Is a software pan across a still image similar to a camera pan?

[guyburns]

I have a collection of 3-screen audio-visuals that I eventually want to convert to 1920 x 1080 format on BluyRay. It will be tricky converting from a 4.5:1 format to a 16:9 format, and I imagine I will sometimes use slow pans to convey a panoramic landscape captured on three slides.

I also want to capture new panoramic views of landscapes, and show them as slow pans, and I was wondering whether there would be any difference on screen between the two methods listed below. The landscape scenes I am talking about would have very little movement; at most, some herbage moving in the wind. Assume the same camera (say a GH2) is used in both situations, set up on a tripod in front of a wilderness scene:

1. Take a number of stills, stitch together a panorama, and generate a software pan across the still;

2. Pan the camera across the scene.

What differences, if any, would I expect to see between the two methods?

 

[AndrewGentle]

Well, unless the sensor is exactly at the centre of the tripod's axis of rotation, the perspective will change slightly as a camera pans over an image. For landscapes at large distances, though, this shouldn't be noticeable. You'll also have the image being distorted by different amounts at different positions, depending on the lens. This changes the image slightly as it passes through different parts of the lens. Apart from that, there shouldn't be much difference. Most people don't really notice.

If you zoom, though, the perspective doesn't change in post like it does in camera. The perspective is compressed as the focal length of a lens increases.

 

[William_Robinette]

Of course the stills will not be in motion. And it will not have any sort of "movement" from grain/noise introduced by the camera. Depending on what you are shooting this could be a dead giveaway.

I don't know, No matter what I find it pretty easy to tell between a still image post-pan/scanned and an actual pan with a video camera in the real world. Not saying either one is better, and if it is expansive landscapes it may work well, but I think that difference will always be there.

 

[Kholi]

Of course the stills will not be in motion. And it will not have any sort of "movement" from grain/noise introduced by the camera. Depending on what you are shooting this could be a dead giveaway.

I don't know, No matter what I find it pretty easy to tell between a still image post-pan/scanned and an actual pan with a video camera in the real world. Not saying either one is better, and if it is expansive landscapes it may work well, but I think that difference will always be there.

I'm allergic to post pans, scans and push ins. Haha.

 

[guyburns]

Another question in a similar vein to pans: I've been studying films to see what camera moves they use. Causes me grief occasionally, because at the end of the film I have to ask my partner what the film was about – and she gets annoyed. Anyway, one type of camera movement I am not sure about is when there is an ultra-slow zoom-in on someone talking. Might take 20 seconds and the movement is imperceptible. How do they do that? Is the camera moving in under motor control, or is the camera zooming under motor control, or is it done after filming?

Another question: how can you tell the difference between a camera zoom-in and an actual camera "move-in"? And is there a technical term for the latter?

If you zoom, though, the perspective doesn't change in post like it does in camera. The perspective is compressed as the focal length of a lens increases.

Is it correct to say that a camera zoom is different from an "in post" zoom as regards perspective? I've been thinking about this and I can't work out why an "in post" zoom would be different from a camera zoom – assuming a perfect lens with no distortion and putting aside the change in resolution i.e. assume you are zooming in on a high-resolution still, and comparing that to a lower-resolution camera zoom.

 

[nosys70]

simply, an object close to the camera will block more background than an object far from the camera. So zooming in the picture will not change that, while going closed to the subject will.

 

[zaarc]

a post 'zoom' is actually just resizing the picture. nothing in it will change in relation to anything else. you will eventually see more grain/noise if you go too far. and a post pan is really more like a dolly shot than a pan. the perceived axis of the camera does not change in relation to the elements in the image.

 

[deltoidjohn]

and a post pan is really more like a dolly shot than a pan. the perceived axis of the camera does not change in relation to the elements in the image.

Actually it is much more similar to a pan than a dolly shot. With a Dolly shot, the position of everything in the frame relative to the other elements will change (this goes for in-out dolly shots as well as left-right tracking shots). The closer an object is to the camera, the more it's position in the frame will change. So if you are doing a dolly shot across a vast landscape, a shrub in the foreground might pass from the far left of the image to the far right, yet the mountains in the distance might appear in the dead centre of the frame the whole time.

With a software pan, everything maintains the same visual relationship to everything else around it - unless you use AE to create masks, split the image into layers, paint in the extra backgrounds and arrange everything in 3D space.

 

[guyburns]

Thanks for the informative responses. I'll sum up for my future reference:

1. Dolly-shot is the general term used when a camera moves. When it moves in, it is called a "push-in".

2. A post-zoom just resizes the picture. Nothing in it will change in relation to anything else – the same applies for a post-pan.

3. Given a lens with close to zero barrel distortion (e.g. the software-corrected lenses for the GH2), and with the sensor located at the centre of rotation, a post-pan will appear similar to a camera pan. But the camera pan of a landscape will have more movement from actual movement of objects in the scene (e.g. wind-blown leaves), and from any noise/grain introduced by the camera (post-pan noise, even if visible, is static). Because of this movement, a camera-pan may appear more alive than a post-pan.

4. Because a still image has less noise, more resolution, and is sharper than a video image, a post-pan of a high-resolution still landscape may look out of place when surrounded by video (or at least be detectable). One partial solution: introduce s small amount of noise/blurriness into the still to make it appear closer to video quality.

5. A post-pan will not appear the same as a dolly shot because in a dolly shot, foreground objects will move, say, left to right, but distant objects will remain stationary.

6. The way to distinguish between a zoom-in and an in-out dolly shot is to look for the movement of objects relative to each other.

 

[vision_filmz]

Push in and software pans can look really nice. I disagree with people saying that it looks bad, if done rite it actually looks very very nice and can resemble the movement of a slider/dolly.