8mm Forum: hell and bowell zoom lens

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Topic: hell and bowell zoom lens

Clyde Miles
Expert Film Handler

Posts: 205
From: Bromsgrove, UK
Registered: Nov 2013

posted April 27, 2014 07:04 AM

i have the black zoom lens f1.1.3 32-65mm that has suddenly started giving me out of focus pictures. everything was fine until recently, but now when i focus centre of picture sides are out of focus and vice versa. there is no fungus and lens is clean and scratch free. any ideas would be much appreciated.

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Dominique De Bast
Film God

Posts: 4486
From: Brussels, Belgium
Registered: Jun 2013

posted April 27, 2014 01:14 PM

I have the same problem with some projectors. The problem is not linked with the lens (it happens with different lenses on the same projector) but with the framer (if it is the correct word in English, I mean the piece of the gate that presses the film toward the lamp). It needs to be adjusted (something I never tried myself but that should not be difficult to do).

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Dominique

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Clyde Miles
Expert Film Handler

Posts: 205
From: Bromsgrove, UK
Registered: Nov 2013

posted April 27, 2014 02:06 PM

hi dom, thank you for the suggestion, but i tried this lens on all my other b&h and still the same problem. it just seemed to happen overnight.

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Dominique De Bast
Film God

Posts: 4486
From: Brussels, Belgium
Registered: Jun 2013

posted April 27, 2014 05:44 PM

Clyde, it may be a problem a never came across, yet. I hope other members will be able to help you.

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Dominique

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Marshall Crist
Master Film Handler

Posts: 300
From: San Pedro, CA USA
Registered: Oct 2008

posted April 28, 2014 10:33 PM

I seem to remember another thread where it was suggested that a slight adjustment to the tiny screw on the side of the lens would address the problem. I am experiencing a bit of this with my Hell & Bowell lens, but haven't mustered the courage to try fiddling with the screw.

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Clyde Miles
Expert Film Handler

Posts: 205
From: Bromsgrove, UK
Registered: Nov 2013

posted April 29, 2014 09:16 AM

where's this screw located, can't find one on mine.

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Marshall Crist
Master Film Handler

Posts: 300
From: San Pedro, CA USA
Registered: Oct 2008

posted April 29, 2014 08:49 PM

On mine it's on the side, about halfway down the length of the lens.

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Clyde Miles
Expert Film Handler

Posts: 205
From: Bromsgrove, UK
Registered: Nov 2013

posted April 30, 2014 03:25 PM

since starting this thread ive purchased another identical zoom and this projects perfect. i want to fix my original lens, as there just to good to throw away.

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Paul Mason
Jedi Master Film Handler

Posts: 540
From: Aldershot, Hampshire, UK
Registered: Nov 2013

posted May 06, 2014 03:24 AM

Clyde, From what you describe the loss of all over sharpness must be due to disturbance of internal lens components that provide correction of the aberrations. If there is an adjustment screw it may be behind the outer sleeve. Any adjustment should be done ideally with the lens in place and the projector running a film. Good luck.

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Paul.

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Clyde Miles
Expert Film Handler

Posts: 205
From: Bromsgrove, UK
Registered: Nov 2013

posted May 06, 2014 04:57 PM

thanks paul, but no screw anywhere on lens

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Paul Mason
Jedi Master Film Handler

Posts: 540
From: Aldershot, Hampshire, UK
Registered: Nov 2013

posted May 07, 2014 02:52 AM

It needs a specialist optical engineer to fix although reducing the effective aperture with an opaque disc with a hole in the middle in front of the lens might work but you lose light of course. Experimentation to find the best trade-off between overall sharpness and light loss would be needed.

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Paul.

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