Is there something wrong with this colour negative?

Discussion in 'Color: Film, Paper, and Chemistry' started by nwilkins, Oct 26, 2012.

  1. nwilkins

    nwilkins Member

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    I got a roll of Portra 400 (120) back from the local lab and one of the pictures has something weird going on (I think). I don't have a ton of experience with colour negatives so I don't know for sure what is happening. I am going to try and scan it to have a better look once I have flattened the film out overnight, but in the meantime has anyone seen this before? Pictures of the negative are below:

    IMG_3541.jpg IMG_3542.jpg
     
  2. Bob-D659

    Bob-D659 Member

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    Double exposed?
     
  3. nwilkins

    nwilkins Member

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    definitely not double exposed, and that wouldn't explain why the dark region is out of sync with the image, especially where it extends to the very bottom of the film.
     
  4. Bob-D659

    Bob-D659 Member

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    What camera are you using?
     
  5. Photo Engineer

    Photo Engineer Subscriber

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    They look ok to me!

    PE
     
  6. Worker 11811

    Worker 11811 Member

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    Just a thought...

    Are you talking about the little "notch" shaped details at the corners of the frames?

    A couple of my cameras do that. I presume it's a small defect in the aperture plate inside the camera.
    While they shouldn't have major defects, a company can't manufacture thousands or millions of cameras over a period of years to decades without having some variation.

    Even if they were manufactured perfectly every time (and they should be VERY close) over the years, wear and tear might have taken its toll.

    I look at it like the rifling in the barrel of a gun. No two are exactly alike.

    In fact, I can tell if a roll of 120 was shot in my Yashica or my Rolleiflex just by looking at the details in the corners of my negatives.
    The Yashica has an ever-so-sleight "dart" in the corner of the frame. Similar to yours, only smaller.

    I'm not saying all cameras have this. In most cameras that do have small defects in the aperture, you probably couldn't tell unless you used a magnifier.

    Regardless, it's probably worth checking your camera over. Look at the aperture plate, the lateral film guides, the pressure skid and the film trap area, in general. It might be simple as a piece of crud stuck in the corner that causes the film to buckle.

    I'm not sure this is the case with your camera but, for two minutes worth of cleaning and checking, you've got nothing to lose.
     
  7. wogster

    wogster Member

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    Actually many cameras have a notch like that, the idea is that each camera model, from the same manufacturer has a different notch, and years later you can tell which camera took the photo based on the notch. Of course this doesn't work if you have cameras from different manufacturers or two cameras that are the same model...
     
  8. nwilkins

    nwilkins Member

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    Sorry I guess I should have been more clear - I thought the problem would be readily apparent (I was hoping it was something relatively common). It is an RB67 and I have taken hundreds of pictures with it and this is the first frame it has happened on. It is happening on only one frame of this roll. It is the frame with the trees (on the left in both pictures). You can see there is some kind of dark region on the emulsion that is roughly the shape of the frame, but not quite lined up with it. In the first picture you can see the dark region extends down to the edge of the film in the corner. In the second picture you can see the dark region does not extend up quite as far as the top of the image, and is clearly changing the density of the image when compared to the small strip at the top without the dark region behind it.
     
  9. polyglot

    polyglot Member

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    You mean how the foggy outer rectangle doesn't line up with the main image rectangle? What's happening (probably) is that you shot a very backlit or flarey scene, or overexposed a bit. Flare inside the camera does not necessarily come from the exit pupil of the lens and therefore it can pass through the film gate at a different angle, resulting in an offset and/or larger region of flare on the film compared to the focused image. Think of the sun being just out of frame, the lens will form an image of the sun on the inside side of the camera or somewhere in the lens barrel. That sun-image is maybe a thousand times brighter than the image you care about, which results in a mass of light bouncing around within the camera and onto your film, and you get veiling glare.

    When you scan this, you'll probably find that all the blacks are a bit washed out from the flare. Setting your blackpoint higher in the scan will clean it up a bit.

    To see a similar effect, shoot an image with very shallow DOF, which will mean you have a larger exit pupil of the lens. You'll therefore see that the edges of the image become blurry, i.e. the film-gate casts a penumbra instead of a clean-edged shadow.
     
  10. nwilkins

    nwilkins Member

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    thanks Polyglot - hopefully that is all that is wrong. The scene itself was actually rather dark and I was using F11 with a lens hood, but the sun did peak out from cloud right as I made the exposure so maybe it is flare.
     
  11. nwilkins

    nwilkins Member

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    okay here is a rough scan - does this look like flare to you guys? The fogged region is wider than the lens image on both sides and extends below, but it is clearly more prominent in the upper right hand corner of the image.

    img743.jpg
     
  12. Photo Engineer

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    Very nice shot. I see the problem now in the neg and pos images. I agree with Polyglot that this appears to be flare from the sun. Note how it appears lighter at the top of the frame just where the sunshine would be brightest.

    Take it again of you can. Nice view.

    PE
     
  13. Ian C

    Ian C Member

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    The spurious hazy rectangle is suspiciously about the same size and shape as the film aperture, but is slightly displaced and skewed at an angle.

    I think that you have a problem with the camera. Somehow unintended light is striking the film. I suspect a failure of the light baffle that normally covers the film aperture in the rear of the body when the reflex mirror is in the viewing position.

    Normally it prevents stray light from reaching the film. It looks like light is somehow being reflected off of the rear surface of the out-of-position light baffle and onto the film, creating the hazy rectangle.

    Yes, it resembles flare, but that doesn’t explain the offset rectangle with perfectly straight borders. Light reflected off of the rear of the light baffle might account for what you’ve shown.

    Note the warning about not touching the light baffle on page 8 of the owner’s manual and this warning is repeated on page 16

    http://www.cameramanuals.org/mamiya_pdf/mamiya_rb67_pro-s-1.pdf

    It might fail on its own or have been tampered with at some point before you acquired the camera if it was bought used.

    That this doesn’t happen on every frame indicates that the problem is intermittent. Eventually, it might occur more frequently if the problem gets worse.

    Note that the hazy area is strongest at the top of the frame. I believe that the baffle pivots with the mirror. The bottom edge is likely the last part to cover the film aperture. Should the baffle “hang up”, the bottom might remain slightly open.

    Any light between the not-quite-closed baffle and film would be somewhat stronger along the bottom than the top. Since the projected image is inverted on the film, the top of the scene corresponds to the bottom edge of the film. That’s where the hazy rectangle in the photo is strongest tending to support the idea that this might be a failure of the baffle to fully close.
     
    Last edited by a moderator: Oct 27, 2012
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  15. nwilkins

    nwilkins Member

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    hmmm. thanks Ian. That explanation is more troubling since it means the camera is malfunctioning, but it seems more likely to me than flare for the reasons you've stated. So far this is the only image where this has happened. I guess I will keep my eye on it and if it happens again I will have to have the camera inspected. This shot is from a large project and I have also been shooting each image in b/w so it will be interesting to see whether there is a problem with the b/w version once I develop that film. Unfortunately the project will probably end up needing to be in colour, and I won't be back to that location for some time, so it's likely a lost image.
     
  16. Ian C

    Ian C Member

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  17. Photo Engineer

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    Ian, your explanation is better than any I have heard. I am having a problem with your explanation (and all others including mine) in explaining how the "flare" goes outside of the frame area into the border. This area is normally masked completely and would even be protected from light via the method you give. So, I'm not sure. Maybe my mind picture is off. IDK. I have changed my mind twice by reviewing the photos posted here.

    I do have an RZ and had an RB and so I am interested in the explanation.

    PE
     
  18. MattKing

    MattKing Subscriber

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    It looks to me like a combination of flare and a small bit of light piping past the edge of the film gate,
     
  19. Photo Engineer

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    Matt, I agree with this in general, but light piping becomes diffuse with distance and therefore the false image should not be so precise. At least that is how I feel.

    PE
     
  20. AgX

    AgX Member

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    As the film is not in contact with the image frame, there must be a point light source, or at least rays that are focused at the film plane to cause sharp borders.
    If the baffle had a leak then whilst handling there would be the effect of diffuse exposure.
     
  21. nwilkins

    nwilkins Member

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    I am also confused by how light is getting to the part of the film which is behind the back's mask, in this case right to the very edge of the film. Interestingly the foggy area is shaped just like the image itself, with the little notches on the corners being extended as if light is being thrown threw the back mask at an extreme angle (which supports the flare theory I think?).

    In racking my brain about this I do remember that at one point during the shoot (not sure if it was this pic) I did attempt to remove the back before putting the dark slide in - I was working very quickly using two backs (colour and b/w) for every shot and I moved the sliders (they only went part way because of the camera's failsafe) to try and unlock it and pulled a little on the back before realizing that it was not coming off - do you think this could have caused the problem?
     
  22. nwilkins

    nwilkins Member

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    so maybe it is flare then? but wouldn't flare also not cause the sharp border?
     
  23. erikg

    erikg Member

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    Sounds very possible, and that would explain the offset.
     
  24. Ian C

    Ian C Member

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    I examined my RZ67 Pro II back assuming that it’s similar to the RB67 back. When viewing the film opening with the dark slide removed, it’s easy to see that the pressure plate is about a 1.5mm deeper than the deepest edge of the short ends of the film aperture. That provides plenty of clearance for light projected at an angle to pass under the ends of the film aperture and strike the film beyond the usual frame boundary at the ends of the frame.

    When image-forming light from the lens is projected back through the film aperture, the maximum angle that light can travel from the rear lens element passes through the aperture and defines the image rectangle on film. This is always about then same size due to the same (or nearly the same) projection angle of the various lenses that fit the camera.

    But in the case of spill light reflecting from the interior of the mirror box past an out-of-position light baffle, the light can travel from the sides of the mirror box past the edge of the baffle obliquely to pass under the ends of the film aperture due to the 1.5mm clearance between the end of the film aperture and film lying against the pressure plate.

    The source of the light is most likely from the lens to the mirror to the focusing screen. Some of the light that strikes the focusing screen must reflect and spread sufficiently to slightly illuminate the interior of the mirror box during viewing. Normally this is no problem if the light baffle is sealing the opening to the film holder as the designer intended. But if the baffle is not fully closed, then some light from the mirror box can bleed thorough the gap between the baffle and the chamber to expose the film—including a small area beyond the usual border due to the clearance mentioned. And, since the light still grazes the edge at the end of the film aperture, this would account for the sharp boundary, even into the area beyond the usual frame boundary.
     
    Last edited by a moderator: Oct 27, 2012
  25. Photo Engineer

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    Ian;

    Your explanation is without film in the back. With film in the back, that 1mm difference is taken up by the thickness of the film due to the pressure the plate exerts. Or, did I misunderstand you?

    PE
     
  26. polyglot

    polyglot Member

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    I just had a look at my RZ back and there's a good 4mm between film gate and pressure plate; plenty of room to have an offset between flare and image. I can also report that I get offset-flare (on two different RZ bodies) just like you've reported when shooting strongly-backlit scenes*, so it's not a fault with just your body. My guess is that there might be something small and reflective on the back of the mirror and that if that is illuminated during exposure then you get flare.

    And it's clearly not a problem with the baffle - the sharpness of the flare image shows that it was formed only while the shutter AND baffle were open, i.e. during exposure. If it was light leakage during handling, the flare would be spread around due to camera motion.



    * with the sun in-frame, you don't see the offset because the sun-image is on the film, so you just get lens-flare. This problem occurs with the sun only just out of frame, which causes it to illuminate the inside of the body. My scanner (Nikon 8000) doesn't really go outside the frame boundary because of how the holder works (and I tend to crop out the unevenly-flared edge-bits before saving!), so I can't easily show you an example. But this is IMHO normal behaviour for an RZ/RB.