Exposing for Slide film

<p>Does Slide film follow the same exposure rules as Print film i.e if the background is lighter than my subject, do I have to similarly open up the aperture ? I ask this as Slide is referred to as reversal film, and this term is potentially confusing. I know Slide film has a smaller latitude, and bracketting is essential, but I wanted to clarify if slide is more comfortable with over/ under exposure, especially for general Garden photography</p>

<p>-- "but I wanted to clarify if slide is more comfortable with over/ under exposure"</p>

<p>To be honest ... with neither ... you either expose a slide within a -0.5 to +0.5 range of the optimum exposure, or the slide is already unusable.<br>

Overexposed stuff is burnt out quick (and cannot be recovered).<br>

Underexposed parts do still contain information, but if you're projecting the slide (rather than scanning and postprocessing), this information in the dark areas is not useful for you.</p>

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<p >As you know, films grant some latitude when it comes to ‘correct’ exposure. You should experiment with black & white and color negative as well as color transparency film to gain some personal experience in this regard. </p>

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<p >Black & white negative film gives paler image tones when underexposed and dense images when overexposed. Color negative films follow this pattern but they fare poorly when underexposed. Both grant wide latitude as they can tolerate exposure errors.</p>

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<p >Why the negative/positive system affords exposure latitude? The negative is merely a means to an end. Nobody looks at the negative and says “there’s Cousin Sally, doesn’t she look gorgeous”. When we present the picture of Sally it’s generally a print on paper. Now consider that the print is manufactured by actually taking a picture of the negative only this time, sensitized paper is the medium, not film. This second re-taking (printing) affords the opportunity to apply corrections. Over and under exposure errors are mitigated by this procedure. The net result is extended exposure latitude.</p>

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<p >Now transparency films yield a positive image and they are scrutinized directly or by projection. When it comes to tolerance for exposure error, transparency films are very finicky. Generally the exposure latitude is about 1/3 of an f/stop. Overexposure yields a lighter washed-out result. Underexposure has a darkening effect that blocks up shadows. Because we tend to like pictures with lots of detail we generally find overexposed transparencies to be more objectionable than underexposure. </p>

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<p >The bottom line is; when working with transparency films correct exposure yields the best results.</p>

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<p >Sidebar: Modern printing machines (one-hour shop type) are now digital. They create a virtual negative by scanning. Technically it makes little difference if these machines see a negative, a positive or a digital file. However the color negative has a slight advantage because it has a built-in self contrast correcting orange mask. The orange is not uniform, its intensity varies due to subject content. It auto-corrects deficiencies inherent in the color dye that must be used within the film. Transparences lack the orange mask advantage. Digital files use chip logic to accomplish, I call it “pixie dust”.</p>

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<p >In this business you need to know about f/stops and shutter speeds and exposure. Nobody said it’s easy. </p>

<p>I recently had a camera meter showing 1 stop underexposure. I took a roll of Fujifilm Sensia 400 slide film to test the meter. I shot a number of shots at the meter's incorrect reading, then I "overexposed" by a stop. The "overexposed" shots turned out to be correct. However, the actual one stop underexposed shots the meter indicated turned out to be quite usable.<br>

If you know what your camera meter is doing, the slide film situation isn't as dire as it might seem. I get at least 99% proper exposures with my F2A and F3HP bodies because I know what to meter and how to adjust for difficult lighting situations.</p>

<p>Hi Antony,<br>

In a basic sense, the rules for metering slide film are the same as for other types of film. Your camera's meter will tend to average the values in the area it is metering and will tend to drive the exposure in the direction of a middle tone. So, if the area being metered is very light in color, you will want to increase exposure over the metered value just the same as with other types of film. Likewise, if you are metering something that should appear very dark, you will need to decrease the exposure from the metered value just as with other types of film.</p>

<p>As you note, slide film is MUCH less forgiving of exposure errors than other film so very close attention to exposure, along with bracketing, is required. In general, the practice with slide film is to try to avoid blown out highlights and accept that shadows may be very dark (but as with all rules there will be exceptions). Spot metering can be very helpful...for example you may want to spot meter a particular flower to expose it properly and then let the background exposure fall wherever it may. Because slide film has such a narrow dynamic range, it is easy to end up with either blown out highlights or blocked up shadows...and so the only solution is often to control the light, either by using artificial light (flash, reflectors, etc.) or by limiting the times when you shoot. For garden photography, gloomy overcast days can work very well.</p>

<p>The short of it is-- color slide film has much less leeway for error than does negative film.</p>

<p>Thus it is critical, to achieve the result you visualize, that you learn how to judge the components of your composition to see what is going to be shadow and light, and which way you need to go in exposure to either fill the shadow, or show the light without going pure white. (for lots more detail, see Ansel Adams on the "zone system")</p>

<p>As digital scanning has come in, I have scanned all my slides in, and found that with digital manipulation a lot of slides I had set aside as "seconds" are recoverable in post-processing. Makes me glad I didn't just throw them out. In the slide days, with a slide copier it was possible sometimes to fix an underexposed slide, but even with digital it's nearly impossible to bring out much detail in burned-out highlights. (for more detail search here for "ozone" system)</p>

<p>For negative film the general recommendation is to expose for the dark areas of the image. For slide film you want to expose for the bright areas of the image. Slides don't handle over exposure very well while negative film does. Negative film has fairly wide exposure latitude. It is my understanding it is generally about 14 stops. For slide film it is about 4 stops. However this will very between brands so use these numbers as general guidelines. </p>

<p>When I was using slide film I generally tried to compose so that the range was 3 stops or less. In my opinion I got better colors with slide film. Yes bracketing is very helpful although I would try to limit it use to only the times when the image has a lot of contrast. Otherwise your role of 36 exposure film will only yield 12 images. A camera with a spot meter is also very helpful. </p>

<p>The rules for slide film are pretty much the opposite as for print film. For print film, you want to expose for the shadows, and let the latitude take care of the highlights. If the subject matter is flat, you can overexpose to increase saturation.<br>

<br /> For slide film, you want to expose for the highlights -- overexposed highlights are simply lost and gone forever. With extremely flat subject matter where you want to increase saturation, you can do it by underexposing -- but think in terms of a third stop (or less) instead of the full stop (or more) of overexposure you might use with print film.<br>

<br /> It's also worth mentioning that slide films differ in both the amount of latitude they provide and where they provide it. Fuji film tends to have a bit more latitude for overexposure than Kodachrome, for example. The highest contrast slide films, especially Velvia 50, also have the least latitude -- for it, I'd say being half a stop off is really too much. With it, a quarter stop change can and will make quite a noticeable/visible improvement.</p>

<p>i shot slide film for 32yrs before switching to digital. to expose slide film note that your headroom is for any purpose zero. if you overexpose by any amount you loose the data. an overexposed area in a slide is clear. so to expose a slide note the brightest area of the scene and expose for that. also, the slide film's dr is about 5 stops. this even less that the jpeg in digital. the jpeg's dr is about 6 stops.<br>

whe i switched to digital a few yrs back, i simply exposed the jpegs as i did the film slides. it worked fine. lastly, be aware that any mistakes in the fieldwork in shooting slides CANNOT be changed/fixed/adjusted in later pping. for slides there is not pping. so it is get right in the field or throw the slide out.</p>

 

<p>If you have to decide between over- and underexposure with slide film, choose underexposure. In this regard, slide film is like a digital sensor. Underexposure can be grainy, but overexposure is a disaster.</p>

<p>The trick with slide film is the narrow latitude. You have to squeeze all detail in between +1.5 and -2.5 stops above and below your meter reading. Anything brighter than +1.5 will be a lost detail. Anything darker than -2.5 will be pure black. The good news is that you can use the narrow latitude to create high-contrast images with lighting like a Rembrandt painting. It just takes practice and careful metering.</p>

<p>When I shoot slide film - yes, I still do - I often use graduated neutral-density filters to control contrast. Graduated ND filters are a godsend for slide film shooters.</p>

 

<p>Expose for the highlights; let the shadows fall where they may.</p>

<p>That was the slide film mantra.</p>

<p>Just note that bracketing does not increase the dynamic range of the film. All it does is provide you with alternative treatments using the same dynamic range. Grads, in certain circumstances a polariser, fill flash, and recomposition can help to reduce the scene dynamic range so it fits on the film. These aside there is no doubt that slide film is more difficult to use than neg film or nearly all digital. Equally there is no doubt that with practice and the use of a metering routine that allows you to map the scene contrast onto the film, lots of people learn to expose it very well.</p>

<p>Addendum and clarification: When I made this statement...</p>

 

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<p>You have to squeeze all detail in between +1.5 and -2.5 stops above and below your meter reading.</p>

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<p>...I was referring to a spot meter reading of an 18% gray card or a surface of equivalent tonality. I was NOT referring to what your camera's multi-area meter reads when looking at the entire scene. The multi-area meter will already take this correction into account to some degree. Sorry for the confusion.</p>

 

<p>Agreed with the statements that slides of no room for error. IMO, if you are off by more than 1/3 stop the slide is trash.</p>

<p>That said, I prefer slides to print film by a huge margin. Nice deep blacks are prefered to me rather than muddy shadows.</p>

<p>It is fairly essential to bracket a shot you expect to be a keeper when shooting slides. this is because of the limited ability to correct any misexposure after the fact. Usually I recommend learning to meter really well (spot meter either you subject in varying light, or meter a mid tone in even light) and then bracket at least 3 exposures (if not 5) in 1/3 stops. This should give you a perfect exposure if you metered accurately. I wouldn't bracket greater than 1/3 stop because the fact is if you are off by 1/3 stop going 1/2 up or down is still going to give a bad exposure.</p>

<p>And a GND filter set is essential when shooting landscapes with sky in them. No two ways about it, the only other option is to bracket a few shots and then digitally merge them in post processing using the scans. However, if you are shooting film it's much more cost effective to use the filter in the first place, and then bracket the shots with the filter. Of course it's debatable the shooting multiple shots from a tripod will actually yield a better result (no tell tale filter falloff), but again this is expensive, and time consuming, and is a much better technique to be used with digital capture.</p>

 

<p>The most important thing in slide film is to ensure you don't blow out the highlights. And based on my experience the way to go about it is follows:<br>

1. Throw the scene out of focus. This helps you identify the tones in the scene. Note which are the brightest areas of the scene and which are the darkest.<br>

2. Take a spot meter reading off the brightest part<br>

3. Take a spot meter reading off the darkest part<br>

4. If the difference between them DOES NOT exceed four to five stops, assign the brightest part of the scene to a zone (I'm assuming you're familiar with the zone system), dialing in +EC as needed. Of course, you would never dial in more than 2 stops of + EC unless you wanted to deliberately blow out the highlights<br>

If the difference between the darkest and brightest parts of the scene are more than 4-5 stops, you have to make a choice - you can't have [detail in] your shadows and highlights too, not with slide film. In such a case, you could use fill flash to fill in shadows, if possible.<br>

The steps spelt out above may seem cumbersome, but once you get the hang of it, it becomes second nature.<br>

Incidently, I have an <a href="http://www.nevillebulsara.com/why-light-matters.htm">article</a> up on my site which you may wish to check out. All the shots in that "article" were shot on slide film, using fill flash to fill in the shadows. You'll see how the principles I spelt out have beeen applied there.<br>

Ideally, you'd actually need to CALIBRATE your meter to each batch of slide film, which is a topic too long to go into here.<br>

I hope this helps, let me know if you need further assistance.<br>

Regards,<br>

nevilleb</p>

 

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<p>you can't have [detail in] your shadows and highlights too, not with slide film</p>

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<p>Unless you use graduated ND filters to control contrast. Filters aren't perfect but they work amazingly well in a lot of conditions.</p>

<p><em></em><br>

<em>Unless you use graduated ND filters to control contrast. Filters aren't perfect but they work amazingly well in a lot of conditions</em><br>

:) In which case, the brightest part is no longer in zone 7+ Mid-tone being zone 5), i.e. to say it doesn't fall beyond the 4-5 stop latitude of slide film.<br>

The bottom line that I wanted to stress on is that you can't overcome the film's range of 4-5 stops of light that it is EXPOSED to.<br>

nevilleb</p>

<p>And besides, there are some situations where you just can't use a graduated filter. <a href="http://www.nevillebulsara.com/wlm7.htm">This one </a>for example.<br>

Observe where the brightest highlights fall in the frame in relation to other tones and you'll see what I mean. As you rightly put it, they work in a lot of conditions (depends on what you're shooting actually), but not all.<br>

Best,<br>

nevilleb</p>