Talk:Exposure (photography)

message: double exposure is when u take one image make a image over it. but u can't over expose it.
: Included multiple exposure bit into preamble/disambig. Hope that covers it. --Redbobblehat (talk) 02:21, 12 February 2009 (UTC)
thread_title:  Double exposure 

message: I fixed the lead where it said higher EV meant MORE total exposure.  Actually, if all you vary is EV, that's backwards, since higher EV means faster shutter or smaller aperture, which gives you LESS exposure.  This is a common confusion, since a higher EV is apppropriate when shooting a brighter (higher luminance) scene.  See exposure value. 
How about a formula for total exposure from EV and scene luminance? Using the formula above for focal-plane illuminance and multiplying by exposure time t we have total exposure:
: E t = {\pi L t \over 4 N^2}
But since {t \over N^2} = 2^{-\mathrm{EV}}, we can write the total exposure as:
: E t = {2^{-\mathrm{EV}} \pi L \over 4}. 
That's the total lux seconds, for L in candela per square meter. Dicklyon 22:58, 2 January 2007 (UTC)
thread_title:  Error in EV interpretation 

message: Why was the link to this page removed: http://wamp.co.uk/index.php?page=grad ?  It nicely shows how exposure varies when ND filters are used.--Tiberius47 02:37, 13 January 2007 (UTC)
replies: text: Better question might be why was this page added.  The same guy added this page to several other articles recently.  It's a whole page to help you divide by 2 a few times, and it's on a commericial selling site.  Shouldn't we just remove all those?  Dicklyon 05:54, 13 January 2007 (UTC)
thread_title:  Removed Link 

message: I've just added a new (extensive) section on exposure settings. My intention was to provide a brief whistle-stop tour highlighting the main issues and referencing other articles (for more expansive information) where I could. In many ways, it's like an inflated disambiguation page, hoping to provide a reasonably brief but helpful context to deeper stuff. It took me ages so please be nice :) --Redbobblehat (talk)
=== video gain ===
I realise that some bits may be contentious - the bit on video gain in particular. I hope you don't find it too objectionable. I worded it very carefully, so please read it carefully before you freak out ;) --Redbobblehat (talk) 02:11, 12 February 2009 (UTC)
thread_title:  Exposure settings 

message: I realise that some bits may be contentious - the bit on video gain in particular. I hope you don't find it too objectionable. I worded it very carefully, so please read it carefully before you freak out ;) --Redbobblehat (talk) 02:11, 12 February 2009 (UTC)
thread_title:  video gain 

message: Because of the distinction between photometry and radiometry, both photometric exposure and luminous exposure quantify only human-visible light. If there is any debate about this use of photometric I suggest we ditch it and just use luminous exposure. To improve clarity and flow, and avoid getting bogged down in "infra-red herrings" ;-) I've tightened up the definition and added a little note with links to the most useful articles about "invisible" light in photography. I hope this is satisfactory. (incidentally, IR filter needs expanding ... ) --Redbobblehat (talk) 19:53, 14 February 2009 (UTC)
replies: text: Seems to me that photometric is the more common and precise term; if luminous is mentioned, it should be given as a synonym. JeffConrad (talk) 02:35, 16 February 2009 (UTC)
thread_title:  Visible & invisible light 

message: And what's up with the Ray 2000?  Looks like Attridge wrote that chapter; I fixed the ref in one place, but the "ibid" made less sense, so I took it out. Dicklyon (talk) 06:57, 16 February 2009 (UTC)
replies: text: Well, "ibid" made sense before someone edited the preceding reference to that book ... I've reformatted and replaced the ref, and found a page where the term "log exposure" and discussion of log10(H) coincide. Now it should be foolproof? IMO the term "log exposure" is unusual and deserves a source ref. "log10(H)" can be found on any characteristic curve, although often abbreviated to "log(H)" which can seem ambiguous when thinking in base-2 log scales. --Redbobblehat (talk) 21:31, 26 February 2009 (UTC)
replies: text: Ibid makes sense on paper, where things don't move; not in a wiki. Dicklyon (talk) 04:31, 27 February 2009 (UTC)
replies: text:  Good point, well made :-) BTW Nice cite book template too ... but copy & pasting it for every page reference seems a bit clumsy... could we justify a special template just for the Manual ... with just the page number as a parameter ? --Redbobblehat (talk) 14:26, 28 February 2009 (UTC)
replies: text: You can name the ref, and put a page range for the whole chapter; or other ways to do this; Jeff will know. Dicklyon (talk) 22:57, 28 February 2009 (UTC)
thread_title:  Citations 

message: Robbie, your "HDR example" image is not a great one, as it is specifically an example of a scene for which no exposure can be considered correct.  Find a more normal scene and make that kind of example. Dicklyon (talk) 17:15, 12 February 2009 (UTC)
replies: text: Ah I just realised I'm Robbie! IMO The HDR image is eminently suited to illustrate the sentence "A photograph may be described as overexposed when the subject tones seem too light, or underexposed if the subject seems too dark. Underexposure may cause loss of shadow detail, also known as crushed blacks, and overexposure may cause loss of highlight detail, also known as blown-highlights." What the file happens to be called or the fact that it's a CGI is irrelevant. I really can't understand your objection to this image. --Redbobblehat (talk) 21:14, 12 February 2009 (UTC)
replies: text: Sorry, I misrecalled your name. Anyway, several problems; if the image is CGI, it doesn't even have an exposure.  But more to the point, the "correctly" exposed one also shows crushed shadows and saturated highlights. Dicklyon (talk) 06:36, 13 February 2009 (UTC)
replies: text:  np. It seems to me that the CGI has been carefully created to 'simulate' all the under/over exposure effects we're talking about. Think of it as a graphic illustration rather than a photographic example ;) I hadn't looked for crushed blacks and blown highlight in the central image, but its good they are there - we can use it to illustrate the effects of limited exposure range/latitude too (which of course is the raison d'etre for the whole HDR thing...). Ray uses the term "optimum exposure" instead of "correct" - would that help allay your concerns? ... I am assuming of course that you don't have in mind an even better image we could use for this ? --Redbobblehat (talk) 13:51, 13 February 2009 (UTC)
replies: text: There's one in commons called Exposure.jpg (but another in en. that shadows it; how we specify commons?). Dicklyon (talk) 16:59, 13 February 2009 (UTC)

text: Not if you read the subsequent 2 sentences: "Often the most obvious methods, such as simply adding or avoiding local lighting, or using neutral density filters are overlooked. Choosing a film stock or camera sensor with a light sensitivity appropriate to the task can be a vital first step." ... ? --Redbobblehat (talk) 21:14, 12 February 2009 (UTC)
replies: text: That seems to be confusing lighting and film selection with exposure; we should clean that up. Dicklyon (talk) 16:54, 13 February 2009 (UTC)
replies: text:  lol! no! :) The whole point is that "lighting and film selection" are inseparable from "exposure"! If you don't recognise that fundamental physical connection, you won't understand the mechanics of photographic exposure at all. I'm sorry mate but the confusion is yours. I'm going to revert your reverts, then I will create a separate photometric exposure section, and restore the 'old' article introduction. I hope that will satisfy all parties ? --Redbobblehat (talk) 17:19, 13 February 2009 (UTC)

text: Wouldn't it be more polite to ask for clarification if something doesn't read well to you, rather than reverting contribs and demanding an explanation ? I would be much happier if you reverted your reverts (sic!) so we can make improvements amicably. --Redbobblehat (talk) 21:32, 12 February 2009 (UTC)
thread_title:  Bad image and explanation 

message: R, your revert edit summary said "D you a really beginning to annoy me now. Please use talk if you don't understand something."  I don't understand that.  Are you sugggesting that my corrections were based on a misunderstanding?  Please explain.  Are you not aware that photometry is based on energy wavelength weighted by the luminosity function, and that the effective stimulus for films needs a non-photometric spectral sensitivity weighting? Dicklyon (talk) 23:28, 14 February 2009 (UTC)
replies: text: Perhaps you should include that in the photometry or photographic film article ? --Redbobblehat (talk) 02:59, 15 February 2009 (UTC)
replies: text: I'm not sure how you mean; the photometry article doesn't need to mention all the non-photometric ways to measure light, does it?  The film article already talks about spectral sensitivity and notes that "Film has a number of disadvantages as a scientific detector: it is difficult to calibrate for photometry..."  Dicklyon (talk) 04:02, 15 February 2009 (UTC)

text: As I already pointed out under #visible & invisible light (above), I do not think that a whole lot of "whereas in radiometry ..." caveats is necessary or helpful in this article. IMO they clutter up the page with superfluous facticles, disrupting the flow of the article to the point of unintelligibility. Referenced articles such as photometric, lux already contain the information you are touting. Wouldn't your deductions be more usefully appended to more specialist articles such as infra red photography or full spectrum photography ? IMO you need to justify inclusion here. --Redbobblehat (talk) 17:21, 15 February 2009 (UTC)
thread_title:  I don't understand 

message: Following the discussion under #Bad image and explanation, your edit (diff) still seems more confused than the original:
*(original)The purpose of exposure adjustment is to control the amount of light reflected (or emitted) from the subject so that it conforms to the the film (or sensor's) exposure sensitivity. Often the most obvious methods, such as simply adding or avoiding local lighting, or using neutral density filters are overlooked. Choosing a film stock or camera sensor with a light sensitivity appropriate to the task can be a vital first step. 
*(your version)The purpose of exposure adjustment (in combination with lighting adjustment) is to control the amount of light from the subject that is allowed to fall on the film, so that it falls into an appropriate region of the film's characteristic curve.
I was considering changing "exposure sensitivity" to "exposure responsivity", but I'm not 100% sure that would be any more correct or helpful. However, I am quite certain that any light falling on the "characteristic curve" (which is a type of diagram), will not make any difference to the photograph (which is another type of diagram altogether). Your version omits the direct reference to the sensitivity (or responsivity) of the film being used, which I believe is an absolutely essential part of the exposure equation.
:I find both versions of "The purpose of exposure adjustment ..." confusing. Is "exposure adjustment" the same as exposure compensation? If not, how does it differ? JeffConrad (talk) 02:47, 16 February 2009 (UTC)
replies: text: Yes, it's very confusing, between the concept of adjusting the camera's exposure settings and adjusing things like lighting.  We need to straighten it out. Dicklyon (talk) 03:43, 16 February 2009 (UTC)
replies: text:  What I'm trying to say is so simple & fundamental. Maybe it's so obvious that you guys are looking too hard to see it, maybe I've not expressed it well enough .... let's call your aperture and shutter your "exposure settings". Imagine you're setting up a studio shot and discover that your aperture and your shutter are jammed at f/2 and 1/2 sec, which will overexpose your ISO 800 film by 5 stops. You can't fix them, you don't have any spares, etc. What else can you change to get the right exposure ? answer: reduce the lighting levels and/or use a less sensitive film... At a really basic level, the task is to somehow balance the scene luminance with the film speed, and that task I called "exposure adjustment". Changing your "exposure settings" is not the only way of getting the right exposure. --Redbobblehat (talk) 06:07, 16 February 2009 (UTC)
replies: text: But you're mixing up at least a couple of things.  Changing your film speed isn't going to change the exposure, but I agree that changing the lighting (scene luminance) will. Dicklyon (talk) 06:15, 16 February 2009 (UTC)
thread_title:  Purpose of exposure adjustment 

message: Several pictures used by Wikipedia give the exposure time as 0.016638935108153 seconds. This is what Nikon are claiming. I do not think that this is a realistic value. To measure to the nearest femtosecond.  —Preceding unsigned comment added by 81.136.231.67 (talk) 14:56, 23 April 2010 (UTC)
replies: text: The cameras are shooting at 1/60.  For some reason the mediawiki software is reading it as 10/601 and when converted to decimal format you get that long number.  Nikon isn't doing anything wrong. gh5046 (talk) 16:14, 23 April 2010 (UTC)
thread_title:  Accuracy 

message: Hello! This is a note to let the editors of this article know that :File:Clifton Beach 5.jpg will be appearing as picture of the day on June 13, 2011. You can view and edit the POTD blurb at Template:POTD/2011-06-13. If this article needs any attention or maintenance, it would be preferable if that could be done before its appearance on the Main Page so Wikipedia doesn't look bad. :) Thanks! howcheng  {chat} 19:34, 12 June 2011 (UTC)
thread_title:  [[:File:Clifton Beach 5.jpg]] to appear as POTD soon 

message: Exposure is not the total amount of light that falls on a photographic medium but the amount of light per area unit (lm*s per m2). Therefore the top entry on this talk page should be removed or changed accordingly. There also should be an addition to the article that there exists a common misconception that exposure is equal with the total amount of light. After all it took nine years for this basic mistake in the introductory sentence of the article to be noticed at all! The total amount of light is dependent on the area of the photographic medium. A larger photographic medium will have to be hit by a larger total amount of light to receive same exposure. At same aperture and shutter speed, FOV being the same, a larger photographic medium will have to receive a larger total amount of light for the same exposure.  — Preceding unsigned comment added by 83.84.4.12 (talk) 16:21, 26 July 2012 (UTC)
replies: text: It doesn't say total; lux, lux seconds, illuminance, are all per area measures of light.  But they're not constants over a scene, so you need to specify where you're measuring it.  Dicklyon (talk) 16:51, 26 July 2012 (UTC)
thread_title: A common misconception: Exposure is not equal to total amount of light 

message: The usage of  is up for discussion, see Talk:Overexposed (album) -- 70.24.245.16 (talk) 21:41, 4 December 2012 (UTC)
thread_title: Overexposed

message: There is no mention of the misnamed 'Exposure Triangle' as an aid to quickly estimate what happens to output level (a proxy for brightness) relative to a given starting situation when changing Exposure and Sensitivity parameters in the field.  The link at the bottom of the article is well done, but unfortunately confuses Exposure and Output Level.  I understand that this would introduce Sensitivity to the article, which understandably appears to have been avoided like the plague, but I think explaining its indicative nature clearly here would help dispel a number of doubts.  Jack Hogan (talk) 07:20, 22 April 2013 (UTC)
thread_title:  Exposure Triangle? 

message: The section on 'exposure control' does a good job of introducing the 'sunny 16 rule', where an ISO of 100, and a time of 1/100 are used. Going into the next section, the results are confusing. The author of this section says they are starting with a 'sunny 16' shot, but has either used ISO 125, or has rounded the 1/100 exposure to a 'nearest' of 1/125 (without explanation). These two sections would follow each other better if they both used ISO 100 and 1/100, giving 1/800 as the new exposure.  — Preceding unsigned comment added by 109.224.166.23 (talk) 16:06, 22 February 2015 (UTC)
thread_title:  Reciprocity section confusing 

message: I came here to find out about historic information, particularly since when automatic exposure exists and what internal methods were used. From personal experience with old cameras, I know that automatic exposure has been around at least since the 1950s. Any information regarding the history of exposure is still missing from the article. --79.242.222.168 (talk) 07:31, 1 June 2016 (UTC)
thread_title:  History 

message: The clause in the opening of this sentence renders the entire entry unintelligible to the average reader. Can someone please explain what function it is trying to serve and where it could be located to serve readers better? 
The other problem with the clause is that it uses the word "time" twice and uses the word being defined as part of its definition. Both definitions appear to lack reference to any published work. 
KeepForgettingMyUserName (talk) 00:47, 23 June 2020 (UTC)
thread_title:  First Paragraph