Ad
Ad
Ad
Pages: [1]   Bottom of Page
Print
Author Topic: 35mm format tilt/shift lens for landscapes  (Read 4196 times)
jeffreybehr
Sr. Member
****
Offline Offline

Posts: 275


WWW
« on: February 19, 2003, 02:34:40 PM »
ReplyReply

Bruce is correct in his description of the usefulness of the Canon TS/E lenses. I too have a 24 but don't carry it much anymore; I guess I have too many other primes (28/1.8 Sigma*, Canon 50/1.4, 85/1.8, 135/2, 200/1.Cool to carry. I wish I'd had it in Yosemite; I was pointed up so much the trees were tilting at about 20 degrees. Of course one can remove this perspective distortion in Photoshop, but that also removes a significant part of the pic. It's better to get it right on whatever kind of 'film' you prefer.
---------------
I just posted those couple pics from Yosemite last weekend, at http://community.webshots.com/user/jeffreybehr, in the 'Yosemite, looking up' album. The 2 'straight' pics are not cropped in any way, while the 'perspectived' pair were cropped using PS's Perspective switch on. I pulled the upper corners in only enough to make the edges vertical. I did not crop any of the tops or bottoms; PS did that in the Perspective adjustment. As you can see, 2664 required more correction (and had PS remove more top and bottom), but 2662 is still missing more than I like to see disappear.

* a EX DG lens, and an excellent one, much better than Canon's 28/1.8. See http://forums.dpreview.com/forums....4055226 for more info.
Logged

AJSJones
Sr. Member
****
Offline Offline

Posts: 353



« Reply #1 on: February 19, 2003, 03:42:54 PM »
ReplyReply

The panoramic stitching is easy but not perfect if there is anything in the foreground - while you may not be rotating the lens, you are moving it while the subject and sensor remain in the same places - this generates a little parallax where the stitching would ideally just be perfect geometric overlap (I found this the first time I tried it with my 24).  If that is a problem, one can contemplate a sideways macrofocusing rail to move the camera by the same amount as the shift but in the opposite direction - thus keeping the lens, subject and sensor plane relationship unchanged...

I must try this out one day but I can attest to the parallax issue with just shifting.  The tilt can still be used to throw the plane of focus towards the horizontal if the tilt/shift axis relationship is set right.
Andy
Logged
jeffreybehr
Sr. Member
****
Offline Offline

Posts: 275


WWW
« Reply #2 on: February 19, 2003, 04:53:35 PM »
ReplyReply

I agree with Andy about shooing panoramas with a TS/E lens. If the camera is fixed and the lens moves, then there has to be some paralax error, and the error's effect is most visible in the foreground as blurred, nonmatching images in the overlapped sections. I tried it and rejected it in favor of a front/back AS-type QR plate (actually a Kirk plate for a Canon 100-400).

I mount the plate with the single hole and point the plate forward. The 28mm and 50mm primes' nodal points are aligned with the plate's front even with the front of the clamp, while my 85 requires the plate and cam to be moved back about a centimeter (0.4"). Works VERY well. Takes only a few minutes to switch QR plates from the RRS 90-degree bracket I usually have mounted, and I don't have to carry a separate pano head.
Logged

b.e.wilson
Full Member
***
Offline Offline

Posts: 104


WWW
« Reply #3 on: February 19, 2003, 08:13:37 AM »
ReplyReply

I don't use a T/S lens, but I do shoot with bellows, that will do the same thing.

The tilt part is, as you say, primarily for DOF control. Or to put it more accurately, to control the plane of focus. By tilting the lens it is possible to move the plane of perfect focus (if I may term it that) away from being perfectly parallel to the film plane. With landscapes possessing both near and far elements, moving the plane of focus and stopping down partway gives sharper images than keeping the lens perpendicular and stopping down a lot.

That being said, I've never really felt the need to tilt a lens as short as 24mm, as f/11 focused at the hyperfocal distance (5 ft) gives 30 lp/mm from 3 feet to infinity. For longer lenses the tilt capability becomes more important.

Shift, moving the lens sideways or up/down, is needed for perspective control. If you are shooting a cliff face, for example, with a rigid lens you need to tilt the camera up to see all of it, which places the film plane at an angle to the cliff. When you do this, the image on the film will keystone, making the top of the cliff appear to receed from the base (to lean back, as it were). So landscape photographers always try to keep the film plane vertical (or parallel to the object), and if we need the camera to "look up", we instead shift the lens up so the top of the cliff is visible, but leave the film plane still vertical. Same thing applies to shooting something from the side, at an angle. If we point the film directly at the object, then shift the lens sideways, we can see the object as it is, and the distant part will not look smaller than the near part.

I should say that most of us, when we recognise the need for tilts and shifts, move to a 4x5 bellows camera. They are great for this sort of thing. Nikon used to sell a bellows for 35mm cameras, but it aded length to the lens and was really only good for macro shots (where, because of the short object-to-lens distances and consequent miniscule DOF, DOF control is very important).

Added in Edit: I forgot to add that for wide-angle lenses like the 24mm lens having shift is very important, as a tilted film plane using a wide angle shows much more convergence than a normal or long lens.

Also, to be obvious, lens tilt controls the angle of the plane of perfect focus, and lens aperture controls the depth of focus on either side of that plane (in perpendicuar direction), however it is oriented. By tilting the lens down enough you can get perfect focus of the desert floor with the lens wide-open, and stopping down the lens would bring tall plants into sharper focus. Here is an example: http://science.uvsc.edu/chemistry/wilson/p...p?Photo_ID=6632
Logged

Peter McLennan
Sr. Member
****
Offline Offline

Posts: 1678


« Reply #4 on: February 19, 2003, 12:41:42 AM »
ReplyReply

Michael, in your 24mm lens test, you mentioned that you sometimes found the Canon perspective correction tilt/shift lens indespensible in landscape shooting.

Care to explain how you use it?  Primarily for depth of field?

Peter McLennan
Logged
Peter McLennan
Sr. Member
****
Offline Offline

Posts: 1678


« Reply #5 on: February 19, 2003, 10:36:19 AM »
ReplyReply

Interesting stuff.  Having control of perspective would be a good thing, a tool I thought was owned by large format photographers only.

More stuff to buy.  

Thanks!

Peter
Logged
dbarthel
Sr. Member
****
Offline Offline

Posts: 281


« Reply #6 on: February 19, 2003, 02:48:50 PM »
ReplyReply

A side use of the shift capability is to create overlapping images for panoramas. Shift left, shoot, center, shoot, and right, shoot.  If you use the camera in portrait format, you can create a very large, precisely lined up image with not a lot of overlap between the three shots. As you are not rotating the lens, simple stitching in PS-Elements is all you need.

Dan
Logged
Tim Gray
Sr. Member
****
Offline Offline

Posts: 2002



WWW
« Reply #7 on: February 19, 2003, 04:30:20 PM »
ReplyReply

Dan, what aspect ratio do you end up with - I'd guess is might be pretty close to square???
Logged
dbarthel
Sr. Member
****
Offline Offline

Posts: 281


« Reply #8 on: February 20, 2003, 07:34:10 AM »
ReplyReply

I've heard the shift the body discussion before, but it seems to me impossible to shift precisely the same amount in the opposite direction of the lens to get pixel by pixel alignment. And unless you get exact pixel alignment, what's the point. As to using one of the kirk plates to rotate the camera around the lens nodal point, that is an excellent suggestion which probably works just as well as an expensive panorama head.

Dan
Logged
Pages: [1]   Top of Page
Print
Jump to:  

Ad
Ad
Ad