Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 68,704   Posts: 1,482,697   Online: 901
      
Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 28
  1. #11

    Join Date
    Dec 2005
    Shooter
    Large Format
    Posts
    109
    Clayton - I hope you don't mind too much I found the copies of your website and posted the link. It is one of my favorite sites, and I felt Roberto, as a new Cirkut owner, should see it .

    I believe somewhere I have a copy of "Gears" on a floppy disc, I think directly from Bob Lang. I've never used it myself, due to the need for an exact measurement of the lens focal length. I suspect I could build a nodal slide and use my long Starrett vernier calipers to get an accurate-enough measurement of FL, but there are always 1001 other things to do.

    From the information Roberto has posted, it seems a former owner of the Outfit has already measured FL and calculated correct gears. Clayton (or anyone), does my suggestion to Roberto to make a focusing scale based on actual distance measurements corresponding the those marked on his gears seem the correct way to get his Cirkut so he can focus it?

    Len

  2. #12

    Join Date
    Apr 2009
    Shooter
    Large Format Pan
    Posts
    22
    Len

    there's no problem posting a link. If anyone wanted to host some of the pages on their own website that's ok by me. Maybe I should put it all up on wikipedia?

    I'm a bit vague on it now but I think when we got the program from Bob Lang, it was in visual basic and rewrote it in C+. He checked it and okayed the new version then it was put up on the website. There were 2 versions, one you could download and run on your pc the other was an online program that ran off the server. You just punched in the numbers and it spat out the answer.

    I never used a focussing scale on my camera. All I did was focus the camera then select the gear to suit that focus distance. If you're shooting scenics you can use one gear for each lens, just the infinity gear. If you're shooting groups a 25 foot gear is all you need.

    An easy test to see if your gearing is correct is to shoot a square target placed at the focus distance. When the film is processed measure the square horizontal and vertical. They should match, the vertical never changes but the horizontal does depending on gearing.

    Len are you still shooting the Cirkut? I moved over to Roundshots a few years ago, a lot less hassle and easy to print any size, plus cheap film too.

    Clayton

  3. #13

    Join Date
    Oct 2009
    Location
    Rome - Italy
    Shooter
    35mm
    Posts
    12
    To Len and Clayton:

    Quote Originally Posted by Len Robertson View Post
    ........................................
    Clayton (or anyone), does my suggestion to Roberto to make a focusing scale based on actual distance measurements corresponding the those marked on his gears seem the correct way to get his Cirkut so he can focus it?

    Len
    Well, as a matter of fact, there's a problem of focusing when used in panoramic way. In my camera, the film plane, with the panoramic outfit, is about 4.4 mm more away than the ground glass plane in "normal mode" (goes behind the ground glass plane); therefore, focusing on the ground glass and then fitting the Cirkut box gives deceptive results (out of focus). But, by knowing in advance the value of the difference among the two planes, is possible (with some artifact) to work out a "supplementary scale" for the "panoramic way". And, as reported further on, the program could help also for this issue.

    As said previously, I suppose that (making reference to the drawing in http://digilander.libero.it/foto_ras...ut_pattern.jpg) the camera should rotate around the axis of the lens in E (supposing the axis is there...), but actually, as I can see in pictures of other Cirkut cameras "at work" (and in mine too), the rotation is around the point F (pivot of the gear plate), and the distance between F and E depends on the diameter of A (the "small gear" actuated by the spring motor), with the camera connected to the tripod by the screw G, fitted in a sliding wooden plate, so that B and A can stay in contact.
    But all the same I agree that for short focal lenghts and for a subject at infinite the axis of rotation is not so important: your experience is worth a thousand times the "theory" !
    Furthermore, this issue seems less important with respect to panoramic digital rotating cameras, because in Cirkut cameras not the full frame is involved, but only the narrow central slit.
    The problem is assembling the correct gear with the correct distance from the subject, for a given lens and for a given "size" of Cirkut camera.
    The program, as I said, works, and works in DOS ("command prompt", under cmd.exe, in Windows).
    It considers (and asks for typing) a number of "variables"; for a few of them is probably unclear how to deal with. But first it asks if you want to measure the subject distance from FILM PLANE or, alternatively, from the REAR NODAL POINT : can we suppose, just for the sake of convenience, that the latter is approximately on E ? In case of a subject at infinite, even if the RNP is not exactly in E, the shift seems not very significant. But, how can we type "infinite" at the "command line" ? With a very very high value in inches (or mm) ? one million inches?
    The "variables" are:
    1. - the actual focal lenght : no problem;
    2. - the "large gear radius" : does it mean the toothed disc B ?
    3. - the "Diameter of film drum with average amount of film": clear and no problem;
    4. - the "Perpendicular distance from center of small gear to the LENS AXIS": assuming that the "small gear" is A, does it mean the distance between E and H ?
    5. - Perpendicular distance from center of small gear to the FILM PLANE (NEGATIVE IF FILM PLANE IS BEHIND GEAR): does it mean the distance between H and C ? If we refer to the drawing, the value should be positive, I suppose;
    6. - the "Slit width": clear, no problem;
    7. - the "Gear pitch" : what does it mean ? Is it the distance between two contiguous teeth of the (large ? small ?) gear or something else ?

    The output of the program is a file in .txt format (gearsOutput.txt), not well readable (at least, in my PC...) if opened as such in "Notepad" (see an example in http://digilander.libero.it/foto_ras/gearsOutput1.pdf). But if opened with Word is perfectly understandable : see an example in http://digilander.libero.it/foto_ras/gearsOutput2.pdf. Please note that the values given in input were "imaginary" and fictitius, just to test the program: therefore, the results are probably not realistic.
    In output we get, for the values typed in input, the "gear #" needed for the various distances (some distances are negative: why?) and the "lens extension" (from film plane, I suppose...; isn't it? can anybody clarify this point? ).
    Roughly judging by this rough test, the program seems well working, but needs some explanation/clarification for the above points.
    And I confirm my opinion: the program deserves to be included in the IAPP website in the "Cirkut section".
    Thanks for your help ! The discussion could look like "pure academy", but the Cirkut camera and the underlying "philosophy" (and technology) are a very important development in the history of photography.

    Roberto.

  4. #14

    Join Date
    Mar 2006
    Location
    Syracuse, NY
    Shooter
    Multi Format
    Posts
    350
    Images
    5
    On #2 the large gear radius in 4.5" for a 6 outfit. It's the radius of the toothed gearhead.
    #4 it's the distance between the lense axis and the center of the small tooth gear center, at a right (90 degree) angle.
    #5 You are correct, between h and c. On the #6 and # 8 outfits the film plane is in front of the gear. Not so with the #5, #6, #10 and #16 cameras.
    See wikipedia or other source for pitch definition, but the pitch on a 6 outfit (as well as the 8, 10, and 16) is 32 pitch. The 5 and 6 cameras have 48 pitch gears.
    I'm happy to put the gear program on my site if someone tells me how. I'm on a mac and not great at programing, but if the server is performing the operations it wouldn't matter.
    http://jamieyoungphoto.com/cameras1.html
    What are you planning to do for film Roberto?
    Jamie

  5. #15

    Join Date
    Oct 2009
    Location
    Rome - Italy
    Shooter
    35mm
    Posts
    12
    Quote Originally Posted by jamie young View Post
    On #2 the large gear radius in 4.5" for a 6 outfit. It's the radius of the toothed gearhead.
    #4 it's the distance between the lense axis and the center of the small tooth gear center, at a right (90 degree) angle.
    #5 You are correct, between h and c. On the #6 and # 8 outfits the film plane is in front of the gear. Not so with the #5, #6, #10 and #16 cameras.
    Thanks for the info !
    I'm happy to put the gear program on my site if someone tells me how. I'm on a mac and not great at programing, but if the server is performing the operations it wouldn't matter.
    http://jamieyoungphoto.com/cameras1.html
    No problem regarding re-programming, if the user is satisfied in using it as "stand alone", in no interactive form (inside a web page). I've copied it in
    http://digilander.libero.it/foto_ras...rkut_gears.zip, just renaming it. It only needs to be unzipped and put in a folder; double click on gears.exe and it goes (in Windows; in Mac I don't know...). In my use I first deleted (better, renamed) the file gearsInput.txt, so I'm prompted to fill the line with the data of my own camera.
    Please do not change the "credits": the programmer made a good job and a lot of thanks should go to Clayton Tume (clay nz) and to Len Robertson who was so clever in exhuming it from "Error 404 no-land". But I think that it should be accompanied by some "help", some descriptive note, also to solve the kind of doubts I had.
    If inserted in a web page, I think some SW gadget would be necessary for interaction: sorry, I can't give any help...
    See wikipedia or other source for pitch definition, but the pitch on a 6 outfit (as well as the 8, 10, and 16) is 32 pitch. The 5 and 6 cameras have 48 pitch gears.
    I've searched on Wikipedia for the definition, finding a lot of different things related to screws, gears etc. Maybe is it the "pitch circle", or "pitch diameter", in http://en.wikipedia.org/wiki/Gear#Pitch ? Seems logically consistent, but on my tripod the gear diameter is 23cm, that is 9.0551 inches; so, where can I get the value "32" ? Mystery!
    What are you planning to do for film Roberto?
    For the moment, I'm just practising with the camera, trying to undestand well how to use it. It came with two huge rolls of film, still wrapped in black plastic. I suppose it's quite old and probably I'll use part of it to test the mechanics of the camera and my ability. Later on, sure I'll have the problem of film availability: I've heard that Aerial Photo Lab has it, and another source could be (I hope...) at Kodak, according to the hint given by 45PSS in the "Help board" of graflex.org. Did you have (and solved) this problem ?
    But, after that, I'll have the problem of processing the film: an amazing adventure, I suspect...

    Thanks a lot.
    Roberto

  6. #16

    Join Date
    Oct 2009
    Location
    Rome - Italy
    Shooter
    35mm
    Posts
    12
    Quote Originally Posted by roberto3912 View Post
    I've copied it in
    http://digilander.libero.it/foto_ras...rkut_gears.zip, just renaming it.
    Roberto
    Sorry, the correct link is http://digilander.libero.it/foto_ras/Cirkut_gears.zip.
    Roberto.

  7. #17

    Join Date
    Oct 2009
    Location
    Rome - Italy
    Shooter
    35mm
    Posts
    12
    Quote Originally Posted by jamie young View Post
    #4 it's the distance between the lense axis and the center of the small tooth gear center, at a right (90 degree) angle.
    Sorry, but it is not clear. Do you mean, referring to the image in http://digilander.libero.it/foto_ras...ut_pattern.jpg, for lense axis, the line "D" ? And for "center of the small tooth gear center", the line "L" ? But I can't understand how this connection could be relevant for the task of the program, all the more so if with the reference to a "90 degree angle" (of what with what?). The same expression "perpendicular" is used for #5, for which we both agree that is the distance H - C.
    ...... but the pitch on a 6 outfit (as well as the 8, 10, and 16) is 32 pitch.
    But mine, on the large gear on top of tripod, has, engraved, the #28.....
    Brave, surprising, expert, tenacious ! :o

  8. #18

    Join Date
    Dec 2005
    Shooter
    Large Format
    Posts
    109
    Clayton - It would be wonderful if you could post your pages to Wikipedia, or somewhere. I don't know if pages found by web archive are good forever and ever, but I doubt it. I've heard there is a way to save entire web pages onto my computer, but don't know how to do it. I'm not shooting Cirkuts at all right now, mainly due to lack of time during periods of nice weather. Not many years until retirement, and taking a Cirkut out on a warm summer day is something I dream about.

    Roberto - Regarding the focusing difference between your focusing back and Cirkut Attachment, I wonder if the camera body (or at least the focusing back) aren't original to the Cirkut Attachment? I have a 5X7 Kodak Pony Premo #9 that can be used with modern sheet film holders, but the ground glass needs to be installed backward (frosted side to the rear of the camera) in order to get accurate focus. I've never understood why, but I suspect it has something to due with the transition from glass plates to sheet film. There was a time when camera makers didn't all use the same standard depth-to-film for their film holders.

    I believe gear pitch is a term indicating somewhat the number of gear teeth per length of measure. It may refer to number of teeth per inch of measurement around the circumference of the gear, but I'm not sure of that. I think the more formal name for pitch is something like pitch diameter or pitch circle and there is a formula that defines it. Somewhere online should be the precise definitions and formulas relating to gears. Another gear term is "pressure angle", relating to the profile of the individual tooth. As I recall, the pressure angle used for Cirkuts isn't as commonly used as it once was. Some people think you can go to a gear manufacturer's catalog and buy Cirkut gears, but getting the correct pitch, pressure angle, and number of teeth you want in a brass gear is very difficult. You are very fortunate to have obtained a Cirkut which includes gears for so many focal lengths of lenses.

    Len

  9. #19

    Join Date
    Mar 2006
    Location
    Syracuse, NY
    Shooter
    Multi Format
    Posts
    350
    Images
    5
    Roberto
    the lense axis "d" goes through the camera back. The small gear center is offset from it. The distance is the amount of offset from the axis line " D" measured at a right angle from "d" The image you show is a side view which doesn't show the measurement needed. A top view would be better. Don't know about the #28 but it's probably a manufacturing #, not the pitch number. Your pitch is 32

  10. #20

    Join Date
    Oct 2009
    Location
    Rome - Italy
    Shooter
    35mm
    Posts
    12
    Quote Originally Posted by Len Robertson View Post
    Clayton - It would be wonderful if you could post your pages to Wikipedia, or somewhere.
    Gosh! My "ambition" is only to make italian collectors (and vintage photogaphy entusiasts...) a little more conscius that, besides Rollei, Leica and Linhof, other cameras existed in the world... By the way, I was intrigued by the kinematics of Cirkut (a camera I dreamed for a long time to have...) and the "rationale" of its movement.
    Regarding the focusing difference between your focusing back and Cirkut Attachment, I wonder if the camera body (or at least the focusing back) aren't original to the Cirkut Attachment?
    But I don't worry for that: I'll put a shim, in front of the groundglass, exactly of the same thickness of the difference.
    I believe gear pitch is a term indicating somewhat the number of gear teeth per length of measure.
    Exact ! I counted the teeth: 290. Then measured the outer diameter: 232mm, that is 9.1338 inches. 290/9.1338 is 32 (rounded value) ! So, it's a "diametral pitch". See this drawing (original in http://www.engineersedge.com/gears/gear_tooth_parts.htm :


    And here the formulas for spur gears:
    http://www.engineersedge.com/gear_formula.htm .

    But, it would have been better, in the Cirkut formula, to use plainly the number of teeth, avoiding a "rounded value" .... After all, to explain the movements in a Cirkut camera and its relative "speed", it's all a question of ratios among teeth in different drives. Isn't it ?

    A panoramic photo of Venice - Piazza San Marco, would not be so bad... Well, probably too many people going around. Some nice "blurring", however...
    Kindest regards.
    Roberto.

Page 2 of 3 FirstFirst 123 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin