Sensor shift

mikeSF · 10-13-2014, 12:44 PM

posting an example to this old thread. I may create a new thread with some examples.

Here are two images at 11mm on the K5. The first, shot normally (no adjustment), and the second with the sensor shift feature applied (re-composed to match the composition).
The effect is remarkable really, great for eliminating or reducing perspective distortion.

Steve.Ledger · 10-19-2014, 05:00 PM

That's got me a bit baffled, Mike.
How does shifting the sensor L/R/U/D correct perspective distortion???
Clue me in

calicojack · 10-20-2014, 05:25 AM

Originally posted by Steve.Ledger

That's got me a bit baffled, Mike.
How does shifting the sensor L/R/U/D correct perspective distortion???
Clue me in

It's actually very simple if you ever learned how to use a view camera.
Normally, with a view camera, you would "Tilt " the camera back to be parallel with the subject. That will eliminate the distortion. Then you would use raising or lowering of the lens or back to recompose. (yes, there is a lot more to it but this thought keeps it simple and compares well).
In the case of only having "Sensor Shift" to work with, you simply start out with the camera level (thereby making the sensor parallel to the vertical face of the building) and then use the up/down sensor shift to recompose.
You can't get to the extremes that you can with a view camera, but the principle is the same.

Steve.Ledger · 10-20-2014, 12:05 PM

Sorry, it still makes no sense to me. Shifting the sensor plate L/R/U/D by the amounts actually possible is not greatly different from simply moving camera position (very) slightly L/R/U/D, sure it moves the sensor off the lens axis, but only very very slightly. It can't possibly eliminate perspective distortion unless the plate also tilts, which it does not.. Of course, like the View Camera you can tilt your camera on the tripod, which any camera is capable of. Using a different focal length helps a lot with perspective or software correction in post, which I think is how Mike's example was actually corrected if you study it carefully, especially at 11mm and especially with the obvious extension distortion far left and right which is typical of software correction.
Sensor shifting for re composition, yes - perspective correction? I can't see it.
So what am I missing here?

vonBaloney · 10-20-2014, 12:17 PM

Yes I think it is confusing because it is presented like the second image was just a sensor shift different than the first, but obviously the sensor was not parallel in the first image (and it looks like it could have been made so without using sensor shift). Right?

**Lowell Goudge** · 10-20-2014, 12:22 PM

You have to remember that sensor shift will work at the magnification ration of the lens. The caption says an 11mm focal length was used, therefore the magnification ratio is probably in the order of 1:100 so let's imagine for example a 1mm shift of the sensor, that would be an effective change of 100 mm on the other side of the lens. I can't see, personally 100 mm in camera height causing that much change in perspective distirtion

Steve.Ledger · 10-20-2014, 12:58 PM

Sorry, how does shifting the sensor on the same plane (because L/R/U/D doesn't change that) change 'magnification ratio' ??

mikeSF · 10-20-2014, 02:19 PM

Hi, sorry I did not notice there were responses here.

Steve, there is no software correction of any kind applied here. The upward shifting of the sensor in the second image allows the camera to be tilted lower for the second image, bringing the more distorted upper periphery closer to the middle of the field where parallel lines are less affected by the distortion. I assure you, there is no trickery here. I had hoped to get out over the weekend to shoot a few more examples, but I had other engagements.
I thought calicojack's explanation was a good one.

---------- Post added 10-20-2014 at 02:24 PM ----------

Originally posted by vonBaloney

Yes I think it is confusing because it is presented like the second image was just a sensor shift different than the first, but obviously the sensor was not parallel in the first image (and it looks like it could have been made so without using sensor shift). Right?

I thought this was pretty clear:
"re-composed to match the composition".
If you merely shift the sensor up and do not recompose, the distortion is still fixed, but you would be looking at much more sky, obviously.

Steve.Ledger · 10-20-2014, 03:11 PM

Originally posted by mikeSF

The upward shifting of the sensor in the second image allows the camera to be tilted lower for the second image

Right, so there was tilting of the camera. Now we're getting somewhere.
So are you saying that without the upwards shifting of the sensor off the lens axis you could not have optically corrected the perspective?
Because calicojack's comment suggests that all you need is the tilt (though calicojack said "tilt the camera back" - which I thought would make things worse)

**dms** · 10-20-2014, 04:22 PM

Lowell's magnification ratio does not seem correct. If the image on the sensor was about 20 mm--then m= 1:100 means the actual bldg. width is 2000 mm, or 2 meters. But the bldg. (unless it is a small model) is likely closer to 10 meters--or a magnification of about 1:500.

Actually looking at the bldg. photo again, likely closer to 20 meter, or about 1:1000 magnification.

mikeSF · 10-20-2014, 04:30 PM

Originally posted by Steve.Ledger

Right, so there was tilting of the camera. Now we're getting somewhere.
So are you saying that without the upwards shifting of the sensor off the lens axis you could not have optically corrected the perspective?
Because calicojack's comment suggests that all you need is the tilt (though calicojack said "tilt the camera back" - which I thought would make things worse)

I'm not sure why you are having so much trouble with this. I assume you dont have camera with which to try this for yourself?
The sensor shift allows your to reposition the camera (tilt) to achieve the same framing, but with a reduction in distortion.
But i'm pretty sure that has already been stated at least once.

---------- Post added 10-20-2014 at 04:31 PM ----------

Originally posted by Steve.Ledger

Right, so there was tilting of the camera. Now we're getting somewhere.

and if the court report reporter will read back my initial post, Lt Colombo would know this already.

vonBaloney · 10-20-2014, 04:53 PM

The sensor shift allows you to get the whole building in the shot without tilting the camera (relative to the building), therefore it is not distorted.

Steve.Ledger · 10-20-2014, 06:02 PM

Originally posted by mikeSF

I'm not sure why you are having so much trouble with this. I assume you dont have camera with which to try this for yourself?

You assume wrong about the camera.
But you are assuming I have had the time and opportunity.

Originally posted by mikeSF

and if the court report reporter will read back my initial post, Lt Colombo would know this already.

Sigh.. Why the sarcasm.. Can't you stay civil?
Where in your initial post did you mention tilting the camera forward???

Originally posted by mikeSF

posting an example to this old thread. I may create a new thread with some examples.

Here are two images at 11mm on the K5. The first, shot normally (no adjustment), and the second with the sensor shift feature applied (re-composed to match the composition).
The effect is remarkable really, great for eliminating or reducing perspective distortion.

Once I get the opportunity to try this myself I'll have more to go on. Until I do, I ask, query and question - sorry if that irks you.

mikeSF · 10-20-2014, 11:49 PM

Originally posted by Steve.Ledger

You assume wrong about the camera.

what are you talking about?

Originally posted by Steve.Ledger

But you are assuming I have had the time and opportunity.

you owe it to yourself and others to refrain from commenting until you try it on your camera.

Originally posted by Steve.Ledger

Sigh.. Why the sarcasm.. Can't you stay civil?
Where in your initial post did you mention tilting the camera forward???

are you really serious?
here is my post:

"...posting an example to this old thread. I may create a new thread with some examples.

Here are two images at 11mm on the K5. The first, shot normally (no adjustment), and the second with the sensor shift feature applied (re-composed to match the composition).
The effect is remarkable really, great for eliminating or reducing perspective distortion."

Steve.Ledger · 10-21-2014, 12:27 AM

Oh good grief I'm not going to argue with you. >> (re-composed to match the composition).<<
I'm not a mind reader for heavens sakes. If you mean't tilt the camera forward then say what you mean.. Please..

Quote:

what are you talking about?

Do you actually read what you write, Mike??

You asked in post #26

Quote:

I assume you dont have camera with which to try this for yourself?

A replied that you assumed wrong about that. I do have a camera to try this and I will when there is time and opportunity (as already mentioned)

Quote:

you owe it to yourself and others to refrain from commenting until you try it on your camera.

A rather condescending comment. I think I'll decide when to post my inquiries without worrying about your approval, okay?

Anyhow I'm done with this thread now. I don't come here to be pushed around by you.

10-20-2014, 02:19 PM	#23
mikeSF Pentaxian Join Date: Jan 2009 Location: East Bay Area, CA Photos: Gallery Posts: 6,620	Hi, sorry I did not notice there were responses here. Steve, there is no software correction of any kind applied here. The upward shifting of the sensor in the second image allows the camera to be tilted lower for the second image, bringing the more distorted upper periphery closer to the middle of the field where parallel lines are less affected by the distortion. I assure you, there is no trickery here. I had hoped to get out over the weekend to shoot a few more examples, but I had other engagements. I thought calicojack's explanation was a good one. ---------- Post added 10-20-2014 at 02:24 PM ---------- Originally posted by vonBaloney Yes I think it is confusing because it is presented like the second image was just a sensor shift different than the first, but obviously the sensor was not parallel in the first image (and it looks like it could have been made so without using sensor shift). Right? I thought this was pretty clear: "re-composed to match the composition". If you merely shift the sensor up and do not recompose, the distortion is still fixed, but you would be looking at much more sky, obviously. Last edited by mikeSF; 10-20-2014 at 02:34 PM.

10-20-2014, 04:22 PM	#25
dms Site Supporter Join Date: Aug 2011 Location: New York, NY Photos: Gallery Posts: 2,192	Lowell's magnification ratio does not seem correct. If the image on the sensor was about 20 mm--then m= 1:100 means the actual bldg. width is 2000 mm, or 2 meters. But the bldg. (unless it is a small model) is likely closer to 10 meters--or a magnification of about 1:500. Actually looking at the bldg. photo again, likely closer to 20 meter, or about 1:1000 magnification. Last edited by dms; 10-20-2014 at 04:48 PM.

10-20-2014, 11:49 PM	#29
mikeSF Pentaxian Join Date: Jan 2009 Location: East Bay Area, CA Photos: Gallery Posts: 6,620	Originally posted by Steve.Ledger You assume wrong about the camera. what are you talking about? Originally posted by Steve.Ledger But you are assuming I have had the time and opportunity. you owe it to yourself and others to refrain from commenting until you try it on your camera. Originally posted by Steve.Ledger Sigh.. Why the sarcasm.. Can't you stay civil? Where in your initial post did you mention tilting the camera forward??? are you really serious? here is my post: "...posting an example to this old thread. I may create a new thread with some examples. Here are two images at 11mm on the K5. The first, shot normally (no adjustment), and the second with the sensor shift feature applied (re-composed to match the composition). The effect is remarkable really, great for eliminating or reducing perspective distortion."

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10-13-2014, 12:44 PM	#16
mikeSF Pentaxian Join Date: Jan 2009 Location: East Bay Area, CA Photos: Gallery Posts: 6,620	posting an example to this old thread. I may create a new thread with some examples. Here are two images at 11mm on the K5. The first, shot normally (no adjustment), and the second with the sensor shift feature applied (re-composed to match the composition). The effect is remarkable really, great for eliminating or reducing perspective distortion.

10-19-2014, 05:00 PM	#17
Steve.Ledger Veteran Member Join Date: Oct 2009 Location: Far North Qld Posts: 3,301	That's got me a bit baffled, Mike. How does shifting the sensor L/R/U/D correct perspective distortion??? Clue me in

10-20-2014, 05:25 AM	#18
calicojack Inactive Account Join Date: Mar 2007 Location: Long Island, N.Y. Photos: Gallery Posts: 1,124	Originally posted by Steve.Ledger That's got me a bit baffled, Mike. How does shifting the sensor L/R/U/D correct perspective distortion??? Clue me in It's actually very simple if you ever learned how to use a view camera. Normally, with a view camera, you would "Tilt " the camera back to be parallel with the subject. That will eliminate the distortion. Then you would use raising or lowering of the lens or back to recompose. (yes, there is a lot more to it but this thought keeps it simple and compares well). In the case of only having "Sensor Shift" to work with, you simply start out with the camera level (thereby making the sensor parallel to the vertical face of the building) and then use the up/down sensor shift to recompose. You can't get to the extremes that you can with a view camera, but the principle is the same.

10-20-2014, 12:05 PM	#19
Steve.Ledger Veteran Member Join Date: Oct 2009 Location: Far North Qld Posts: 3,301	Sorry, it still makes no sense to me. Shifting the sensor plate L/R/U/D by the amounts actually possible is not greatly different from simply moving camera position (very) slightly L/R/U/D, sure it moves the sensor off the lens axis, but only very very slightly. It can't possibly eliminate perspective distortion unless the plate also tilts, which it does not.. Of course, like the View Camera you can tilt your camera on the tripod, which any camera is capable of. Using a different focal length helps a lot with perspective or software correction in post, which I think is how Mike's example was actually corrected if you study it carefully, especially at 11mm and especially with the obvious extension distortion far left and right which is typical of software correction. Sensor shifting for re composition, yes - perspective correction? I can't see it. So what am I missing here?

10-20-2014, 12:17 PM	#20
vonBaloney Pentaxian Join Date: Oct 2011 Location: Albuquerque, NM Posts: 6,029	Yes I think it is confusing because it is presented like the second image was just a sensor shift different than the first, but obviously the sensor was not parallel in the first image (and it looks like it could have been made so without using sensor shift). Right?

10-20-2014, 12:22 PM	#21
Lowell Goudge Site Supporter Join Date: Jan 2007 Location: Toronto Photos: Gallery \| Albums Posts: 17,886	You have to remember that sensor shift will work at the magnification ration of the lens. The caption says an 11mm focal length was used, therefore the magnification ratio is probably in the order of 1:100 so let's imagine for example a 1mm shift of the sensor, that would be an effective change of 100 mm on the other side of the lens. I can't see, personally 100 mm in camera height causing that much change in perspective distirtion

10-20-2014, 12:58 PM	#22
Steve.Ledger Veteran Member Join Date: Oct 2009 Location: Far North Qld Posts: 3,301	Sorry, how does shifting the sensor on the same plane (because L/R/U/D doesn't change that) change 'magnification ratio' ??

10-20-2014, 03:11 PM	#24
Steve.Ledger Veteran Member Join Date: Oct 2009 Location: Far North Qld Posts: 3,301	Originally posted by mikeSF The upward shifting of the sensor in the second image allows the camera to be tilted lower for the second image Right, so there was tilting of the camera. Now we're getting somewhere. So are you saying that without the upwards shifting of the sensor off the lens axis you could not have optically corrected the perspective? Because calicojack's comment suggests that all you need is the tilt (though calicojack said "tilt the camera back" - which I thought would make things worse)

10-20-2014, 04:30 PM	#26
mikeSF Pentaxian Join Date: Jan 2009 Location: East Bay Area, CA Photos: Gallery Posts: 6,620	Originally posted by Steve.Ledger Right, so there was tilting of the camera. Now we're getting somewhere. So are you saying that without the upwards shifting of the sensor off the lens axis you could not have optically corrected the perspective? Because calicojack's comment suggests that all you need is the tilt (though calicojack said "tilt the camera back" - which I thought would make things worse) I'm not sure why you are having so much trouble with this. I assume you dont have camera with which to try this for yourself? The sensor shift allows your to reposition the camera (tilt) to achieve the same framing, but with a reduction in distortion. But i'm pretty sure that has already been stated at least once. ---------- Post added 10-20-2014 at 04:31 PM ---------- Originally posted by Steve.Ledger Right, so there was tilting of the camera. Now we're getting somewhere. and if the court report reporter will read back my initial post, Lt Colombo would know this already.

10-20-2014, 04:53 PM	#27
vonBaloney Pentaxian Join Date: Oct 2011 Location: Albuquerque, NM Posts: 6,029	The sensor shift allows you to get the whole building in the shot without tilting the camera (relative to the building), therefore it is not distorted.

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10-20-2014, 06:02 PM	#28
Steve.Ledger Veteran Member Join Date: Oct 2009 Location: Far North Qld Posts: 3,301	Originally posted by mikeSF I'm not sure why you are having so much trouble with this. I assume you dont have camera with which to try this for yourself? You assume wrong about the camera. But you are assuming I have had the time and opportunity. Originally posted by mikeSF and if the court report reporter will read back my initial post, Lt Colombo would know this already. Sigh.. Why the sarcasm.. Can't you stay civil? Where in your initial post did you mention tilting the camera forward??? Originally posted by mikeSF posting an example to this old thread. I may create a new thread with some examples. Here are two images at 11mm on the K5. The first, shot normally (no adjustment), and the second with the sensor shift feature applied (re-composed to match the composition). The effect is remarkable really, great for eliminating or reducing perspective distortion. Once I get the opportunity to try this myself I'll have more to go on. Until I do, I ask, query and question - sorry if that irks you.

10-21-2014, 12:27 AM	#30
Steve.Ledger Veteran Member Join Date: Oct 2009 Location: Far North Qld Posts: 3,301	Oh good grief I'm not going to argue with you. >> (re-composed to match the composition).<< I'm not a mind reader for heavens sakes. If you mean't tilt the camera forward then say what you mean.. Please.. Quote: what are you talking about? Do you actually read what you write, Mike?? You asked in post #26 Quote: I assume you dont have camera with which to try this for yourself? A replied that you assumed wrong about that. I do have a camera to try this and I will when there is time and opportunity (as already mentioned) Quote: you owe it to yourself and others to refrain from commenting until you try it on your camera. A rather condescending comment. I think I'll decide when to post my inquiries without worrying about your approval, okay? Anyhow I'm done with this thread now. I don't come here to be pushed around by you.