated images Photoshop does a pretty good job.

    Here's a video shows how to do it in CS5.

    http://www.youtube.com/watch?v=intzev1gsbI
    Thanks for that...cheers!

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    Re: Focus Stacking & FoV change

    Quote Originally Posted by dougpetersonci View Post
    Depending on the application you can move the subject rather than camera to keep constant the absolute size/magnification of the in-focus slice. That has it's own disadvantages too.


    [/SIZE]
    Doug, can you explain why this is so? I cannot figure out why there would be a difference between moving the subject and movind the camera.

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    Re: Focus Stacking & FoV change

    Quote Originally Posted by Wayne Fox View Post
    Photoshop will also align the images to correct for the slight size variations and do a focus stack for you. Helicon does a better job and has more control, but for uncomplicated images Photoshop does a pretty good job.

    Here's a video shows how to do it in CS5.

    http://www.youtube.com/watch?v=intzev1gsbI
    Thanks, Wayne... having paid a fortune for Adobe Photoshop 5.5 MC I was hoping it would do the job, but I will probably get Helicon.

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    Re: Focus Stacking & FoV change

    if you focus on something farther out, by adjusting the lens closer to the sensor, the image will get a bit smaller. you could compensate by moving the entire camera closer first (or moving the subject closer to the camera). probably only practical for a macro application.
    since the mag = ratio of distances, a new subject distance (greater) means you will have to reduce the image distance to get focus, so the ratio would have to change

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