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DIY fix for Canon CN-E prime?

John Hoare
 
Edited

I have a Canon CN-E 24mm and the focus-marks on the lens are adrift by between 4mm and 10mm (ie depending on where the lens is focused, the rotation-distance on the barrel between actual sharp and marked sharp differs by between 4mm and 10mm).
 
Is DIY calibration an option, by simply loosening the screws around the focus-ring and rotating the focus-ring relative to the barrel?  Or am I being optimistic on how easy this is?!
 
Anyone tried this?
 
And if DIY is a bad idea, any recommendations on who/what/where (London)?
Thanks
 
--
John Hoare
Lighting Cameraman, London

Timur Civan
 

The collimation of the lens' mount may be off.  Or the mount itself. 

I would have a professional perform the service. 

On Wed, Oct 24, 2018 at 10:40 AM John Hoare <johnhoare65@...> wrote:

[Edited Message Follows]

I have a Canon CN-E 24mm and the focus-marks on the lens are adrift by between 4mm and 10mm (ie depending on where the lens is focused, the rotation-distance on the barrel between actual sharp and marked sharp differs by between 4mm and 10mm).
 
Is DIY calibration an option, by simply loosening the screws around the focus-ring and rotating the focus-ring relative to the barrel?  Or am I being optimistic on how easy this is?!
 
Anyone tried this?
 
And if DIY is a bad idea, any recommendations on who/what/where (London)?
Thanks
 
--
John Hoare
Lighting Cameraman, London

--
Timur Civan
Director of Photography 
www.timurcivan.com
917-589-4424

Matthew Duclos
 

Loosening the screws on the focus barrel will simply remove the focus sleeve. The proper adjustment should be made to the flange depth using appropriate shims.for London, I highly recommend TLS in Leicester. They'll be able to properly collimate. Also, best to check the camera first. If the camera Mount is out of alignment, even the most delicate, precise lens adjustments will be futile .
--
- Matthew Duclos
Lens Tech/Geek
Los Angeles, USA

Derek wiesehahn
 

Sounds like the lens back focus may be off and it will need to be re-shimmed. Having said that, if this is the only lens which is behaving this way on your camera body then its definitely the lens, but if the markings on other lenses are also not lining up then it may be the flange focal distance of the camera itself, in which case, the mount on the camera will need to be tightened and or shimmed.
If it is the lens back focus you can have it professionally collimated or buy a pack of shims from Canon and do it yourself using the trial and error method:

Put the lens on a camera, point it out the window at a distant object and focus. The infinity mark will likely not match up with the witness mark. Remove the mount and add (or subtract) shims as necessary until the infinity mark lines up correctly when the lens is focussed on a distant object. 

Derek Wiesehahn
DOP/NYC

On Oct 24, 2018, at 1:00 PM, Timur Civan <timurcivan@...> wrote:

The collimation of the lens' mount may be off.  Or the mount itself. 

I would have a professional perform the service. 

On Wed, Oct 24, 2018 at 10:40 AM John Hoare <johnhoare65@...> wrote:

[Edited Message Follows]

I have a Canon CN-E 24mm and the focus-marks on the lens are adrift by between 4mm and 10mm (ie depending on where the lens is focused, the rotation-distance on the barrel between actual sharp and marked sharp differs by between 4mm and 10mm).
 
Is DIY calibration an option, by simply loosening the screws around the focus-ring and rotating the focus-ring relative to the barrel?  Or am I being optimistic on how easy this is?!
 
Anyone tried this?
 
And if DIY is a bad idea, any recommendations on who/what/where (London)?
Thanks
 
--
John Hoare
Lighting Cameraman, London


--
Timur Civan
Director of Photography 
www.timurcivan.com
917-589-4424

Carlo
 

Canon has a cine lens service center nearby:

 

Canon Europe Ltd

3 The Square Stockley Park

Uxbridge Middlesex UB11 1ET

United Kingdom

 

--

Carlo Beltrano

Canon Canada Inc.

 

From: cml-glass@... [mailto:cml-glass@...] On Behalf Of John Hoare
Sent: October-24-18 8:39 AM
To: cml-glass@...
Subject: [cml-glass] DIY fix for Canon CN-E prime?

 

[Edited Message Follows]

I have a Canon CN-E 24mm and the focus-marks on the lens are adrift by between 4mm and 10mm (ie depending on where the lens is focused, the rotation-distance on the barrel between actual sharp and marked sharp differs by between 4mm and 10mm).

 

Is DIY calibration an option, by simply loosening the screws around the focus-ring and rotating the focus-ring relative to the barrel?  Or am I being optimistic on how easy this is?!

 

Anyone tried this?

 

And if DIY is a bad idea, any recommendations on who/what/where (London)?

Thanks

 

--

John Hoare
Lighting Cameraman, London

John Hoare
 

Thanks Timur!
John

John Hoare
 

Thank you Matthew!
John

John Hoare
 

Thank you Derek!
John

John Hoare
 
Edited

Thank you Carlo!

I am getting it looked at by Canon Broadcast in UK. 
The other Canon primes in the set are good, so I'm pretty sure it's the lens that's out.
Regards
John