Collapsing Building

Started 3 months ago | Questions thread
petrochemist Senior Member • Posts: 2,806
Re: Collapsing Building
2

D Cox wrote:

petrochemist wrote:

Jestertheclown wrote:

D Cox wrote:

Autonerd wrote:

grisog wrote:

Everyone, THANK YOU! Now I understand why its happening and what I need to do different. Also, thanks for showing me how it can be fixed,

In addition to what was said above, I think a wider angle (which you would be using if standing closer) will exacerbate the problem, as a wider angle distorts more. If you can get further back and zoom in, you'll have less rounding.

For photographing buildings, they used to use view cameras or "shift" lenses that could move relative to the film plane. Perspective correction in post is cheaper and easier.

Aaron

Shift lenses are really just ultra-wide lenses (which the OP already has) with cropping in the camera. The film or plate still has to be kept exactly vertical to avoid converging verticals in the building.

Don Cox

Not all shift lenses are wide angles Both Nikon & Canon make FF models with focal lengths of 85-90mm see PC-E Nikkor 85mm f/2.8D TS-E 90mm f/2.8

Even these cover a wider angle of view than ordinary 90mm lenses. What makes a lens "wide angle" is the image circle diameter relative to the focal length. For example, I have a 60mm lens that covers 5x4 inch as a wide angle.

These 90mm lenses are not large format lenses but sold for 35mm 'full frame' The angle of view recorded by the camera will always be less than a 'normal' lens (roughly half using the definition of a normal lens as one whose focal length matches the diagonal of the sensor).

I've never seen a definition of wide angle lenses that refers to the image circle, it's always the film/sensor size. Generally quoting a >60° FOV for wide angle (as per Collins dictionary).

A few sources such as wikipedia relate the focal length to senor size making a lens 'ultra wide; when it's focal length is shorter than the short side of the sensor.

It the lens mount is unable to provide movements the image circle becomes fairly irrelevant after it's big enough to cover the sensor.

I believe the most popular tilt/shift lenses in both Canon's & Nikon's ranges are 17mm which would indeed make them ultra-wides, each range also includes a wide angle (35mm), normal (45mm) & long lens. NB. Not technically 'telephoto' as their physical length is greater than their focal length - indeed to get the tilt shift mechanism in behind the rear element they probably need to be retrofocus designs.

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