Dirty spot in Bolex Reflex Viewfinder

[Lauri Sundberg]

Greetings.

I have noticed a small black spot in the viewfinder of my Bolex h16 Reflex and have a hard time locating it even after opening the viewfinder.

What I was wondering is whether this is just a cosmetic problem or if it will show up in the film.

 

Any help is much appreciated.

 

-Lauri

[John Holland]

I expect its dust or dirt on the prism and wont show on the film .

[Guest Glenn Brady]

The turret can be rotated and the prism, which is hinged, exposed for cleaning. Dirt visible in the viewfinder is usually found on top of the prism, not in the viewfinder tube.

[Dom Jaeger]

In my experience, visible specks in the viewfinder are usually either on the groundglass at the top of the prism (accessible when you rotate the turret and swing out the prism), on the optics just above the groundglass (harder to reach) or in the eyepiece.

 

By swinging out the prism while looking through the viewfinder you can see if it's on the groundglass. To clean it, try blowing it with a puffer or compressed air before resorting to lens tissue and isopropyl alcohol. The surface is very easily damaged, so avoid rubbing it - if a single swipe doesn't work , probably best to leave it.

 

By adjusting the eyepiece diopter you can see if it is in the eyepiece optics (the speck will rotate).

 

It won't affect the film, so you could just live with it. The only optical surfaces that really need to be clean are the front and rear lens elements, and the front and rear surfaces of the prism, none of which will be in sharp focus through the viewfinder.

[Chris Millar]

Best way to know if its on the ground glass (most likely) is that it'll (mostly) be in focus when the grain of the ground glass is in focus also.

 

Its more unlikely but possible for crap to get into the periscope prism too, but it should be blurry and can be proved via the methods Dom points out. Worst case is fungal etching, which even when cleaned will leave an area of less defined image in your finder...

 

Any crap o damage In all cases but the front and rear faces of the prism will have no affect on your captured footage - luckily enough those too faces are the easiest to examine

[Lauri Sundberg]

Thanks for all the advice people.

 

It seems that the dirt is in the groundglass.

I think I will just run with it for a couple of days and shooting and than try to get around to properly clean it off.

The most important news for me is that it does not affect the pictures, as I have already shot some footage with it.

 

Have a good weekend everyone.