Prompted by a post a few threats back and by so many other similar posts, I thought Id try to explain the wide-angle distortion that occurs with the default Poser ridiculously wide-angle lens settings. Im no Dr. Geep (no one is) so please forgive the lack of humor and entertainment value, but here goes

This mini tutorial is aimed primarily at non photography-knowledgeable Poser users and Poser novices in general.

As all photographers among us know and understand (or should know and understand) this apparent distortion happens when a lens with a wide angle of view is used for close up pictures like Head or, to a lesser degree, Head/Shoulder portrait type pictures.

This has really nothing to do with the angle of view of the lens but with the distance that the lens is from the subject. To illustrate this, Ive prepared a scene with two identically sized spheres, offset left to right so you can see one next to the other, and the same distance front to back between spheres, in each example.

The reason for that is that the front to back distance between the tip of the nose and back of the ears of a human head, for example, does not change no matter how close of far away the camera is. The only thing that is different in the examples is the angle of view of the lens, from wide-angle to telephoto (narrow angle). I have tried to make the pictures so that the front sphere (on the left) is the same size in each example simply by moving the camera closer or further away.

The illustrations along the left are the picture examples and the along the right, the illustrations of the set-up. As you can see, the closer the camera is to the subject, the smaller the rear sphere appears although its the same size and the same distance from the front sphere in each example.

This is why in Head, Head/Shoulder portraits made with a wide-angle lens/camera settings, the nose appears un-naturally large and prominent while the ears or other elements further away appear disproportionately small.

Its the distance the camera lens is from the subject.

In relation to the camera position, in a wide-angle picture the rear object may be more than twice the distance from the front object while in a telephoto picture, the rear object may only be a fraction of the distance from the front object even though both objects are same distance from each other.

As you can see, and like I said before, this is not a function of the angle of view of the lens, but of the distance that the lens is from the subject. In order to get a more pleasing and realistic perspective view, move the camera lens back away from the subject and then compensate by reducing the angle of view so that your subject will still fill the frame.

I hope this is of some help to some of you. BTW, this is not against wide angle camera/lens settings. They definitely have their use and place, but not in traditional portrait pictures (emphasis on traditional). Thank you for reading

Just kidding. I'm with you 100%.

BTW, you can change the focal length defaults, the same way you change other setttings. ("Set preferred state" under Preferences.) I have mine set to default to 100mm. Before I did that, I'd always forget, and then find I had tweaked Vicky's face so that it looked good at 25mm but not at any reasonable setting.

guslaw, Thank you for that illuminating explanation. Very, very helpful for those of us who are point-and-shooters and not 'real' photographers. (BTW 'prompted by a few threats back' great freudian slip.) randym77, great tip from you too. I always forgot to reset my lense settings. No worries now!

Definitely helpful for this non-photog! In other words, the natural thing in Poser is just to slide the camera forward and back until the SIZE is right, without thinking about other settings. With an actual camera, the error of this method would be more obvious.....

Yeah okham, more or less except... To avoid the wide-angle distortion in head or head and shoulder portrait type pictures that I'm talking about it's important to set the 'Focal' (length) of the camera to something in the neighborhood of 80mm to 100mm and then "...just slide the camera forward and back until the SIZE is right" That's for P4 and, I think, P4PP (don't have PP). For P5 set 'Perspective' as well to the same 'Focal' value. These are just starting points, experiment and play around...

OK, I get it... start with the proper focal length, and then slide!

I was very sad that Thither or what ever it is called moved trough walls only in preview and not renders. That said, I have a terrible time rendering in interior setups! I feel the key might be camera "scale" but I just have not figured out how to make that work. Can you explain? Also, I have not been succesfull putting figures in settings imported as backdrops by guestimating the camera location and angle... is there a method for extrapolating the horizon in a scene where it is not evident as a natural horizon so that the Poser camera can be positioned with the horizon guide? I assume the key is to line up the horizons and do a seperate render on a plane to capture a shadow to composit. If you can help me with this, can anyone point me to good interior backgrounds. Reason being I have had no luck shooting my own images for cyclorama or the Nerd Background... I have no idea how nerd was able to capture the ground (from just before the feet according to ReadMe) and sky in an image and my attempts to stitch multiple pictures is not working so great :( No matter how wide angle I go on my digital it just cant capture any scope accept at a distance. Thank you.

Guslaw, Thanks for sheding some light on proper camera positioning and focal length. Re-check my earlier thread, as I have posted corrected pics, which look MUCH better. -The Starkdog

Starkdog, Been there, done that. Check the comment I left you there... Looking good.

momodot, The Hither ('Thither' is close enough) dial controls the clipping plane. Objects in front of the clipping plane are not visible, but only in the preview window. You're right, it's a shame that it doesn't work in renders. Could be very usefull if it did. I have not played with 'interior' type setups in Poser so I can't tell you what the best approach is. I think that you might be on the right track though with the Scale dial. Set the focal length of the camera lens to a relatively wide angle (28mm or less) and then tweak it by 'zooming' in and out with the Scale dial until you get something you like... dunno, have to try it myself. I'm not sure I fully understand your next question so I won't try to respond for now and go off somewhere into left field. Sorry... As far as making your own textures for cyclorama type background sets, of those I have seen, the textures for the groundplane portion seem to be made up of several stiched pictures of beach, grass, whatever, taken vertically, camera pointing almost straight down. This then in turn is stiched to a middle-ground picture(s), taken with the camera tilted down slightly, and finally a more or less conventional wide angle scenic shot(s) for the vertical plane. There propably is a lot of postwork involved to skillfully disguise and blend all the seams. I've never tried it myself and I'm sure that it's not easy. Taking panoramic wide-angle scenic pictures with a digital camera is very difficult. Digital cameras are notoriously lacking in true wide angle capability. The built-in zoom lens of virtually all digital cameras only zoom-out to a modest wide angle (35mm, or 28mm maximum, equivilant on a 35mm film camera). Unfortunately, this is the state of digital camera technology today. Even expensive high-end 'pro' level interchangeable lens DSLRs (Digital Single Lens Reflex) cameras like the latest Nikon D70 or Canon EOS 20D are very limited in that area. The few truly realy wide angle lenses that are available for those cameras are very expensive ($1000+, and that's for the lens only). I hope this answers some of your questions. Sorry I couldn't be more help..

While we're on this, a related question that I need for various Python uses. I'm sure this has been answered before, and I even had a usable number at one time, but can't find it now. Various formulas that relate focal length and field of view require the film size. What's the virtual "film size" of Poser's camera?

Thanks. I did not know why my digital camera wide angle did not seem the same as my old conventional camera which I have not used in a long time. The matter I did not articulate well is how can one render over an image imported as a background... that is, how can one place the camera properly in such a scene if there is no horizon to align the Poser horizon guide? I have tried to place the camera intuitivly but I guess I must trace the orthognals to estimate the vanishing point and move the camera so the horizon guide intersects that point? I must try this when I get a chance.

Ockham, I'm pretty sure that focal lengths in Poser, as with those quoted for digital cameras, are the equivalent focal length that would give that angle of view on a 35mm camera. Momodot, there's several options within Poser 5. See the Guides sub-menu, right at the bottom of the Display menu. There are some optical problems with wide-angle on digital sensors. It's not hard to make the short focal-length lens that gives the angle of view with the small digital sensor. But the digital sensors struggle toi pick up light coming are axtreme angles, so the optical design gets more complicated. SLR cameras have to use the same tricks to make room for the mirror, but they don't have zoom lenses which go to extreme wide angle.