Bellows factors measuring?

Discussion in 'Large Format Cameras and Accessories' started by ToddB, Sep 27, 2012.

  1. ToddB

    ToddB Member

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    OK guys.. Been out of the loop on shooting these guys for awhile. On bellows factor measuring,. Where do you measure. My camera doesn't have any type of mark to measure from.

    ToddB
     
  2. BrianShaw

    BrianShaw Member

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    generally speaking... lens board to film plane/board is sufficiently accurate.
     
  3. DREW WILEY

    DREW WILEY Member

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    I've made up various tape rules with markings for various lenses, calibrated film plane to lens node.
    But it's a lot easier to use one of those little calculator devices from Calumet. You place a target
    at the subject plane and measure its size on the groundglass with a special ruler marked in exposure
    compensation values. I hope they still offer them.
     
  4. BrianShaw

    BrianShaw Member

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  5. SteveR

    SteveR Member

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    I used to use a target thingo, found it a bit fiddly, now I use a simple old sewing tape measure. I've got my lens focal lengths marked along one edge, and D-stops (in inches) along the other edge. Quick and simple to hold it up and see how many stops between the focal length and actual bellows draw. I never used to look forward to calculating bellows factor 'till this little strap came along, can't recommend it enough.
     
  6. rjbuzzclick

    rjbuzzclick Member

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    I do a similar thing with a length of string with a knot every two inches. It's quick and easy.
     
  7. BainDarret

    BainDarret Subscriber

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    I just use a tape measure.
    If I'm using an 8 inch lens (203 Ektar) then at infinity I measure from a point on each standard that are 8 inches apart.
    If I focus on something and the standards are 11 inches apart, measured from the same points, then I know to allow one stop extra exposure.
    At a distance of 16 inches I know to allow two stops extra exposure.
    You can also work in fractions of a stop i.e 9.5 inches or 12.5 inches.
    This also works with my other lenses 101 Ektar = 4 inches, 135 Optar = 5.5 inches etc.
    I don't know if this is accurate enough for colour transparency work but it does well enough for black and white.

    Mike
     
  8. johnielvis

    johnielvis Member

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    man, that's cornball style---the way to do it is to put a ruler in the focus plane...measure it on the ground glass and get the magnification---then calculate directly from there (1+M)^2....works better than trying to measure between standards and is ALWAYS right no matter what the lens.
     
  9. SteveR

    SteveR Member

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    Maybe, but it works every time, plus you don't have to switch into 'left-brain' mode to do the math. It's never steered me wrong, always spot on, plenty of bright colorful chromes testify to its reliability.
     
  10. E. von Hoegh

    E. von Hoegh Member

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    Ummm.... if you're asking regarding your Rollei, you really don't need to worry. It doesn'f focus close enough for this to be much of a factor, unless you're using chrome film at the closest focussing distances.
     
  11. Doremus Scudder

    Doremus Scudder Member

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    Ladies and Gentlemen:

    There's a sticky thread on just this topic with more information and techniques than anyone would ever want to know at the top of this forum topic.

    Maybe we should look/post there...

    Just a thought.

    Best,

    Doremus
     
  12. jnanian

    jnanian Advertiser Advertiser

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  13. ToddB

    ToddB Member

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    Hey EVH,

    I also own Omega View 4x5.. Used a Toyo in school. Been a while.

    ToddB
     
  14. Maris

    Maris Member

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    Bellows measuring? I go from lens board to film plane using the dressmakers tape measure sewn into the edge of my focussing cloth.
     
  15. Mike645

    Mike645 Member

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    A different way to do it....

    Try a Kiev 88 metered prism - gives you a reading directly from the ground glass. Very nice angle on the eyepiece. You can make a cardboard frame to eliminate stray light (or better still stick your head under the dark cloth). Don't forget that you will need the battery compartment converter. Experiment a bit using a reliable hand held or spot meter - or your digital camera - to check readouts and adjust as necessary. Mine works without the need for adjustment. Some scope for moving around the ground glass screen on 5x4, more (obviously) on 5x7 and 8x10 etc. Very useful for close up/macro work once you get the hang of it. If you can't get a reading (green light) increase the film speed setting until you can and then do the easy mental arithmetic to get the correct exposure for the film you are using. Through the lens metering on a monorail or technical/view for 30-50 quid (e-bay prices). Got mine from the Ukraine in first class condition 35 GBP + 9.50 GBP for the battery converter. As far as I know the Kiev metered prism one of only a few that work indepently of a camera. The Mamiya C220/C330 finder is another, but they are relatively expensive - twice the price and they lack the angled eyepiece.

    Oh, and if you use it in the horizontal position it turns your image the right way round...

    Mike.
     
  16. CPorter

    CPorter Member

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    Cornball or not use the method that works best for you, a millimeter scale on a monorail makes it very easy for me. For my 120mm Nikon for example, I set the film plane 120mm from the lensboard, then note the distance on the monorail from inside to inside of the front and rear standard (30mm in this case) or outside to outside, does not matter. I've calculated what the BEF is at 13mm intervals (half inch) for several inches of bellows extension. Only after I have achieved final focus do I think about any possible extension, I quickly look to see if the inside to inside distance between the standards is greater than 30mm, if it's 56mm for example, then I know I have extended the bellows, just look at my little table and note the factor for a bellows extension from 30mm inside the standards to 56mm---------a one inch extension, +2/3 stop or 1.5x in this case---very quick. It only takes a few minutes to work out a small table for each lens that you have.
     
  17. Vaughn

    Vaughn Subscriber

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    Heck, If it looks like I have extended my bellows too far I just add a stop and move on! LOL!

    Vaughn
     
  18. mark

    mark Member

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    BW means ball park like Vaughn said unless you are looking at big magnification then I use one of those calculator thingies like on Brunner's site. Chrome on the other hand requires measurement. Too expensive to screw up and too short a lattitude.
     
  19. jeffreyg

    jeffreyg Subscriber

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    As others have mentioned, I measure from the lens board to the film plane. One day I did the math for my three lenses and marked a small retractable tape according to fstop changes by half-stop changes each lens a different color. I attached it to my lightmeter strap. Then happily forgot the formula - just measure and see the exposure compensation for that measurement.

    http://www.jeffreyglasser.com/
     
  20. PanaDP

    PanaDP Member

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    I posted this in the bellows extension sticky. I measure from groundglass to lensboard and do the following:

    I know this has been well and thoroughly covered but perhaps the way I prefer to do it will be of use to somebody. I don't really care for doing math in the field. I want everything prepared for me. I just sit down at my computer and fogure out the bellows extensions for a given focal length that will evenly correspond to stop corrections in 1/3 stop increments going out as far as the bellows on my camera will allow. I then make a small table with P-Touch tape and stick it to the lensboard for that lens. That ensures that I can simply set up the photograph I want and then choose the closest stop correction from the table.

    Here's how the tables look, this one is for a 90mm:

    90mm

    +1/3 - 106mm (4 3/16")

    +2/3 - 121mm (4 3/4")

    +1 - 127mm (5")

    +1 1/3 - 142mm (5 9/16")

    +1 2/3 - 156mm (6 1/8")

    +2 - 180mm (7 1/16")

    +2 1/3 - 202mm (7 15/16")

    +2 2/3 - 226mm (8 7/8")

    +3 - 255mm (10")

    +3 1/3 - 285mm (11 1/4")

    +3 2/3 - 321mm (12 5/8")

    +4 - 360mm (14 3/16")

    +4 1/3 - 404mm (15 15/16")

    +4 2/3 - 454mm (17 7/8")
     
  21. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member Moderator

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    I figure it by magnification as mentioned above (the ruler in the scene measured on the groundglass), but I don't always put the ruler in the scene if I think I can estimate it based on knowing about how big the subject is compared to the size of the format (i.e., a portrait where I can see both shoulders maybe with a little extra space is about 1:3 on 8x10"), but with higher magnification I'll measure it. I have a table taped to the backs of all my cameras, my light meter, and in my notebook to convert magnification factor to exposure factor. I've posted the table around here somewhere as a doc file.

    For small formats, you don't actually have to measure on the groundglass. Just make sure the ruler covers the full width of the frame.
     
  22. jnanian

    jnanian Advertiser Advertiser

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    if john cook were here he would chime in, between yarns told about the days working in hollywood
    he made this post which is part of the large format site

    http://www.largeformatphotography.info/bellows-factor.html
    scroll down and you will see it ...

    its a little different than what rick said but similar ...

    its pretty easy ...
     
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