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Thread: ..help needed..movements/dof/focus shift (?)..(pics attached)..

  1. #1

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    ..help needed..movements/dof/focus shift (?)..(pics attached)..

    ..hello..
    ..long time reader, seldom poster here..
    ..its time i need your help..:-)..
    ..me and a good friend of mine use to go out with our chamonix f1s to do some landscapes..
    ..we think we more or less know what we are doing after having done our "using the view camera"- and "the camera"-lessons..:-)..
    ..as these are the first landscapes taken with the chamonix after having done some with a speed graphic there are things that occur that havent occured with the speeds and we dont know why..so i assume there is some error in thinking, but lets see..

    ..photo #1:

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    ..this picture had been taken with a nikkor 5.6/150mm focused with an open aperture at the flowers in front of the trees then closed down to about f22..before focusing the front standard had been tilted forward and the rear standard had been tilted backwards..before taking the shot shapness in the desired area was controlled by the chamonix reflex viewer..

    ..why is the focal plane behind the flowers and also why is the focal plane so thin despite f22 or maybe even smaller ?

    ..photo #2:

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    ..this picture had been focussed at the rocks in front of the tree with some front tilt to get the tree into sharpness also..
    ..sharpness had been controlled via a dark cloth and aperture was closed down to about f32 after controlling sharpness wide open..
    ..lens was a nikkor f8/90mm..no rear movement..

    ..why is the rock not sharp..?..:-)..

    ..photo #3:

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    ..the most tricky of all the photos for us..

    ..taken with the f8/90mm nikkor also..
    ..front tilt, a little bit of front fall, f32, sharpness controlled via darkcloth, focused right into the middle of the valley..no rear movement..
    ..now the rocks in the foreground are sharp, the valley itself is not, but the upper left corner is sharp indeed..:-)..

    ..would we need to close down the aperture even more..?
    ..do the lenses have some focus shift..?..(so much focus shift..???)..
    ..is there some error in thinking when applying rear movements..?

    ..anyway..
    ..i am sure there are things we havent thought of..
    ..please let me know what your ideas are..
    ..any input highly appreciated..
    ..thx in advance, erik..

  2. #2

    Join Date
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    769

    Re: ..help needed..movements/dof/focus shift (?)..(pics attached)..

    Questions for you.

    1) When you were composing on the ground glass, were these areas in sharp focus (but they are not on the film)? If so, there is the possibility that the position of your ground glass is not in the same plane as the film - this sometimes happens, for e.g., if a fresnel is installed incorrectly, or there is some grit between the back and the camera, or there is some slop in the back such that the ground glass shifts for some reason or the other (gravity, when you press on it with a loupe etc). Set up a scale at an angle to the camera. With all movements zeroed, focus on some point (e.g., the 6 inch mark) - so the 6 inch marking should be in focus and the 5 inch and 7 inch should be out of focus. Make an exposure (use a large aperture to limit DOF) and see if this is exactly what shows up on the film. If it isn't, you know this is a problem area.

    2) I am not sure what you mean by sharpness being controlled by the dark cloth or reflex finder - I am assuming you were using these to make it dark enough to evaluate sharpness and either should be adequate if you were able to see the image.

    3) Were you using a loupe to evaluate focus? The loupe can make you fixate on one area - its usually a good idea to evaluate the whole image without the loupe and make movements as you pay attention to the whole image as you try to find the best plane of focus and then also use a loupe to ensure critical focus - this is especially true with smaller formats. I've experienced both of the following errors - 1) fixate on the thing I am focusing on through the loupe without paying attention to other parts of the picture being in or out focus and 2) pay attention to the overall image but find that nothing is in critically sharp focus.

    4) I doubt if you are experiencing focus shift, given the lenses you are using.

    5) I also do not think you should need to stop the aperture down more (pictures 1 especially is very straightforward and not particularly demanding of DOF).

    6) There is always the possibility that you are applying too much movements but this should show up on the ground glass if everything is working properly. So you should be bale to see it. Your description makes it sound like everything looks good on the ground glass but not on the film, which is what leads me to suspect point 1 above.

    Good luck tracking down the gremlin.

    Cheers, DJ

  3. #3
    ic-racer's Avatar
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    Re: ..help needed..movements/dof/focus shift (?)..(pics attached)..

    http://www.trenholm.org/hmmerk/download.html

    Also, do you know how to test or measure that your ground glass is in the correct position?

  4. #4

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    Re: ..help needed..movements/dof/focus shift (?)..(pics attached)..

    Early Chamonix cameras had the ground glass in the wrong place. Check to make sure that the lens board-to-film plane distance is equal to the lens board-to-front side of ground glass distance. Also check whether the GG is in properly, with frosted side facing the lens.

  5. #5
    Huub
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    Re: ..help needed..movements/dof/focus shift (?)..(pics attached)..

    Also: be aware that you mostly need a tiny bit of tilt in landscape photography, especially with the shorter focal lengths. It is easy to overdo it and don't ask me how i know...

    The rules of Scheimpflug state the the plane of focus, the lens plane and the film plane need a common intersection to achieve proper focussing. The wikipedia article on this principle is a good read: http://en.wikipedia.org/wiki/Scheimpflug_principle. When i want to use tilt on my own view camera i first focus without applying movements. I then step aside the camera and guestimade how much tilt i need by looking where the these three planes should meet, which is mostly somewhere under the tripod head... Then under the focussing cloth again for the last adjustments, using a loupe.

  6. #6

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    Re: ..help needed..movements/dof/focus shift (?)..(pics attached)..

    ..well..what can i say..active forum this is..:-)..
    ..thx a lot for the input..
    ..a few things i have to say regarding the input you gave me..

    ..1) the chamonixs are brand new and as far as i can say seem to be proper adjusted..nevertheless soem test photos will be necessary..thx for this..
    ..2) i also think that the problem lies beneath the complex topic of movements and scheimpflug..thx for the links..how can it be that even if closed down properly the dof/focal plane is that thin even with a 90mm lens..?..can it be..?
    ..3) i think i can rule out that there is some grid between the back and the camera and i also think that i can rule out that the fresnel is warped or so..portraits at a closer distance than infinity worked fine (without movements)..
    ..4) yes, i meant that either the reflex viewer or the dark cloth were used to inspect the image projected to the groundglass properly..its hard to say if things were CRITICALLY sharp when focusing, but anyways, focus was checked after applying the movements..but focus was checked wide open..aperture had been closed down afterwards as when closed down there was not too much to see with f32 or smaller..:-)..

    ..please keep going..any input is highly appreciated..

  7. #7
    ic-racer's Avatar
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    Re: ..help needed..movements/dof/focus shift (?)..(pics attached)..

    [QUOTE=psy501;1151840]
    ..2) i also think that the problem lies beneath the complex topic of movements and scheimpflug..thx for the links..how can it be that even if closed down properly the dof/focal plane is that thin even with a 90mm lens..?..can it be..?
    /QUOTE]

    The illusion that is called "depth of field" is dependent on many things. Importantly, how closely you examine the negatives and/or prints. The closer you examine (greater the magnification) the illusion of 'depth of field' gets smaller and smaller.

  8. #8
    Huub
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    Re: ..help needed..movements/dof/focus shift (?)..(pics attached)..

    I asked my son to do a bit of basic mathematics on the amount of tilt needed for both your lenses. When you asume the camera is 2 m above the ground, the film plane vertical and the plane of focus horizontal, a 90 mm should be tilted 2,6 degrees and a 150 mm 4,3 degrees to achieve perfect focus.

  9. #9

    Re: ..help needed..movements/dof/focus shift (?)..(pics attached)..

    There is definitely something wrong here. Before I begin let me just say that your compositions are excellent and as soon as these technical things are fixed you should be fine.

    Assuming your camera is operating correctly(which others have commented on) and other little things are correct. A level camera to start, everything zeroed that you want zeroed, film holders correct, etc. the first thing I would like to know is are you sure you stopped the lens down, to me it almost looks like you shot the images at or close to the maximum aperture. 2nd thing would be the closeness of the foreground. If the close objects are very close then that is a more difficult situation. Thirdly, you might want to try focusing first then applying movements, in picture 1 you seem to suggest that you applied movements before focusing which would throw me off.

    For dof in #3, I probably would have tried swing first and see where that gets me. Swing would help with the foreground vertical cliff and could help with the distant mountains, maybe just one maybe both. You would then need to add a little tilt to get the foreground sharp which might also help with the background as well.

    #2 You seemed to have focused on the foreground and tilted on the foreground as well. I don't usually focus and tilt in the same area. However, given your emphasis on this part of the image it is surprising that there are unsharp areas here; possibly your tilt was in too high a plane, your camera was not zeroed, your f-stop was incorrect, you used shift at the last moment and didn't check focus afterward.

    #3 there is vignetting here which if not from a filter or hood,suggests possibly too much movements were used for this image. I use a 150 a lot and this type of image is a good one to shoot at f22 with a little tilt. Not sure if you used a lot of vertical shift which could change the area of focus.

    In closing, next time you are out, after you have adjusted the camera but before you have closed the shutter and put in the film holder, take a close look at the image through the viewfinder. While you are looking at the image slowly close down the aperture and check for sharpness. If it's sharp then unsharp in the neg, you could be doing something like jarring the camera when putting in the film holder, etc. And lastly, I'm guessing the Chamonix has more movements than the speed graphic which is good unless you overuse them. All the best

  10. #10

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    Re: ..help needed..movements/dof/focus shift (?)..(pics attached)..

    ..well..
    ..thanks to all for the valuable input..

    @ john borrelli: thx especially for laying out in so much detail..this is extremely helpful..
    ..we will have a thorough look at the cameras if everything is working properly, but as these are brand new chamonixs i think i can assume this..

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