Talk:Telecentric lens

message: I just moved a couple of diagrams to Talk:Cardinal point (optics) - you may want them here ?
:Image:BFP.png 
:Image:BFP aperture.png 
--195.137.93.171 (talk) 04:15, 7 March 2008 (UTC)
replies: text: The lens depicted is not telecentric.--Srleffler (talk) 04:39, 7 March 2008 (UTC)
replies: text: Correction: the version without the aperture is not telecentric, the one with the focal plane aperture is.--Srleffler (talk) 03:10, 8 March 2008 (UTC)
thread_title:  Diagrams 

message: has a nice illustration, using an M C Escher-inspired Lego creation to show the 'isometric' effect.
--195.137.93.171 (talk) 03:49, 8 March 2008 (UTC)
thread_title:  Escher image - 'isometric' effect 

message: * Pericentric lens
I deleted the above broken link - I would guess the original link-target has been removed as advertising a specific product  ?
(Mind you, there are many others in :Category:Photographic_lenses!)
It was unlikely to have been telecentric, producing extremely distorted images of cylindrical surfaces. ('See also' can sometimes usefully contain the opposite of the article's topic, but probably not usefully here.)
There may have been a better place to mention it - any ideas? (Not Anamorphic lens unless it gets de-merged from cine formats !) There doesn't seem to be an existing article for 'silver ball mirror lenses'. I've added it to Anamorphosis#External_links, but that's Art, not Science !
--195.137.93.171 (talk) 04:11, 8 March 2008 (UTC)
thread_title:  See also Pericentric lens ?  Hypercentric lens ? 

message: Can't a simple lens be telecentric ?
If you put a narrow aperture in the focal plane of a simple lens, it fits the definition.
OK - it may not be much good !
I find the terminology 'Telecentric lens' confusing, since it is not really a property of the glass, but rather depends on the location of the aperture. Question of definition, really, but it could de-mistify a little. Too late.
--195.137.93.171 (talk) 04:46, 8 March 2008 (UTC)
thread_title:  A telecentric lens is a compound lens ? 

message: I presume that the magnification still changes if you re-focus a system with a telecentric lens ? (ie if you change both object and image distances) People reading the article may get the impression that the magnification is a fixed value, intrinsic to the lens design.  —Preceding unsigned comment added by 195.137.93.171 (talk) 05:14, 8 March 2008 (UTC)
thread_title:  geometric invariance ? 

message: I think this type should not be regarded as secondary - it should be numbered 3 in the heading and have its own section.
Why ? I am sure that semiconductor printing applications must use the double telecentric type, although this is currently listed in the 'object space' section. 
I have worked in a 'wafer fab', but that doesn't mean I've ever seen the lenses ! I would prove this by explaining another property of the lenses that is not very clearly explained in the article. The lenses do not suffer from 'wide-angle lens distortion' - most obvious when spheres (or heads) get elongated into ellipses at the edges of the image. (Yes, I know it is not 'really' distortion if you consider that the photographic print should be viewed from a distance of lens-focal-length x enlargement ... Viewing-distance does not apply to semiconductor chips !)
I am sure that a lens must be double-telecentric to eliminate this perspective effect, so the semiconductor wafer industry must use double-telecentric lenses. Given the volume of the industry, that strongly implies they are probably about as common as the other two single-telecentric lenses. (Of course, there is x-ray and e-beam lithography ... but electron optics is similar - I don't know about x-ray lenses).
The Edmund Optics page in the first link gives an illustration of "Doubly telecentric 0.25X reduction camera lens for microlithographic use operating at the ArF laser line (0.193 microns)"
--195.137.93.171 (talk) 05:47, 8 March 2008 (UTC)
thread_title:  double telecentric - semiconductor printing 

message: Thinking about 'apertures at the focal plane' reminds me of some (pretty rare) microscope objectives that have a variable aperture somewhere near the focal plane. Plus condensers, too. Does anyone know if they are telecentric ? It would make sense.
 suggests so, but may not be an authoritative forum. It seems almost all objectives and condensers may be telecentric. 'Infinity corrected' is different, but an objective can be both that and telecentric. Maybe since 'telecentric' is ubiquitous it hasn't been used as a buzzword in microscopy ?
That would make microscopy the oldest and biggest application of telecentric lenses.
--195.137.93.171 (talk) 06:00, 8 March 2008 (UTC)
thread_title:  Microscope objectives & condensers ? 

message: @Materialscientist, what it the reasoning for your rollback?  — Preceding unsigned comment added by 2601:281:8300:2740:AC26:CDC1:17D8:9127 (talk) 05:42, 13 November 2021 (UTC)
replies: text: I don't know what Materialscientist's reasoning was, but I notice that you removed a bunch of content in your edits. Generally, if you're going to remove content it's a good idea to say why either in the edit comment field or on the talk page. Users will respond better to your edits if they understand what you are doing. --Srleffler (talk) 02:15, 15 November 2021 (UTC)
thread_title:  Rollback by Materialscientist?