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Cleaning bolex ground glass


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#1 Steven Budden

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Posted 26 July 2005 - 11:52 AM

Questions questions...

When I look through the viewfinder on my bolex there are some black specks, which I think are on the ground glass.

So I have two questions...

A. Where is the ground glass?

B. How to safely clean it?

Also, I can't get this accursed pressure plate off. You unscrew that screw at the bottom and it should just lift off? It seems still attached and I don't want to force anything.

Thanks!

Steven
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#2 Mike Lary

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Posted 26 July 2005 - 12:17 PM

Also, I can't get this accursed pressure plate off. You unscrew that screw at the bottom and it should just lift off? It seems still attached and I don't want to force anything.

<{POST_SNAPBACK}>

On my Bolex (Rex 0) I remove the pressure plate by unscrewing the bottom screw, then lifting the pin that locks the plate in position (at the top of the plate), swing the plate out, then lift the assembly by pulling on the screw head. If the plate isn't in the right position, the screw feels locked. You might have to jiggle the screw head gently while moving the plate to get a feel for when it releases.

When you put the plate back in, make sure it locks in place (the pin should hold it tight), otherwise you'll have problems when you start filming.

Edited by MikeL, 26 July 2005 - 12:17 PM.

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#3 Steven Budden

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Posted 26 July 2005 - 05:38 PM

Thanks, I'll mess with it more tonight. It says that in the manual too I'm just confused by it being stuck.

And can the ground glass be reached that way?

Steven
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#4 Mike Lary

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Posted 26 July 2005 - 07:04 PM

And can the ground glass be reached that way?

<{POST_SNAPBACK}>

Is your camera an RX? If so, you can rotate the turret all the way around and access the reflex glass - it swings out on a little hinge. I've only used an air can to clean mine, and never had a need to do more, but I might use the frayed edge of a torn lens tissue to try and remove specs that don't blow off. I have no idea whether or not water or other liquids would damage the glass.

If the dust isn't there, it might be in the reflex viewer (plenty of glass and mirror surface in there) or on the round glass on the top of the camera body that throws light up into the viewer. I had to do a thorough cleaning on mine when I got it. Disassembling the viewer isn't difficult, but it took awhile without instructions and there are several small screws to keep track of. Reassembly has to be precise. After giving it a good cleaning, it brightened things up a bit.

I hope that helps.
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#5 Chris Keth

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Posted 26 July 2005 - 10:10 PM

Is your camera an RX? If so, you can rotate the turret all the way around and access the reflex glass - it swings out on a little hinge. I've only used an air can to clean mine, and never had a need to do more, but I might use the frayed edge of a torn lens tissue to try and remove specs that don't blow off. I have no idea whether or not water or other liquids would damage the glass.

If the dust isn't there, it might be in the reflex viewer (plenty of glass and mirror surface in there) or on the round glass on the top of the camera body that throws light up into the viewer. I had to do a thorough cleaning on mine when I got it. Disassembling the viewer isn't difficult, but it took awhile without instructions and there are several small screws to keep track of. Reassembly has to be precise. After giving it a good cleaning, it brightened things up a bit.

I hope that helps.

<{POST_SNAPBACK}>



Good lens cleaner and tissue won't damage the glass if you're careful. Don't just use windex or anything like that as it will damage coatings.
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#6 Steven Budden

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Posted 26 July 2005 - 10:58 PM

Thanks. It is an SBM.

So the ground glass surface is just that surface under the shutter?

I got it converted to super and when I got it back there were little black specs in there, like shavings or something?

Steven
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#7 Mike Lary

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Posted 26 July 2005 - 11:52 PM

So the ground glass surface is just that surface under the shutter?

<{POST_SNAPBACK}>

I've never worked with an SBM, but the camera specs indicate that the ground glass is on the prism, just like the clockwork RX models. They didn't replace or modify the ground glass when they did the S16 conversion, did they?
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#8 Steven Budden

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Posted 27 July 2005 - 12:19 AM

No, and actually I have a new clue. It's fuzz, and it only shows up when I look through a lens... any lens. So I don't think it's on the ground glass right? It's seems to be perfectly in focus, the fuzz.

?

Steven

PS. I got the pressure plate off finally, thanks!
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#9 Mike Lary

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Posted 27 July 2005 - 12:54 AM

It's fuzz, and it only shows up when I look through a lens... any lens. So I don't think it's on the ground glass right? It's seems to be perfectly in focus, the fuzz.

<{POST_SNAPBACK}>

Wouldn't dust on the ground glass always be in focus because that's where the image resolves?
You might be able to identify junk on the reflex prism by:
removing the pressure plate, locking the shutter open, shining a flashlight beam through the gate from the inside of the camera, and looking into the front of the prism, then vary the angle of the beam so debris will cast little shadows.
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#10 Robert Skates

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Posted 27 July 2005 - 06:00 AM

The prism is often the source of dust as seen through the viewfinder. The viewfinder tube and internal glass also could use some attention. Dust seems to gather on the upper portion of the prism where it meets the viewfinder tube. You can check this by pulling the ground glass. If the dust still appears in finder, the prism and or viewfinder tube needs cleaning. The prism and viewfinder tube are easy to remove and clean.
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#11 Steven Budden

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Posted 27 July 2005 - 11:28 AM

Thanks...

Another thing I just learned from a reputable bolex guy...

Use scotch tape to pull dirt, etc off of the ground glass.

Steven
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#12 Ian Vatcher

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Posted 31 August 2005 - 07:59 AM

Hey guys,
Just something I read about the grain on the ground glass when focusing the diopter.
this was taken from a good Bolex tips site by Joel Schlemowitz.

http://homepage.news...rses/bolex.html  

The groundglass is etched with a field of grain, so when the grainy pattern is at its sharpest the diopter is set.


Now whether this grain can be removed, I am not sure.

I hope this is of some relevance to your question. ;)
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#13 Steven Budden

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Posted 02 September 2005 - 03:10 PM

Hey guys,
Just something I read about the grain on the ground glass when focusing the diopter.
this was taken from a good Bolex tips site by Joel Schlemowitz.

http://homepage.news...rses/bolex.html 
Now whether this grain can be removed, I am not sure.

I hope this is of some relevance to your question. ;)

<{POST_SNAPBACK}>


Thanks, I've figured it out since I asked that. The grain can't be removed. It is in fact how the image is projected on the glass... otherwise it would just shine through.

Steven
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