Super friggin cool bellows factor compensator thingie.

Discussion in 'Large Format Cameras and Accessories' started by JBrunner, Dec 27, 2007.

  1. JBrunner

    JBrunner Moderator Staff Member

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    There's a few of these around. Most are better than mine, but mine is distinctly super friggin cool. I stuck the link in my signature. Enjoy.
     
    Last edited by a moderator: Dec 27, 2007
  2. richard ide

    richard ide Subscriber

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    Thanks Jason. Will be put to use tomorrow.
     
  3. Steve Sherman

    Steve Sherman Subscriber

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    A different really super trick

    You want to know how many stops to adjust for bellows factor?

    Try this really super trick idea.

    Take the lens you are using and convert it to inches, a 210mm lens is 8 1/4" if your bellows is racked out to 11 inches, you are basically at a one f-stop increase, ( convert the inches to f-stop numbers) f 8 to f 11 is one stop. Rack out to 16 in. and you are twice as long as lens, so you would be at 2 full f-stops. This would also be life size and I can't imagine having much need for any further magnification. It's all proportional, go down to a 6" lens racked out to about 8" and you would again have about a 1 f-stop increase in exposure. It is easy to calculate fractions of inches using 1/3's of f-stops.

    For those who question if this method is precise enough, I used this method for years in table top photography using chrome film which demands much greater accuracy than does panchromatic films.


    Cheers baby!
     
  4. Jim Noel

    Jim Noel Member

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    I'm gvlad you think so much of the BF calculator. It is nothing new. I made one like it in the 1940's after reading an article in one of the mags of the time. Calumet sold one for many years, and may still do so.

    Isn't it odd how old ideas come around and are "rediscovered" by a new worker.
     
  5. JBrunner

    JBrunner Moderator Staff Member

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    Like I said, there's a few of these around. I've been using the Calumet version for years. It finally ratted up so bad I couldn't read it, so even calling it "rediscovered" would be a stretch, because I never lost it, but there are probably a quite few people new to LF that haven't seen one. I just made a super friggin cool new one. :smile:
     
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  6. jnanian

    jnanian Advertiser

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    jason

    the focus image is the bomb. <g>
    thanks for the coolstuff!

    john
     
  7. rwyoung

    rwyoung Member

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    I just keep a tape measure and a cheap calculator in my bag. The tape measure has both inches and metric scales. Measure from apeture to film plane (D). Then compute D / focal lenght of lens and square it. That is your compensation factor. Relatively easy to convert from that to stops or adjust exposure time. Most of the time I don't even bother with the calculator, you can get this pretty close in your head after a few times.

    Just remember to measure from the apeture, which is not necessarily the lensboard.

    But you know what would be fun, offer the same thing without your fabulous mug, as a TIF or similar so that people can insert their own super friggin' cool image. :smile: Of course you should do a little branding so that with your fabulous mug it is the "deluxe" model...
     
  8. JBrunner

    JBrunner Moderator Staff Member

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    Math make brain hurt. Solution: Keep brain wet.

    Seriously, there are about 7 ways to do this. All I know is I never screw up with the BF calculator. However, whatever floats your boat. We all tend to work with what we are comfortable with, and for some reason it is usually the first way we learned how to do something. Steve's and your method was the second way I learned. I've never been much of a slide rule type of photographer. I try to keep that side of my brain as un-engaged as possible during photography. :smile:
     
    Last edited by a moderator: Dec 28, 2007
  9. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member

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    I use a similar method, but without a target, so it works for small formats too. I just have a table with magnification factor and bellows factor taped to my meter and all my camera backs. I compare the width of the scene at the subject distance to the width of the format to determine the magnification factor, usually estimating, but if I'm unsure or if it's a still life, I might actually put a tape measure in the scene, like the target in Jason's thingie or the Calumet thingie or the thingie linked to the lfinfo.com page, and then I look up the magnification on the table to get the bellows factor.
     
  10. CPorter

    CPorter Member

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    I tried to open the link on your site Jason but when I do it locks my computer up, oh well.

    This is not to tell you how to do it, but for LF beginners with rails like myself that may want to use this method: I just use the millimeter scale on my rail. When the inside to inside measurements of both standards are at 126mm apart, I know that my 210mm lens is at infinity. I simply made up a small chart with the extension factors at 1/2 inch increments forward of inifinity to about 5 inches. Did the math one time for the chart (just a few minutes). So, when the inside distance of the standards are, say,at 178mm, that's 2 inches forward of infinity, and my chart says 1.5x.
     
  11. JBrunner

    JBrunner Moderator Staff Member

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    It's a pdf, so you may need acrobat reader. It opens ok on the two computers I have here, and a test across town. Computers.....

    I'm certainly not telling anyone how to do it.:surprised: :smile: (hehe we said "do it" hehe) You should do whatever works best for you. I haven't been able to try what you do, because all of my cameras are so old, they don't have any numbers on the rails. I could tape some on, but I haven't the heart. (or head)
     
    Last edited by a moderator: Dec 28, 2007
  12. brimc76

    brimc76 Member

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    Thanks Jason.
     
  13. seawolf66

    seawolf66 Member

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    J Brunner thanks yours is easyer to use than the Quick Disc by Phillip Salzgeber : Thanks
     
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  15. Thomas Bertilsson

    Thomas Bertilsson Subscriber

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    Jason, you are a good man. Saves me a lot of headache.
    - Thomas
     
  16. RobertP

    RobertP Member

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    I've had a quick disc in my wallet for years. It has been in there so long that it has made a 3" diameter circular impression into the leather. A few weeks ago I was checking out at the store and laid my wallet on the counter. The lady teller took one look at the wallet and looked at me and said " I'm impressed" After getting over the shock I started trying to explain but she was laughing so hard I just gave up.Time to buy a new wallet and go with the square disc.
     
  17. JBrunner

    JBrunner Moderator Staff Member

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    That will be even more funny! She may never recover.
     
  18. walter23

    walter23 Subscriber

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    I saw a studio portraiture video wherein the photographer was using a sinar for some macro shots. He had a little doohickey from calumet that you put in the scene, then measure the size of on the ground glass. The size on the GG gives you a bellows factor from a lookup table.
     
  19. JBrunner

    JBrunner Moderator Staff Member

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    That sounds familiar. I think I've seen something like that somewhere.
     
  20. Ole

    Ole Moderator Staff Member

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  21. RobertP

    RobertP Member

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    Just don't laminate it to heavy card stock and carry it in your wallet. :wink:
     
  22. argus

    argus Member

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    Thanks for showing us, Jason.

    Actually I like my current Quickdisc better, because you can also critically focus on it. With your version, that will be a bit more difficult, but maybe a hint for further improvement?

    G
     
  23. Nacio Jan Brown

    Nacio Jan Brown Member

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    Quick Disc + CD or DVD

    For easier focusing I scaled up the Quick Disc ruler on a copy machine to match the diameter of a CD. The bright silver is easy to see in any light. njb
     
  24. cao

    cao Member

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    Death match: Brunner vs. Calumet

    Funny thing: in a fit of boredom, I derived the eqn for magnification from required change in aperture. When I measured, the Brunner thingy conforms within my error for measuring the reference square; the Calumet gadget that came with a used Cambo Legend is way off. What gives here? Not cool enough?
     
  25. ZachInIsrael

    ZachInIsrael Member

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    Thanks Jason, I downloaded it and watched your videos on youtube. I am about to work on some macro work with my sinar and this will be right handy.

    I liked the developing videos too
     
  26. Sirius Glass

    Sirius Glass Subscriber

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    Good! Now I know what a doohickey is!

    Sgteve