Talk:Guide number

message: Recently  added a rather long list of guide numbers. I removed it but  reverted me. I see this list as unencyclopaedic - it serves no purpose in explaining what guide numbers are or how they work. Surely people who have those models of flash either already know what GN their flash does, or could easily look it up in the manual. Or the flash is automatic and they don't need to know. The only purpose I can think of is for bragging rights (my GN is bigger than yours!) or comparing models before buying.
Wikipedia is not a shopping guide, nor an indiscriminate collection of information. The article already gives a few examples for guide numbers. A few better examples would be welcome, but this large list is not useful. --Imroy (talk) 06:39, 1 February 2008 (UTC)
replies: text: (Responding eight years later!) A list like that is why we have list-based articles. In this case, we have Flash comparison, so we don’t duplicate information here that is going to rapidly change anyway. Greg L (talk) 20:30, 5 August 2017 (UTC)
thread_title:  List of guide numbers 

message: I don't see the link to the Strobist page justified. I think it adds no real value.  —Preceding unsigned comment added by 60.241.91.114 (talk) 05:39, 4 January 2011 (UTC)
thread_title:  Strobist Reference 

message: It might be nice to add a comment why exposure duration is not relevant to GN  (because GN relates to the total energy of light emitted by the flash, regardless to how long it takes to emit that energy).  —Preceding unsigned comment added by 60.241.91.114 (talk) 05:42, 4 January 2011 (UTC)
replies: text: (Responding six years later): The duration of the flash is intimately linked to the illuminating power of the flash device. The shutter speed, however, is largely irrelevant. This has now been properly addressed in the article. Greg L (talk) 20:32, 5 August 2017 (UTC)
thread_title:  Exposure Duration 

message: The authors have the concept of a guide number wrong, as well as the specifics. Too much to edit, it needs to be rewritten. 
For example; the opening sentence has an error: "The guide number for an electronic flash measures its ability to illuminate the subject to be photographed at a specific film or sensor sensitivity and angle of view." This is incorrect, a guide number is Not affected by angle of view. 
Under the next topic, "Value" there is another major error: "The guide number is the product of the maximum flash-to-subject distance and the f-number of the aperture that will correctly expose film or a digital sensor with the specified sensitivity." A guide number is the product of ANY distance to subject and proper aperture.
I could continue, for instance; a guide number is NOT a measure of distance, and so is not qualified as either "feet" or "meters." The last sentence is completely erroneous, a guide number has nothing to do with the reflectance of surroundings (although the exposure does.)  I'll have to give this some study, but it's so wrong in so many place it cannot be fixed by limited edits. Truthhurts34 (talk) 00:21, 20 February 2013 (UTC)
replies: text: (Responding four years later): I couldn’t agree more. The article was beyond repair. I threw it out and started anew. The issue of “feet and meters” should have been clearer in the original article. Guide numbers are scaled differently for use in the U.S. because photographers measure distances in feet in the U.S. As there is no single, universally accepted way that all manufacturers abide by to express guide numbers when marketing to the U.S., some manufacturers of flash devices use nomenclature that misleading makes guide numbers appear to be a unit of measure for distance. This confusing-looking practice has now been properly explained. The industry-wide practices in this regard may suck, but it is what it is. See This article requires rewriting, below. Greg L (talk) 17:12, 6 September 2017 (UTC)
thread_title:  Wrong too many ways to count.... 

message: Link [2] to the blog article  "The Inverse Square Law - Myth Busted", as well as the text related to that article, is of very low quality.
In fact, the author of that blog article now admits at the top of his page that his article is fundamentally flawed. 
It should be removed as a link, and the text under "Distance" should be edit to reflect that.
Source: http://www.diyphotography.net/the-inverse-square-law-cheat-sheet-myth-basted  — Preceding unsigned comment added by 208.184.67.190 (talk) 02:39, 19 September 2013 (UTC)
replies: text: I agree. In fact, the original author retracted the claim in a followup post. http://www.diyphotography.net/the-inverse-square-law-experiment-done-right-myth-unbusted/ -- therefore, I'm going to edit this article to remove the misinformation.  — Preceding unsigned comment added by Mattdm (talk • contribs) 17:09, 4 January 2015 (UTC)
thread_title:  Distance section - link to "The Inverse Square Law - Myth Busted"