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Author Topic: T/S lens tilts for landscapes  (Read 3648 times)
gtal
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« on: August 31, 2004, 08:57:45 PM »
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[font color=\'#000000\']Rather than memorize tables, you can use a workflow most LF photographers do:

1) Set the tilt at a neutral position (i.e. no tilt)
2) Use the focus ring to focus on the closest element
3) Tilt the lens until the farthest element is in focus
4) Use the focus ring to re-focus the closest element

Repeat steps 3,4 until focus is achieved.

After a couple of iterations you should have both the closest and farthest elements in focus, then use your preview button to determine the correct aperture to get the rest of the desired elements looking sharp.

Guy[/font]
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Sfleming
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« Reply #1 on: September 01, 2004, 12:02:36 AM »
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[font color=\'#000000\']Jack,

Was  there ever a lion  with ice-blue eyes?   Or are you using a bit of creative license?

(I've been meaning to ask you this for a while.)  Cheesy[/font]
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gtal
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« Reply #2 on: September 01, 2004, 10:00:42 AM »
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[font color=\'#000000\']Jack - you're mixing two different optical principles. The DOF split is the result of hyperfocal focusing, while the effect of tilts is based on the Scheimpflug principle. The combined effect will determine what parts of your image appear sharp (at a given enlargement ratio for the hyperfocal method) but they are not directly related.

Guy[/font]
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AJSJones
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« Reply #3 on: September 01, 2004, 05:35:25 PM »
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[font color=\'#000000\']A few ways to skin the "tilting cat"!

My note wasn't intended to subsitute for systematic approaches to determining tilt (any approach that gets it right is right!) but as an aid, especially for folks who have the lens but no LF format experience with movements and who might have a dim viewfinder, especially for the last part of checking focus after stopping down.  

Guy, Thanks for the succinct description of the "focus for near, tilt for far" approach - I'm improving exactly that workflow with practice on my Ebony.  I don't memorize these numbers - they're in the back of my field notes book, right alongside the hyperfocal distance table, to which I see a good analogy - an aid to setting up the shot.

Andy[/font]
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AJSJones
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« Reply #4 on: August 31, 2004, 03:12:39 PM »
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[font color=\'#000000\']The post here may be useful if you are thinking of or using a T/S lens for landscape photography and have trouble setting the tilt at a good starting point

Andy[/font]
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Jack Flesher
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« Reply #5 on: August 31, 2004, 11:19:01 PM »
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[font color=\'#000000\']Actually, I find it is easier to utilize a simple law of optical physics -- the one that states that your DOF extends from 1/3 in front of your main subject to 2/3 behind it -- when you set your TSE lens.  To put this to use, simply focus about 1/3rd of the way into the image and apply tilt until the background and forground elements pop into focus.  While it is unlikely they will perfect at first go, you usually only need a slight re-adjustment.  In practice this method has far fewer iterations than the above method [/font]
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Jack Flesher
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« Reply #6 on: September 01, 2004, 12:26:27 AM »
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[font color=\'#000000\']
Quote
Jack,

Was there ever a lion with ice-blue eyes? Or are you using a bit of creative license?

(I've been meaning to ask you this for a while.)
Actually it's really hard to tell on that 60x60 avatar, but one is saphire blue and the emerald green. To answer your question, I was bored one day and got wrapped up experimenting with CS' color replacement brush [/font]
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Jack Flesher
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« Reply #7 on: September 01, 2004, 01:06:12 PM »
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[font color=\'#000000\']
Quote
Jack - you're mixing two different optical principles. The DOF split is the result of hyperfocal focusing, while the effect of tilts is based on the Scheimpflug principle. The combined effect will determine what parts of your image appear sharp (at a given enlargement ratio for the hyperfocal method) but they are not directly related.

Guy
Guy:

I'm well aware of the Scheimpflug principle as I shot LF for many years. Schempflug is used specifically for altering the Plane of Focus (PoF) effectively increasing DoF between near and far elements. The Dof split as you refer to it still exists wiht Scheimpflug, only now it is at angle to the imaging plane instead of parallel to it. Moreover, the SHAPE of the DOF zone is now changed from co-planar to an anguled-triangle extending foward with its apex at a point below your lens (assuming forward lens tilt).

Hence I am not mixing optical princles, but rather combining them in a way that increases efficiency in the field -- a skill I honed to perfection years ago shooting landscapes with 4x5 and 8x10 field cameras.

So, to restate, by BEGINNING with your focus point at the theoretical hyperfocal for the elements you want in focus just as though the lens were NOT tilted (and assuming you could stop down to a small enough aperture) -- as opposed to your method starting with the closest object -- and THEN applying forward tilt -- which will extend Dof forward and down from the front object and rearward and up from the back object at the same time -- you get to your desired final focus point with far fewer iterations than with your method. Any experienced LF shooter will tell you the same thing...

Cheers,
Jack[/font]
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Gary Ferguson
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« Reply #8 on: September 03, 2004, 11:03:10 AM »
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[font color=\'#000000\']I use all three of Canon's T&S lenses. The key practical issue isn't the nuances of focusing technique, it's the fact that a 35mm viewfinder and focusing screen just isn't accurate enough for genuinely precise work. And the problem is exacerbated rather than helped with the sloppy fitting Canon angle finder.

You'll normally get away with it using T&S stopped down for landscapes. But try using small format T&S lenses for demanding, close-up product shots and you quickly realise a 35mm viewfinder is a fairly rough and ready tool compared with a x7 loupe on a 4x5 groundglass.[/font]
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