[paperbag846]

Regarding leaving room on the edges for cropping, one might as well be using a shorter lens.

Well, sure, the difference between 15mm and 16mm FOV isn't really gonna change the impact of your photo.

[henryjing]

me too

I much prefer the unaltered one.

[mikeSF]

unless there are parallel lines that absolutely define the subject and must remain parallel, i much prefer the unaltered appearance and also feel that "correcting" it pretty much changes your 15mm FOV into an 18mm or 21mm or what have you. I figure when you get that wide, most will expect this effect in the photograph so it is not terribly troubling.

Likewise, i simply do not understand de-fishing the distortion of a fisheye.

[paperbag846]

changes your 15mm FOV into an 18mm or 21mm or what have you

Not true. 21mm requires something like a 50% crop. It more like changes your 15mm image into a 16-17mm image.

[GeneV]

This is all part of a creative process. If you prefer the version with the building leaning back, then you don't need to do anything about keystoning and the question asked by the OP is not terribly relevant. If that is the preference, don't use a shift lens or front rise in a view camera. It is also not an all or nothing proposition. Taking a version with spaces for correction and one that does not allows flexibility. I have made corrections that I ended up discarding and some that I liked.

[GeneV]

Not true. 21mm requires something like a 50% crop. It more like changes your 15mm image into a 16-17mm image.

One could say a similar thing about using rise in a view camera. You are taking an image with a lens that throws a much wider view and essentially cropping for the top part of it. I suppose that another way to go with a DSLR is to pick a lens wide enough to include the top of the structure while the camera is parallel to it, and then crop out the foreground.

[Big G]

Tilt and shift lens would sort this out for you .

[paperbag846]

One could say a similar thing about using rise in a view camera. You are taking an image with a lens that throws a much wider view and essentially cropping for the top part of it. I suppose that another way to go with a DSLR is to pick a lens wide enough to include the top of the structure while the camera is parallel to it, and then crop out the foreground.

I guess the point is, the only "natural" way to take a photo of a building with parallel lines is to hover exactly in front-centre of it... impractical. If this is the perspective you want, there is an alternative, and you don't lose *so* much FOV from the image.

[GeneV]

Tilt and shift lens would sort this out for you .

Maybe, but why is that better than PP?

Those who want the scene to appear exactly as it did to a person standing in the spot of the photographer are still not going to get that perspective.

[GeneV]

I guess the point is, the only "natural" way to take a photo of a building with parallel lines is to hover exactly in front-centre of it... impractical. If this is the perspective you want, there is an alternative, and you don't lose *so* much FOV from the image.

I agree that the amount you lose is usually not that significant. It is still worth planning for.

[paperbag846]

It is still worth planning for.

Agreed there .

I was more responding to another comment -"why bother since you lose FOV, might as well shoot with a shorter lens".

Which isn't super helpful if you own a 15 already. And cropping brings you no where close to 21mm, or 18mm for that matter, as suggested.

[mikeSF]

Not true. 21mm requires something like a 50% crop. It more like changes your 15mm image into a 16-17mm image.

thx for that clarification...i obviously dont know what the math comes out to be but find that clipping the edges to correct distortions has an obvious effect on the FOV, that cathedral example has a striking loss of information after correction.

[Big G]

Maybe, but why is that better than PP?

Those who want the scene to appear exactly as it did to a person standing in the spot of the photographer are still not going to get that perspective.

No, not maybe, it definitely would. Why do you think architectural photographers use T&S techniques to correct distortion in vertical lines? If you want your verticals to be leaning, then don't bother with T&S or correcting in PP.

This thread is about correcting keystoning / distorted verticals which is exactly what T&S is meant to do.

[GeneV]

No, not maybe, it definitely would. Why do you think architectural photographers use T&S techniques to correct distortion in vertical lines? If you want your verticals to be leaning, then don't bother with T&S or correcting in PP.

This thread is about correcting keystoning / distorted verticals which is exactly what T&S is meant to do.

Actually the answer is not "maybe" but "no." To be precise, this thread is about keystoning with the DA15, which is not a tilt and shift lens. The only choice if you need this field of view on APS-c is post processing. To my knowledge, there is no tilt or shift lens in a FL that is remotely helpful on a Pentax DSLR in the kind of space where you would use a DA15.

[Big G]

Actually the answer is not "maybe" but "no." To be precise, this thread is about keystoning with the DA15, which is not a tilt and shift lens. The only choice if you need this field of view on APS-c is post processing. To my knowledge, there is no tilt or shift lens in a FL that is remotely helpful on a Pentax DSLR in the kind of space where you would use a DA15.

Oh stop being so pedantic and obtuse. I was only making a passing flippant remark that a T&S lens would achieve the desired effect.