So what I'd looking for is the lens used nearly wide open with the sort of movements that would be required to straighten up buildings when looking upwards (refer to the pictures I uploaded further up this thread as a guide to just how much I look upwards with these shots). Needless to say, there would often be bright light sources either in-frame or just outside of the frame (but still very much in the flare zone) - think street lights clearly in-shot, car headlights pointing towards the camera, neon signs, etc. Because I am capturing stars, I would generally use the lens at around f4.5 or f5 (certainly not stopped down very much). I guess my main application would see me using it for star trail pictures in bright, urban areas - with the lens being used to ensure buildings look straight even when looking quite sharply upwards. StarTrailsFromFilesIMGP5352-7294_Step7sRGBSMALL by Ed Hurst, on FlickrĬlick to expand.G'day Steve - great to hear from you and thanks for the offer of help it's much appreciated. StarTrailsFromFilesIMGP8661-9999And0001-0928Step9sRGBSMALL by Ed Hurst, on Flickr StarTrailsFromFilesIMGP1961-4360_Step7sRGBSMALL by Ed Hurst, on Flickr International Towers, Barangaroo, Sydney - by night by Ed Hurst, on Flickr As a side note, you will also see bright lights all around, so any lens also needs not to be heavily flare-prone. They show built scenes (with geometry that shows up distortion) when the lens is looking upwards. Here are some examples of what I am keen to avoid.
With 23mm lens (or, with the 645Z, the 25mm) I am already at the limit of what I can include with some scenes, so fixing the issue by losing some of the image isn't really practical. When I have tried to fix the perspective in post, using my current camera (645Z), the perspective can end up looking 'right' but at the twin costs of a) losing some of the scene around the edges and b) some minor loss of quality as parts of the scene are stretched. The same basic focusing principles apply to T/S lenses on an SLR.Thanks for the question! My main purpose is fixing perspective - but without losing any of the image around the edges. If your subject is very three-dimensional then movements might not be the answer, it may simply be better to stop down. It must also be remembered that the focusing plane is a flat surface. This will mean that both targets cannot be in focus at once. Don’t be tempted to go straight to sharp focus on the second target. Return to the first target, re-focus and repeat until both are in sharp focus.Ĭare must be taken to apply tilt in small amounts. If the image gets sharper at the second target then you are moving in the right direction, if it gets less sharp then too much tilt has already been applied. The second target is then scrutinised, using a magnifying loupe on the ground glass, and a small amount of extra movement applied. A movement is applied (usually tilt in a classic landscape) and the far target focused on. The following is a simplified description of focusing using Scheimpflug with a view camera.įirst, one selects two targets on the ground glass (one near and one far along the same plane). Quote from: David Ward "The usual focusing method using tilt is iterative, there are alternative methods based on measurements and tables but they’re both slower and less accurate. The "front focal plane" estimation and the "parallel-to-film" lens estimation are both unnecessary with the simpler and solid Scheimpflug technique. So, using the "parallel-to-film" lens plane requires yet another estimation. This hypothetical plane intersects the center of the lens, but it runs parallel to the film plane, regardless of how the lens is tilted/swung. In addition, the hinge method adds another somewhat intangible variable with its reliance on the abstract "parallel-to-film" lens plane. There is nothing physical to indicate the location of this plane some distance in the air in front of the lens, so it has to be estimated. The "front focal plane" of the hinge theory exists in the air, one focal length (the infinity focal length?) from the optical center of the lens. In contrast, the "hinge" theory is merely a more abstract variant of the Scheimpflug principle, which adds intangible, unseen "planes."
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