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Author Topic: How do you choose Canon TS, 17mm or 24mm, for interior, cathedral, palace, etc.  (Read 14484 times)

EinstStein

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My widest and most frequent used travel lens is 25mm. I like to shoot interior architecture such as place, cathedral, etc. Even shooting the exterior used a lot of wide angle. But I feel I want it wide, such as 17mm or 15mm.

But this is about the plain lens.

Now I want to get a Canon TS lens, but not sure 17mm or 24mm.

How do you choose between TS 17 or TS 24? if you have experience on both.

I know I want plain 17mm over plain 25mm, does this implies I should get the TS of the same length? or get the TS one step up  (24mm)?
   
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ErikKaffehr

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Hi,

It depends on how you use the lens. T&S capability just gives you the option to shoot the camera level. But you can also stitch with a T&S lens.

This is a vertical stitch from two images from the 24/3.5 TSE LII:


Best regards
Erik

My widest and most frequent used travel lens is 25mm. I like to shoot interior architecture such as place, cathedral, etc. Even shooting the exterior used a lot of wide angle. But I feel I want it wide, such as 17mm or 15mm.

But this is about the plain lens.

Now I want to get a Canon TS lens, but not sure 17mm or 24mm.

How do you choose between TS 17 or TS 24? if you have experience on both.

I know I want plain 17mm over plain 25mm, does this implies I should get the TS of the same length? or get the TS one step up  (24mm)?
 
« Last Edit: August 10, 2016, 06:42:52 am by ErikKaffehr »
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EinstStein

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If you very often need to stitch 24mm, then I think 17mm would be a better choice.

I am curious, why the top of the tower is wider than the bottom? Perspect adjust in PS?
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Guillermo Luijk

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I used to shoot a lot with a 10-22 on APS for interiors (eq. 16-35) and I enjoyed the low end very often. However when I decided to purchase a TS for FF I preferrerd the 24mm because even if it forces you to think harder about how to shoot it is a guarantee that it will end with pleasant looking images. 17mm has to be used more carefully because it makes it easy to fall in the "frame it all" mistake that can end in images where the focal length is perceived before the subject itself.

About Erik's image, I guess he was not facing the building orthogonally so the top of the tower suffers from an extra vanishing point that makes it longer there than in the basement. Linear projection plays these tricks.

Regards


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« Last Edit: December 25, 2015, 04:24:15 pm by Guillermo Luijk »
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ErikKaffehr

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Hi,

I think Guillermo has a good points. I used Lightroom's 'upright' on it and it does not solve the problem.

I have read that when doing perspective correction, the convergence of verticals should not be corrected fully.

Best regards
Erik


I used to shoot a lot with a 10-22 on APS for interiors (eq. 16-35) and I enjoyed the low end very often. However when I decided to purchase a TS for FF I preferrerd the 24mm because even if it forces you to think harder about how to shoot it is a guarantee that it will end with pleasant looking images. 17mm has to be used more carefully because it makes it easy to fall in the "frame it all" mistake that can end in images where the focal length is perceived before the subject itself.

About Erik's image, I guess he was not facing the building orthogonally so the top of the tower suffers from an extra vanishing point that makes it longer there than in the basement. Linear projection plays these tricks.

Regards


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Erik Kaffehr
 

pfigen

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"I have read that when doing perspective correction, the convergence of verticals should not be corrected fully."

There are those who think that, but you've overcorrected here, making the top wider than the bottom. That's what you might see if you were shooting down on your subject, which is why is looks so weird here. I don't use Lightroom, but the normal way of correcting is to dupe your background layer in Ps, place vertical guides where they need to be and use Free Transform to make the building perfectly straight. There are precious few times where you don't want to fully correct and even fewer where you'd want to overcorrect.
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Bart_van_der_Wolf

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I have read that when doing perspective correction, the convergence of verticals should not be corrected fully.

Hi Erik,

That's often correct, because the shots that are using these extreme angles of view are often taken from a very (too?) short distance. So if shot perfectly square (or corrected by Upright and similar) the horizontal perspective plane's vanishing point is still on the horizon, but we are looking up, which confuses our mind. If we were to view the image from the proper (very short) distance and from the bottom of the image looking up, perspective would be correct.

Software like Capture One Pro (I know you are not comfortable with it) by default under-corrects the keystone correction to some 80% of the full correction (see attachement). Of course the user can adjust that to anything, between 10% and 120%, that suits the subject and the viewing conditions of the final image.
One can also use panorama stitching software on a single or composite image, and place the horizon line slightly higher by changing the pitch value.

Cheers,
Bart
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phila

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I use the 17mm a lot and it is an excellent lens (as is the 24 from what I understand). If you are shooting interiors etc then you really can't get too wide. You can always crop if required. The only downside to the 17mm is that because you can't use a lens hood you can get the occasional flair from lights etc.

ErikKaffehr

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Hi Bart,

I sort of think of Capture One as an alternative (*) converter and I bought licenses for both the 7 and the 8 version. V9 was just released after I bought V8 :-(. I can of course use V9 for both Sony and P45+, by switching licenses. I see RawTherapee as another optionů

Your input is most valued, as usual. Thanks for taking time to educate mostly uninterested students! :-)

I think that "upright" in LR doesn't make lines orthogonal at normal settings but leaves in some convergence, but it doesn't work on this image. Thanks for the suggestion changing the "pitch" parameter in stitching.

Best regards
Erik

(*) I am perfectly happy with LR as a workflow solution, and I try to avoid doing non parametric editing. But sometimes I need a better raw converter. So I would export to TIFF using an alternative converter, but I would still print and do whatever I do from Lightroom.

Hi Erik,

That's often correct, because the shots that are using these extreme angles of view are often taken from a very (too?) short distance. So if shot perfectly square (or corrected by Upright and similar) the horizontal perspective plane's vanishing point is still on the horizon, but we are looking up, which confuses our mind. If we were to view the image from the proper (very short) distance and from the bottom of the image looking up, perspective would be correct.

Software like Capture One Pro (I know you are not comfortable with it) by default under-corrects the keystone correction to some 80% of the full correction (see attachement). Of course the user can adjust that to anything, between 10% and 120%, that suits the subject and the viewing conditions of the final image.
One can also use panorama stitching software on a single or composite image, and place the horizon line slightly higher by changing the pitch value.

Cheers,
Bart
« Last Edit: December 26, 2015, 05:54:38 am by ErikKaffehr »
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Chris Barrett

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I don't understand that mindset.  While I agree that there is often an optical illusion of building tops diverging when they are perfectly straight... I haven't met a single professional architectural photographer that would overcompensate.

I've changed my C1 Pro Keystone Correction default to 100%.

Also, I'd agree that correcting small distortions is often best done in Photoshop with Transform>Distort.  You can get absolutely exact with it, where you often can't with perspective correction.

-CB

Also, If you think the 24mm would be a decent focal length, I'd grab that.  It's a much sharper lens than the 17 and far easier to filter or shade.  I own both and hate having to pull the 17 out... but when you need super wide, it get's the job done.

Bart_van_der_Wolf

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I don't understand that mindset.  While I agree that there is often an optical illusion of building tops diverging when they are perfectly straight... I haven't met a single professional architectural photographer that would overcompensate.

Hi Chris,

Not sure I follow, there is not a mindset, just plain geometric distortion. The visual distortion starts when we look at the rectified image capture from the wrong perspective position (center of the image instead of from the bottom, and from too far away for achieving the original perspective). It's like the road signs painted on the road surface. They only look correct/legible if viewed from a shallow angle. Here and here are some more exciting examples that need to be viewed from a single perspective point, or they will look very wrong.

There is no over-compensation, but rather under-compensation by using <100% correction for upward viewing directions. Percentages larger than 100% can be useful for very high vantage points, to create more realistic depth perspective.

Quote
I've changed my C1 Pro Keystone Correction default to 100%.

As would probably be more common for shots of interiors, but not necessarily for outdoor shots of facades or high structures which were taken from a very (too) close position.

Quote
Also, I'd agree that correcting small distortions is often best done in Photoshop with Transform>Distort.  You can get absolutely exact with it, where you often can't with perspective correction.

I'm curious why you'd want to use Distort for perspective corrections, which does something completely different. Perspective correction changes the projection plane (a 3-dimensional change on a flat plane), distort just distorts unlike the lens projection on a flat plane does.

Cheers,
Bart
« Last Edit: December 26, 2015, 01:10:46 pm by BartvanderWolf »
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EinstStein

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I use the 17mm a lot and it is an excellent lens (as is the 24 from what I understand). If you are shooting interiors etc then you really can't get too wide. You can always crop if required. The only downside to the 17mm is that because you can't use a lens hood you can get the occasional flair from lights etc.

The flare might be a problem for interior, as often there are lightings which are hard to avoid.
like this example
« Last Edit: December 26, 2015, 02:02:41 pm by EinstStein »
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alatreille

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Software like Capture One Pro (I know you are not comfortable with it) by default under-corrects the keystone correction to some 80% of the full correction (see attachement). Of course the user can adjust that to anything, between 10% and 120%, that suits the subject and the viewing conditions of the final image.
One can also use panorama stitching software on a single or composite image, and place the horizon line slightly higher by changing the pitch value.

This continues to frustrate me.  Why it isn't just set to 100% as default I don't know.
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alatreille

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Hi Bart,

I think what Chris is trying to say is professional AP's understand that Architects like straight lines.

More often than not a building is comprised of a series of horizontal and vertical lines.....they design things to be straight (generalisation as Mr Frank Gehry as an example doesn't often do this)...therefore, whether right or wrong...a vertical line of a building is preferable to our clients being straight.

The photographs we make are often used in presentations on paper and on screen with all sorts of graphics relating to them or even overlayed on them..thus from a graphical point of view...perfectly straight lines are easier for them to work with.

To my eye....also more pleasing.

What Chris said about the 24/17 relationship is very true - the 17 requires 'taming'.

AL
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Slobodan Blagojevic

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...Why it isn't just set to 100% as default I don't know.

Ancient Greeks already knew why.
« Last Edit: December 26, 2015, 10:04:02 pm by Slobodan Blagojevic »
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alatreille

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Yes...I studied all of that and Bannister Fletchers bible still sit's on my desk..

Ancient Greeks already new why.
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EinstStein

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Who do people use SW correction at all if it is TS lens?
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Bart_van_der_Wolf

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This continues to frustrate me.  Why it isn't just set to 100% as default I don't know.

Hi Al,

Because 100% is mathematically wrong, from a perspective/projection point of view. The top of a building is much further away than the base, so it should be (imaged) smaller (both horizontally and vertically), which introduces keystoning.

If an architect wants to see a distorted* projection reality (which is fine for me, I understand that if they designed straight and not tapered), then by all means set it to 100% (and make it a default if you want/need). But for a normal observer, one expects perspective to render more distant objects smaller than the same objects closer by. The only way to come close to such an image capture is to shoot the building facade perpendicular, from a position at half its height. That way, both top and bottom will get stretched equally due to the flat plane projection (wide angle effect when viewed from the wrong distance), and no key-stoning will occur.

*) the initial uncorrected projection distortion is due to looking at the image from a different perspective point (perpendicular to the dead center of the image) than the one used to take the shot (looking up from say 1.5 metres or some 4.6 feet to say 10 metres or 30 feet at mid building height), from too close a shooting distance.

Cheers,
Bart
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Guillermo Luijk

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The only way to come close to such an image capture is to shoot the building facade perpendicular, from a position at half its height. That way, both top and bottom will get stretched equally due to the flat plane projection (wide angle effect when viewed from the wrong distance), and no key-stoning will occur.

Even in that case you can get a vanishing perspective on both ends, as our vision really works. As long as you sacrifice the straight lines:




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« Last Edit: December 28, 2015, 03:47:27 am by Guillermo Luijk »
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Ray

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I'm curious why you'd want to use Distort for perspective corrections, which does something completely different. Perspective correction changes the projection plane (a 3-dimensional change on a flat plane), distort just distorts unlike the lens projection on a flat plane does.

Cheers,
Bart

Hi Bart,
I'm not sure what the problem is. I use Distort quite often. The Perspective control (in Free Transform) just seems to apply equal degrees of distortion on both sides of the image, but in opposite directions. Some images require a greater degree of distortion correction on one side, as Erik's image does.

In the attached, modified version of Erik's image, hope you don't mind, Erik  ;) , I used Distort, Warp and Context-Aware fill, in Photoshop. It's not perfect but it looks less distorted, doesn't it?


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