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Thread: A good book on LF exposure, reciprocity and bellows extension exposure compensation

  1. #1

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    A good book on LF exposure, reciprocity and bellows extension exposure compensation

    Been stuck inside, so spending some time experimenting with my view camera. I am looking for a resource, maybe a good book, that covers, in detail, the issues of film reciprocity for long exposures, and the exposure compensation required when using long bellows extensions.

    Thought maybe Ansel's book "The Camera" would cover this but not so much, and then I thought "View Camera Technique" would cover it, but looking thru the table of contents, I don't see it listed.

    Can anyone recommend a good book that covers these two issues as they pertain to Large Format photography and the view camera?

    Thanks in advance for any input.

    Best,
    -Tim

  2. #2

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    Re: A good book on LF exposure, reciprocity and bellows extension exposure compensati

    Quote Originally Posted by Timmyjoe View Post
    Can anyone recommend a good book that covers these two issues as they pertain to Large Format photography and the view camera?
    Exposure has to be adjusted for reciprocity failure and for magnification for all sizes of camera. In these respects LF is nothing special. Any good book on macro/closeup photography will explain how to adjust exposure for magnification. Film information sheets give film-specific information on exposure compensation for very long and short exposures.

    The first post in this https://www.largeformatphotography.i...mainly)-lenses discussion has a link to a list of sources of all sorts of useful information. It also has an annotated list of books on cluseup/macro.

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    Re: A good book on LF exposure, reciprocity and bellows extension exposure compensati

    Quote Originally Posted by Timmyjoe View Post
    Been stuck inside, so spending some time experimenting with my view camera. I am looking for a resource, maybe a good book, that covers, in detail, the issues of film reciprocity for long exposures, and the exposure compensation required when using long bellows extensions.

    Thought maybe Ansel's book "The Camera" would cover this but not so much, and then I thought "View Camera Technique" would cover it, but looking thru the table of contents, I don't see it listed.

    Can anyone recommend a good book that covers these two issues as they pertain to Large Format photography and the view camera?

    Thanks in advance for any input.

    Best,
    -Tim
    It's pretty simple to calculate yourself. Since f stop is a ratio of the lens focal length to the diameter of the lens pupil. Think of macro shots as using a longer focal length lens. So just calculate the pupil size for whatever aperture you want to shoot at. Then measure the bellows extension, and use those to numbers to calculate you effective f stop. Then use that effective f stop yo calculate exposure.

    Sent from my ONEPLUS A6003 using Tapatalk

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    Re: A good book on LF exposure, reciprocity and bellows extension exposure compensati

    Quote Originally Posted by Wheathins View Post
    It's pretty simple to calculate yourself. Since f stop is a ratio of the lens focal length to the diameter of the lens pupil. Think of macro shots as using a longer focal length lens. So just calculate the pupil size for whatever aperture you want to shoot at. Then measure the bellows extension, and use those to numbers to calculate you effective f stop. Then use that effective f stop yo calculate exposure.
    There's more to it than that. See the Lefkowitz book mentioned in the link.

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    Re: A good book on LF exposure, reciprocity and bellows extension exposure compensati

    Quote Originally Posted by Timmyjoe View Post
    I am looking for a resource ... that covers, in detail, ... the exposure compensation required when using long bellows extensions.
    If you don't mind using simple math, forum participant and former moderator Ken Lee has a good page on his website: https://kennethleegallery.com/html/tech/bellows.php

    My personal view is that a lot of the allegedly simple, workaround methods are more trouble than they are worth. The forum home page article on computing bellows compensation was prepared 24 years ago. At one point, the article says "[This method] requires no fancy gadgets to purchase nor algebraic formulae to memorize." A few things have happened since 1998, such as almost everyone having a smartphone in their pocket with a calculator app. If you want to understand what's going on behind the math, you'll find it useful to read about the inverse square law.

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    Re: A good book on LF exposure, reciprocity and bellows extension exposure compensati

    Quote Originally Posted by Timmyjoe View Post
    I am looking for a resource ... that covers, in detail, the issues of film reciprocity...
    I'll just comment on the nuts and bolts of the computation. The available information depends on what film you're talking about.

    Kodak's data sheet for Portra 160 and Portra 400 tells you nothing about how to compute reciprocity failure. It tells you to "experiment". Many people use an app called Reciprocity Timer, about which there are discussions on this and other photography forums.

    Ilford, on the other hand, does give guidance on computing reciprocity failure for its films: Ilford Film Reciprocity Failure Compensation. For Ilford, you can use Reciprocity Timer or do the math. The math is dead simple, and I imagine that every smartphone calculator has the necessary x^y function. I've just finished making an exposure worksheet. Ilford's formula, for HP4+ and HP5+, is in the last box of the worksheet, which is attached to post #8 in this current thread: https://www.largeformatphotography.i...sure-Worksheet

    If you read Ilford's data sheet on reciprocity failure, note the caveats to the calculations.

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    Re: A good book on LF exposure, reciprocity and bellows extension exposure compensati

    Quote Originally Posted by r.e. View Post
    I'll just comment on the nuts and bolts of the computation. The available information depends on what film you're talking about.

    Kodak's data sheet for Portra 160 and Portra 400 tells you nothing about how to compute reciprocity failure. It tells you to "experiment". Many people use an app called Reciprocity Timer, about which there are discussions on this and other photography forums.

    Ilford, on the other hand, does give guidance on computing reciprocity failure for its films: Ilford Film Reciprocity Failure Compensation. For Ilford, you can use Reciprocity Timer or do the math. The math is dead simple, and I imagine that every smartphone calculator has the necessary x^y function. I've just finished making an exposure worksheet. Ilford's formula, for HP4+ and HP5+, is in the last box of the worksheet, which is attached to post #8 in this current thread: https://www.largeformatphotography.i...sure-Worksheet

    If you read Ilford's data sheet on reciprocity failure, note the caveats to the calculations.
    Instead of a Kodak specification that doesn't give specific data, it's easier to use apps that give specific recommendations.

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    Re: A good book on LF exposure, reciprocity and bellows extension exposure compensati

    Quote Originally Posted by WarrenXL View Post
    Instead of a Kodak specification that doesn't give specific data, it's easier to use apps that give specific recommendations.
    Which apps are recommended that are accurate and well researched?

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    Resident Heretic Bruce Watson's Avatar
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    Re: A good book on LF exposure, reciprocity and bellows extension exposure compensati

    Quote Originally Posted by Timmyjoe View Post
    Been stuck inside, so spending some time experimenting with my view camera. I am looking for a resource, maybe a good book, that covers, in detail, the issues of film reciprocity for long exposures, and the exposure compensation required when using long bellows extensions.
    I've read a lot of photography books over the years, and never found one that treated reciprocity failure in what I'd call a good way. Probably because it's more of an exposure issue than anything else. The information is there when they describe how a latent image is formed, but they typically don't label it has having anything to do with reciprocity failure. Yet, this is exactly what reciprocity failure is -- not enough photons being captured to form a latent image.

    What they tend to miss, is that reciprocity failure seldom happens to the entire image at once. Typically it occurs to just parts of an image. That is, the shadows. The cause of "empty shadows" in LF photography is reciprocity failure more often than you'd probably think. Perhaps instead of "empty shadows" we should be calling it "reciprocity failure of the shadows". We don't because it could easily be caused by an simple exposure miscalculation.

    I suspect the reason it's used as a blanket term (the sheet is "in reciprocity failure") is because we can't work with only part of the image in the darkroom. That is, we develop the whole sheet at one time, the parts that are in reciprocity failure along with those that are not. Which is perhaps why people get so confused by the idea of reciprocity failure. They think it has to be the whole sheet, when often it is not.

    For example, a big old dry-stacked stone wall lit at least somewhat from some direction that isn't head on. The spaces between the stones are therefore in shadow. Some shallow, some deep. With a typical shutter speed of, say, 1/4sec, areas that are three stops down from the "middle", or from Zone VI (or whatever the middle of that scale is), or whatever you want to call it, easily end up in reciprocity failure, depending on the film. Certainly they will with Tri-X.

    I fought this with Tri-X and HC110H for months. I just couldn't control it (it would ether be over or under exposed, no matter how careful I was). Then I got a tip (from this board I think) that said I should try it with TMY instead. So I did. First try, nailed it. And every try after that. It wasn't my methodology really, it was that my subject and how I needed to photograph it pushed the shadows into reciprocity failure with Tri-X. But TMY is an order of magnitude better -- reciprocity failure starts at about 1s equivalent exposures with Tri-X but at about 10 seconds with TMY (it's been more than a decade, so I could be wrong about the specifics).

    After working the books for a few days it occurred to me what had happened and that I had tripped over reciprocity failure characteristics for Tri-X. But I know from that trip through the books that none of them will tell you what I've just told you.

    And, of course, there's zero reason to believe me. Why should you? It's really easy to test it yourself so you can see it when it happens.

    --------------------------------------------------------------------------------

    As to bellows factor... early on I used to worry about this too. But then I found that I didn't really need it much for the photography I was doing, so I left all the measurement stuff at home. On the rare occasions that I actually needed it, I would expose a sheet normally, then expose a sheet with half a stop more exposure and move on. Then pick the one to work with that looked better on the light table. I've never done anything that required enough of a closeup to make calculating bellows factor worth the trouble. But hey -- I'm one of the resident heretics here.

    Bruce Watson

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    Re: A good book on LF exposure, reciprocity and bellows extension exposure compensati

    don't always need to "compensate" for reciprocity failure...in fact it can be a great tool in achieving expansions in otherwise flat lighting situations, as I did with the following images - three(ish) stops of range at about a five minute exposure times, processed normally, and gave a great expansions:
    Click image for larger version. 

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ID:	232973 Click image for larger version. 

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