 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
| PhotoKB HomeDiscussion Groups Digital Photography Digital PhotoDSLR CamerasZLR CamerasPoint & Shoot CamerasFilm Photography 35 mmLarge FormatMedium formatDarkroomFilm and LabsOther EquipmentPhoto Technique Nature PhotographyPeople PhotographyTechnique GeneralGeneral Photo Topics General TopicsAustralian PhotographyUK PhotographyDirectoryPhoto Clubs |
Photo Forum / Film Photography / Darkroom / May 2004Film Pre-Exposure?
Is anybody using pre-exposure when takeing pictures? I know it requires multiple exposure capability but can be done, at least for one frame, in advance of the actual picture takeing. I've been lazy up till now but think the added shadow density and gain of a stop or two in EI might be worth the extra effort. What about technique? Will a plastic bag over the lens and a three or four stops down exposure do the job? Dan > Is anybody using pre-exposure when takeing pictures? I know it > requires multiple exposure capability but can be done, at least [quoted text clipped - 5 lines] > What about technique? Will a plastic bag over the lens and a three > or four stops down exposure do the job? Dan The idea was for sheet film where you are processing each sheet seperately. Never the less you could shoot the whole roll through the camera,...there's really no reason you can't. If I was doing it I would make a round disk out of white opaque plexiglass, mounted into a stepping ring the thread size of the lens. Or you could cut a square 4x4 piece and use a slip in filter holder.  SignatureLF website http://members.bellatlantic.net/~gblank <<<For best results expand this window at least 6" at 1152 x 768 resolution > Is anybody using pre-exposure when takeing pictures? I know it > requires multiple exposure capability but can be done, at least > for one frame, in advance of the actual picture takeing. > > I've been lazy up till now but think the added shadow density and > gain of a stop or two in EI might be worth the extra effort. Generally this is not a good idea. It lowers contrast in the shadows, just where you need it. Lens designers have been striving for decades to reduce flare....so why the hell do you want to add it? > What about technique? Will a plastic bag over the lens and a three > or four stops down exposure do the job? Dan Put the plastic bag over your head... mikescarpitti@yahoo.com (Michael Scarpitti) wrote in message > Put the plastic bag over your head... Follow your own advice, Scarcrappi. As for the question, yes it can be done, and there are many reasons to do so, but what are yours? What are you trying to achieve by doing so? Alexis www.alexisneel.com > mikescarpitti@yahoo.com (Michael Scarpitti) wrote in message > > Put the plastic bag over your head... [quoted text clipped - 8 lines] > > www.alexisneel.com This is folly. Nothing to be gained except ruined shadow contrast. There are better ways, such as compemsating devlopment, that will accomplish your goal better. Quit listening to morons. >>mikescarpitti@yahoo.com (Michael Scarpitti) wrote in message >> [quoted text clipped - 15 lines] > > Quit listening to morons. Michael, if the detail was not recorded in the shadows to begin with, no amount of compensating development can put it there. That is why a pre-exposure can be extremely useful. Francis A. Miniter mikescarpitti@yahoo.com (Michael Scarpitti) wrote in message > This is folly. Nothing to be gained except ruined shadow contrast. > There are better ways, such as compemsating devlopment, that will > accomplish your goal better. Wrong, as usual. > Quit listening to morons. Oh I have stopped listening to you a long time ago. Not that you had anything to say except for dribble, or how did you put it...oh yeah, dreck. > mikescarpitti@yahoo.com (Michael Scarpitti) wrote in message > This is folly. Nothing to be gained except ruined shadow contrast. > > There are better ways, such as compemsating devlopment, that will [quoted text clipped - 7 lines] > anything to say except for dribble, or how did you put it...oh yeah, > dreck. Flashing film is idiocy. You gain NOTHING. Latensification, in which film is exposed to an extremely faint light for a long period, does help for some problems in photography caused by reciprocity failure, i.e., extremely long exposures made under dim light. : mikescarpitti@yahoo.com (Michael Scarpitti) wrote in message > This is folly. Nothing to be gained except ruined shadow contrast. : > There are better ways, such as compemsating devlopment, that will : > accomplish your goal better. : Wrong, as usual. : > Quit listening to morons. : Oh I have stopped listening to you a long time ago. Not that you had : anything to say except for dribble, or how did you put it...oh yeah, : dreck. I think that dreck is the word I used to discribe scarpitti's photographs. I personally think that he should put is dreck back online to show the world that he is an incompatent<SP?> photographer. SignatureKeep working millions on welfare depend on you ------------------- fwp@deepthought.com > > [quoted text clipped - 10 lines] >to reduce flare....so why the hell do you want to add it? > Wrong. The technique, implemented by shooting the sky at 4-5 stops below meter reading, is often used to add detail in the shadow areas without affecting the highlights. A uniform increase of 1 unit of exposure value in Zone 1 yields 2 or Zone 2. Zone 2 becomes 2 1/2. Zone 3 becomes 4 1/4. By the time you are at Zone 8, the affect is only 1/128th additional light, not noticeable to the human eye. Flare, on the other hand, is a lens affect, not an exposure affect. > > [quoted text clipped - 3 lines] > >Put the plastic bag over your head... Michael, such passive-aggresive or anti-social behavior is not helpful. Nor is it funny. Francis A. Miniter On 5/11/2004 8:14 AM Francis A. Miniter spake thus: >>> What about technique? Will a plastic bag over the lens and a three or >>> four stops down exposure do the job? [quoted text clipped - 3 lines] > Michael, such passive-aggresive or anti-social behavior is not helpful. Nor > is it funny. Quite the contrary: it is both. Helpful in reminding all of his true nature, and funny as only a fool self-destructing can be. SignatureI was quickly apprised that an "RSS feed" was not, as I had naively imagined, some new and unspeakable form of sexual debauchery practised by young persons of dubious morality, but a way of providing news articles to the cybernetic publishing moguls of the World Wide Wait so they can fill the airwaves with even more useless drivel. - Cynical shop talk from comp.publish.prepress > > > > [quoted text clipped - 18 lines] > 1/128th additional light, not noticeable to the human eye. Flare, on > the other hand, is a lens affect, not an exposure affect. Utter crap. Such an exposure is fog, and it ruins the shadow contrast in the same way as flare. Complete waste of effort. >>>>Is anybody using pre-exposure when takeing pictures? I know it >>>>requires multiple exposure capability but can be done, at least [quoted text clipped - 18 lines] > Utter crap. Such an exposure is fog, and it ruins the shadow contrast > in the same way as flare. Complete waste of effort. Flare, as I mentioned before, is a lens effect, resulting from light scattering in a compound lens. See Langford, Advanced Photography (Focal Press, 4th ed.) pp. 12 et seq. This is an uncontrolled non-image forming event unlike pre-exposure which is deliberate and calculated to increase low shadow values so they will register on the negative. Adams, The Camera (Little Brown 1st Ed, 3d printing) p. 71. While pre-exposure does reduce contrast, this is a desirable effect in high contrast scenes. Adams, The Negative (Morgan & Morgan, 1st Ed) pp. 109-110. See his comparative images on page 109. I could give you more citations, but it is late and I am tired. Besides, this is a widely accepted photographic technique. Francis A. Miniter > >>>>Is anybody using pre-exposure when takeing pictures? I know it > >>>>requires multiple exposure capability but can be done, at least [quoted text clipped - 32 lines] > > Francis A. Miniter Latensification is the exposure to film of very low level light to stimulate the latent image. It is different from thie kind of fogging exposure you are discussing. The only use I know of for deliberate fogging was during the B&W era of motion pictures, where it was used in night scenes to keep the screen from getting too dark. In this application, it does not rescue any shadow detail, but simply makes a better presentation for projection. >> >> [quoted text clipped - 22 lines] > > Francis A. Miniter Correction: The 4 1/4 should be Zone 3 1/4. To put it in a table form: Zone Exposure Unit Addition Result 1 1 1 2 2 2 1 3 3 4 1 5 4 8 1 9 5 16 1 17 6 32 1 33 7 64 1 65 8 128 1 129 9 256 1 257 This illustrates better how little effect pre-exposure has on mid-tone and highlight values. Francis A. Miniter > To put it in a table form: > [quoted text clipped - 14 lines] > > Francis A. Miniter Have you been reading Otis Sprow? He mentions A. Adams's revised edition of The Negative where is discussed Zone II pre-exposures. Mr. Scarpitti may have a point. Look at zones 1, 2, and 3 in particular. Notice the compression. In practice, though, results may be just the opposite. That would depend on the toe characteristics of any one film/developer combination. My Bronica ETRSi and Mamiya RB67 Pro S both have multiple exposure provision. Mr. Sprow mentions a piece of white diffused plastic for metering and exposure. The sky won't do in the woods although an 8x10 or there-abouts grey card likely will do. All in all it looks as though I ought to give the technique a go. Dan > > To put it in a table form: > > [quoted text clipped - 12 lines] > > This illustrates better how little effect pre-exposure has on mid-tone > > and highlight values. The problem, as I have stated, is the effect it has on shadow values. > > > > Francis A. Miniter [quoted text clipped - 11 lines] > All in all it looks as though I ought to give the technique a go. > Dan > The problem, as I have stated, is the effect it has on shadow values. Lowering contrast in the shadows will produce a favourable negative if used on the right subject. Example: <http://www.photoportale.de/pp/pp_public.php?action=userpicture&series=338&pictur e=3&user=75> Stefan > > > The problem, as I have stated, is the effect it has on shadow values. [quoted text clipped - 4 lines] > > Stefan Could you explain exactly what you did on this image? Equipment, film, etc? Press photographers used to "shoot the sky" to effect this. Exposure should be around 4-5 stops less than middle gray (obviously you need to test this procedure). I also have plans somewhere for a camera mod using grain of wheat lamps to preflash film in roll cameras, one of the cameras modified was a M-3. Gives a real 1-2 stop boost in shadow detail. Threshold effect. Get enough photons in those really dark areas to print. It looks better than inky black shadows or half-baked dodging. One can also post flash film by hanging it in a dark (real dark not near dark) darkroom and use a #3 safelite to expose the film. Signaturedarkroommike ---------- > Is anybody using pre-exposure when takeing pictures? I know it > requires multiple exposure capability but can be done, at least [quoted text clipped - 5 lines] > What about technique? Will a plastic bag over the lens and a three > or four stops down exposure do the job? Dan Speaking of Pre-Exposure: > Press photographers used to "shoot the sky" to effect this. Exposure should > be around 4-5 stops less than middle gray (obviously you need to test this [quoted text clipped - 11 lines] > > darkroommike Pre-expose and Post expose. Where are those that need that extra stop or two or three or four of film speed. Going from f2.8 to f2 or f1.4 in some cases can cost thousands. Seems like just about everbody is traveling in the slow lane. Slow films, no mention of pre or post exposure, forget the speed boosting Perfection XR-1, and likely another trick or two or three I've not yet encountered. I know! It's today's optics. Even the latest fast films won't do the latest optics justice. What else could it be? Dan > Press photographers used to "shoot the sky" to effect this. Exposure should > be around 4-5 stops less than middle gray (obviously you need to test this [quoted text clipped - 4 lines] > > Gives a real 1-2 stop boost in shadow detail. Utter bullshit. It's just fog. On 5/14/2004 8:42 AM Michael Scarpitti spake thus: >> Press photographers used to "shoot the sky" to effect this. Exposure >> should be around 4-5 stops less than middle gray (obviously you need to [quoted text clipped - 6 lines] > > Utter bullshit. It's just fog. Admit it; you just don't like it because Ansel Adams did it. SignatureI was quickly apprised that an "RSS feed" was not, as I had naively imagined, some new and unspeakable form of sexual debauchery practised by young persons of dubious morality, but a way of providing news articles to the cybernetic publishing moguls of the World Wide Wait so they can fill the airwaves with even more useless drivel. - Cynical shop talk from comp.publish.prepress > On 5/14/2004 8:42 AM Michael Scarpitti spake thus: > [quoted text clipped - 13 lines] > > Admit it; you just don't like it because Ansel Adams did it. I have no knowledge that Adams did it or didn't do it, nor could I care less. It's a stupid technique that ruins shadow separation. >>On 5/14/2004 8:42 AM Michael Scarpitti spake thus: >> [quoted text clipped - 13 lines] > I have no knowledge that Adams did it or didn't do it, nor could I > care less. It's a stupid technique that ruins shadow separation. That is strange. At 1:09 PM of 5/12/04 you responded to my post of 11:12 PM of 5/11/04 in which I referred you to two books of Adams and two pictures of his illustrating the technique. Did you not read the post to which you replied? Francis A. Miniter > That is strange. At 1:09 PM of 5/12/04 you responded to my post of > 11:12 PM of 5/11/04 in which I referred you to two books of Adams and > two pictures of his illustrating the technique. Did you not read the > post to which you replied? "Never try to teach a pig to sing. It wastes your time and annoys the pig." -- Robert A. Heinlein, in the voice of Lazarus Long. "Never wrestle with a pig. You both get dirty and the pig enjoys it." -- unknown, possibly Teddy Roosevelt SignatureI may be a scwewy wabbit, but I'm not going to Alcatwaz! -- E. J. Fudd, 1954 Donald Qualls, aka The Silent Observer Lathe Building Pages http://silent1.home.netcom.com/HomebuiltLathe.htm Speedway 7x12 Lathe Pages http://silent1.home.netcom.com/my7x12.htm Opinions expressed are my own -- take them for what they're worth and don't expect them to be perfect. On 5/15/2004 6:13 PM Donald Qualls spake thus: >> That is strange. At 1:09 PM of 5/12/04 you responded to my post of >> 11:12 PM of 5/11/04 in which I referred you to two books of Adams and [quoted text clipped - 6 lines] > "Never wrestle with a pig. You both get dirty and the pig enjoys it." > -- unknown, possibly Teddy Roosevelt Time for a song: 'Twas the pig fair last September, the day I well remember, I was walking up and down in drunken pride, When my knees began to flutter, as I sank down in the gutter, And a pig came up and lay down by my side. As I sat there in the gutter, thinking thoughts I could not utter, I thought I heard a passing lady say, "You can tell the man who boozes by the company he chooses", And with that the pig got up and walked away. SignatureI was quickly apprised that an "RSS feed" was not, as I had naively imagined, some new and unspeakable form of sexual debauchery practised by young persons of dubious morality, but a way of providing news articles to the cybernetic publishing moguls of the World Wide Wait so they can fill the airwaves with even more useless drivel. - Cynical shop talk from comp.publish.prepress > "Never try to teach a pig to sing. It wastes your time and annoys the > pig." -- Robert A. Heinlein, in the voice of Lazarus Long. > > "Never wrestle with a pig. You both get dirty and the pig enjoys it." > -- unknown, possibly Teddy Roosevelt "Never argue with an idiot. Observers will have trouble telling the difference." SignatureNicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. Remove spaces etc. to reply: n o lindan at net com dot com psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ > > "Never try to teach a pig to sing. It wastes your time and annoys the > > pig." -- Robert A. Heinlein, in the voice of Lazarus Long. [quoted text clipped - 4 lines] > "Never argue with an idiot. Observers will have trouble telling the > difference." Never argue with a zonehead. They don't realize how stupid they are. They just go to their 'holy books' and quote Adams, chapter and verse. What difference is there between zoneheads and religious zealots? NONE. > Never argue with a zonehead. They don't realize how stupid they are. > They just go to their 'holy books' and quote Adams, chapter and verse. > What difference is there between zoneheads and religious zealots? > NONE. What is the difference between Mike Scarpathetic, Hans Beckert, and a liar? Nothing... > >>On 5/14/2004 8:42 AM Michael Scarpitti spake thus: > >> [quoted text clipped - 18 lines] > two pictures of his illustrating the technique. Did you not read the > post to which you replied? OK, prior to that post I HAD no knowledge of this technique being used by Adams, and in any event it does not matter what Adams did or didn't do. Adams was not an emulsion scientist, but I have a book by an emulsion scientist that explains in detail what can be done with latensification, which is a very low-level exposure to light used to offset reciprocity failure, and to keep the latent image from fading, on film used for long exposures, such as those made in astronomy. 'The Science of Photography' by Baines, revised by Bomback, cotains an extensive discussion of this on pages 199-208. If you can cite a better authority, do so. This technique has NOTHING to do with 'flash' exposures that are being discussed here, which contribute NOTHING to the negative that cannot be effected better in other ways. Fog is fog is fog. > Francis A. Miniter > "...I have a book by an > emulsion scientist that explains in detail what can be done with > ... a very low-level exposure to light used to offset reciprocity > failure, 'The Science of Photography' by Baines, revised by Bomback, > cotains an extensive discussion of this on pages 199-208. That's something to keep in mind. Glad you reminded me of the areas of the scene where in reciprocity failure can occure. Important low light areas which are subject to R. failure are likely the ones which benefit most from pre-exposure. That would be according to Baines. Those low light areas where light levels are above R. failure are where pre-exposure has less effect. Dan > > "...I have a book by an > > emulsion scientist that explains in detail what can be done with [quoted text clipped - 9 lines] > Those low light areas where light levels are above R. failure are > where pre-exposure has less effect. Dan Latensification is POST-exposure. > Is anybody using pre-exposure when takeing pictures? I know it > requires multiple exposure capability but can be done, at least [quoted text clipped - 5 lines] > What about technique? Will a plastic bag over the lens and a three > or four stops down exposure do the job? Dan Dan: The technique works well in some circumstances when the shadow values are really off the scale and your visualization indicates they would enhance the final print. Such a scenario as a beach scene where the subject has greatly shadowed areas compared to the brightly lit "other" side(s). I have metered a little gray card I carry around in the ol' bag but almost any printed medium can be used as middle gray. Rack the focus out and make the exposure as you suggest (3 or 4 stops down) then expose the subject. Develop "normally". I have used this on roll film where it is difficult to alter development per frame.I do have a couple of prints made from negatives produced with this technique and will send you one email (650x650) for brevity if you wish. Truly, dr bob. > > Is anybody using pre-exposure when takeing pictures? I know it > > requires multiple exposure capability but can be done, at least [quoted text clipped - 21 lines] > > Truly, dr bob. The theory of pre-exposure is based on the fact that film has a threshold exposure below which nothing is recorded. If that threshold is supplied by non-image light, more of the image light will be recorded by being added to the pre-exposure. This is a very old technique. I first read of it in Principles of Optics by Hardy and Perrin, published in 1932. Yes, contrast is lowered, but the shadow threshold is reduced. The loss of contrast is made up by slightly more than normal development. > > > Is anybody using pre-exposure when takeing pictures? I know it > > > requires multiple exposure capability but can be done, at least [quoted text clipped - 29 lines] > 1932. Yes, contrast is lowered, but the shadow threshold is reduced. The > loss of contrast is made up by slightly more than normal development. Pat: Post-exposure latensification is what I am talking about. It is/was used to help offset latent image decay from very long exposures, e.g., astrophotography. I would never fog film according to the technique you cite. In the B&W movie days, some overall fog was often added to night scenes, but not to provide more shadow detail, but simply to lighten the image overall. It does NOT increase shadow detail one whit, because it was done after the negative was developed, at the duplication stage, I presume at the interpositive stage. It was done this way so as not to endanger the original negative. If you watch Universal horror films of the 30's and 40's, you can see it as a slightly milky image in night scenes, especially in films such as 'The Wolf Man' with Lon Chaney Jr. It was also used for 'day for night' scenes, which were shot under normal daylight, but underexposed about two stops or so. The idea was to flatten out the scene. Dan: I use pre-fog or pre-exposure, to increase the Exposure Index and reduce the contrast of very slow microfilms. Al Doyle > Is anybody using pre-exposure when takeing pictures? I know it > requires multiple exposure capability but can be done, at least [quoted text clipped - 5 lines] > What about technique? Will a plastic bag over the lens and a three > or four stops down exposure do the job? Dan > Dan: > > I use pre-fog or pre-exposure, to increase the Exposure Index > and reduce the contrast of very slow microfilms. > > Al Doyle But 'regular' films don't benefit from that! >Is anybody using pre-exposure when takeing pictures? I know it >requires multiple exposure capability but can be done, at least [quoted text clipped - 5 lines] >What about technique? Will a plastic bag over the lens and a three >or four stops down exposure do the job? Dan Ansel Adams used a gray card. 'nuff said. jim h ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ http://www.jamesphotography.ca -free downloads -scanning service Even a bit of humour... |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.