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Author Topic: Shift the lens or shift the back?  (Read 790 times)

andyptak

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Shift the lens or shift the back?
« on: May 23, 2018, 05:11:02 PM »

This question is actually about using Canon TS lenses on a Sony a7R3, but I thought that medium format people might be more knowledgeable on the subject. I have the option of mounting the lens or the camera on my tripod, resulting in the opposite piece doing the shifting and I'm not sure which is best. Thanks.
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Ken

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Re: Shift the lens or shift the back?
« Reply #1 on: May 23, 2018, 05:25:29 PM »

I don't know anything about your camera and lens, but on a view camera it doesn't matter whether you shift the front and/or rear standard as long as your image circle covers the film/sensor. By "shift" I presume you mean parallel movement, and not tilt.
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Doug Peterson

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Re: Shift the lens or shift the back?
« Reply #2 on: May 23, 2018, 05:46:04 PM »

Moving the lens changes the point of view.

That makes fine tuning composition more challenging and stitching more problematic.

Wherever possible, and otherwise not problematic (e.g. keeping the lens static requires an adapter that is a less secure mounting point than on the body), it is preferable to move the back. The point of view remains 100% static.

Note that the challenges above may or may not affect a specific photographers workflow. They will be more problematic when you have significant subject matter in the foreground close to the camera (rather than just stuff at/near infinity) and more significant if you do any shift-and-stitching.

Doing a quick left-right panoramic stitch by moving the back is one of my favorite parts of using a tech camera like the Arca Swiss RM3Di. The corners and edges of the final frame stay put (unlike rotate-and-stitch where the image gets warped) meaning I can do the composition in-the-field.

dchew

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Re: Shift the lens or shift the back?
« Reply #3 on: May 23, 2018, 06:13:08 PM »

Personally I prefer to shift the back. There are a few reasons, neither of which are terribly important. Note I am shifting for two reasons: either to account for perspective or to stitch two images together as a panorama:
  • It is easy to do either with my camera, which is sort of "ambidextrous" when it comes to front/back orientation. I can mount the lens on the "front" and shift the back, or I can spin the camera around, mount the lens on the "back" of the camera and shift the lens. Point is, I don't sacrifice the solid mounting, or have to change mounting either way. I don't think I've ever shifted the lens; it is always the back.
  • If I have a long, flat horizon (like an ocean), stitching software sometimes curves the horizon to fix cloud movement. Shifting the back means I can manually align images myself quite simply in PS.
  • Perspective doesn't change at all. If I shift the back, the orientation of a bush relative to something in the distance won't change as I shift.
In your case, as long as you don't sacrifice stability by mounting from the lens, I would think shifting the camera would be preferred.

Dave

Edit: Looks like I said almost the same things Doug did. Hey, at least that puts me in good company!
« Last Edit: May 24, 2018, 08:02:03 AM by dchew »
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JoeKitchen

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Re: Shift the lens or shift the back?
« Reply #4 on: May 24, 2018, 07:32:14 AM »

As was pointed, fine tuning is difficult with certain situations when you shift the lens.  For instance, if I am shooting an interior and I want to compose an one-point image where the camera lens is directly under/over a line in the ceiling or floor, so it is perfectly vertical in the image, shifting the lens will throw that off.  Shifting the back won't. 
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Joe Kitchen
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"Photography is one percent inspiration and ninety-nine percent moving furniture."  Arnold Newman
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gebseng

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Re: Shift the lens or shift the back?
« Reply #5 on: May 26, 2018, 05:08:10 AM »

How do you mount your lens to the tripod, like this:
https://lh3.googleusercontent.com/-3i8rOoTFCCM/VD20PQsxJNI/AAAAAAAANKY/lkHQ5tArjF8/w1898-h1302-no/Zork4-1200.jpg

that would make sense, since you would actually shift the sensor then.

If it's like this:
http://www.fredmiranda.com/A7R-review/00_review%20images/t_ts-e24.jpg

It would be just the same as mounting the camera itself, of course.

best,

geb
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andyptak

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Re: Shift the lens or shift the back?
« Reply #6 on: May 26, 2018, 08:50:12 AM »

Thanks a lot guys.
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