Cloudy Lens & Focusing Problems Pentax 67

[joburger63]

Hi Guys,

As mentioned on a previous thread, I am running through the testing of a Pentax 67 II system. I've noticed two issues which are concerning. The first is a cloudy, foggy lack of clarity looking through the camera's view finder.
Is this a common problem when using older equipment? If any other forum members have experienced this problem, how did you resolve it?

The second issue I've had is difficulty of focusing. The centre circle and the outside area is difficult to get into a sharp focus with any degree of confidence. Does this indicate that the system needs an overhaul? Are other focusing screens available i.e. split screen for this system?
Any advice forum members can offer will be gratefully received.
Thanks,
Chris

 

[Joachim_I]

The viewfinder can be easily removed for cleaning. But I am sure you already did that. The eyepiece also can be removed for cleaning. I am not aware of any fogging problems. The P67II is not that old.

Regarding focusing, there is a bunch of interchangable focusing screens including some with split screen and/or cross lines. They are described in the manual (which you can easily find on the net).

 

[joburger63]

Thanks again Joachim. I haven't tried anyhing you have mentioned in the thread, so very useful indeed! Thanks again.

 

[Ian C]

Atmospheric Hazing

What you’re seeing is atmospheric hazing—the gummy accumulation of condensed junk from cooking, heating, fireplaces, smoking, candles, aerosols, drying paint, adhesives, air pollution, dirt, dust, and possibly fungus in the air onto the optical surfaces. It’s exactly what happens to the windows inside a home or an automobile.

The Pentax 6x7 is just a big SLR. The surfaces involved are: the exposed surfaces of the lens assembly (including the surfaces exposed to the air inside the lens, which isn’t air-tight), the surface of the reflex mirror (don’t attempt to clean the mirror or you’ll ruin it), the focusing screen, the condenser lens directly above the focusing screen, the clear bottom and rear surfaces of the pentaprism, and the eyepiece lenses. See the diagram on this page:

http://en.wikipedia.org/wiki/Single-lens_reflex_camera
Much of the hazy deposit is carried by moisture in the air. While you can access and clean some of these surfaces, disassembling all of this for a proper cleaning is a delicate job and should only be attempted by someone with the correct tools and experience.

Reflex mirrors are front-surface mirrors that have a very soft aluminum reflecting surface that can’t be cleaned without ruining the mirror. It can only be replaced by an experienced technician—provided that the replacement mirror is available.

It’s much easier to prevent hazing in the first place by keeping the gear stored in sealed multiple layers of vapor-proof plastic bagging along with a freshly-charged silica gel desiccant pack of sufficient size to keep the air surrounding the equipment dry.

The haziness you asked about is common in used equipment that hasn’t been stored in a dry, sealed mini-environment as described above.

 

[benjiboy]

In addition to the previous posters remarks, this is a job for a professional, if lenses are dismantled they need to be re- collimated on an optical table to ensure the lens element line up to a central datum line, and are all parallel to each other on an optical table http://en.wikipedia.org/wiki/Optical_table to ensure that the optic performs to the manufacturers specification.

 

[mtjade2007]

Is your diopter properly adjusted? It is not that straight forward in adjusting thew diopter. If properly adjusted the AE prism is very easy to focus.