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BOLEX EBM SUPER16 PROBLEM


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#1 Giorgio Taricco

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Posted 29 March 2012 - 11:30 AM

Hi all guys,
finally I have received my new super16 camera.
It's a Bolex EBM converted to super16 by Cameraspro.
The camera is an NOS from Bolex and it has been converted by Cameraspro (time ago) that also did a complete check and re-lubicate the camera.
The camera is in mint conditions, everything works as it should but...
looking in the viefinder I can see horrible spots on the left side and some spots all over the reflex prism.
I've try to clean the prism carefully without success, it seems that the spots are in the rear face of the prism or worst case, beteween the two glass.
The spots seems like the etched surface of the prism has been deteriorated,
Now my question is:
can be some type of glue applicated during the conversion?
How can I clean if it's possible?
The seller told me that he wasn't aware of the problem and that maybe during the shipping some grease of the shutter might got very thin so some grease drops on the prism.
To me this theory seems a non-sense... also because it cannot be cleaned up.
What do you think?
How much would be the price for a new prism or a repair job?
Thanks
Giorgio
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#2 Jean-Louis Seguin

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Posted 29 March 2012 - 03:41 PM

Hi Giorgio,

Your problem may be caused by the silver coating on the rhomboid prism being deteriorated. When the silver is no longer there, it reflects nothing and you see no light in those spots.

If this is the case, only replacement of the prism will remedy the problem. The rhomboid prism on the EBM is not accessible to the casual user.

Perhaps if you can post some close-up pictures, we can determine if this is in fact the case.

Cheers,
Jean-Louis
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#3 Giorgio Taricco

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Posted 30 March 2012 - 03:40 AM

Hi Jean-Louis,
thanks for your tip.
Could you please tell me in your opinion if this is the problem, how much I would spend to solve it?
Also, can you tell me where the rhomboid prism if located exactly?
Thanks
Giorgio
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#4 Chris Millar

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Posted 30 March 2012 - 04:06 AM

stealing Jean-Louis thunder...


its the prism that acts like a periscope from the top of your ground glass to the bottom of the finder assembly on top of your camera.


A bit of a mission with that model Posted Image
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#5 Giorgio Taricco

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Posted 30 March 2012 - 05:45 AM

Uhmm...more I look in the finder and more I'm disappointed.
Here just a couple of bad pics of what appears looking in the viewfinder.
That's a very good job.
what do you think seeing the pics?
Giorgio

Posted Image
Posted Image
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#6 Jean-Louis Seguin

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Posted 30 March 2012 - 07:46 AM

While I can't be 100% sure based only on the pictures, it certainly does look like the problem I mentioned: silver coating of the rhomboid prism is damaged.

I will PM you about repair options.

Cheers,
Jean-Louis
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#7 Chris Millar

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Posted 30 March 2012 - 02:47 PM

If it were the silvering on the mirrors on the periscope prism wouldn't it be slightly out of focus if you were focused on the GG ? Or, another way of putting it: f you can see the 'grain' of the ground glass in crisp focus at the same time as this wouldn't it be the ground glass surface itself ?

Remember, in either of those particular cases it wont affect your image on film.

If the EBM is like every other RX bolex out there you should be able to flip out the GG/prism and inspect it, it hinges on one side and has a small tab you can either get a finger nail around (or carefully use a toothpick or similar if your fingers are clumsy). Dont worry, it'll flip right back into proper reference again as its spring loaded with properly adjusted stop (youd hope!).

With a bit of wrangling you might be able to have a restricted look at the bottom side of the periscope (rhomboid) prism also. Get a bright bright flashlight in there, try illuminating it from the eyepiece to backlight it and so on...
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#8 Giorgio Taricco

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Posted 31 March 2012 - 04:36 AM

I'm trying to understand in which case a spot in the viewfinder on a Bolex EBM will affect the film image.
I've found a lot of infos on the web and they are all controversial.
So, if the spots are on the reflex prism, will my film be affected?
If the spots are due to the silver coating of the rhomboid prism, will the film be affected?
Please, take a look at the pics below, there is something strange in your opinion...?
Thanks
Giorgio

Posted Image
Posted Image
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#9 Chris Millar

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Posted 31 March 2012 - 05:15 AM

So, if the spots are on the reflex prism, will my film be affected?


It depends - if they are on the top (the ground glass) - then no ... If they are on the front or rear surfaces or inside the prism, then yes - if they are on the rear then you wont see them in the finder so you can rule that one out anyway.

If the spots are due to the silver coating of the rhomboid prism, will the film be affected?

No, the rhomboid prism is specific to the optics required to get an enlarged finder view of the image rear projected on to the ground glass. The image going to film doesn't go via this route at all.


Its hard to tell from those images if there is anything wrong - there certainly is some spots on the prism, but I know from experience that perfectly fine prisms under harsh flash light will look like this (I photographed one last year and all sorts of crap that wasn't really there turned up). What we really need to see is the top of the prism where the ground glass is ...

hang on.. what is that - what looks like bare metal offcut doing there ??

If you were to mill/machine/file out the prism area for an unobstructed super16 view you might do a bad job and leave a rough edge in there that could (still) obstruct the ground glass - you might even leave a few spots of swarf on the ground glass while you're at it. Maybe its just a glint of light that makes me think I'm seeing this. Closer up views of the area around the top of the prism will help us, (looking up and down) - prism swung out.
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#10 Chris Millar

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Posted 31 March 2012 - 05:22 AM

I remember now ...

A way to determine if a smudge is before or after the air gap in between the ground glass and periscope prism is to put something in there and see if the smudge falls behind the object or stays in front. Try that toothpick again or a twisted bit of paper (something soft), put it in the area above the prism and move it about looking in the finder, you'll soon spot it - you might need to illuminate it to be sure - but if the paper sits on top of the smudge you know its in the groundglass prism.
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#11 Giorgio Taricco

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Posted 31 March 2012 - 05:58 AM

I was asking if you see something strange in the pics as for what I know there is a missing part on the prism assembly...
It seems that the field lens was removed during the Super 16 conversion...
is it a normal procedure?
I have not contacted Cameraspro as I don't know how many years ago the conversion has been made and in any case being in Italy any possible repair job would be expensive due to double shipping cost.
I'm just interested to know what the fault is and how to solve the problem.
The seller sent me some enlarged shot of a film shooted with this camera and thay looks superb... yes but what's happen between the shot and the postage to me..?
Giorgio
PS: forgot to mention an important detail:
when I focus the groun glass with the finder diopter adjustment I can focus exactly the spots in the same way.
when the GG is out of focus the spots are also out of focus, so I think they are definitely on the GG?

Edited by Giorgio Taricco, 31 March 2012 - 06:01 AM.

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#12 Giorgio Taricco

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Posted 31 March 2012 - 06:11 AM

Here some pics of the upper part.
Posted Image
Posted Image
:blink:
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#13 Jean-Louis Seguin

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Posted 31 March 2012 - 09:56 AM

Yes, there is a missing part on top of the prism assembly: the grounglass mask!
In a regular 16mm camera, there is a groundglass mask with a condenser lens sitting on top to magnify the image a little.
In a super-16 conversion, it is normal to remove the condenser lens but the groundglass mask must be enlarged to the super-16 area and re-installed or alternately simply make a new groundglass mask to the proper super16 dimensions.
The reason that the condenser lens has to be removed is that it enlarges the expanded groundglass image too much for the viewfinder optics.
Consider that he original groundglass mask measures roughly 9.3mm x 7mm and the enlarged mask should be 12.5mm x 7mm (for a 16:9 ratio).
I suspect whoever did the conversion is relying solely on the secondary light baffle in the viewfinder optics to provide some framing references. Not the preferred way to go.
And the presence of the "bare metal offcut" is not normal either. Evidence of sloppy work.

Cheers,
Jean-Louis

Edited by Jean-Louis Seguin, 31 March 2012 - 09:57 AM.

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#14 Giorgio Taricco

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Posted 31 March 2012 - 12:42 PM

Thanks guys, thanks Jean Louis.
Not happy at all to read your answers about poor quality job and missing part..
I have contacted the seller to tell him about all the faults of the camera and to have the camera repaired or a full refund.
I must admit that he is a very good and honest guy to me but I can't believe he was not aware of the pronblems.
I will see, anyway if he will refuse to repair the camera at his expense I will get my money back and I will try to find an Arri 16Bl, I really don't like the dark vision of the Bolex, I'd like to have a much brighter finder to shoot in poor light situation and this camera is not what was I'm looking for.
Thanks
Giorgio
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#15 Jean-Louis Seguin

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Posted 31 March 2012 - 02:47 PM

The Arri 16BL is a fine camera but not a good candidate for super-16 conversion.
The only place willing to do it is Aranda in Australia and I remember seeing that the price for a conversion is around $5000.

Cheers,
Jean-Louis
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#16 Chris Millar

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Posted 31 March 2012 - 05:04 PM

I have done my own conversions to super16 of an EL and and SB - both bayonet systems as your EBM is also.

I got my own new ground glass masks laser cut by a custom gobo manufacturer to the exact (enough) specs of the super16 frame - the tricky part is to install it ;)

Still interested to see a picture of the top of the prism looking down at it (i.e. at the ground glass) - that'll confirm what is going on up there.

Edited by Chris Millar, 31 March 2012 - 05:04 PM.

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#17 Giorgio Taricco

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Posted 31 March 2012 - 06:39 PM

HI JEAN lOUIS,
I KNOW THAT THE ARRI 16 bl IS NOT A GOOD CANDIDATE FOR A SUPER16 CONVERSION BUT IT LIKE ME VERY MUCH, I WILL SEE.
THE OTHER WAY TO GO IS TO BUY A 35MM CAMERA BECAUSE I ALWAYS LIKE THE TECHNISCOPE 2 PERFORATION SYSTEM AND I'M VERY TEMPTED. NOT TOO MUCH READING ABOUT THAT SO DO YOU KNOW GUYS IF THE ARRI IIC IS A EASY CAMERA TO CONVERT TO 2 PERFORATION OR NOT?
WHAT'S ABOUT THE KONVAS 1M AND 2M CAMERAS?
GIORGIO

Edited by Giorgio Taricco, 31 March 2012 - 06:39 PM.

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#18 Guy Danieli

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Posted 01 April 2012 - 08:40 PM

Giorgio

Donot try to remove the front prism! You will never be able to put it back in the right position without the Bolex colimator

Guy
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#19 Guy Danieli

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Posted 01 April 2012 - 08:50 PM

Giorgio

You said that the camera was never used and on the board, you said that the film looks great. I do not understand. I do not remember the camera, but it's possible. We made so many conversions!

If you find a prism. You have to remove the front of the camera and remove the little plate on the top and you will see the top prism. You have to remove the viewfinder . Change the prism and put the new one in the right position ,put back the front and the viewfinder. That's it. After that, you have to re-seal the camera and adjust the claw, film frame etc... or your film will lose the loop .

Guy
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#20 Chris Millar

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Posted 01 April 2012 - 10:05 PM

Without the benefit of inspection I'm still not convinced it is either prism. It could be, but it could also be the ground glass or something else in that area also.

Are you talking about getting the pull down out of sync with the shutter ?? Or are you talking about getting the two driving cogs out of phase and having a too small or too large loop ?? In either case why does removing the front of the camera necessitate breaking the internal seals and dealing with the film transport ?



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