Talk:Einstein ring

starting from which mass size ?
Is the math universal or does bending only aply to large masses. For example if one took the right distance, and optics, could one use the moon for it ?. (i do think because the moon has been used to proove that light can be bended during an eclips. But i wonder if it could be made usefully in optics based on a distance satelite to have a combined largest lens. ..Also how about small masses ? the given formula doesnt seam to contain limits. —Preceding unsigned comment added by 82.217.115.160 (talk) 12:12, 11 June 2010 (UTC)
 * The math of general relativity is universal, at least at non-quantum scales. But there is a practical aspect to it; the Moon has too large an angular size and is too bright. If seen from sufficiently far away, it could perhaps produce a ring but it wouldn't be useful for astronomy purposes. Praemonitus (talk) 18:18, 12 February 2022 (UTC)

14MB gif
The animation is cool and useful, but it's frickin' enormous! I'll have a go at optimising it into something more practical. ▫ UrbaneLegend talk 18:46, 18 May 2006 (UTC)
 * Done. It's down to a much more manageable 579KB. I've speeded it up too. ▫ UrbaneLegend talk 08:53, 22 May 2006 (UTC)

Hubble Finds Double Einstein Ring
I don't know anything on this subject, but if someone with more knowledge than me wants to, there's an article about the Hubble taking snapshots of a double Einstein Ring:

http://hubblesite.org/newscenter/archive/releases/2008/04/

Dan —Preceding unsigned comment added by 121.223.78.8 (talk) 23:47, 13 January 2008 (UTC)

confusing bending space time or light only
The articles decribe that light is bended, actualy i think this i a wrong dicritption, its not light that is bended but the framwwork of space and time itself. Even if something was leaving the distant solar world and came to us, that would be bended too., not only light travels the space time but matter also can. In other words, einstein rings are not like a prisma that bends light in a fixed space time. an einstein ring bends the space itself whatever passes through. Can someone with a highee degree confirm that an einstein ring is not like a prisma bending light. —Preceding unsigned comment added by 79.153.198.224 (talk) 21:57, 21 June 2009 (UTC)

The equation is incorrect
for distances D_SL = 0, can not be zero deflection, because it would mean that the light goes in a straight line near the lens, which is contrary to the assumption: the lens is considered. — Preceding unsigned comment added by 83.7.233.185 (talk) 19:26, 7 May 2012 (UTC)

You are right that D_LS cannot be zero, and that makes sense! If the distance between the source and the lens is 0, then the source IS the lens. A star cannot deflect it's own light in this way, so the deflection angle is zero. 168.149.234.219 (talk) 21:21, 12 November 2020 (UTC) Megan

Length
The statement "Note that, over cosmological distances $$d_{LS}\ne d_S-d_L$$ in general." has nothing to do with cosmological distances, but in fact applies to all distances where the line segments are not collinear. — Preceding unsigned comment added by 124.176.52.63 (talk) 00:19, 2 December 2014 (UTC)

According to the accompanying diagram, $$d_{LS} = d_S-d_L$$. If the distances $$d_{LS}$$ and $$d_{L}$$ refer to the 'slanted' distances, then the diagram should reflect that.

Gravitational Lensing & Diffraction
The majority of images shown have large amounts of light in the center of their rings. Such a thing is only possible through diffraction. Simulations rarely yield any image of light centered around a gravitational mass, even though the reality shown is quite opposite as light diffracts around black holes and dark matter. Yet no attempt is made in the article to explain or differentiate between the majority of images with light in the exact center of their mass, and the minority of others that do not. No reference is made to diffraction and its relationship with gravitational lensing. A mention to gravitational diffraction should be made within the context of the article. Best regards Ezra Kirkpatrick (talk) 22:08, 6 October 2021 (UTC)
 * That light in the centre is the foreground object doing the lensing. The effect is not "diffraction". Graeme Bartlett (talk) 23:58, 7 September 2022 (UTC)

Perfect Einstein Ring?
This seems like new information that ought to be added if someone can validate that it's been confirmed and accepted as real.

https://www.space.com/james-webb-space-telescope-perfect-einstein-ring Netgecko99 (talk) 17:32, 7 September 2022 (UTC)