Dark Areas on Photos

Discussion in 'Medium Format' started by JLachiw, Feb 4, 2020.

  1. Hello all,

    I recently got a Rolleiflex SL66, and ran a few rolls through it. On some negatives, there is a noticeably dark area at the top of some photos (when inverted from the negatives). I've attached a particularly extreme example of the issue, but that image is unedited: that's how it came out of my scanner.
    Let me know what you might think it is? Is it a scanner issue, a shutter issue, or a film magazine issue?

    Thanks

    example.jpg
     
  2. At first sight I'm inclined to think it's insufficient agitation during development -- "bromide drag."
    (But I'm not always right!)

    That is there seems to be soft vertical streaks in addition to the darkness in the corner. Not familiar with that camera -- does the film travel vertically or horizontally in it? Rephrased, is the top edge of this image along the edge of the film or does it run across the width. The latter would tend to rule out my theory.
     
    Last edited: Feb 4, 2020
  3. The camera has vertically traveling film, and a vertically traveling shutter. I used a Pentacon Six before, with a horizontally traveling shutter, and horizontally traveling film, and that camera had inconsistent curtain speeds at 1/1000, so I'd get dark streaks. However, those were across the entire negative, whereas these are very localized.

    Would bromide drag occur even if it was lab developed? I've used them for several years, never had an issue before.
     
  4. Take it back to the lab and ask them. It certainly looks like development issues, not enough developer in a tank, and not enough agitation. What does the rebate look like, is the printed film data faint at the top too?
     
  5. Highly unlikely to be a processing fault, let alone 'bromide drag', which exists in myth far more than in reality.

    Much more likely to be a shutter fault.

    If you can see a more transparent area and streaks on the negatives, then it can't possibly be a scanner fault.
     
  6. Well, I take "bromide drag" as a handy term for variations in developer exhaustion affecting surrounding areas as a result of not being agitated enough to diffuse. I might expect that sort of effect likely to appear in 'stand developing', but if the film in this camera travels vertically, the streaks are across the width of the film which doesn't fit that idea too well, thinking of using a simple tank. Of course we -- at least I -- don't know how it was processed equipment-wise anyway.

    So then if the shutter, a focal plane type, also travels vertically, some sort of jerky motion might create exposure variations, but one would expect them to appear as horizontal streaks parallel to the edge of the curtain in this view.

    Perhaps there are two things happening, the other being an obstruction of some sort toward that upper right corner (actually the lower left in camera). (A flap of torn tape off the film roll?! :confused: )

    If it's light variation the rather soft edges of all the stuff suggests to me the problem isn't right at the film plane, and that same condition makes me think it's not a scan issue. (Although if there is a ripple/regulation problem in the scanner power supply ...) I might also wonder, for the sake of completeness -- do the rebate areas outside the frame look "normal" and are the frame numbers well developed?

    Isn't this fun! I suppose it all helps to exercise our minds to prevent Alzheimer's!!! :eek:

    (Back to lurking ...)
     
  7. Thanks everyone for the input. I think I can rule out processing errors since the mark appears quite consistently in the same spot on negatives, but it does not overlap into another frame. I'll have to look over the camera and the magazine, check if there might be something internally blocking part of the film or causing it to be less exposed. Hopefully it isn't the shutter, I seem to have terrible luck with medium format cameras with focal plane shutters, and I especially don't want to try and find someone to service a Rolleiflex SL66. I can only imagine how expensive that would be.

    Anyways, thanks again, and I'll be sure to update if I find any solution.
     
  8. At 1000th of a second, the slit in a medium-format FP shutter is only about 1mm wide. That means it only takes a fleck of paint, dust or other detritus on the edge of one blind to cause an uneven exposure streak down the entire frame.

    So if the opposing edges of both blinds are dirty (or maybe covered in decomposed black foam) then it's easy to see how multiple streaks could be formed.

    Add in the distinct possibility of one blind travelling faster or slower than another, and an area with complete lack of exposure is quite likely.

    Any FP shutter that's lain unused for a long time should certainly be visually checked and 'exercised' by repeated firing before use. Then, if there is a fault, it may clear itself, or worsen. That's a matter of luck!
     
    Last edited: Feb 6, 2020
  9. Last night I checked the shutter with my phone's camera, it can manage some slow-motion but nothing too impressive, and I was able to see that the left side of the shutter starts traveling before the right side. Essentially, what should be a vertical slit is instead slightly angled, so that's what's causing that dark area.

    Now, anyone know how hard it is to adjust the tensioning for the shutter curtain on a Rolleiflex SL66? I've found quite a few photos of the shutter mechanism itself, and there are two quite obvious tensioning knobs for each curtain. Would adjusting it be as self-explanatory as that, or would it be more complicated?
     
  10. If one of the shutter blinds is leaning to one side, then I suspect it either has a broken tape or there are sticky rollers or bearings on one side.

    Usually, there's just one tensioning spring per blind that affects the whole roller equally, it's not split side-to-side. However, Rollei might have done something different.

    Roller tension needs to be equal between the two blinds, otherwise the 'slit' will vary in width as it crosses the frame, and give uneven exposure in the direction of shutter travel. That's not what appears to be happening here. It's much more likely that you have excessive friction in the roller(s) or bearings that the guide-tapes of the shutter run over. Maybe even a loose or broken tape. Whatever. The shutter needs attention.

    The last thing I would do is mess with the blind tension. First port of call would be to check the condition of the bearings, rollers and tapes. Because if you release the blind tension, as you should do before re-tensioning the shutter, you'll need quite sophisticated timing equipment to check the run of the shutter.
     
    Last edited: Feb 6, 2020
  11. I don't know if this will help narrow down the issue, but when cocking the shutter, the seam between the curtains is perfectly horizontal. It only appears angled when firing the shutter.

    Also, are there any actions I can take before tearing down the camera?
     
  12. Rule out the rolling shutter on the Phone video first...
     
    Jochen likes this.
  13. If you have a flash with that crazy stroboscopic repeating function, you could set it to something like 1/64th 'power' and 100Hz.
    Then look through the shutter with the flash firing. With a bit of luck, you should see a few 'snapshots' of the shutter slit at various points across its travel.
    Only exercising the shutter a few dozen times and at all speeds. Also cleaning any crap off the metal edges of the shutter blinds - very carefully!
     
  14. Anyone know what's hidden behind the rear plate of the SL66? The plate covering the shutter area has several screws holding it on, but even in the repair manual I paid $10 for, there's no description about whats behind it. I imagine removing that would let me check on the shutter curtains, but I don't want some springs flying out at me, or parts of the camera falling loose. I've found photos of both side panels removed, but none of the back panel, so should I assume its off-limits?
     

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