BetterPhoto Q&A
Category: Photo Exposure Troubleshooting

Exposure Problem

I recently purchased a used Rolleiflex SL35 with a 50 and 70 mm lens. I shot my first roll last week but about half of the photographs came out with a shadow on the right side, about 1/8th of the print, as though they have been underexposed along the edge. I noticed that some have this quite bad, while others have a slight tinge of it. One vertical picture has it on the bottom, while all the other pictures, taken horizontally, have it on the right side.

I am curious if anyone might know what this is. I was using 200 kodak gold film, the proper ASA setting, good light and seems like the proper aperture and shutter speed settings as, aside from the edge, the exposure of the rest of the prints look fine.

I have 2 ideas so far: one that light was coming in through the eyepiece. I have no eye cup on it. Two: it has something to do with the shutter speed. I had the camera checked out at a shop after I bought it and they said that the shutter speeds were fast on the higher settings and could use adjustment. I don't know if a fast shutter would cause this problem, as no flash was involved and light was good that day.

Thanks for any suggestions!

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July 05, 2002

If so, this sounds like "shutter capping." A focal plane shutter has two curtains. When the shutter is fired, the first (opening or leading) curtain is released. After a delay, the exact time for which is determined by the shutter speed selected, the second (closing or trailing) curtain is released.

The shutter curtains always travel at the same speed, regardless of the shutter speed selected. Shutter speed is changed by changing the time delay between releasing the first and second curtains. At shutter speeds faster than the X-Sync speed (the one used for flash), the second curtain is released before the first one has completely traveled. [This is why the X-Sync speed, or slower, must be used with flash.] At the faster shutter speeds, the delay becomes so short that the film is exposed by a slit traveleing across the film gate.

If the opening curtain starts to slow (or even stops) before its end of travel, the closing curtain will start to catch up to it resulting in the "slit" becoming narrower near the end of shutter curtain travel and the portion of film near the end of shutter travel receives less exposure than the the rest of the frame. If the "capping" is severe enough, the second curtain completely catches up with the first one resulting in a completely unexposed strip at a frame edge.

Shutter capping is most often found in older cameras with heavily used shutters. The problem is usually the weakening of the spring[s] that pull the opening shutter curtain across the film gate, but it can also be the opening curtain binding slightly near the end of travel. Have the shop check it out specifically for shutter capping. If they have the equipment to test shutter speed, they should be able to set it up to test for capping near the end of travel. You can also run your own test. Evidence of capping in the print (the underexposed strip near the edge) is almost always more severe at higher shutter speeds than lower ones. Run a roll of film through, use various shutter speeds and make note of what shutter speed was used for which frame. Then look to see if the problem is worse at the higher shutter speeds.

On most cameras it can be fixed by adjustment of the spring tension on the shutter curtains, or by cleaning the shutter curtain mechanism, or both.

Note:
The image on film inside the camera is upside down and reversed from what you see in the print. If the shutter curtains travel from right to left, you will see it on the right side of the print. (This is why I suspect it's capping.) Likewise, on cameras with vertical travel focal plane shutters, if they travel from top to bottom, you will see it at the top of the print.

-- John

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July 05, 2002

I guess this is something I will need to really watch out for when buying older used slr's. I guess it pays to have it checked out first, regardless of the asking price.

Thanks,
Byron

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July 06, 2002

The cost for fixing will vary from shop to shop. Since it's a Rollei (I also have a Rollei 35S), I know of one or two shops that specialize in them. Contact me off-forum and I'll send you the names of one or two people to contact that specialize in cameras like yours (and have an excellent reputation among the collectors of them). You should be able to get a ballpark cost from them for a shutter overhaul and can make some decisions from that. (Typically firm estimates are only made after actually looking at the camera.)

My name below this with the date next to is hyperlinked to my page here. Go to my page and use the "Contact" button below my picture on it to send an email directly to me. It will contain your email address when I receive it, as if you had sent it to me directly.

-- John

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July 07, 2002

I just posted a note about this exact same thing.....but my "black strip" happens when I use the flash. But I think John just nailed it for me!

I use only shutter speeds of 125 and 250 so I think until I can get a new camera or pay for repair I wont use flash photography!

Thanks to Byron for having a problem and to John for answering!

Now I am not so confused!

Connie

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August 22, 2002

First:
Are you certain your camera can properly X-sync the flash at 1/125th and 1/250th? Most newer SLR's can sync at 1/125th but only a few newer ones can sync at 1/250th. Most older cameras with focal plane shutters must use 1/60th to sync the flash properly. Look at your shutter speed dial. The flash sync speed is typically marked in a different color. Sometimes that speed and all the slower shutter speeds are marked in a different color. Yet another scheme I've seen has a red "X" next to the flash sync speed. I have one camera that has the all the shutter speeds marked in black except the X-sync speed which is marked in red (that speed or any slower one will sync properly). Another has the X-sync and all slower speeds marked in blue; all the faster speeds are marked in black. Colors used and how its marked varies from camera to camera, but it's nearly always marked somehow. Hopefully this is what has been happening as using the proper shutter speed fixes it and no repair is required.

The reason is how focal plane shutters work. It consists of two curtains, an opening (first) curtain and a closing (second) curtain. The curtains *always* travel at the same speed across the film plane. Shutter speed is controlled by changing the amount of delay time between releasing the two curtains. Set a shutter speed fast enough and the closing curtain is released *before* the opening one has fully traveled. At speed such as 1/1000th or 1/2000th, it's more like a narrow slit traveling across the film plane. The X-sync speed for a focal plane shutter is the fastest shutter speed at which the opening curtain fully travels *before* the closing curtain is released. The flash is fired by the camera between while the film plane is fully open. Newer cameras have faster traveling shutter curtains, and they are more vertical ones than before (vertical shutters travel a shorter distance [2/3 that of horizontal ones]).

Second:
What you describe can also happen if the X-sync timing is off and the flash is not being fired between the opening curtain completing its travel and the closing curtain starting its travel. If your camera is *supposed* to X-sync at 1/125 and 1/250, then this is likely the problem. This problem requires a trip to the repair shop to have the flash sync timing adjusted. How much work it is depends very heavily on the camera, its shutter design and how easy it is to get to the adjustment (amount of disassembly required). Some are simple and others are not.

-- John

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August 22, 2002