3D perspective unfortunately seems to be beyond the people in this forum who only seem to be capable of thinking in 2D so I won't bother going any further.

3D is now used in all kinds of computer software/graphics and many programs and books have been written about spherical environment mapping, image based modelling etc. All these handle perspective correctly and even simulate camera lens perspectives. They do this correctly by using the LENS FOCAL LENGTH and known distortions. They even use the aperture in the calcs. You can't do it without the focal length because that sets the perspective. Life would be very easy if only distance was required.

Without going into this too deeply this page more or less confirms that FL is needed for proper perspectives.

As seen in the examples, the combination of the “Focal Length” and the “Aperture” parameters have a direct effect on the corresponding perspective. In order to be able to match the perspective of the real-live camera and the Houdini camera we have to get the right combination.

http://nccasymposium.bmth.ac.uk/2007/muhittin_bilginer/page_02/page2.html

Even software such as ShifN for correcting verticals needs to know the FL of the lens used.

--

That's perfectly normal for an UWA lens. Circular objects often appear oval. It isn't a fault and shouldn't be corrected.... it's the view.
WA views very often have all the Intersection Points within the frame.
Telephoto views have the IP points well outside the frame which causes the compression.

In this sketch all the box corners are square even though they don't look it. If you were to zoom in the angles would change until it's obvious that they are square.

The bottom left corner is similar to the boat. Notice how much wider the front is compared to the back.




It's a pity there wasn't a foreground object in the boat shots it would have shown the difference up better.

You can see on the 22mm shot that the right VP/IP (of the buildings)has been moved further to the right and might be even out of the frame, causing some telephoto compression and the heights of the buildings to become more equal to one another. Bit like a door opening.

--

Good to hear that he's still about, probably about 48 now.

It would be interesting to see how well the Pentax tracks a
winger.

-

Some good action shots there Steve. What looks like a break in the last shot is my favourite.

Would that lens be able to cope if Barrow ever got another player as fast as Les Quirk (The Arrow from Barrow ) Later sold to St. Helens and seen here in 1990......

http://www.youtube.com/watch?v=PzBPfJ1dCN0

It's for the GR

--

The front/near edge is the part least effected. The pole on the boat only changes 128 to 149 The far one changes by a lot more from 59 - 101.

Already had one post deleted on this thread so I think it's time
to call it a day.

--

It's unlikely that half a door pan would have such a serious effect on the angles. Besides that a kind of tele/WA compression/expansion is visible.

The boat looks abit distorted in the 14mm shot, but that may be just normal WA perpective which can't be matched by a longer lens.

--

Sorry he didn't pan the camera If you look at the left end of the white boat where it says VAII it's in line with the door reveal beyond on both shots meaning the camera is in the same position for both shots and because all perspectives begin at the edge or corner, he's kept the left side of the picture the same in both shots. The change in perspective is due to the change in focal length only.

The brass plate in the door reveal is also in the same position on both shots so the height of the camera was also constant being neither lowered or raised.

There are two flagpoles sticking up on the near far boats. I've measured these in pixels with a screen pixel ruler and they are
14mm 128 and 59 ...... 128/59 = 2.17 Ratio
22mm 149 and 101...... 149/101 = 1.47 Ratio
So quite a big difference in perspective.

--

Here's a very nice example from a good photographer who understands perspective v focal length. He could have cropped the LHS of the 14mm shot, but realised that by using 22mm he would make all the buildings nearer to the same size. He remained in the same position, but panned the camera.

8th and 9th shots down page
Nyhavn at sunset by itshimitis

PentaxforumsUS

--

It does and you can actually see it. The easiest test is what I've done above or a corner of a box as per the sketch.

A tripod is essential and it's hard to get the ruler central because it's only a couple of inches away from the lens.

With a box you can see the perspective on the lettering...




Tripod not moved, but panned upwards for 2nd shot.
18mm and 55mm focal lengths used.

-