Tested 2 Mamiya RB67s. Both ended up with poor image quality. Unsure what's going on?

voightlandertroubles

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Hi all!

Sorry again for another thread. It's been busy getting camera presents for family! I had the fortune to test 2 Mamiya RB67s for my best friend over the weekend. He got the rolls back today and noticed that each RB67 had an issue with the images. Was hoping to get some advice as to what could be the cause?

Each camera was shot at around 1/400sec and F/8, with infinity focus and we've tested over 15 RB67s this year, but we haven't come across to these issues.

RB67 #1 - Pretty much every roll came out blurry and out of focus. Unsure what may be the cause behind it. Example of images:



RB67 #2 - Mixed bag. Half were blurry and had 3 blank rolls in the middle of the roll. Only 1-2 were in focus and they were shot at a lower speed. These were the images:





What could be the issue behind both cameras? I'm a bit perplexed as it appears the lenses are clear and I've tested RB67s many times without issues, so unsure what happened here!
 

Donald Qualls

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Misfocus could be due to the mirror landing too high or low when the camera is cocked, or the ground glass in the viewfinder being raised (by something under it that shouldn't be there) or upside down (throws off the plane of focus by the thickness of the glass). Blank frames in the middle of the roll (on mine, a Pro-S with Pro film backs) could be due to dark slide interlock failure combined with forgetting to pull the dark slide, lens on T mode, or the body failing to fire the lens after firing the mirror.

I've only got and only handled one RB67 (love that camera -- just wish I could add a couple pounds of lightness); the experts will be along shortly to tell you all the ways I'm wrong and all the other things that could have caused these problems.
 

FotoD

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Looks a lot like camera movement (NW/SE direction). What tripod and head were you using?
 

Ian C

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The questions in post #1 require more information. We need to know: the focal length of the lens. The RB67 with a lens is heavy enough to require a steady tripod in many situations to obtain a crisp image. It would also be useful to know the film used and any filters you might have on the lens.

With a scene like that shown in photo #1, if it’s your intention to make the image reasonably well focused from near to far, then you’d get decent results with hyperfocal focusing. Depending on the focal length of the lens, the light intensity and film speed, that will likely require a relatively small aperture.
 

pbromaghin

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Are you using lenses known to be good, or ones that came with the camera? Pic 3 shows the most camera shake, but they all look a bit soft, even the in-focus area of the portrait, as if there is misalignment inside the lens. If the film and focus plains were out of agreement, somewhere other than where you intended, rather than nowhere, would be in focus and it would be most pronounced at closer distance.
 

Alex Benjamin

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Camera shake. You see it clearly when you enlarge the houses in the upper left of the third image.

A detail, but it doesn't help that most images are overexposed by 1 to 2 stops.
 

Mamiya_Repair

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What is happening here is that the shutter blades are not closing at the beginning of the shutter release cycle. This typically happens in the older non-C lenses but can be seen in later versions also. I have seen this caused by oily shutter blades or sticking mechanism due to an impact. You end up with a very slow shutter speed, maybe 1/10 of a second or so, that is why you have overexposure and blurry images.
 

Alex Benjamin

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This makes a lot of sense. Would explain why at a 1/400 shutter speed the motion of the waves isn't completely frozen, even though it should be. That had me confused, as it didn't fit with my feeling that it was motion blur from camera shake. At 1/10 of a second, you would indeed have motion blur from camera shake, unfrozen water movement, and overexposure.
 

Donald Qualls

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Andrew O'Neill said:
we still do not know if the OP used a tripod or not...
Click to expand...

A 1/400 it's not at all hard to hold an RB67 steady. At 1/10 it's not impossible (especially with a good strap and/or left side handle) but surely not easy and very unlikely to happen if you're expecting 1/400.
 
OP
OP

voightlandertroubles

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Thank you for the answers!
So the photos were taken handheld - similar like this shot earlier in the week and the metering/settings were identical as the image below. The lens is a Mamiya Sekor 127mm F/3.8 lens. They images above on the beach were also taken on Ektar 100 so it should've been sufficiently exposed according to my light meter.


 

flavio81

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Are you relying on the infinity stop? Or are you checking through the viewfinder, using the magnifier, confirming that the shots are correctly focused?

Is the focusing screen sitting fully?

Have you guys confimed the shutter is operating correctly? It is easy to test, just remove the rotating back (1 latch) and then fire the camera looking through the film gate.

I have never experienced such a problem with the RB67 cameras I owned, they always gave sharp pictures even handheld down to 1/30. It is a wonderful machine.
 

Alex Benjamin

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voightlandertroubles said:
The lens is a Mamiya Sekor 127mm F/3.8 lens.
Click to expand...

If you are using the same lens with two different cameras and ending up with the same problem, then strongest possibility is that it's a lens problem.

As I mentioned before, the photographs are obviously overexposed. If you metered right - and no doubt you did -, then, again, this points to the shutter blades opening for longer than what is set on the lens.
 
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voightlandertroubles

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I'm relying both on the infinity stop, and viewing through the magnifier to make sure it's fully in focus. I believe it is sitting correctly as well. My theory is the shutter blades are not closing at the beginning of the shutter release cycle. It would explain why it's overexposed and blurry if the shutter is sticky and slower than what it should be.
 

Alan Edward Klein

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As someone else mentioned, getting the same results using one lens on two camera bodies points to the lens. Buy another lens to try it out. 65mm or 50mm make good wide angle landscape lenses.
 

Sirius Glass

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chassis said:
Camera movement.

Do controlled experiments. Shoot a roll of test shots on a tripod with adequate light to use f/11 and 1/125.
Click to expand...


I too recommend controlled experiments with notes taken for each exposure. I often recommend CLAs, but first see if you can show that a CLA is not needed, and then if one is needed then you can be specific as possible about the problem.
 
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