Re: slide exposure?
Francis wrote: > > Hi all > This may sound like a dumb question, but I honestly don't know (eek I just > blew my cover ;-). > I, as you've probably read, have a P3n, and, as you likely know, it only > meters in full stops, so, as you might have guessed, I'm wondering if that > will have a significant affect on the exposure when using slid film. It > wouldn't really make sense, but I've heard people talk about being sure to > under expose it half a stop (which I can't do )-: ). > > Francis > PENTAX SAMURAI I always underexposed a full stop - but I like things really saturated, when shooting K64 annsan
Re: slide exposure?
The following site explains the DX coding pattern: http://www.geocities.com/thombell/dx.html#exposure Dave S On Wed, 16 Feb 2005 17:14:09 +0100, keller.schaefer <[EMAIL PROTECTED]> wrote: > > At 06:33 PM 2/15/2005 +0100, you wrote: > > > > >Francis, > > > > > >I think your camera meters and exposes stepless - it only indicates the > > >speeds rounded to the next full value. > > > > Do you mean that it actually does have half stop (or whatever you call it) > > shutter speeds but only when it is in auto exposure mode it? Or does that > > only work with A or newer lenses (I don't have any)? > > Yes, exactly, in automatic mode both speeds and apertures (with an A lens) are > 'stepless', i.e. the program might decide to use f=6,27 @ 1/362s. > > > >But otherwise your question is a good one. As there is no exposure > > >compensation dial and the ISO speed is set automatically, the only > > >remaining > > >option would be to modify the pattern on the film canister to show a higher > > >film speed to the camera > > > > Does that work? I had thought of doing that when I wanted to push the film > > but wasn't sure if I might fry some thing. > > The DX coding is no secret and I am sure it can be found on the web. To modify > it you would either have to grind off or add paint (or a piece of tape) where > needed. > > Regards, > > Sven > >
Re: slide exposure?
if you were to need to do this regularly, there is metalized adhesive labels already coded at specific ISOs available from B&H. Herb - Original Message - From: "keller.schaefer" <[EMAIL PROTECTED]> To: Sent: Wednesday, February 16, 2005 11:14 AM Subject: RE: slide exposure? The DX coding is no secret and I am sure it can be found on the web. To modify it you would either have to grind off or add paint (or a piece of tape) where needed.
RE: slide exposure?
> At 06:33 PM 2/15/2005 +0100, you wrote: > > >Francis, > > > >I think your camera meters and exposes stepless - it only indicates the > >speeds rounded to the next full value. > > Do you mean that it actually does have half stop (or whatever you call it) > shutter speeds but only when it is in auto exposure mode it? Or does that > only work with A or newer lenses (I don't have any)? Yes, exactly, in automatic mode both speeds and apertures (with an A lens) are 'stepless', i.e. the program might decide to use f=6,27 @ 1/362s. > >But otherwise your question is a good one. As there is no exposure > >compensation dial and the ISO speed is set automatically, the only remaining > >option would be to modify the pattern on the film canister to show a higher > >film speed to the camera > > Does that work? I had thought of doing that when I wanted to push the film > but wasn't sure if I might fry some thing. The DX coding is no secret and I am sure it can be found on the web. To modify it you would either have to grind off or add paint (or a piece of tape) where needed. Regards, Sven
RE: slide exposure?
At 06:33 PM 2/15/2005 +0100, you wrote: Francis, I think your camera meters and exposes stepless - it only indicates the speeds rounded to the next full value. Do you mean that it actually does have half stop (or whatever you call it) shutter speeds but only when it is in auto exposure mode it? Or does that only work with A or newer lenses (I don't have any)? But otherwise your question is a good one. As there is no exposure compensation dial and the ISO speed is set automatically, the only remaining option would be to modify the pattern on the film canister to show a higher film speed to the camera Does that work? I had thought of doing that when I wanted to push the film but wasn't sure if I might fry some thing. - but that is not an everyday solution. Anyhow - are you sure you WANT to expose 1/2 stop under? Not at all! That is mainly what I am wondering. Is it necessary? I have heard that it makes a big difference to how good the color is. My advice would be to invest in a test roll of the film you want to use and try it out. I'm far to cheap for that ;-) Be sure to use the exposure lock often, i.e. whenever there are abnormal lighting conditions and try to 'balance' the lighter and darker portions that the camera sees before locking (at least that is how I do it) ... and I am sure you will get good results. I almost never use the exposure lock because it's in such an inconvenient place but I use manual exposure a lot of the time, whenever the lighting is tricky I just aim it at something neutral to meter. Ultimately, when you start bothering about 1/2 stops you will need a different camera ;-) I knew it! I knew it! Hey dad, where is that cheque book. :) Regards, Sven Thanks for the advice, Francis
Re: slide exposure?
Francis wrote: At 10:21 AM 2/15/2005 -0700, you wrote: For a short non-technical answer... I typically let the meter determine exposure unless I'm shooting in unusual lighting/circumstances where I know better than the meter, for instance shooting a subject in a snow covered scene or with significant backlighting. Remember, the meter itself will not determine the exposure made on the film, the aperture and shutter speed will. Typically with slide film you'll want to expose for the highlights so they don't 'burn out', but in practice in fairly even lighting it's not a major concern. Ah ha -- that is just what I wanted to hear! So in friendly lighting situations (no bright highlights) it should tell me the optimum exposure (as it does when using print film)? This kinda makes sense but I've heard that under exposing just a touch gives better colors. This only really works for slides. Print film seems to work better if the exposure is dead on or a bit over. Tom C. Francis -- I can understand why mankind hasn't given up war. During a war you get to drive tanks through the sides of buildings and shoot foreigners - two things that are usually frowned on during peacetime. --P.J. O'Rourke
RE: slide exposure?
An example of when you would override the meter is a situation like: A pastel water lily is floating in a pool of water that to the eye looks basically black. A significant amount of water will surround the water lily in the composition. The meter 'sees' the large dark area and will attempt to create an 'average exposure' for the scene. It will indicate that a longer exposure time or larger aperture is required because of the large area of darkness. This will cause the dark water area to become lighter, but will overexpose the pastel colored flower making it too light. In this case a shorter exposure time or smaller aperture than what the meter recommends may be required to properly expose the flower. So another guding principle is to meter based on the main subject of the composition, the part of the scene that MUST be properly exposed, which may not necessarily be the entire scene. Tom C. From: Francis <[EMAIL PROTECTED]> Reply-To: pentax-discuss@pdml.net To: pentax-discuss@pdml.net Subject: RE: slide exposure? Date: Tue, 15 Feb 2005 11:39:33 -0800 At 10:21 AM 2/15/2005 -0700, you wrote: For a short non-technical answer... I typically let the meter determine exposure unless I'm shooting in unusual lighting/circumstances where I know better than the meter, for instance shooting a subject in a snow covered scene or with significant backlighting. Remember, the meter itself will not determine the exposure made on the film, the aperture and shutter speed will. Typically with slide film you'll want to expose for the highlights so they don't 'burn out', but in practice in fairly even lighting it's not a major concern. Ah ha -- that is just what I wanted to hear! So in friendly lighting situations (no bright highlights) it should tell me the optimum exposure (as it does when using print film)? This kinda makes sense but I've heard that under exposing just a touch gives better colors. Tom C. Francis
RE: slide exposure?
Underexposing can make colors *appear* more saturated. It runs the risk of losing detail in shadows and darker areas, however. I've shot Velvia for quite a while (ISO 50) and always had good results shooting it as rated. Same with Provia. Example 1: http://pug.komkon.org/00febr/WoodenBoats.htm Example 2: http://pug.komkon.org/01nov/docked.html Example 3: http://pug.komkon.org/04oct/elan.html I would trust the camera's meter for the correct exposure unless you know/suspect some compensation is needed. Why not take a test roll of film and bracket your exposures, writing down the data, and then compare and see what you think? Tom C. From: Francis <[EMAIL PROTECTED]> Reply-To: pentax-discuss@pdml.net To: pentax-discuss@pdml.net Subject: RE: slide exposure? Date: Tue, 15 Feb 2005 11:39:33 -0800 At 10:21 AM 2/15/2005 -0700, you wrote: For a short non-technical answer... I typically let the meter determine exposure unless I'm shooting in unusual lighting/circumstances where I know better than the meter, for instance shooting a subject in a snow covered scene or with significant backlighting. Remember, the meter itself will not determine the exposure made on the film, the aperture and shutter speed will. Typically with slide film you'll want to expose for the highlights so they don't 'burn out', but in practice in fairly even lighting it's not a major concern. Ah ha -- that is just what I wanted to hear! So in friendly lighting situations (no bright highlights) it should tell me the optimum exposure (as it does when using print film)? This kinda makes sense but I've heard that under exposing just a touch gives better colors. Tom C. Francis
RE: slide exposure?
At 10:21 AM 2/15/2005 -0700, you wrote: For a short non-technical answer... I typically let the meter determine exposure unless I'm shooting in unusual lighting/circumstances where I know better than the meter, for instance shooting a subject in a snow covered scene or with significant backlighting. Remember, the meter itself will not determine the exposure made on the film, the aperture and shutter speed will. Typically with slide film you'll want to expose for the highlights so they don't 'burn out', but in practice in fairly even lighting it's not a major concern. Ah ha -- that is just what I wanted to hear! So in friendly lighting situations (no bright highlights) it should tell me the optimum exposure (as it does when using print film)? This kinda makes sense but I've heard that under exposing just a touch gives better colors. Tom C. Francis
Re: slide exposure?
If you manipulate your aperture, you can adjust exposure in 1/2 stop increments. This is how I did it on my old P30T. Once you get a feel for it, you can tell based on how the speed LED's change whether you're close to a half-stop over or under the indicated speed, or dead on. The other option is to put it in auto mode and trust the meter, and this may be easier most of the time. -Mat On Tue, 15 Feb 2005 11:08:32 -0800, Francis <[EMAIL PROTECTED]> wrote: > At 09:11 AM 2/15/2005 -0800, you wrote: > > >OK, I'm far from a P3n expert, but I have played with a couple briefly. If > >you can set the film ISO to a higher rating, the film will essentially be > >under exposed. Can you manually adjust the ISO on the camera? > > Unfortunately not, It only takes Dx film. I can manually under expose each > frame but only in full stops. > > >Shel > Francis > >
RE: slide exposure?
At 09:11 AM 2/15/2005 -0800, you wrote: OK, I'm far from a P3n expert, but I have played with a couple briefly. If you can set the film ISO to a higher rating, the film will essentially be under exposed. Can you manually adjust the ISO on the camera? Unfortunately not, It only takes Dx film. I can manually under expose each frame but only in full stops. Shel Francis
RE: slide exposure?
Francis, I think your camera meters and exposes stepless - it only indicates the speeds rounded to the next full value. But otherwise your question is a good one. As there is no exposure compensation dial and the ISO speed is set automatically, the only remaining option would be to modify the pattern on the film canister to show a higher film speed to the camera - but that is not an everyday solution. Anyhow - are you sure you WANT to expose 1/2 stop under? My advice would be to invest in a test roll of the film you want to use and try it out. Be sure to use the exposure lock often, i.e. whenever there are abnormal lighting conditions and try to 'balance' the lighter and darker portions that the camera sees before locking (at least that is how I do it) ... and I am sure you will get good results. Ultimately, when you start bothering about 1/2 stops you will need a different camera ;-) Regards, Sven -Ursprungliche Nachricht- Von: Francis [mailto:[EMAIL PROTECTED] Gesendet: Dienstag, 15. Februar 2005 17:45 An: pentax-discuss@pdml.net Betreff: slide exposure? Hi all This may sound like a dumb question, but I honestly don't know (eek I just blew my cover ;-). I, as you've probably read, have a P3n, and, as you likely know, it only meters in full stops, so, as you might have guessed, I'm wondering if that will have a significant affect on the exposure when using slid film. It wouldn't really make sense, but I've heard people talk about being sure to under expose it half a stop (which I can't do )-: ). Francis PENTAX SAMURAI
RE: slide exposure?
For a short non-technical answer... I typically let the meter determine exposure unless I'm shooting in unusual lighting/circumstances where I know better than the meter, for instance shooting a subject in a snow covered scene or with significant backlighting. Remember, the meter itself will not determine the exposure made on the film, the aperture and shutter speed will. Typically with slide film you'll want to expose for the highlights so they don't 'burn out', but in practice in fairly even lighting it's not a major concern. Tom C. From: Francis <[EMAIL PROTECTED]> Reply-To: pentax-discuss@pdml.net To: pentax-discuss@pdml.net Subject: slide exposure? Date: Tue, 15 Feb 2005 08:44:55 -0800 Hi all This may sound like a dumb question, but I honestly don't know (eek I just blew my cover ;-). I, as you've probably read, have a P3n, and, as you likely know, it only meters in full stops, so, as you might have guessed, I'm wondering if that will have a significant affect on the exposure when using slid film. It wouldn't really make sense, but I've heard people talk about being sure to under expose it half a stop (which I can't do )-: ). Francis PENTAX SAMURAI
RE: slide exposure?
OK, I'm far from a P3n expert, but I have played with a couple briefly. If you can set the film ISO to a higher rating, the film will essentially be under exposed. Can you manually adjust the ISO on the camera? Shel > [Original Message] > From: Francis <[EMAIL PROTECTED]> > This may sound like a dumb question, but I honestly don't know (eek I just > blew my cover ;-). > I, as you've probably read, have a P3n, and, as you likely know, it only > meters in full stops, so, as you might have guessed, I'm wondering if that > will have a significant affect on the exposure when using slid film. It > wouldn't really make sense, but I've heard people talk about being sure to > under expose it half a stop (which I can't do )-: ).
slide exposure?
Hi all This may sound like a dumb question, but I honestly don't know (eek I just blew my cover ;-). I, as you've probably read, have a P3n, and, as you likely know, it only meters in full stops, so, as you might have guessed, I'm wondering if that will have a significant affect on the exposure when using slid film. It wouldn't really make sense, but I've heard people talk about being sure to under expose it half a stop (which I can't do )-: ). Francis PENTAX SAMURAI
Re: slide exposure
On Fri, 31 Oct 2003, Chris Brogden wrote: > On Thu, 30 Oct 2003 [EMAIL PROTECTED] wrote: > > > Sort of Tri-X like in the toe and T-max like at the top... > > > What's the deal with this? Is one more forgiving of under-exposure than > the other? Yep, basically. Specifically, T-Max is contrastier at low levels of exposure (the "toe" of the film response curve) than Tri-X. This means that you get better tonal separation in dark tones but it is easier to underexpose to the point where you get nothing at all recorded on the film. For those of you who haven't seen published film curves, they look something like this: exposure 1/ / / / 0/ film density 0 1 The curve for Tri-X is flatter at the ends than that for T-Max, meaning that there is less change in the density of the film at increasingly high and low levels of light. This makes Tri-X more forgiving of under and over-exposure than T-max, but also a little muddy and flat looking. After more than a decade of using T-max 400 film for journalism (because it pushes better, has finer grain, and is in general contrastier than Tri-X) I am rediscovering the subtle, "old-fashioned" tonality of more traditional films in the form of Ilford Pan-F. DJE
Re: slide exposure
Graywolf wrote >In both cases the limit on density is the thinest part of the image (clear film base). Now with a negative that is the shadows (clear film prints black). With a positive that is the highlights (clear film views white). If you do not have and image there you do not have an image. That make sense? Yes, lots. >So actually both cases are exactly the same: "No Density, No Detail". However they are usually expressed in terms of the media. Negatives: "Expose for the Shadows". Positives: "Expose for the Highlights". >But you will always get it right if you remember, "No Density, No Detail". Interesting. So a sensor, since it is using numbers, because it is digital, has no density in the highlights? (Like what John said before about the numbers above a certain number going to white -- I'll have to go back and reread that.) Cool. Good explanation. Marnie aka Doe I've just noticed that darker changes existing colors more than lighter does. I.E. Late day shooting. And shadows that have more than black, all kinds of colors get darker and more complex in lengthening shadows. While areas hit directly by the sun just tend to get lighter, not more complex in color range. But maybe that's me.
Re: slide exposure
John Francis wrote: >This means that an image overexposed by one stop would have counts that (after scaling) would range from 0 to 511. This is clipped to the range 0 to 255, with everything above 255 ending up mapped to 255. The visual effect is that the bright areas of the image are all washed out to white. An underexposed image, on the other hand, simply has values in the range 0 to 127. You can get back to the 0 to 255 range by simply multiplying all the values by two, although you lose one bit of precision. Egad, that almost makes sense and math is not my strong suit (also still resting my brain from informational overload). And it's easier to lighten (successfully) in photo editing programs than it is to darken (successfully). Darkening tends to gray things out. Marnie aka Doe Well, in my experience. And that a nontechnical answer as well. :-)
Re: slide exposure
> Question is, why is underexposure easier to handle? Presumably white is > represented by some number, say 255, and black by 0. You'd think exposure > would fall off either end just as easily. Does it have to do with an > exponential response curve of some sort like film has? Sort of Tri-X like > in the toe and T-max like at the top... Yes, pretty much. Think of a CCD sensor as a device for counting photons. If you double the exposure time (increasing exposure by one stop) you'll get twice as many photons in the bucket. Halve the exposure time and you only get half as many photons. This means that an image overexposed by one stop would have counts that (after scaling) would range from 0 to 511. This is clipped to the range 0 to 255, with everything above 255 ending up mapped to 255. The visual effect is that the bright areas of the image are all washed out to white. An underexposed image, on the other hand, simply has values in the range 0 to 127. You can get back to the 0 to 255 range by simply multiplying all the values by two, although you lose one bit of precision.
slide exposure
> With slide film it's a good idea to get the exposure right. > But if you are going to err, err on the side of underexposure. > There's nothing you can do about a blown-out highlight, but > you *can* extract detail from overly-dark areas at the cost > of lower signal-to-noise ratio. I'm amazed at what I've been able to pull out of (somewhat deliberately) underexposed Velvia slides after scanning them. How they did it before the negative scanner I'm not sure. You can get some neat pastel effects by deliberatly overexposing the right slide film, but it's not what most folks are looking for. > Negative film has a lot more latitude to start with. But > it usually has more latitude for overexposure, so that's the > way to go if you're not sure. A lot of people recommend overexposing print film by up to a stop as a matter of course. I'm not sure I'd recommend that, but everything I've read suggests that it tolerates overexposure much better than underexposure. Color negative film looks nasty underexposed. As to digital, I'm curious. It DOES behave more like slide film than print film in that it has less exposure latitude and overexposed highlights blow out easily. Underexposure can be amazingly well finessed in photoshop, to the point that a lot of pros are saying that you "gain a stop with digital" because you can deliberately underexpose by a stop and still get a good image out of it in post-processing. Question is, why is underexposure easier to handle? Presumably white is represented by some number, say 255, and black by 0. You'd think exposure would fall off either end just as easily. Does it have to do with an exponential response curve of some sort like film has? Sort of Tri-X like in the toe and T-max like at the top... DJE
