Under or over?

[Rob_K]

Just a little experiment here! Attached are two double-images of comet C/2020 F3 (NEOWISE). You probably get the idea - you have to cross your eyes to create a third, central "3D" image. Sitting back from the monitor and relaxing makes it easier.

I know that not everyone sees these the same - which one shows the comet in front of the stars, A or B?

[croweater (Richard)]

Hi Rob. B the comet looks in front to me.
cheers, Richard

[multiweb (Marc)]

A for me. Comet in front and little galaxy behind the stars.

[LewisM]

Try it on an iPhone SE... I think I need eye surgery now

[Stonius (Markus)]

It's A, and I can say that as professional stereographer. :-)


It's an nice shot. I'm always fascinated by shots of the heavens that manage to include Z depth. Some people have used librations of the moon to create 3D moon shots, which is pretty cool.



A couple of small suggestions - I would put the 'A' label on the same place in both eyes (otherwise it introduces retinal rivalry in that part of the frame).



Also, the format of these images works against you. Stereoscopic images work in a left-right plane. At the edge of the image you often get issues with the stereo window. I'm not sure if you shot the image this way (due to the way the comet was moving at the time) or if you created it from a single image, but you will find you'd get better mileage from formats that are not tall and skinny because your eyes can move more before it hits the edge of the stereo window. Do you have any more image to play with on either side?


Cheers, and well done mate.


Markus

[LewisM]

Strangely, B is more pleasing to me. A works, but B gave me more depth.

[Stonius (Markus)]

Originally Posted by LewisM

Strangely, B is more pleasing to me. A works, but B gave me more depth.

Me too. The reason is because any object that is in front of the edge of the window, yet is cut off by the edge of that same window will cause retinal rivalry at that boundary. Physics doesn't work like that. If you're looking at me standing in front of a window, but the edge of the window occludes me, your brain is being given two contradictory stereo depth cues.


Things that work best 'in front of' the convergence point are particles (like stars) where this seems not to matter so much.


A middle way would be to have the comet lie at the point of convergence and have the stars pushed back in z depth. Then the window ceases to be an issue :-)

[Terry B]

For me the B image has the comet closer and the little galaxy in the background.
I'm left eye dominant so maybe that makes a difference.

[alval (Alan)]

To me A looks behind the stars and B looks in front of them. I wear glasses if that makes any difference. Without them its what comet and stars?

[astronobob (Bob)]

A has the comet in front and Galaxy behind
B has the opposite/backward, Galaxy front - comet back..

[Rainmaker (Matt)]

A .... Comet in front
B .... galaxy in front

[OICURMT]

Cross-eyed method : A - Comet in Front
Relaxed eye method : B - Comet in front

[doug mc]

A. Comet behind. B. Comet in front with galaxy far background. Stars have 3d depth. Definitely B best.