Memiya RB67 strange light streaks

[Kduck]

Hi guys,
I'm new to APUG. I have a Mamiya RB 67. Sometimes when I take long exposures with it I get light streaks coming from stationary light sources such as lamps. In the attached photo the open door down the hallway has light streaks coming from it as well as the windows up above. Do you think this is a shutter issue or maybe mirror shake of some kind?

 

[shutterfinger]

The light streaks look like camera movement to me.
How are you doing the exposures? Please be specific.

 

[analoguey]

The rest of the image is crisp - so possibly it reflects light falling from the windows onto the wall(image), via blinds or curtains?

 

[Kduck]

I used a cable release when I took the photo. I'm using a motorized 120/220 back. I don't have a great tripod so it's possible there could have been some camera shake although it's weird that it's only coming from light sources.

 

[shutterfinger]

The rest of the image is crisp

Well, it appears that way until....
I saved the image to my machine, opened it in PS CS5, increased size to 300% via navigator. It starts so show pixels at 250% but not bad enough to distort the image. The bright areas register the camera movement as the brighter light does not need as much exposure time as the darker areas. The door at the far center of the image has both vertical and horizontal movement, minor but very detectable. The lighter gray railings and the lighter doorways on the left center have just detectable motion blur. The mid gray and lower tones have no distinguishable motion blur.


Seems like you need a better tripod as the one you're using is transmitting vibration from the shutter operation to the image. Go over your tripod and check that all screws and bolts are tight.


When you set up make sure all clamps are very snug. Some tripods will have leg give when weight is applied to them so once the camera is firmly attached push outward on each leg at the foot with your foot to make sure they are at full spread. Open the shutter with a card in front of the lens, wait 2 to 3 seconds, remove the card and start timing, replace the card in front of the lens at the end of exposure then close the shutter.

 

[cramej]

The shutter is not closing completely after the exposure and still exposing the film while you are winding it. Your lens needs a CLA.

 

[John Koehrer]

The shutter is not closing completely after the exposure and still exposing the film while you are winding it. Your lens needs a CLA.

Maybe, maybe not.
It's hand held. I'd expect movement over bad shutter.

Check the shutter at a similar speed. If it hangs, iIt's easier to see from the rear of the camera.

 

[analoguey]

Well, it appears that way until....
I saved the image to my machine, opened it in PS CS5, increased size to 300% via navigator. It starts so show pixels at 250% but not bad enough to distort the image. The bright areas register the camera movement as the brighter light does not need as much exposure time as the darker areas. The door at the far center of the image has both vertical and horizontal movement, minor but very detectable. The lighter gray railings and the lighter doorways on the left center have just detectable motion blur. The mid gray and lower tones have no distinguishable motion blur.

Opened it larger again, you're right! I missed that. I also noticed the motion blur in the window(?) on the right as well.
Wonder if the OP's now tried a shot with a more stable tripod + cable release

 

[j-dogg]

The shutter is not closing completely after the exposure and still exposing the film while you are winding it. Your lens needs a CLA.

My money is on this....try it with a normal non-motorized back

 

[nwilkins]

I was also going to guess that the shutter is not quite closing in time when the motorized back starts advancing the film. looks like the film is being moved while some light is still getting in.

 

[roger-wilco-66]

You need quite a swing on a tripod or hand held to produce this. Also, the motion is very linear and in the direction of the film advance.

My money is also on the shutter closing too slow. I'd try another lens and see what gives.

Cheers,
Mark

 

[camtec]

Why not remove the lens from the camera, cock it and release it and observe the blades to ascertain that they are closing? Instructions on how to do this upon request.

 

[rco3]

You know there's a slow response setting on that motorized back so that it waits longer after exposure to wind the film, right? Are you leaving the back set to advance at the normal time? Might be winding before the shutter closes. Just a thought.

 

[Kduck]

I think I figured this out. I had the mirror lock on. I didn't relize that it doesn't close the shutter until you move the mirror lock dial to the off position. As a result, the shutter remained open until I cocked the shutter for the next shot. The streaks were caused by the camera advancing the film to the next frame while the shutter was still open.

 

[DcAnalogue]

I don't think the mirror lock "On" could cause the issue.... unless you used "T" speed mode.
Shooting with mirror lock on didn't gave me any problem with normal speeds (and a manual back)...

 

[nwilkins]

yes the mirror lock up feature, when engaged, opens and closes the shutter at the speed specified on the lens. Chances are you had the lens on "T" setting, instead of a specific shutter speed, which holds the shutter open until you cock it for the next shot.