I'm finally getting sometime to use my TS-E lens. It is the first time for me on a digital camera. I used to think you have to tilt the lens downwards to bring the FG and BG in focus. However for some funny reason my front element is always upward. I checked the images in lightroom and sure there is something wrong.
http://www.usa.canon.com/uploadedimages/FCK/Image/2009/Tilt%20Shift%20Whats%20New/Canon%20TiltShift%20Concepts.pdf (like here in the last picture).
And when I tilt it downward I see that the DOF is reduced almost like a thin line/plane.
What am I doing wrong?
thank you for your time,
Posted by David Bostedo on February 10, 2010 at 1:53 PM
PrashanTeju - I haven't used a TS lens, so take this with a grain of salt, but it seems like maybe you're a little confused. When you tilt, you're not really increasing the DOF to get the FG and BG in focus. Instead, you're just moving the plane of focus at an angle relative to the camera and subject.
So if you take the normal plane of focus, which is parallel to the sensor, and tilt it so that it intersects something in the FG and BG, both of the point will be in focus. Focus will still fall off as you move away from that plane, the same as usual. So it's a matter of tilting the lens so that the plane of sharpest focus lies along the points you want it to. If you're getting a thin line of focus, then the only place in the image your focus distance and plane of sharpest focus meet is at that line (similar to the third example in the doc you referenced).
As far as the shift up in the last picture that you mentioned, that's purely to do perspective correction. If you are shooting from ground level at tall objects, it wouldn't be strange to always have some upward shift.
David,
I have used LF camera in the past so I know a little bit how these things work. I'm guessing that there is something wrong with the aperture of the lens. Thanks for your reply.
Posted by Dan Baumbach on February 10, 2010 at 3:09 PM
Tilting up sounds right. Areas closer to the lens require a greater distance from the focal plane to be in focus. The foreground, bottom of the image, area is closer to the focal plane. The part of the lens transmitting the foreground has to be further from the focal plane than the part of the lens transmitting the background, hence tilting the lens up to shorten the distance from the distant area of the image to the focal plane.
Does that make sense?
- Dan
Posted by David Bostedo on February 10, 2010 at 3:42 PM
I have used LF camera in the past so I know a little bit how these things work.
Thanks for the info PrashanTeju....I'll just slink back under my rock now and be quiet.
I have used LF camera in the past so I know a little bit how these things work.
Thanks for the info PrashanTeju....I'll just slink back under my rock now and be quiet. >>>
David,
sorry if it sounded rude. it ain't my first language. I understand the Scheimflug principle that is all I wanted to say. However practical tips help a lot. And when you have a camera with small viewfinder and no live view it helps if somebody points in the right direction.
Posted by David Bostedo on February 10, 2010 at 5:06 PM
It wasn't rude at all PrashanTeju, and I took no offense...I meant my comment in jest (hoping that the smiley icon would get that across). Good luck!
Posted by Dan Borzynski on February 10, 2010 at 6:38 PM
Something is wrong here.
First, PrashanTeju, let's be sure I understand what you are trying to do. If you repeat what you are trying to do indoors, it would be (more or less) pointing the camera straight forward and trying to bring the entire floor into focus using the tilt feature of the lens. Does that sound correct?
If so, then what you need to do is tilt the front element of the lens forward so that the front element is more or less pointing down, not up. This should match your 4x5 experience. Without seeing a picture of what you are doing and the results, I suspect that you are using too much tilt.
(EDIT FROM POSTING EARLIER: THIS PARAGRAPH IS DEAD WRONG! Is the back of the camera pointing forwards towards the floor? If so, that might be the problem. Starting with a zeroed position for camera and lens, if you tip the back of the camera towards the floor downwards beyond 45 degrees and then use the TS features of the lens, you will actually need to tip the front of the TS lens *upwards* to bring everything in focus. The same thing happens with 4x5. You would essentially be correcting to much rear tilt with a little bit of front tilt.)
Also, another general question: if you zero the lens and shoot like it is a "normal" lens, is it sharp? I'm just trying to rule out a problem with the lens.
Dan, what you are describing for tilt is rear tilt. Front tilt is exactly the opposite, so he should be pointing the front element downwards, at least assuming my second paragraph is correct. The Canon TS lenses only have front tilt.
Dan,
you got me.
1. I will check out if the lens is sharp at zeroed position,
2. I'm tilting the camera plane - habit picked up while using WA lenses on SLRs. Probably little bit too much and to compensate it I need forward tilt.
Thanks I will post my experience soon. And few pictures too.
Posted by Dan Borzynski on February 11, 2010 at 6:23 PM
I should add that there is nothing wrong with tilting the camera foward if it matches your compositional aims. It just reduces the amount of tilt needed to something rather minimal, especially on a 35 mm based body and becomes extremely easy to overshoot the needed amount of tilt. Been there, done that
As you are probably discovering, movements are a bit easier to do on a LF camera than the 35mm - based bodies. The bigger viewfinder alone makes a huge difference in judging how quickly the tilts affect focus.
I really have no idea why I wrote what I did in that editted paragraph about needing to use a bit of upwards tilt. Simply from Scheimpflug, it is completely non-sensical.
Discussion
10 replieshttp://www.usa.canon.com/uploadedimages/FCK/Image/2009/Tilt%20Shift%20Whats%20New/Canon%20TiltShift%20Concepts.pdf (like here in the last picture).
And when I tilt it downward I see that the DOF is reduced almost like a thin line/plane.
What am I doing wrong?
thank you for your time,
So if you take the normal plane of focus, which is parallel to the sensor, and tilt it so that it intersects something in the FG and BG, both of the point will be in focus. Focus will still fall off as you move away from that plane, the same as usual. So it's a matter of tilting the lens so that the plane of sharpest focus lies along the points you want it to. If you're getting a thin line of focus, then the only place in the image your focus distance and plane of sharpest focus meet is at that line (similar to the third example in the doc you referenced).
As far as the shift up in the last picture that you mentioned, that's purely to do perspective correction. If you are shooting from ground level at tall objects, it wouldn't be strange to always have some upward shift.
I think the Cambridge in Colour guide to Tilt-Shift lenses might be useful (and there's a part 2).
Hope that helps...
I have used LF camera in the past so I know a little bit how these things work. I'm guessing that there is something wrong with the aperture of the lens. Thanks for your reply.
Does that make sense?
- Dan
Thanks for the info PrashanTeju....I'll just slink back under my rock now and be quiet.
Thanks for the info PrashanTeju....I'll just slink back under my rock now and be quiet. >>>
David,
sorry if it sounded rude. it ain't my first language. I understand the Scheimflug principle that is all I wanted to say. However practical tips help a lot. And when you have a camera with small viewfinder and no live view it helps if somebody points in the right direction.
First, PrashanTeju, let's be sure I understand what you are trying to do. If you repeat what you are trying to do indoors, it would be (more or less) pointing the camera straight forward and trying to bring the entire floor into focus using the tilt feature of the lens. Does that sound correct?
If so, then what you need to do is tilt the front element of the lens forward so that the front element is more or less pointing down, not up. This should match your 4x5 experience. Without seeing a picture of what you are doing and the results, I suspect that you are using too much tilt.
(EDIT FROM POSTING EARLIER: THIS PARAGRAPH IS DEAD WRONG! Is the back of the camera pointing forwards towards the floor? If so, that might be the problem. Starting with a zeroed position for camera and lens, if you tip the back of the camera towards the floor downwards beyond 45 degrees and then use the TS features of the lens, you will actually need to tip the front of the TS lens *upwards* to bring everything in focus. The same thing happens with 4x5. You would essentially be correcting to much rear tilt with a little bit of front tilt.)
Also, another general question: if you zero the lens and shoot like it is a "normal" lens, is it sharp? I'm just trying to rule out a problem with the lens.
Dan, what you are describing for tilt is rear tilt. Front tilt is exactly the opposite, so he should be pointing the front element downwards, at least assuming my second paragraph is correct. The Canon TS lenses only have front tilt.
you got me.
1. I will check out if the lens is sharp at zeroed position,
2. I'm tilting the camera plane - habit picked up while using WA lenses on SLRs. Probably little bit too much and to compensate it I need forward tilt.
Thanks I will post my experience soon. And few pictures too.
As you are probably discovering, movements are a bit easier to do on a LF camera than the 35mm - based bodies. The bigger viewfinder alone makes a huge difference in judging how quickly the tilts affect focus.
I really have no idea why I wrote what I did in that editted paragraph about needing to use a bit of upwards tilt. Simply from Scheimpflug, it is completely non-sensical.